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Author Topic: Getting the Heat out...  (Read 3806 times)
Iver
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« on: October 06, 2009, 01:57:20 AM »

It's been a while since I installed a newly rebuilt 8v92 in our MC9.(475hp).  After several short test runs to get everything working properly, I thought it was time to test the engine on a hill climb. We live on the coast of B.C. so it is no problem finding a mountain to climb. During all the first test drives the engine maintained a steady temp. of 195 degrees, in local driving or on the freeway.  (T-stats 195's)

The hill we climbed starts out slow but increases to 8% grade. I had no problem at first, certainly no lack of power and I held the rpm to17to 1800. After about 20 min. of climbing the engine temp started to rise. My gauge on the dash is not real accurate but I could watch it slowly moving upward.
I decided not to push it so I pulled over in one of the "chain-up" lanes and went around to the engine to check the rear gauge. It read 205.  After about 5 min. or so idling it went back to 195 and stayed there.  I considered my options and decided to retreat and head back down the hill.  Again the temp never went above 195.

The cooling system is stock with the addition of the large rads.

My questions are these....
1.  Would lower temp thermostats keep the engine temp down when hill climbing?

2. Is it possible to keep this 8-92 cool without major modifications?

3. Does anyone have a MC9 with a 8-92 with no cooling problems?

I have a friend with an Eagle with a 8-92 (large side radiator) whose temp never goes over 190* on any hill in any weather.

4. Has anyone converted a MC9 to a "side radiator"?

       Thanks,  Iver

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NewbeeMC9
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1981 MC9 8V71, HT 740




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« Reply #1 on: October 06, 2009, 03:54:16 AM »


Just out of curiosity, why did you choose 195 t-stats?


Temps won't stay below 190, even with an added side radiator, if you have 195 t-stats.



Seems this would be the easy place to start since you did get larger radiators.

Louvers in the rear door might be the next consideration.





just a thought

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luvrbus
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« Reply #2 on: October 06, 2009, 04:18:41 AM »

A while back on this board the operating temps were discussed about thermostats 205 is going to be about the normal range the for a 195 degree thermostat.
The 195 is when they start to open fully open at around 200+ thermostats are to keep the engine from falling below the 195 degree temps has nothing to do with going above the range of the thermostat in other words change to a 180 and maybe your engine will operate around 195.



good luck
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RickB
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81 MCI 9 smooth side 8V71 Allison 754




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« Reply #3 on: October 06, 2009, 06:14:14 AM »

Iver,

I would get her up to 200 or so again and then I would IR gun the inlet and outlet of both stats and just for good measure I would check all the individual cylinders at the exhaust manifold to make sure that you don't have more going on here than you might think.

IR the radiators for cold spots (blockages) and the water pump inlet and outlet as well.

Let us know what you find out.

Rick
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Iver
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« Reply #4 on: October 06, 2009, 10:30:38 AM »

Actually I don't think I would have chosen the 195's but my engine rebuilder put  them in according to the "book" which shows 195.
I don't have a temp gun yet but it is on my shopping list. I guess what I will do first is to change the t-stats and do another test.
I like the idea of louvres in the engine doors as well.

Another question....I want to change the temp gauge on the dash as it is not real accurate. Does the sending unit need to changed as well?
        Thanks, Iver
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luvrbus
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« Reply #5 on: October 06, 2009, 10:57:54 AM »

Iver, my  book shows 180 to 190  for the manual 8v92 engine. You will love the 8v92 fwiw if you reduce it 450 hp there will less heat,less smoke and better fuel milage and watch your foot keep it around 1800 rpm at all times on hard pulls and it will  serve you well for a long time.Louvers are not going to help with the internal cooling on a 8v92 but they do keep your engine compartment cooler 


good luck
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edvanland
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« Reply #6 on: October 06, 2009, 03:16:35 PM »

