pyrometer gauge

[gmcbuffalo]

When I am pulling a hill my pyrometers will read 1000 on the right and 900 on the left, is this a problem or normal? 8v92 and 5sp tranny.
GregM

[Jon Wehrenberg]

Likely normal.

The key is to determine what your readings have been over your time of ownership and to notice variation from those values.

I cannot remember what the spread was between the two pyros on my other bus but I think there was about the same spread as yours, but my higher pyro read a little higher, around 1100.

When my manifold gaskets started to fail my pyros went down and so did my turbo boost so the gauges did tell something was different.

[truk4u]

Greg,

I keep mine between 900 and 1000 and the needles are real close. I doubt that 100 degree difference is a concern and is probably normal.

[dalej]

Greg,

Check around the manifold on the right side (muffler side) for black exhaust residue, I had a gasket leaking and that made the temp run higher. Replaced it and it came back in line with the other.

Gaskets are easy to replace if thats the problem.

[Joe Cannarozzi]

I am with Peter on this one. Pyro is the most useless gauge on the dash. He unlike us in the flat lands is out West in the mountains where it supposedly becomes critical. I know from previous discussions Peter pulls hills with the throttle on the floor and if that driving technique does not produce too much exhaust temp nothing will.

Our 85 is not equipped with the gauge, no big loss. They are expensive to replace and very temperamental

[BrianE]

Don't agree with you on this one Joe. Running an 8V in the mountains one needs to pay attention to both pyrometer and boost. Sustained pyrometer temps above 1100 and/or boost above 20" IS going to result in an overheated engine. As I learned the hard way, this situation can easily be avoided by slowing down and shifting down to keep RPM's above 1700. The 8V is a great engine but it needs to be closely watched when working hard. Additionally, the cooling system on the 8V needs more attention due both to its' design and its' age.


Peter's experience is with the rare installation of a pyrometer gauge on his very early Series 60 Prevost. The 60 isn't nearly so temp critical. The engine cools better due to a better cooling system and it's basic ability to dissipate heat due to less mass. Also the 60 lugs down better and the 6 speed tranny doesn't hurt either.

[tdelorme]

My pyro needles had always stayed exactly the same. Both sides went up or down in sync. When the right side started moving up faster and coming down slower, I called the Detroit guy I trust. He said it was no big deal, more that likely some buildup on the sensor and to pay more attention to my oil and water temperatures. Several trips later they came back into sync and and are once agin the "pyro twins." It did get me in the habit of keeping a closer watch on the important gages.

[gmcbuffalo]

Thanks
DaleJ I did have a leaking right side exhaust awhile back and did replace the gasket. Maybe I should looking for a smaller leak?

Ii dirve the hills in Cruise control watching the tach, when it drops to 1700 I manually drop to a lower gear and go up when I am running 2100 again.

GregM

[dalej]

I drive pretty close to that, I shift just when the tach get to 1500 or just above.

[Loc]

The Prevost manual says not to exceed 1200 degrees on the pyros for an 8V92. I personally always tried to keep them to around 900 climbing hills which required gearing down and keeping the RPM's up. The 8V is a strong engine, but it does not like to get hot (I learned this the hard way). Keeping the temps a little lower will still get you up the hill and will keep the engine a lot happier. My pyro guages on the 8V92 were about 75 degrees (what appeared to be about 3/4 of the difference between the marks) different.

[Joe Cannarozzi]

All of these suggestions of how to run an 8-V up a hill brings back very vivid memories of a previous discussion on how to do that properly. I was outnumbered at the time but it now seems I was not alone:)

Thank you, I love you all for all for your infinite wisdom. Let the truth be known.

I have neither pyro's turbo boost or manifold pressure AND a mechanical (non-computer) engine. Yall worry too much. :eek:

The manifold pressure would be the most useful for the way I drive. Turbo boost is basically the same gauge.


How do I know if the exhaust temps are rising without a pyro, easy. If I put my foot on the floor and the RPM's are continuing to drop the exhaust Temp is rising. (I try to never do that. It is the ultimate litmus test for how hard to push and agreat habbit to get into)

[truk4u]

Now that finally explains it all.. Peter has a series 60 and Joe has no pyro. Now I understand why both think the gauge is useless.:rolleyes:

I watch mine like a hawk, thanks to Brian!;) You would be amazed at how quickly you can hit the 1100/1200 mark if your not paying attention in the hills.

