General mechanical questions

[Joe Cannarozzi]

First of all I,m really disapointed with a lot of things Ive learned about this 8v92t. For discussion sake lets set the baseline for NORMAL oil consumption at say a gallon every2500 and that none of that is from leaky gaskets. Mine is less than that just slightly but almost all of it is comming from the air box down tubes and it really makes a mess of the front of my toad ,especially,and every thing else as well. The local detroit deisel guys have ordererd me some catch system or reservoir with will have to be drained. That seemed to me to be a pretty basic solution. Mabye something that i could fashion myself pretty easily? Also this motor is 210000 and theres paperwork that detroit deisel already redid it at 117000. PITTIFULL. It is my conclusion that oil consumption is directly related to performance and reliability and for this horse I believe thet when it goes to 1 gal everyyyyy, I Dont know? Where is that point/ Have I already reached it? Ive many many more questions Ill stop here.

[Jon Wehrenberg]

Joe,

Contrary to the BS you will hear around the truck barn, an 8V92 should not drip or leak oil from anywhere, including the breathers. If it is you are seeing some evidence of ring wear, which should also be reflected in oil consumption. Your usage of a gallon in 2500 miles suggest the engine is not worn out yet.

I put about 250,000 on mine in the previous bus and it started out covering my engine rear doors after every trip. I kept the engine clean and could not find oil coming from anywhere and assumed the breathers were the source. So I hung some oil cans on two of them, and I extended the other two (I think there are four, but correct me if I'm wrong) so they would drip or spray beyond the rear of the coach.

Same old, same old. The doors kept getting a film on them and the Jeep had the same film. Others on this forum may call me anal, but the reality is I like a clean engine. It finally occurred to me what was happening and it turned out to be a fuel line fitting near the water pump, almost out of sight that was the source of the mist. All my oil consumption was just that. It had no leakage. The engine by its very nature tends to use oil as you are seeing.

I took the cans and extenders off the breather tube and from that point on the engine never leaked or dripped anything.

As far as life expectancy mine was treated to 5000 mile oil changes. I consider our motorhome usage severe duty so I changed oil and all filters at 5000 miles and when I ended up with a crack that ran between two of the valves in one of the heads we rebuilt the engine. Had I know that was the problem and not something more sinister that was dumping coolant into the cylinder we would have replaced the head and kept on driving. The engine was as clean inside as it was outside.

You must use straight 40 weight oil. I'm sure you use 15W40 in your Cat and that will not be good for your 8V92.

The 8V92 is a sweet engine, reliable and has a nice sound. It gets lousy mileage, but is generally a good engine for the Prevost. Not as good as the Series 60, but still a good engine.

[Joe Cannarozzi]

Let me see if I understand. What was comming out of your air boxes was not oil but actually fuel? I have no shortage on power, took a 2000 mile trip with 7000lb. in tow at70 and 75 and experianced verry little downshifting. I guess what I,m asking is will power fade before reliability? I,m OK with this senerio I,ll run it till it begins to get noticably tired and make sure the oil is fresh and full, and not worry about it. I Like a clean engine also ,this is not anal.Also my jake and idle kick are inop. Im pretty sure its electrical not a mechanical problem but I dont know where to go. I,ve got service manuals from prevo and also all the builders manuals as well. Is the dash 12 volt or 24 w if its 12 where does it step down, and what of all these clear plastic plug in relays used all over by the converter and prevo both? Are they all alike ,they look it, I,m thinking I should have some spares. I,m using strait 30 ,is strait 40 noticably better or its just 10 thicker so why not?

[Just Plain Jeff]

I think 8v92 engines have generally gotten a bad rap.

Having run 3 coaches with them, I can say this much; the key here is preventive MAINTENANCE. The engine is better balanced than a Series 60 and at most highway speeds it performs exactly the same.

Here are the problems I had with mine:

1. The Angola ate about 1 quart of oil per 1K miles (actually a little less). At 130K miles I replaced the original hoses (not the engine's fault). But at about 150K on a Prevost coach, if you have a DN 50 generator (OTR only) you will probably have to replace it. It is a big job, and usually done from the bedroom. That sucker is about 750 lbs and usually the main bearing goes. It is a 3-phase 24V generator, running off the same oil supply as the engine, driven off the camshaft. It is one of those deals where the longer it is running badly the worse things can get.

