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Question about cooling
I’d like to know an answer that nobody has been able to provide me with other than what their personal experience’s have been. I’d like a true factual answer rather than a guess or an opinion!
Ive got a 1992 H3-40 equipped with an 8v-92 ddec 2 and a HT-754 auto trans.
It’s an ex seated coach that Ive converted and not on the heavy side.
Runs great but always seems to run hotter than normal if there is a normal which brings me to my question. What is normal temperature? For me to keep the temps in the 180’s I have to run 68 mph or less! Anything above 170 mph it runs 195 plus!
Keep in mind this is in Florida on a 70* day with NO sun!
The radiator has been changed keeping the original part number and the fan has been locked in direct drive (no clutch)
I even staggered some air fins on the radiator body work to help catch air!
I installed a new stone/air deflector that was previously removed and was told this would help immensely but no change at all!
Not pulling a trailer or a car so what IS the proper temps that is safe for this combination because the hot summer days are just ahead and not being able to run at least 70 on flat ground us not gonna cut it!
Thanks
Ace
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47 Replies
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Ace,
This is solely by memory. My 8V92 ran 180 plus or minus a few degrees either way that was the cycling of the radiator shutters and / or the themostat. This was an 87 DDEC I so it preceded the clutched fan.
If I hit a long steep hill and locked it wide open in 4th (it wouldn’t maintain speed in 5th) by the top, on the hottest day, pulling a toad I was at 190 to 195. Shutters and thermostats were open because the temps exceeded their normal operating range.
It was geared low so top speed was 69-72 depending on if I was going level or downhill or into a strong headwind or not. I think the low gearing which kept the revs up also helped cooling because the engine was not lugging.
An opinion:
But compared to my 4 stroke Series 60 it seemed like the 8V92 demanded good coolant maintenance otherwise the radiator would plug. No matter how hard I worked to keep up with coolant changes and conditioning filters the radiator seemd to last about 10 years and need to be rodded or recored. The Series 60 never gave me any issues with radiator plugging. I know it was happening because after about 8 years from a new radiator core the temps would be “normal” about 5 to 10 degrees hotter, and instead od 195 on a hill it was 210 at which point the radiator would get pulled and recored. I thought it was related to the 2 stroke and that caused the plugging I never experienced with the S-60. I used an off brand coolant once, but all other times over my 15 years owning that coach I used Power Cool.
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Ace,
My 94 Liberty with the 8V92 would always run 180 and I never saw anything beyond 190. It had been rebuilt and the colling system functioned well. The fan had been converted to plastic from metal, but that had no effect on cooling and it cycled on and off as needed depending on temperature. There are a lot of 8V92’s still out there running and we have some here on the forum in both H’s and XL’s.
I assume you have checked all the basics such as water pump, thermostat’s and a 50/50 coolant mix and not just water.
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As I recall, I used to run as high as 205 or so during hot(110F), high load(57000#) hillclimbs. I had to maintain that temp by slowing down as necessary while keeping rpm’s high. High rpm’s are important to the 8V92 under load. My bus had new radiator, the new type coolant, fixed plastic fan.
I can push the S60 harder and maintain an extra 5-8 mph on hills, but I can’t conceive of having a problem running 70-75 level with a properly functioning 8V92 on level ground.
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Just re-read your post. Do you have the S60 plastic, multi-bladed (9?) fan or are you still running the cast aluminum antique?
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My 89-8v-92 had plastic fan and I ran it hard. No overheating problems. Towing in 100F. Bob
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Just re-read your post again and noticed you want a “true factual answer” as opposed to opinion.
Interesting. I guess I’d start with an inquiry to DD asking them what the normal operating coolant temp range is for an 8V92. I’d actually like to know the answer myself.