[Joe Cannarozzi]

Tom you have to learn how to become one with your bus:D:rolleyes:

Everyone does it a little differently:)

So even WITH a computer on the 8-V it does not have the ability to get you up the hill "foot on the floor "(hammer head style) correctly compensating for all potential scenarios, but you are forced to drive it? Oh my gosh.

[Jon Wehrenberg]

As much as I like the Series 60, I don't see it as an improvement over the 8V92 except for fuel mileage.

My 8V92 would pull the hills with the same results as the Series 60 at the same speeds. I don't know if I was at one with the bus, but I do know in both coaches anticipation is required, and that the six speed transmission in particular needs to be in performance mode at least, or like the five speed needs to be manually shifted.

"Balls to the wall" is how I attacked the hills. In the 8V92 I increased my speed as I got near the bottom of the hill to keep the revs up. Forth gear in my bus at 2100 was 55 MPH. If I dropped below 55 to about 50 or 52 I dropped it into 4th and left it there until I bumped into the governor so it would not "hunt" back and forth between 4th and 5th gear.

It just so happens on the current bus 4th tops at at 55 also, but I have 5th and 6th available if the bus needs them. Same techniques as driving the 8V92, except at the bottom of the hill I gain speed in 5th instead of 6th gear and manually downshift the same way at the same speeds.

Foot to the floor the entire time.

My pyros never exceeded 1100 as I recall. I don't know if that was DDEC controlling that or if it was just the way the bus was set up.

[Loc]

With my 8V92 which had DDEC II, the pyros would max out at 1300. Don't count on the DDEC brain keeping you safe.

[gmcbuffalo]

DaleJ
I checked to site of the old leak, felt like I could feel a leak. So I took the insulation off the pipe from the manifold to the turbo and remounted it. Now I could feel a big leak at the junction of the manifold and pipe to turbo. I turns out that I think I have a major leak in the exhaust manifold right side of bus rear cylinder.

Replacing the manifold gaskets, is this a project that I should tackle or bring to the DD or like diesel folks?

GregM

[Joe Cannarozzi]

I think you could do it. Some of the manifold studs are threaded into the water jacket so do not let them turn out. It sounds like ti is the pipe flanges/clamps. What exactly is leaking the flange at the head or the flange for the pipe? Either way a dooable project.

Dumb question. I guess the exhaust blankets keep engine compartment temps down but do they increase the exhaust temp when pulling a grade?

[gmcbuffalo]

Joe iThe leak appears to be coming from where the exhaust manifold attaches to the block. right rear cylinder. I thought it was coming form the pipe joint on the manifold, but after taking it off and on the leak is blowing on the back of my hand. I pushed a screwdriver blade down between the head and manifold and it slowed the leak.


On the blankets I have no idea, they were on the bus when I bought it. The previous owner said he like to go fast so he had a new (suppositly larger) radiator put in, and blankets on every hot pipe.

Greg

[Jon Wehrenberg]

Greg,

Plan on losing coolant. Make sure you have a big pan under the bus when you loosen the manifold nuts.

If you live a clean life and if the planets are properly aligned you may get away with out spilling a drop. For a few days before you tackle the project start applying penetrating oil to the manifold nuts. When you begin the oil may have done the job and you will not lose a stud or drop of coolant.

Those manifolds are very susceptible to cracking, especially at the rear where there is an ear that sticks out at the end. Before you begin you may wish to do a very good inspection to make sure you have manifolds without cracks. If you find a crack it needs to be replaced.

If you do loosen a stud you will need new studs and if I am not mistaken there are special tools for installing studs. They need to be installed tightly.

For all 8V92 owners, one inspection that needs to be done regularly is to look for cracks in the two pipes that go from the manifolds to the turbo inlet. All along and around the perimeter of the exhaust manifolds there needs to be an inspection to look for soot. Soot is the first indicator of a cracked manifold casting or a failing mainifold gasket. Any of these problems will result in the loss of turbo boost at the very least.

[dalej]

Greg,

A bit of a trick I learned to changing manifold gaskets.

