8V92TA Running Hot

[cfherrman]

Do you hook the lines that feed the cooler together then?

 

[Huffa]

I've done this in the past with a truck when the cooler burst a seam and another couldn't be acquired fast enough. Only detriment was an increase in exhaust temperature which was easily compensated for by an easier application of throttle, and a slight alteration of the driving style. No long term effects when the replacement cooler arrived and was installed.

That's been over 20 years ago and the truck was still around till last fall when sold off. Not many grain haulers around here running straight trucks any longer.

So with that being said why would I ditch the cooler if it can be cleaned and is otherwise in good condition? There is no room for adjusting driving style here, we're regularly pulling up hill and its full noise otherwise you won't make it

 

[1693TA]

I didn't mean to "ditch" the cooler at all. In the reference cited it was grain hauling season and the cooler was bypassed to keep the truck working. The cooler was replaced about a month later with a new DDA unit.

 

[Huffa]

Oh yip I see cheers

 

[1693TA]

Do you hook the lines that feed the cooler together then?

The cooler is fed through the cylinder block. You install a plug in the block and plug the discharge line from the cooler outlet at the engine. I used a piece of pipe and a cap clamped into the rubber hose lines for this. Basically you are converting to a non aftercooled cylinder block. This photo kinda shows what is done to bypass the cooler:

 

[cfherrman]

Ok, I'm not getting the part on how blocking the flow is better then a partially blocked cooler would make the engine run cooler?

Is the return coolant from the aftercooler extra hot on a partially blocked cooler than as it stays too long in the cooler?

 

[mekanik]

The cooler fins get blocked and restrict the air flow from the turbo and blower into the air box.
Its not from coolant flow through the aftercooler.

 

[cfherrman]

Ok so you are temporarily deleting the after cooler?

 

[Huffa]

Na it's going back in. Its in good nick, wasn't even dirty At a crossroads of weather to carry on and pull heads or not as we're this far, mechanic is reluctant to fo that, he just can't see it being the heads in his opinion, so next thing to do if it goes back together is to set the top tune and then reverse flush the block/heads cooling system as per Detroit manual.

 

[1693TA]

You might pull your water pump off and ensure the impeller is firmly attached to the driving shaft while it's apart and down. Referencing the photo below I have seen the nut retaining the impeller to the driving shaft come loose allowing the impeller to chew up the deflector causing cavitation of the coolant and subsequent overheating of the engine. This was on an engine generator set and it would only overheat when carrying facility load, or was being load banked. The impellers are a heavy bronze casting and if they become loose they destroy themselves, the shaft, and anything else it comes into contact with.

 

[Huffa]

Ok thanks will do. Water pump has to come off for flush. However we have done the water pump recently, it was perfect

 

[Coaldust]

Unless you are experiencing combustion gas pressurizing the cooling system, or water in the basement, I wouldn’t remove the heads, either. Probably create new problems by doing so.

 

[Huffa]

Huffa,

Don’t mess around. Those cylinder heads crack at the first overheat. Or, if you look at them funny.

I'm getting confused

 

[Coaldust]

Don’t be. Troubleshoot the heating problem, first. The cylinder heads are not causing the overheating. You could install new reman heads, and be disappointed when the engine still overheats.

 

[Coaldust]

With it hot, take a top tank and a bottom tank temperature and share your results. Are you trusting the dash gauge? How do you know it’s accurate?

 

[Huffa]

Ok. So it has two gauges, one on each head, one electronic and the other capillary, both read within khooey of one another. I have tried the heat gun on the radiator and engine ages ago, I found it jumped around a lot with the different metals and painted or not, wasn't good for much imop

 

[Truck Shop]

Two ways to check for cracked heads, test for gases with a bottle test or attach a hose to the highest
point with a gauge run into cab so it can be watched under load conditions.

 

[Vetech63]

I'm still not convinced this is an engine problem.

 

[mekanik]

There should be a place to drain the coolant at the rear of the engine block on both sides? If you could plumb a pressure gauge in and measure the coolant pressure in the block it will tell you the pump is working and the oil cooler is not blocking the coolant flow. I would expect to see close to 40 PSI above rad cap pressure at 2000 RPM.

 

[John C.]

I use a coolant system pressure test cap. If you have combustion gas in the cooling system, you can watch the pressure climb as soon as you start the engine.