Anyone have any ideas?

[Ace]

My recent trip to Charleston found my temps going up AGAIN while the MPH went up. I thought I had this problem fixed when we found the t-stats clogged with a shop rag, but obviously more work is needed.
At 70-75 MPH it would run 195+°
At 60-70 MPH it would run 180°-190°
Idling it runs 164°
After idling in rest area at 164°  and then returning to interstate, at 70 mph, it will run at 180° and stay there for about 30 or so miles, them jump up 2° for about 30 miles and then jump again and again.
No coolant loss anywhere!
Tried the misters when it reached 199° once for 3 minutes (yes Susan timed it) and it dropped the temps to 187°.
3 minutes used ONE gallon of water so the misters ARE working but what is next? Thermostats and water pump were changed! I think having the radiator rodded out will probably help. Maybe some shop rag is still lodged and possibly moving, possibly not. I just don't know!


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[muldoonman]

Had mine in the shop last fall for service Ace and don't know if your bus has the same set up, but somebody had shut valve that controls belt tension and belts would slip at high seed. At idle it looked normal back there. Justin Griffith out of Granger Tx. found that little problem. Saved me another 3 hour trip to Houston Prevost.

[luvrbus]

Which fan do have the 30 inch or 32 inch it sounds like a air movement problem those plastic thermostatic fans lose a lot of pitch over the years at high speeds

good luck

[Ace]

I don't think the belt is slipping due to no traces but definitely gonna check to be sure.
I also DO need a new fan since the one if have now has a small break on one blade.
Any suggestions as to what fan will be best? I'd have to measure mine to see which it is!


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[blue_goose]

Ask someone with an Eagle and the 8v92 they can tell you about heat.  As long a you stay below 210 you are ok, but it is better to keep it a cool as you can.  I never got a large on but a lot of Eagle owners bought fans that could be adjusted.  Some on will chime in and tell you where to get one and that should fix the problem.
Jack

[luvrbus]

You are probably right on the 1 st guess Ace I read the Hayden trouble shooting guide it is about what you described good cooling at low speeds bad cooling at high speeds points to the radiator according to Hayden I wouldn't run the engine at 210 normal is 175 to 195 degrees for 8v92 DDEC 

good luck

[Ace]

Yea I'm thinking the tubes are clogged and it never ran above 185 before! I'm not a fan of running it in the 90 plus range. That's just puttin money in the shops pocket!


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[Lin]

I don't know when you last cleaned the radiator fins.  Dust and residue build up can reduce efficiency too.  Once a year, we buy a can of swamp cooler coil cleaner to spray into the radiators.  There are probably even stronger coil cleaner chemicals that HVAC people use.

[Ace]

Lin the radiator was replaced about 2 years ago and it is clean now. Well I know I can see thru it pretty good so I suspect it's clean!
I really think there's more rag in the system and it's causing the problem.
Now to find someone local that can rod it out. Most local companies have closed because radiators today are replaced, not repaired!


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[RJ]

Ace -

Some random thoughts from the right side of the left coast:

1)  Wind resistance.  Takes a lot more energy to push that big, non-aerodynamic brick down the super slab at 75 mph vs 65.  And as you know, with a two-stroke, more power being used equals more heat being generated.

2)  Air Flow.  In this case, is all of the air actually flowing thru the radiator?  Are there gaps around the shrouding that could allow bypassing?  As you know, MCIs are notorious for the rubber seal deteriorating around the rads and causing problems.  Granted, you've got a Prevost, just wondering if something similar might be happening in your case.

3)  Cooling Fan.  As has already been mentioned, perhaps the cooling fan is having issues?

4)  Coolant Chemical Mix.  Anti-freeze is a lousy coolant.  Good at keeping everything from freezing when it's cold, but at the normal 50/50 mix, it's not so good at keeping things cool.  Since you're in FL, you could probably run a 70/30 water/coolant mix and not have any issues.

5)  Possibly plugged radiator.  Since it's only two years old, I wouldn't think this would be the problem, but wouldn't rule it out, either.

6)  If you could figure out a way to take exhaust manifold temp readings while on the slab, you might be able to find out if there's a heat discrepancy somewhere in the exhaust system.

7)  Muffler.  Is it possible that you've got some type of restriction in the exhaust, perhaps internally to the muffler, that only shows up under certain conditions - high load, high rpm, high road speed?

Those are just a few thoughts that came to mind. . .

FWIW & HTH. . .

[Ace]

RJ thanks for the many things to give thought to but to fill everyone in on what's been done from beginning read below!
Original radiator was replaced ONLY due to deterioration, no leakage and it NEVER ran above 185 at any speed.
New, (used 3 month old) radiator was shipped to me via ebay purchase wrapped in plastic and on a skid.
Un wrapped the radiator, hosed it off, let it dry and painted it gloss black.
Next day, Susan and I installed it with no problems.
Took our first hwy trip with others somewhere in SC and  before we got out of Florida, it ran hot enough to illuminate the CEL. Cooled it down, topped it off and all was good since then except it's always ran in the HIGH 190's.
With help from other Busnuts, they recommended sealing the gap around the radiator since I DID in fact remove the original non working shutters. I did that! One also said to see if I had the original rock/air deflector under the coach. I DID NOT so I made one. I has removed the original black tank which left a large opening in the engine bay. I reinstalled that using it as a pan to hold all my Hoses and cables.
Still after all that no help!
I since said let's change the t-stats and water pump which I already had but never put in.
This is when we found the T-stats were clogged up with what appeared a red shop rag apparently was IN the radiator when shipped and I/We never seen and or caught!
Replacing the water pump also showed signs of red rag so the shop flushed out everything including the oil cooler. I wasn't there for that part so I'm stating what I was told.
Thinking we found the culprit, we travelled on but as you see, it still runs hot! Hotter than I really like!
Now I know you guys say 200 210 is ok but I find it really hard to buy that when before the radiator was changed it NEVER ran above 185° at any speed AND checking with Prevost, they too suggest no hotter than 190 on any given day and when I mentioned I lived In Florida, he bumped that to 195 MAX! Yea he says it won't shut down until it hits 215 but that's a safety thing nothing else. It's not meant to run there!
As for the muffler and all else? Everything was replaced NEW from exhaust gaskets to tail pipe so I do t think that's an issue.


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[luvrbus]

On the mechanical 8v92 the alarms go off at 205 and shutdown is 212 fwiw

[Ace]

That's still out of the norm from what it used to be!


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[Ed Hackenbruch]

 I would think that maybe like you said there is still more rag in the system. I would pull the t-stats and the water pump and see if more has come thru.  Then maybe a wire or boroscope to check up the hoses and inside the top and bottom of the tank?

[DMoedave]

As far as the fan blade, I had a good experience with Crowley fans. went from a 6 blade to a nine.