On my first gasket I replaced, I started to take out the manifold bolts and as Jon said you will have antifreeze running from the block. I quickly put the bolt back in. I then realized that the manifold will come off with out removing the bolts all the way, it can just be lifted up to take it off.

You don't really have to worry about the rusted taps on the bolts because the bolts will turn out of the head. Just loosen all the taps or bolts about 3 or 4 turns.

You will have to use a side cutter to notch the head gaskets below the bolts for the gasket to be removed the same way the manifold comes off.

Then just notch you new gasket so it will slide down into place and then slide the manifold into place and tighten all the taps and/or bolts.

[Petervs]

Jon, you said "As much as I like the Series 60, I don't see it as an improvement over the 8V92 except for fuel mileage."

You are full of prunes here. The Series 60 is better because:

A. No worries about overheating ever.
B. More torque, run it at any rpm without worries
C. Designed in the late twentieth century.
D. Any shop can work on it, but none ever need to because they do not quit.
E. 25% fuel mileage improvement is nothing to sneeze at
F. No more blown exhaust manifold gaskets.
G. No more DDEC computer in the valley under the turbo where it is so hot it takes a fuel cooled heat exchanger to prevent the computer from melting
H. Will run the life of the chassis, the 8V generally need overhaul at 500,000 miles give or take.
I. Jake Brake has more power on the Series 60

Seriously Jon, would you trade back to an 8V?

And for how long will there actually be parts available for them? Sure there will always be specialty shops that work on them, but Detroit Diesel has been bought and sold a few times now, and they certainly do not make serious profit on these old engines. Other than our busses, a few stationary applications and a bunch of boats these engines are no longer in common use on the highway. The truckers switched to the modern engines long ago for the same reasons.

Detroit will quit supporting the 8V some day, as soon as they can in my opinion. On the other hand, the Series 60 will be supported for the rest of my lifetime I am sure.

Reconsider maybe?

[gmcbuffalo]

Is there only one level row of manifold bolts? I don't see any staggered bolts or top and bottom ones.
Greg

[Jon Wehrenberg]

Peter, In the context of what you say you are almost completely right. I meant the engines were equal as far as performance in pulling the hills. But you are right on most of your points.

However, I never had overheating problems on my 8V92.

I could work on my 8V92 without disassembling my bedroom.

The lugging ability of the Series 60 (which is over rated) is more than offset by a 5 speed transmission that works the 8V92 engine in the full 1500 to 2100 RPM range. The Series 60 and six speed combination shifts smoother, but it lugs down in the default mode to the point at which downshifts do not let you accelerate back up to speed but only hold the reduced speed. To get the most out of the Series 60 / six speed combination you have to go to performance mode and tolerate harsh shifts and you do have to shift manually to hold the revs.

The 500,000 mile life of the 8V92 is greatly in excess of what anybody on this forum will see so having an engine that may last the life of the chassis is so far beyond overkill it is ridiculous. Our engines will rust internally so I question the engine life in our application and long storage periods.

I think the design is elegant in an 8V92. It is too bad it was done in by emissions requirements because it was replaced by an engine that lacks the simplicity and possesses a sound so unique any one of us can tell it from any other engine on the road. You cannot get that 8V92 sound from engines that suck, squeeze, bang and blow.

I never had my DDEC computer melt so I don't see that as a problem.

[Joe Cannarozzi]

Greg 1 row.

[Petervs]

Jon,

My coach has a series 60 and a 5 speed tranny. It shifts great, it is always in the right gear, I only need to manually downshift if I am going down a long hill. It does not have any performance mode, or whatever, there is only the one mode it runs in. I think it is the same tranny you had with your 8V.

One of the things I like about my coach is that the engine, tranny, and chassis are very well suited to each other, it works really well as a unit. Marathon told me my coach was the very first 45 footer and first coach they built with a Series 60. Some vehicles have that special something when all the parts work well together. Bonanzas and IO-520s, Cessna 210s and IO-520s, and a few cars have that nice feeling about them, as does my coach.

Oh, and you don't have to tear apart the bedroom, because they do not need to be worked on. Honestly, I do not think they even have an access hatch in my bedroom.

Jon, I was not saying you had overheating problems , only that the 8V was prone to them if driven badly. I think no matter how you drive the Series 60 you are safe from overheating, as long as you watch the idiot lights on the dash if there is some kind of mechanical issue.