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Would direct this toward Don Farchild?? In the past discussion I understand concern 200F isn’t a problem and oil temp can run 30F higher Than coolant temp. The experts Don or Clifford are the 2 stroke guys. Detroit of course is by the book. I had trouble getting mine over 190.If memory serves me rite the shut down kicks in around 208F. My understanding is you need a little temp in it for best performance. Do you have Turbo Blankets? Clifford will prob read in. Bob
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to answer a few questions regarding the replies are,
yes the proper coolant and level is always where it’s supposed to be. The fan that’s in it is the one that was in it when I got it and its plastic, not metal! Without looking at it, I can’t say how many blades it has but I’m thinking 5 maybe 7. Is there a better fan to use that would be a direct replacement without any modification?
The water pump has never been changed since I bought the bus but I have a brand new one in the box as well as new thermostats. They’ve never been changed either! Since I need to drain the coolant to do one or the other, I might as well do both!
Mechanic here that owns a bus garage says to me, “gouge on it”! “It’s not in danger until it reaches 205”! The problem I have with this is, it doesn’t cost him anything if he runs his hot but it cost me dearly, not to mention, the first radiator that didn’t leak but the fins would fall off if you blew your breath across them, never let it get above 185 even pulling hills! I wouldn’t think a new radiator would need cleaning out after one year!
I guess next move is to change water pump and thermostats and go from there!
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170 is low end . I ran 190 stats in mine. I’ll do some ck for you- my memory has slipped some but I thought low 190’s was ideal. Bob
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Ace,
You may have a clue to the question. If your original radiator was able to keep the temps low, when it was recored did they change the number of tubes or anything?
Like you I agree the mechanic probably is repeating an old wives tale, and from my own experience and from reading a lot of posts the magic number for the 8V92 seems to be 180, with a rise to 190 or 195 on long steep hills even on hot days.
That would be my objective and I think changing pumps and thermostats won’t hurt. But if the temps do not change I would consider the radiator to be the problem.
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Hi Ace,
I have gone through about the same as you. My radiator was also falling apart and we replaced it last year. Climbing a mountain I would get over 200 degrees and did not like that. We also replaced the thermostats and while I had it torn apart replaced the turbo and repaired the Jake brakes. The remaining item I have to address is the shutter assembly is missing on our coach and that leaves a 4 inch gap between the outer door seal and the radiator allowing hot air from the engine compartment to be pulled in to the radiator. We just took a 500 mile trip to the beach going up and down our hills and the temp stayed at 180, but as the outside temps rise, so will my engine temp. Are you going by the dash guage or are you verifying it will the engine compartment gauge. Sometimes there is a difference in those two. Fun to chase these issues!!! -
Just got in yesterday from Gulf Coast and temp in the high 80’s low 90’s and mine (8V92TA-HT-755CR) runs right at 195 and oil about 20 degrees higher. Pulling a Ford Edge and running about 70 mph. Tacking about 2000 Rpm’s. There is a 60 mph speep limit coming off Surfside Beach that has a 60 mph speed limit and the temp would run around 185. Last summer when we had it out in the 105 and up temps and it was about the same. Oil temp may have been 10 or 15 degrees higher.
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Ace,
You have posted an interesting question about cooling. Here is what I can add to the potential solution that may cure overheating.
Pay attention to the suction side of the cooling system. You will need to drain the coolant. The next step could be handled a couple of ways.
My suggestion would be to remove and inspect all the coolant hoses on the suction side. Carefully inspect the hose on the inside for delimitation of rubber plies.
My guess is one or more of the older hoses cannot stand up to the suction demand of coolant at high rpm slightly closing the hose.
Another place to look is the main lower radiator hose should contain a wire loop inside to hold the hose completely open.
AL
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On our coaches almost exclusively piping is used in lieu of hoses. The hoses used on the coolant system (not converter installed hoses, but those related to the engine and chassis) are the very durable (generally) blue hoses that are used in short sections to join the piping.
I agree with what Al says on the generator.
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Jon,
You are right with short sections of hose used in cooling system.
What I did notice was the year of the bus. With appox. 22 years of service there could be any number of fix-it repairs done over time to keep this bus on the road.
Getting his mind to think about the odd stuff that might of happen over time.
Just saying,
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