8V92 running water temp

[Jon Wehrenberg]

You need to define what you are talking about. Are you overhauling the engine? If that is what you are doing Prevost is not going to do that. Only a Detroit Diesel shop or someone equally qualified will do the overhaul. I question why you are doing an overhaul. What specifically requires you to do that.

But no matter what your decision regarding an overhaul, one thing that is critical is the cooling system and if you are experiencing 195 degree temps as normal it is probable your radiator is becoming plugged. Before you ever consider rebuilding an engine it is critical you fix the cooling system so that new engine isn't damaged by high temps. Prevost can replace your radiator or have the existing one recored. I suspect Coach Worx can do that also. I would ask for quotes.

[AmeriStar]

The 2 cycle Detroits were the workhorse of the bus industries for over 40 years for one simple reason, they were tough and would run even beyond needing an O H. With that said, the main enemy of the 2 cycles is HEAT. The 92 series was designed to operate at 180 -185. On occasion an increase to 190 - 195 might be warrented due to engine load, ambient temputure or altitude, but sustained operation at the increased temps will shorten the life of the engine dramatically. Remember the design of the 92 series evolved when most of the country had a 55 mph speed limit.

Usually a lack of cooling capacity is the culprit for increased temps. Cooling system's are the most overlooked mechanical systems on buses. CHANGE your antifreeze every 2 years. I know that 15 or 20 years ago the engine builders actually put tags on the filling necks that said 'permanant glycol antifreeze', this led to the radiators becoming plugged and many engine failures. Buses do not have the front radiator set up of most vehicles that force air thru, air flow in buses is disrupted because of their inlet location and highly rely on the fan system to 'pull' air thru.

I still love the sound of the 2 cycles, and there are still quite a few on the road, because they are a great engine. Service your cooling systems, fluid, belts & radiators and the 92will give you many trouble free miles.

[Yankee802]

My fault guys, I'm sorry. I miss-used the word overhaul, it's more than my annual maintenance, because in addition to the normal annual stuff, I'm replacing a ton of stuff, tires, batteries, bags, shocks, fuel lines, and having the radiator flushed and looked at. So other than regular maintenance, the engine isn't being touched. If it's found that my radiator requires it, I'll replace it.

[Jon Wehrenberg]

If you are experiencing the temperatures you posted you need to get a look at the core to see if the radiator is getting plugged. Usually flushing the radiator will not cure the problem.

Maybe it is my imagination but the 2 cycle engines appear to need good cooling system maintenance and at a minimum it requires strict adherance to the coolant change schedules called for. I am not aware of the Series 60 engines having problems with build up in the radiator core.

[BillhymerMD]

Driving to Cape Canaveral for shuttle lift off and dash temp reads 205 - 210; stop bus and walk to rear to look at gauge in engine compartment and it reads 175. Which temp should I believe???...likely the engine compartment gauge I guess. However, I'll have the radiator recored anyway I suppose.

[Jon Wehrenberg]

Michael,

The damage high temps can do to your engine is substantial so in this case it is better to err on the side of conservatism. At the very least break the tie and get an IR temperature gun which you can point at the engine block to see which of the two readings is the more accurate. You can always use the gun at rest areas to check tire and hub temps.

One of the problems with trying to get readings after a run is that as soon as you lift off the accelerator pedal to coast into a rest area you are removing the heat of combustion and the engine can cool down pretty quickly masking a problem. Driving on the flat in Florida your temps should be at their lowest point unless you are running flat out into a headwind. If you hit the hills and mountains you would likely see an engine shutdown or the creation of a boat anchor if it does not shut down fast enough.

Recoring or replacing your radiator is not cheap, but compared to an engine it is chump change. Once you verify which gauge is the more accurate by aiming the IR gun at the location of the temperature sensors you will know enough good information to ignore what may be a guage problem, or to proceed further to verify the core is getting plugged.

[BillhymerMD]

Bryan mentioned that he has noticed the same temperature difference between the mechanical gauge and dash gauge. Has anyone else observed this and if so what was done about it?

[rahangman]

The past summer I agonized over temperature differential between drivers "indicator" and the direct reading gauge in the engine copartment. Using an IR gun as Jon suggested pretty much determined the inevitable. And yes, he is right, I found that by the time I would pull over to check rear gauge it would be several degrees lower with just a moment at no load. Do the radiator, it is not cheap, but it sure makes the difference. PM me if you like for some ideas. I used a local tour bus company as it is a bit of a job for anyone not outfitted to do this big(ger) job.

[Jon Wehrenberg]

Michael,

Let's assume Bryan is correct. If he is you have a gauge issue. But what if you do not have a gauge issue?

If your gauge is reasonably accurate, and by that I mean within 10 degrees, you still have a serious problem which is going to cost you a whole lot more than an IR gun, and 5 to 10 times the cost of a recored radiator if you continue to be in denial. You need to see temps in the 180 to 185 degree range and you are so far above that range with running on flat roads something is wrong.

Don't trust your DDEC to save your engine. It might, but if your temps are really as high as your gauge shows it is now the only and last chance you have to save your engine. Do we have your attention?

When you tell a patient they have a terminal disease don't they go through a period of denial? Does that period of denial change the outcome?

[BillhymerMD]

Actually Jon there are 5 stages of grief and denial is the first of the five stages. They occur in this order: Denial, Anger, Bargaining, Depression and Acceptance. I have moved beyond denial and anger and am now in the bargaining stage. I am looking forward to depression but it should only be a short hop and skip to acceptance. However, perhaps Im already at acceptance as Coach Worx is set to take my radiator out for recoreing in a couple of weeks. Thanks, Mike