2. There are people who say, "The 8V92 has slobber tubes for a reason." They are right. It means that the engine isn't being properly maintained and I can show you some people who have all kinds of blobs in their driveway. I have some in my driveway from the previous owner who had a BB and knew better, but let them barf out instead of getting into the engine.

3. There is a distinction here, and it is a fine one: Actually the 8V92 runs at lower heat dissipation in a bus than the Series 60. The Series 60 has much more mass, therefore it seems to be running hotter. In other words, the 8V92 runs hotter, but because the 60 is so much larger it requires more cooling.

4. I like silver better than green, so I may use chrome paint on my engine to venerate the memory of the great 8V92.

5. You will hear a lot of trash talk about the 8V, mostly as a result of people who paid through the nose for a Series 60. Much of this results from the salespeople who got people to fork over big cash for the new engine transmission combo. Either that or they need to have the low-end kick that a 60 gives. POG IV will be on the Bonneville Salt flats, so we will have to see about that.

6. People are running into all kinds of tweaky problems with 8V92s now and that has tarnished their reputation. No kidding, the engine has been replaced now for about 12 years by the 60, and many of these engines haven't been properly maintained (see above). Any engine, and I don't care what it is, that hasn't been maintained for 12 or more years is going to have problems.

7. Be sure to keep your straight weight oil with you; it is the specified weight for the engine. I used 30 weight because I felt my intermittent use of the engine and complete lack of any mechanical knowledge, or knowledge in general, would lead me to read the instruction manual and do what the manufacturer said.

8. The 8V92 is pretty easy to get out of a bus, that's part of the reason you have a 3-part back bumper, but there are a whole lot of things that you can do to prevent that event from occurring with good maintenance, check your SCAs, keep it clean, fix when necessary and run ahead of problems not behind them.

Other than that I am going to stop typing now.

[Joe Cannarozzi]

I Have this alternator you describe. It works well no visible leaks or odd sounds. Our bus has a rear gally and bath so its very easy to access for now.I had it open for a couple of weeks cleaning fixing things. So back to my original question For sure the previous owner neglected it, evedent by what I paid and the condition when I got it. So if its using some oil but I take care of it from here on out, these catch cans will stop the MESS. Its got all the pull I need and for the next few years it probably wont go but 8 or 10 k a year.

[Just Plain Jeff]

No one can answer your question completely.

Probably the first thing to do is try to clean the engine compartment thoroughly and monitor for any spots, leaks and so on.

If you bought the coach right, you may be able to stay ahead of major issues.

Stay with us here and if you run into snags along the way, we'll try to get you the best info we can!

[dalej]

We use mobil 1640 its a straight 40 weight oil. We have very little oil use. One time a oil salesman said to use Rotella T 15-40, big mistake, burnt more oil then diesel. Used it for a trip to Florida, changed the oil back to 40 weight when we got home.

We have a can on the back of our engine to collect oil out of the drip tubes but hardly have any oil in it. You can get them at DD parts.

We recently had a tune up at DD in Omaha and the 8v guy said that someone put aftermarket injectors in and they wern't vaporizing diesel like they should. He put Detroit parts back in adjusted the rack and it runs great. It doesn't take a mile to pass a car now. Since we bought the bus used didn't have anything to compare it to before.

I really like the 8v, maybe its because I would have to spend 150,000 to try a 60. I have a friend that bought a 96 liberty down in Fl. so may he will let me drive his and try it out.

[Jon Wehrenberg]

Joe, I may not have been clear. The breathers that were perceived as the problem were not. The real problem on my old coach was a very minute fuel leak. The breathers were not the issue at all.

The point I wanted to make was if you are presistent you can get the 8V92 to be a dry engine. Mine was.

[Joe Cannarozzi]

Thank you all for your comments I will cotinue to persevere.

[Ray Davis]

My coach is fairly new to me, so I can't speak with a whole lot of experience, but in trip so far running about 1000 miles, I've checked the oil many times, and it doesn't appear to be down at all! This is a 92 vintage 8v92.

I am running straight 40wt as suggested. No apparent leaks, and no indication of burning oil.

I've got other problems, but that's a different thread! :D

[Jon Wehrenberg]

Ray,

If the oil level in your 8V92 is not going down be afraid. Very afraid.

