Overheating

[CUMMINS]

My M35 has just started over heating. Its done it twice in the last two days,but it has been around 100 degrees here.I checked the thermostat, I put new headgaskets in about 3 monthes ago, and have retorqued the heads 3 times, The truck will overheat in less than 10 miles of high rpm driving, the first time the temp got to around 230 before I found a spot to pull over, but it still ran fine after it cooled down, the EGTs stayed below 1000 degrees pre turbo, what am I over looking

 

[Jones]

Fresh radiator hoses? Old ones may collapse or some of the interior may delaminate, fold inward and cause a restriction. Radiator in need of a cleanout? Having them rodded and boiled out works wonders.

 

[spicergear]

If you get the radiator redone, get them to 'band' it as well. Will keep it around and healthy for a long time.

 

[cranetruck]

First time I had occasion to remove the radiator, I found 1/2 cup full of coresand and debris in the lower radiator hose. After cleaning it, I installed a coolant filter (see image).
Coolant "wears out" even if the truck isn't operated, replace it with fresh every 2 to 3 years and use additives to make it more efficient.
If the coolant isn't a clear greenish color, replace it and make sure the 3 gallons or so in the engine also gets replaced (radiator holds about 5 gallons for a total of .
I also installed a separate thermocouple probe next to the temp sending unit to verify that the dash gauge was reading correctly. When the needle is straight up on my gauge it's about 176°F.
Overheating is not problem for me, as a matter of fact I use a custom radiator cover to keep the temp up, even in the summer (image below). Used it on my recent trip to GA/FL and only removed it for the trip up the mountain with the 9,000 lb laundry trailer in tow.
Temp still didn't get much over 200°F for that part of the trip. I find the multifuel engine very efficient....

 

[Opie]

I'm apparently not smart enough to find the drain plug on the deuce multifuel engine block to get the last few gallons out. Any hints on where it is? Well, beyond the data plate statement on the dash that it's on the right hand (?passenger?) side.

 

[cranetruck]

If you can't drain the block (plugs seized or whatever), repeatedly drain/fill the raditor, run until t-stat opens to mix all coolant. Do it over, 4 or 5 times. This will leave only a small percentage of the original coolant in the system. The last fill-up will be with antifreeze plus additives. Then run it again to mix. To speed things up, the T-stat can also be removed for a quick mixing.
I have done this over a period of several days. Drain the radiator and refill with distilled water, drive as usual (which should open the T-stat and mix the coolant), then drain the radiator and refill with distilled water. After 4 or five times you fill the radiator with the antifreeze and additives for the right final mixture.

 

[devilman96]

Just a few hints... do these step by step.

Pop the cap and run it for a minute... Are there lots of bubbles coming out? If so get a leak test kit.. (IE head gasket or crack)
When your truck is hot feel the front of the radiator and see if there are cool spots in it, is it equally warm across the core? If not its plugged.
Or... Is your thermostat opening? Its RARE they don't work but usually get blamed and replaced first because its easy.
Start yanking hoses and changing them looking for debris and the likes.
Flush the system, you can add a gallon of CLR to your mix and run the motor for about 30 mins to clean it out. Afterwards FLUSH THE SNOT OUT OF IT!!!
Make SURE you have a 50/50 mix of antifreeze, to much will cause over heating also.

The filter shown above in Cranetruck's pics is the way to go for long term maintenance... Napa PN 4019

 

[m35a2cowner]

Coolant

I once replaced head gaskets on a gas motor and picked up a cooling problem pretty soon afterward. Turned out the head gasket replacement had broken loose some crud that plugger off some of the radiator. Removed the radiator (sadly after having put another set of head gaskets in thinking might have gotten wrong gaskets) and had it "rodded" out (run some kind of wire or brush through core) and reinstalled it and no more over heating until I got rid of 10 years later. On a related matter, I purchased some NAPA coolant inhibitor restorer. From the old days at mechanic school I remember the truck instructors saying to put this in to replenish the rust inhibitors as well as adjust the PH (similar to the previously mentioned coolant/water filter without the anti-cavitation element). Has anyone done this? Any reason not to? Its much-much-much cheaper than antifreeze and you just pour it in with the existing antifreeze. Thanks

 

[m108]

RE: Coolant

I think the block drain is at the very back on the passenger side under the oil pressure sending unit.