Lastly I must comment on your mention of the unique sound made by an 8V. Well, I agree it is a cool sound. But sheesh, that is the same argument made by the Harley guys and their potato-potato sound. The sound is not a valid reason to make an engine from an engineering standpoint. The value of an engine comes from it's efficiency and reliability. The biggest reason the 8V was phased out was the efficiency not the emissions. Detroit could not sell them to truckers when they could not compete on fuel used.

You never stated whether you would trade back......and not because you might get a $50,000 refund on the price differential of the same bus with 8V vs Series 60. I think the marketplace has voted with it's pocketbook.

I rest my case,

Respectfully submitted,
Czar of Crap!

[Jon Wehrenberg]

Hey Czar, Your comments are on the money.

Prevost should have paired the Series 60 with the five speed. I agree with your observation about it. Unfortunately the buyers were all over Prevost for the six speed, and Prevost needed the shorter overall length to get the Series 60 to fit the 40 foot bus.

I think the five speed is more robust, and while the shifts are not as smooth it let the engine revs build up more so pulling a hill was easier from the driver's point of view. Just stick your foot to the floor and things would work out.

No I will not go back to an 8V92. It puts out a lot of soot and my garage reflected the difference between the two. The oil got real dirty between changes. The 8V92 required good coolant maintenance otherwise the radiator got plugged and the engine was at risk of cylinder liner damage, more so than the Series 60.

The turbo inlet tubes were expensive and lasted about ten years on my 8V92. The steel oil pan did not last in the frozen north either and I had to replace it as well. The aluminum pan on my Series 60 shows no sign of corrosion.

The 8V92 had a lot of stuff like the power steering pump, compressor and worst of all the alternator buried on the front (actually the rear) of the engine and servicing or replacing them there was a challenge. The Series 60 has all that stuff accessible. For all those reasons I will stick with a Series 60, but they were equal in power in my mind as far as hill climbing.

[jimblu]

I just did some repairs on a pair of marine 6V92 535 HP. OEM Detroit valves, springs, cam followers, gaskets, injectors, fuel jumper tubes, and much more were readily available and as cheap as bicycle parts in Aviation, Volvo or Cat dollars. Parts will be around. Mechanics who do it, not so much. I was dragged out of never again to work in a friends confined engine room......

[dalej]

jimblu,

WE NEED TO TALK!

Seriously, You sound like you must know a thing or two about the 8V. I plan on driving mine until Jan says.... Dale that's enough, I don't trust you driving this bus anymore.

PS, I really enjoy working on my bus, anything I can do myself is a good thing.

[Joe Cannarozzi]

If you ever get any traction out of your idea Dale let me know. I would like to help to set the valves and the rack on ours too.

We have 110,000 on a factory remanufactured engine and it has not been touched the entire time.

I keep getting told the jake works fine and I can barley feel it.

[dalej]

Joe,

We'll be waiting.

[Jon Wehrenberg]

Joe,

The Jake is easy to diagnose. If you want to know if it is working let me know.

[Joe Cannarozzi]

I was once told it was working but it was weak.:confused:

I know it works to some degree. It would hold the bus right at 38 in 3rd coming down Mt. eagle with it on and I needed some occasional brake without it.

[jimblu]

[QUOTE=dalej;49050]jimblu,

WE NEED TO TALK!

Just drive it down here to Grand Cayman and I'll help you. I haven't even seen my bus this year:mad:

Once you get the valve covers off a tune up is fairly easy with a few specific tools, and often unnecessary. The DD book is very good on the tune up, useless on gaining access.

I relocated the batteries in my Liberty to make access easier.
It had 180,000 miles on it when I bought it, a tuneup produced no change in power or mileage and it produces full power on a dyno (375 at the wheels).

It doesn't leak oil, but uses some, and only gets 6 MPG at 60-65. For the amount I have been able to use it, it doesn't matter much:(

The Jacobs Engine Brake is not as good as a 4 cycle engine, keeping it downshifted helps.

Got busy otherwise right after acquisition. Too busy to even think about it.

Tried to make several events, haven't been able to get away. Some day!