For your sake I hope you have one of the rare engines that doesn't use any oil, but usually a lack of oil consumption indicates fuel may be leaking from the injector feed line into the crankcase.

Pull your dipstick and sniff the oil on the end for the smell of diesel fuel. If you find any smell of diesel fuel get that leak resolved as quickly as possible. It is easy to get at it just by removing the valve covers.

When the oil level rises you KNOW you have a problem.

[ken&ellen]

Jon, My 1991 Liberty uses very little oil and my Jake works great. Our trip to Daytona and then back again to the POG rally required little over a quart added. I took your advise and checked the dip stick....no diesel smell. The only dip stick problem is behind the wheel.:D I figured I would take the shot before JDUB does. Ken

[Jon Wehrenberg]

Ken,

That is good. An 8V92 rarely uses NO oil. This stuff is worse than planes. When we fly them we always know something will break, quit or lie to us. When we drive a bus our brain goes into relax mode because how much can wrong, right?

Ray, don't worry unnecessarily but always be vigilant. These things are generally very reliable and the more we know the more we are capable of keeping them reliable by heading off issues.

[Joe Cannarozzi]

Has anyone ever taken apart an air dryer to rebuild and found no, and I mean not even a single silicon bead. The first time I drained the air tanks if I knew that there was that much water in them before hand I would have caught it to measure because I believe the lower rear tank was completely full! This prompted me to service the dryer and Ive never encountered this before, completely GONE, no pellets. Im sure nobody ever touched it before I and it wouldnt supprise me if the tanks were never drained either. Nice hu.

[Jon Wehrenberg]

Joe,

I think you have just hit on one of the biggest reasons why POG is going to gel. Jerry did a great job of talking about maintenance and pointing out the dire consequences of not dealing with the myriad issues that need attention at POG I.

Very few owners appreciate or understand what it takes to keep the bus reliable and safe and I can say prior to doing the work myself I was among them. As a trucker come to POG and put on a seminar.

Jon

[ken&ellen]

Jon, When I owned my Mooney I was either flying or preparing 89Mike for her next trip. Some of that diligence was lost driving cars and trucks over the last few years. POG has gotten me back in the PM mode. Just yesterday I noticed a higher than normal temp on my genset coolant. A little cleaning, flushing, and refilling the fluid I am back in the normal range. Ken

[Joe Cannarozzi]

Jon one of the many things that was damaged by moisture was the pnewmatic belt tensioner for the fan .There is a different one for the a/c ,it has a threaded end where the ram comes through. The one I,m working on has c-clips holding the top and bottom on. The clip has spun in the end cap and I cant seem to get it back to where you can put the tool in the holes top squeese it. The rebuild kit was about 15 bucks and I think the whole thing is 300something. Also is there any reason other than convience that I even replace it? I put a LARGE turnbuckle in its place and it seems o/k? The only reason I can think of is that because of the exessive length of the belt, just like the tires, the belt tension is greatly affected by ambiant temp. and it will be looser when hot than cold, although this hasent proved to be the case when tested and checked after I put the turnbuckle on.

[Jon Wehrenberg]

Joe,

There is no down side to what you did except on a dark rainy night if a belt fails it is nice to reach up, turn a valve and have the cylinders retract so you can change the belt, turn the valve after the belt is on and away you go.

All non bus air coaches of your vintage came with mechanical tensioners instead of the air cylinder tensioners so your set up is not unusual.

Jon

[Ray Davis]

Jon,

I checked the dipstick tonight, no smell of diesel. The dipstick may have gone down a bit, it was pretty full when I started, and now it's running 1/2 way between the full and empty, but the engine hasn't run in about a day, so it's kinda hard to compare since I was checking after driving and getting fuel.

Oil was very black, however, not like new oil. I've probably put 1000 miles on since the oil change at Prevost

[Jon Wehrenberg]

I'm glad because it sounds like you do use a little oil, and espcially glad no diesel smell. The black is kind of normal. I changed mine every 5000 miles (filters too) and it was dark. The Series 60 still looks fairly clean so I think the 8V92 just tends to make the oil a little dirty.

[dalej]

Jon, I check my transmission fluid according to your writings on trans fluid changing. ( I didn’t loosen the check plug and start the bus and check the level like you said to do, do you think I should?) don't know if you seen I had a hose from the filter get a hole from rubbing on the transmission. It took 4 qts. Thanks for the info.