I have a 8V92 in my MCI 7 with automatic.  When I bought it had real problems with the overheating. Put in new slightly larger radiators with dimples, air scoops, and 175 degree thermastats. On hot days on a long climb I open up the rear doors and that helps by about 10 to 12 degrees. I also found some very bright aluman panels and cut the bottom of the rear doors and put a piece of this on each side.  It allows some of the heat out when running.  By the way I live in Cornvill Arizona so any which way I go I have a long 6 or 7 per cent grade to climb and I normally am towing a trailer.  I keep a eye on the temp gauge and the tach.  When the RPMs go down I down shift and keep it at 1900 to 2000 RPMs. I don't care how fast I am going when I top the hill, just how cool it is. Works for me. Next step is a very large trans cooler.
ED
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Ed Van
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loosenut
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« Reply #7 on: October 06, 2009, 03:28:41 PM »

Get your ir device before you do much to the engine.  My temperature gauge on a 6v92ta is inaccurate when compared to an ir gun.  My gauge showed over 200 yet I couldn't find a 200 temp in the engine compartment.  I checked at the thermostats, freeze plugs, radiator in and outlets etc.

Once you have reliable data you might not need to change a thing.

Mike
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RickB
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« Reply #8 on: October 06, 2009, 04:04:55 PM »

Iver,

The stats are gonna cost you alot more than the IR gun. They are on sale at Harbor freight for $35 or so.

The IR gun will save you the stat money if that's not the problem.

Rick
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johns4104s
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« Reply #9 on: October 06, 2009, 05:05:53 PM »

Iver,

Be aware the IR is only approximate, you need to have a good gauge and yes you should also change out/match with the sending unit. i also have a 8v92 with Allison auto. They changed to big radiators, its turned down to 400 hp, They also installed a tranny cooler. I have to really push it with a 5000ib trailer to get it to 200 deg.

John
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rv_safetyman
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« Reply #10 on: October 06, 2009, 05:10:58 PM »

Be a bit careful about putting all your eggs in the IR temperature measuring device basket.  High quality units have adjustments for emissivity.  The issue is that a black body radiates heat differently from a shiny light colored body.  The expensive ones ($200-300) are quite accurate and yield repeatable results.  

We used them many years ago to measure dynamic belt temperature in our belt test lab.  We calibrated them often with a black body instrument (belts are black).

I suspect that the cheaper units are set for a black body, but I don't know that.  Further, they are most likely significantly less reliable as compared to laboratory units.  I think the cheap ones are great for finding differences in temperatures and for looking for hot spots in things like electrical cabinets.

In this case, folks are trying to have you "calibrate" your dash gauge with an instrument of unknown accuracy.

Couple that with the thought that a two stroke engine is very unforgiving about maximum temperature and if you are off by 5 or 10 degrees, you can get yourself in trouble.

It might pay you to hunt around and see if you can find a company with a high accuracy unit that would allow you to compare your unit with.  An alternative would be to see if you can find a lab that has temperature calibration equipment that will check your newly purchased gun.  You could also consider purchasing a brand name unit with calibration information included with the unit.

Jim

OOPS, John and I posted at the same time.
« Last Edit: October 06, 2009, 05:14:07 PM by rv_safetyman » Logged

Jim Shepherd
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harpold700 3
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« Reply #11 on: October 06, 2009, 05:19:32 PM »

Go with low temp stats,170 180max. I run 92 power in my log trucks for years, anything over 200 degrees is certain death for your engine. My 8-71 is going to get a set of 160's.  I live in Princeton give me a call, 250-295-3568. Got lots you should know. Gord
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luvrbus
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« Reply #12 on: October 06, 2009, 05:24:53 PM »

Jim is right on about the IR guns after 5 of the cheaper ones I broke down and bought a Raytek ST 60 XB but I probably use one more than most the cheap ones have such a close spot distance area some are like 12 inches .  


good luck
« Last Edit: October 06, 2009, 05:41:31 PM by luvrbus » Logged

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luvrbus
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« Reply #13 on: October 06, 2009, 05:33:56 PM »

Iver, lots of advice here but the 8v92 needs to operate at 175 degrees minimum don't run it too cold that is why the 180 degree t stats are the best choice
good luck
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Doug1968
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« Reply #14 on: October 06, 2009, 06:15:52 PM »

Hey you guys,

I've been following this discussion and I was wondering if anyone was going to talk about a mist water system? I've read on some postings about some who have installed the mist systems to assist with lowering motor temperature during the climb through the mountains.

Do these systems help? 

Doug
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1986 MCI 102A3 - 8V92 - 5 speed
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