Jim

[dalej]

Jim,

Where do you live? Jan and I did our open water at Grand Cayman. We rented a home on the north side in the Brinkleys area.

[truk4u]

Dear Czar of Crap,

How many 8V's have you owned?

[Petervs]

TomTruk,

In the future, please address your querry to "Your Majesty, Czar of Crap" .

I have not owned any 2 stroke Detroits. I did my research prior to purchase and opted to avoid those engines for reasons stated above. One does not have to actually have personally had , say, the measles, to know that you don't want to have em.

I am not saying they are like measles, nor am I saying they are bad motors. They just require greater care in ownership, more operating expenses, and from my point of view, you run a greater risk of having to overhaul them during the course of ownership to the tune of $15,000-20,000 . I think it is unlikely one would ever have to overhaul a Series 60 during the course of a coach lifespan.

I also realize I spent the extra money up front during acquisition, the 8V owners can spend it as they go along. In the end it might be a cost breakeven.

[BrianE]

Joe, I'm with you on the weak Jake. When we had the engine OH on the green machine, I asked the very experienced overhaul mechanic to do whatever he could to improve the Jake and was told not to expect much. When it was returned all shiny and new, the damn thing wasn't a bit better. All I can say is that you would really miss having it in the mountains. Around town it only helps if you manually shift down to assist it which (IMHO) is more trouble than it's worth. :(

[Joe Cannarozzi]

I have not had the opportunity to go West but as for here and points east there is nothing that is not manageable without a Jake. We have other priorities and I put it aside, maybe the dern thing works:eek:


For a bus, slow is cool: Deb is way more comfortable when I ease around. The tank goes a while longer.

[truk4u]

Your Majesty, Czar of Crapola,

I had measles when I was a puppy and that gives me more credibility when discussing the subject.:o:rolleyes:

You make some good points regarding the 8V, but your love fest for the 60 matched up to an out of date 5 speed may cloud your objectivity. May I make just a few comments oh great Czar......

1. The truckers chose the 60 because they had no choice when the 8V was being phased out as road power, but the engines continued on in the marine industry and Jdub loved them as jobsite power.

2. I can do a top OH for less than 5K and an inframe for less the 10K, so your OH numbers may be just a tad inflated.

3. I consistently get 6.8 mpg, remember I own one. My 2 previous series 60's got just over 7.0, so your 25% fuel savings may need to be tweaked just a bit.

4. Parts and service are still quite readily available and are usually cheaper than parts for the 60.

I only point out these few items great Czar, in hopes of putting the minds at ease of those who cannot pony up the bucks for a later model series 60 or those folks that, gasp, cannot pay cash for an older Prevost. I think our mission should be to help those newbies sort through all this crap (all hale the Czar) and encourage, rather than discourage the purchase of a bus instead of a pile of sticks & staples. I personally don't see the downside of a Prevost with an 8V, put hey, I'm not a Czar.;)

[BrianE]

Tom's comments are definately NOT a load of crap. The mileage claim sounds a little poopy though. :rolleyes:

[jimblu]

Jim,

Where do you live? Jan and I did our open water at Grand Cayman. We rented a home on the north side in the Brinkleys area.

As they say here, right by where the drive in movie used to be (before it blew down)

South Coast, 10 miles east of Georgetown.

[gmcbuffalo]

What does the ProDriver measure to get you the fuel mileage? Are there sensors that come with the ProDriver that you put on the fuel lines?
GregM

[Petervs]

Greg,
The ProDriver is connected to the DDEC computer and gets its readouts from that. Several of us have installed them, there are just 4 wires, power, ground, and 2 attached behind the port where you would plug in a reader for the DDEC codes beside thew driver seat.

You can often buy them on eBay for about $300. The amount of info depends on the version of DDEC you have.

Also gives you cruise control speed setting, miles to oil change, trip odometer, gallons of fuel used, error code readouts if you experience any, etc.

The DDEC controls how many atoms of fuel is injected with each piston travel and provides the data to the ProDriver which is able to display it.

I will help you install one if you like.

[gmcbuffalo]

My Beaver display panel has a fuel used gauge but not very accurate, I'll check what it is using for data retrieval and start looking for a ProDriver.
Thanks Peter
GregM

[Jon Wehrenberg]

I have always recorded every gallon of fuel I have added to my buses.