Question....What does the little canister that holds trans. fluid do? It has a full/add on the dip stick. (its by the anti-freeze holding tank)

[Jon Wehrenberg]

The little cannister is your power steering reservoir.

If you are embarking on a program to zero out all of your maintenance so you know exactly where you are, there is a filter inside that reservoir. It needs to be serviced, but it is low on the list of things to do because there are other serious maintenance items I suggest everybody tackle first.

The easy way to check the transmission fluid level is with the stick, cold as in first thing in the morning, or at full operating temperature after being driven. The only problem with the dip stick is if the fluid is clean it is very difficult to see and have confidence in the reading. I end up reading it about five times before I am confident it is where it needs to be.

If you (Like me) have a hard time gaining confidence the fluid level is correct, and you can reach under to the side of the transmission that is the accurate way to check but only when cold.

Just in case there is any question this procedure is for the five speed Allison only. The Allison world transmission (six speed) has the fluid level readout on the gear selector pad.

[dalej]

Is there a great engine/trans spray on cleaner that can be washed off with water? I'm starting to plan for oct. and want a trial run on coach WOW! Don't know if I should just start sandblasting and painting the engine compartment. How much inspecting do other Previes do? Maybe I should just back out of POG rally II since my anxiety level starts to climb when I think about others (Jon) inspecting the inner most parts of a coach, kinda of like a prostrate exam.:( Now about the cleaner, any ideas!

[Jon Wehrenberg]

Forget about those clowns that pick on me. I only clean the inside of my air cleaner housing once a year.

All kidding aside, I have successfully used Simple Green, Krud Kutter, and mineral spirits. Typically if the engine grease and dirt is heavy, hard, and "baked" on I mix solvent such as mineral spirits with Simple Green and brush it in vigorously. The only precautions I recommend is to not spray water or engine cleaner directly on the DDEC controller or the electrical connections.

A clean engine will not only get you the anal award, but it helps you identify and fix minor leaks before they become serious issues.

I have never used a power washer on my engine or transmission, although I know the techs at Prevost have a steam Jenny that they use. Avoid any strong spray or chemicals on your radiator. The fins are extremely fragile.

I always dry my engine and engine compartment after washing. (Water spots:D ) Actually drying it minimizes corrosion because with the washing fluids any oil that might have prevented corrosion is now gone.

You ask how much inspection we do? I can't speak for anybody else, but I get under the coach every 5000 miles to change oil and lube it and I do a very detailed inspection at that time. I look for any hoses or wires rubbing, I check for leaks, (air, coolant, fuel, oil, etc.), I examine all brake pad or shoe thicknesses, and generally verify everything is in order. If you rely on someone else to do your routine service they should be told to do the same level of detailed inspection. It doesn't take more than an hour to be assured that things are as they should be.

In the engine compartment I give that an inspection to the same extent at the same time. Again, I look for rubbing or chafing wires and hoses, I look for leaks, listen for air leaks, and verify all fluid levels and belts are OK. When travelling I check coolant and oil levels daily. I check transmission levels prior to every trip, along with tire pressures which I REALLY want to be right.

If you have a clean engine (painting it to match your coach is optional) you will note any drips or leaks. I examine the spot where I was parked and verify there is no wet spots on the ground.

If you come to POG II I think it would be worthwhile for all of us to walk around a couple of coaches and do an inspection, not to embarass the owner but to show how and what can be checked. There is nothing more frustrating than needing repair on the road, when they could have been found and corrected at the home base.

[Just Plain Jeff]

When Jon was selling Avon products, he used to endorse those.

A guy will do darn-near anything to make his bus payments.

http://www.the-village.co.uk/buildings/image/mainstream.jpg

[dalej]

Jon, if I make a liter of spray what is the ratio? 500ml of mineral spirits 500ml of simple green? Do I add water? can you let me know, I'm going to try it.

[dalej]

Jon, so does the power steering use Dextron II too? that is what it says on the little canister that I mentioned.

[Kevin Erion]

Jon,
On my way down from West Yellowstone to Zion, Utah I saw some engine temps in the middle between the 195-220 on the gauge on the dash. When I look in the engine bay I always see a diffrent temp on that gauge, a little higher I'm afraid. How do we know what to believe. I know that I have to just get the base line of what the normal position on the gauge is but it would be nice to know what the engine temp really is.