 

[Opie]

RE: Coolant

Thanks M108! I'm off from work tomorrow and will give it a look.
Opie

 

[CUMMINS]

Thanks for the replies. My truck is still over heating after trying everything, I have flushed the radiator repeatedly,and the water pump and themostat are fine. I have taken the thermostat out and ran the truck with out the fan belt to check for bubbles and there are a few that come out of the tank of the radiator through the vent pipe to the radiator filler neck, I'm guessing this isn't good, I don't see how the head gaskets could already be leaking compression into the cooling system, could the heads be cracked?

 

[devilman96]

Could be ether or... I always have my heads crack tested when I have them shaved... Usually its pointless but once in a blue moon it saves ya a lot of work and heart ache.

Napa sells a leak detector kit which uses a chemical to check the gases bubbling in the cooling system... Might want to get one and see what is up before going any further.

 

[houdel]

Just a thought - DO NOT use regular automotive antifreeze in a Deuce! Prestone, Wally World, Dexcool, etc antifreezes are designed for GASOLINE and light duty diesel engines. HD diesels as in the Deuce and other HD trucks use wet cylinder liners and MUST use antifreeze especially formulated for HD diesels. The reason is that wet liners run hotter than gasoline or light duty diesel engines, where the cylinder heat is transferred into the engine block and then to the antifreeze. Regular antifreeze will boil when it contacts a hot wet liner (technically known as cavitation) creating air bubbles on the surface of the liner. These bubbles will eventually rust through the liners and then your engine is then crap. HD diesel antifreeze contains SCAs (Supplemental Cooling Additives) which cause the antifreeze to wet the entire surface of the liner and prevent cavitation. You can buy test strips at HD truck shops to test the SCA and pH level of your antifreeze, you can also buy SCA recharges to bring your antifreeze back into spec without having to do a complete drain, flush and refill.

It is possible that if you added regular antifreeze to you system when you changed the head gaskets that could be a part of your problem.

 

[cranetruck]

I agree with Lee on the antifreeze and using test strips for acidity and freeze point.
Image shows my mix.

 

[cranetruck]

This picture should help in troubleshooting the cooling system.

 

[JasonS]

Cavitation erosion is similar to ultrasonic cleaning in that the cylinder wall vibrates causing the coolant to vaporize into microbubbles. When the cylinder wall moves away from the coolant, the pressure is reduced enough tor the coolant to vaporize. These bubbles inplode on the surface of the cylinder and erode away at the cylinder. I thought that the multi had dry sleeves???

 

[houdel]

I'm not 100% certain, but I'm pretty sure I've read they are wet liners. Never taken a LDT apart so I can't speak from experience. Perhaps Bjorn can answer. The pics in the part manual don't help either. I did see a liner tool kit advertised on Ebay, one of the pics showed the tool installed on a liner, and it sure LOOKED like a wet liner.

 

[gbooth]

The are not wet liners I replaced one in my truck wet liners have sealing O rings on them and the one I replaced did not. the way to tell is when you have the engine apart after you pull the liner out the water passage is continual.

 

[CUMMINS]

For my anti freeze I have used John Deere and Texaco antifreeze with a Napa rust inhibitor, so I don't think cavitation is the problem, I've seen 7.3 IDI diesels with cavitation and they would suck in coolant through the cylinder wall and burn it, and they would put steam out the exhaust pipe, I must have cracked a head or blew the gasket for some reason, anyone know were I could get a running motor or set of heads some what close to me(neighboring state) or shipped to me. I can't get the classified section to open for me so I can't see whats for sale. Thanks again for the help.

 

[jwaller]

I just purchased a multi from GL. I should be picking it up very soon. I'd be willing to pull the heads and sell them to you if I feel they are good.