Because of data that has been recorded for years I can very accurately calculate MPG if it wasn't for devices called the generator or the Webasto.

Since I keep a log book of maintenance on the bus and the generator I can make reasonably accurate adjustments to reflect fuel used by the generator, again going over a period of time that can be expressed in years. I have almost no ability to quantify Webasto use, but because we avoid the cold weather now, that fuel use over a long period of time is unlikely to skew the numbers. I know from calculating the Pro Driver is very accurate. I have come to rely on it and for those who want to know what affects your efficiency I think the following ranking is accurate.

Drive fast, lose mileage. There is obviously a compromise required here. The best speed may be real slow, but we have to consider other drivers. But it is clear 70, 75 or 80 really increase fuel consumption.

High head winds make a big difference. I watched an average Pro Driver mileage based on about three thousand miles of driving get pulled down by about 1/2 MPG within about 600 to 700 MPG just because I was in headwinds of about 15 to 20 MPG.

Hills also drop the mileage a lot. No matter what you make up by coasting downhill, it is never enough to offset the fuel used during the climb up the hills.

Towing heavy vehicles, or even just having a heavy coach. Weight is the enemy. The lighter the Toad, the lighter the bus, the better mileage.

Cold air also has an effect. It is small and since I do not record temperatures I cannot provide a value for the impact cold outside temperatures have on mileage, but it does adversely impact it.

So the solution to fight high fuel prices and low MPG is to drive slow, only with the wind, going downhill, with a Smart car for a toad in the summer in Phoenix.

[Sid Tuls]

Jon, I just got back to Amarillo from Visalia and this time I didn't tow my Tahoe and drove about 1300 miles @ 68 mph and got 6.9 mpg. I almost always tow and get 6.1-6.2 mpg. I guess this is quite a surprize for me. Just thought you would like to know.

[truk4u]

Today driving through NY, PA and OH, I got 7 plus on the pro driver, not towing, full fuel and 1/4 water. Cruise was set at 64 mph, 1750 rpm. Not bad for a poopy 8V!:eek:


4904

[Sid Tuls]

Tom, is what I posted good for a 60 ?

[Joe Cannarozzi]

Experiment Sid. Your bus is probably as heavy without a toad as ours is with one 47500 and you had some climbs? If so that ain't bad. Try going 63 and note the difference.

Are you keeping that beautiful powercoated Thompson oil pan shined up, there may be a czar for that now.

[Jon Wehrenberg]

Tom,

I hate to bust your bubble, but take the picture again after the ProDriver has a trip length of 3000 to 5000 miles. 300 miles ain't nothing.

On any given day, when driving on the flat with few hills, with no toad and with a tailwind, even as small as 10 MPH while driving around 60 MPH I can see ridiculously high MPG figures. But if I encounter average conditions, such as hills, towing something and the normal winds, including those on the nose I end up at 7.7 to 7.8.

FWIW I think the change in fuels has resulted in a .1 or .2 MPG loss.

[truk4u]

The problem with longer runs on the trip computer is the gen and webasto throw the numbers off. I clear the trip at each fueling and also compare the pro driver miles to the odometer. In the last few weeks, I have put 90 hrs on the gen and some webasto time, as well as traveling through WV and PA, so I know that is effecting my log mpg and the pro driver on some legs.

I agree the terrain, winds and star alignment effect the mpg, but for the most part, I can get pretty close in estimating how far I can go before worrying about fueling.

I also wanted potential 8V buyers/owners to know that a well running 8V can produce decent fuel numbers as long as speed is controlled. Would my numbers be less if towing a big trailer or Hummer, absolutely.

Sid - Sounds about right based on my previous 60's and I'm sure you were in the hills.

[Jon Wehrenberg]

The ProDriver reflects accurate MPG for the coach and is unaffected by the use of the generator or Webasto. Calculating average MPG based on the amount of fuel added to the tanks IS affected by the use of the Webasto and generator.

[Kenneth Brewer]

The ProDriver reflects accurate MPG for the coach and is unaffected by the use of the generator or Webasto. Calculating average MPG based on the amount of fuel added to the tanks IS affected by the use of the Webasto and generator.

Thanks, Jon. If I had thought about it, I would, or should, have realized that (about the ProDriver).