I have an infared hand held temp gauge and I read the tire temps when I stop, 145 today when the road temp was 135, I thought that was not so bad. 205 to 210 on the rear end housing, again I think within the OK range. I see that on the gauges that come on the semi's that I have driven.

I also try to do the same with the engine, chassis inspection every time I change the oil and filters. I look forward to POG II and do a little exchange of stories, I am afraid I am on the fast learning curve due to only having our Marathon for just 1 year.

Thanks for all the great info, As I write this we are at Zion River RV Park in Virgin Utah sucking the power out of the pole. They asked if I would take my floor mat of the grass and I ask for 120 volts on each side instead of 113. They said that was the power companys problem, not the parks. OK, the place is very nice and the kids love the small river just outside the door, but I don't buy the power issue, they should have spent a little more to make sure when it is hot out that we have the power we are paying for!
Kevin

[Jon Wehrenberg]

Dale,

Do not add water. I usually scrape the heavy stuff off first. If there is still a fairly heavy coating of crud then I mix about 50/50 and brush vigorously into the grease and dirt. Sometimes I have to do that repeatedly until I get the grease all loosened and dissolved. Then I hose it off. That is the only water I use.

Once the engine is clean, then all I need to remove any oil film or light accumulation is to spray it with Simple Green or Crud Cutter or even 409. Let it set to work a little and then hose it off.

The power steering reservoir takes whatever fluid is specified. Dextron II sounds right. There should be a label on the rear doors that lists that kind of information (I'm shooting from the lip on that last comment, but I think the specs for all fluids such as engine oil etc. are listed somewhere back there.)

Jon

[Jon Wehrenberg]

Kevin,

I don't remember what year your coach is or what engine. A Series 60 will typically read around 195, and depending on ambient and hills will climb to a gauge reading of 205, and maybe 210 if it is really working like pulling a heavy load up a long grade in hot outside temperatures. If the thermostatic clutch is working right it will kick in a 204 on the low speed setting and if temps increase to 208 the second speed should kick in. If you are consistently running higher than that you might try locking the fan. I tend to trust the dash gauges.

If you have the 8V92, same conditions as above, I would expect to see the guage hit 205 or thereabouts, with the normal reading around 180.

What I question is if the temperatures are getting excessive why DDEC is not giving you a warning light. Typically if the DDEC sees excessive temps it will start to warn you and take away power to protect the engine. Less power obviously means less heat to dissipate.

Seeing low shore power is frustrating. We dealt with that in Polk City at POGI. Theoretically the power delivered to your coach should be a nominal 120, with an acceptable low of 110 or thereabouts. All of our on board equipment can handle that but with the lower voltage comes higher amp draw from our loads. Over the years we learned if the problem is campground wide and not site specific, we just have to manage our loads. When low votage occurs your AC units may shut down if it gets to 105 or somewhere around that voltage, so to minimize that possibility we leave stuff like the hot water heater off during the day. I have my inverters set for the lowest charge rate also so they draw a minimum. There is not much else we can do because we need the refrigerator, lights, and a few other essentials.

[MangoMike]

Kevin,

Jon's right about POG #1. All my Cruise Airs stopped working when the voltage got about 106 or lower and their control panels starting flashing LO (I believe this was the code). We just gave up and started running the Genset during the day to keep the coach cool and Mrs. Mango happy.

Have fun on the road.

Mike

[MangoMike]

Kevin,

On the way down to Myrtle Beach last Thanksgiving we started seeing the engine temp rise. To the point that the check engine light came on and we had to pull over. I stopped at a truck stop and we checked the belts, they thought it might be the thermostat or perhaps the DDEC controls but basically no answer. So I did what everyone does when they have a problem - I called Jon.

Turns out it was the electric clutch on the engine fan. You don't notice its not working when you're idling as it usually doesn't kick in. But it makes a huge difference when you're cruising down the road and it doesn't work. You can mechanically engage it with a bolt located right on the fan blade and it's on at all times. In fact mine is still engaged as Prevost wants $800 for the new electic clutch. Working great, although I'm probably waisting some power and lower speeds as the fan is always on.

Hope this helps.
Mike

[Jerry Winchester]

Kevin,

Having just run that route from West Yellowstone to Las Vegas, I can tell you the highest ambient temperature we encountered was +/-105 and towing the Hummer while running the OTR AC, the temps ran higher than normal with the high being just above 210. Several times I shut the AC down, usually for no more than 5 minutes, and manually shifted to a lower gear to keep the engine from working so hard while we were climbing a tough grade (Laughlin, NV to Kingman, AZ)

Usually as I started down the the other side or across the flat land, the temps would come back to normal (195 on an 8V92).

As for the power, we were at Outdoor Resorts in LV and tripped the breaker twice. The voltage seemed to be okay, but with three Cruisairs running along with the other things that cycle off and on, any adverse load (inverter trying to charge the batteries with the load share set on 50amps) would trip the breaker. I even changed spots. No relief. Then we stayed at a park in Amarillo and you could turn on everything in the coach with no problems. Go figure.

I have accepted the fact that in given places, power management is just how it is going to be. Complaining generally gets you some concerned looks, but little more than that. They figure they don't "own" the power source, but I would have thought the breaker tripping was different. Guess not.

[Jon Wehrenberg]

Kevin,

Jerry's post kicked my flatlander brain in gear. One thing I overlooked was that you might be at a much higher elevation that normally driven and that is going to affect your cooling ability. Thin air from the higher altitude does not have the ability to cool the more dense air at sea level has.

Jerry,

If your 8V92 normal temperature runs around 195 you may be nearing the usefull life of your radiator core. The number I would expect to see the temperature cycle around is 180, maybe a little hotter in extreme ambient temps., but on flat ground 195 seems to high.

I don't have enough experience yet on the Series 60, but the 8V92 seemed to be prone to coolant problems if not changed on schedule and if the chemistry was not maintained with the conditioning filter(s).

[Jerry Winchester]

I am on that quest this week. My 8V92 mechanic will be down this week and besides changing out the valve cover gaskets and chasing down a few oil leaks, we are going to check the cooling system and determine if we need to remove the radiator and have it recored.

I am also thinking that while we have the valve covers off, we may peek at the valve adjustment and see how that looks. I have all the go-no go gauges for this, but with 25 years of 92 series experience, I think old dad can check this one out and make any necessary adjustments. Only problem is he has to have home grown tomatos for lunch :eek:

[MangoMike]

Hey JW,

With 25 years experience I'm thinking leave Rae at home (with the pool boy) and bring Dad to POG II. We'll all learn a thing or two.

MM

[lewpopp]

Hmmmmm, you are getting free experienced help and you are worrying about home grown Tomatoes. You would overnite a part for the coach, why not consider your dear ol dad the same way.

[Kevin Erion]

Guys,
Thanks for all the ideas. Jon, I have a 99 with series 60, I think that you are correct about the altitude and then add in the fact that I am towing about 17,000LBS. I think that the fan is working correct and I do drop down to 3rd gear and run about 33 at 1750 RPM up the big hills.
I think the power in the parks is up to the owner/ builder at the time the park is built. I am no electrical contractor but I think if you spend the money to make sure you have the needed power, it could be there.
Having fun with the wife and kids in Zion but a big fire is within 5 miles and has closed the main west side entrance to Zion NP. A little scary but what the heck, so is life!
Kevin

[Jon Wehrenberg]

Kevin,

Based on that I think your temperatures are what can be expected. The fact DDEC is not giving you a warning or pulling HP says you are OK.

You are in excess of what Prevost likes to see you tow, and given that I think that you are not only generating heat from the needed power you are producing but the transmission is contributing to the heat.

The Series 60 by design runs hotter than the 8V92, so my guess is you are OK. If you have any concerns however, you can lock up the fan until you get into lower temperatures or altitudes. The bolts are the two metric bolts in the end of the fan shaft, and the fan has two tabs near the hub that can be lined up with threaded holes on the clutch housing.

[Kevin Erion]

Jon,
I think I will try the fan lock up for the rest of this trip and see if I notice a drop in the temp. I am sure that I am a little heavy but why then did Prevost sell me a 20K tow hitch/engine cradle?
Kevin

[Jon Wehrenberg]

I have no idea why they would sell you something that makes you exceed the GCW. I wish they would post the answer.