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Ok- I'm about to embark on an oil cooler gasket replacement. Has anyone done it? Any tips? My search of the site has not given me any guidance, so I'll post whatever I learn in the process. if you know of any resources, please let me know.

 

My oil cooler leaks coolant intermittently, mostly not at all bust occasionally a lot, enough to require a gallon or more of new fluid in a day or two.

 

I found the cummins parts for $35 on ebay.

 

I'd welcome any input...

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                                          This might help.

 

 

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I'm assuming that you only leaking coolant and not mixing oil and coolant right? If so the gasket and seal change is rather straightforward. Remove what you have to get workspace. Next, you spin off your oil filter and unbolt the oil cooler. Replace the seal and gaskets and reassemble. 

 

Now I'll warn there is a seal under the lower radiator neck on the block as well so verify the leak source with a coolant system tester on a cold engine and follow the coolant trail back to its source. Like my last coolant leak happen to be the passenger rear corner of the head gasket. This is way more involved than a oil cooler gasket.

 

This brings up another subject to make sure to change coolant on a regular basis. Don't rely on the 5 years and 100k miles coolants even these don't make it that far. With the Mighty Cummins requiring a large current draw to fire up the engine, the negative polarity is rushing through the coolant and charging the coolant. This will make it corrosive. Hence the gasket failure. Make sure yo flush the block out really well and reload with fresh coolant and fresh thermostat. 

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I always inspect oil cooler core and oil by-pass valve for damage and debris. Debris is an indication of an internal engine failure such as bearings or even a camshaft. I always pressure test the oil cooler core also.

 

 

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That does help, thanks. I have no reason to suspect any internal failures, but it's obviously prudent to check everything I can while I have it open.

 

Definitely going to look into that Cummins Quickserve info source too.

 

And thank you, Mopar1973Man as well. 

 

I was seeing occasional coolant drips and sometimes large puddles in hot weather this summer, enough to warrant up to a gallon of new coolant on two occasions. I avoided really overheating it. No oil / coolant cross contaminations, just clean looking coolant dripping after I shut it off.

 

Strangely, it has stopped all together and I was monitoring it and waiting for the right time to get into it. I had a similar intermittent leak from one side of the radiator core two winters ago, but only during warmup on very cold mornings. That too went away. I never used and stop-leak... I guess I would save that for an emergency...

 

But based on the age of the engine, 370K, and some unknown service history (I acquired it at 320K) my inclination is to replace just about every renewable part I can easily reach. The truck is presently up on blocks for a rebuilt transmission and a new clutch, so this is the time to hit all the other stuff that has been waiting. I'm doing a new radiator, hoses, Power Steering pump & hoses, rear main seal, and trying to address this coolant leak. I'll also be doing new injectors, but that'll be a whole different thread.

 

I could see clearly that it was not leaking from around the water pump, and that it was behind there along the block somewhere. Because the AC compressor and other plumbing is in the way, it was hard to tell, but I guess it has to be either the oil cooler or the lower hose neck. Since it hasn't leaked since summer, and hasn't lost coolant, I'm not sure I'll be bale to get it to leak with a pressure test but I have ordered the tester and I'll try it out. Hopefully I'll find some trace of the old leak once I get it all exposed. There has been no sign of leakage up around the head gasket, which I appreciate.

 

And thanks for the warning on coolant- duly noted.

 

Edited by piñon&juniper

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I hate intermittent leaks. Cooling system pressure tester is what I recommend to pinpoint the leaks.

 

Also this is what Cummins has to say about coolant. I myself use Fleetgaurd ES Compleat in both my 2nd gen Cummins powered trucks and tend to stay away from light duty automotive coolants such as Prestone.

Screenshot_20181021-113742.png

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3 minutes ago, 04Mach1 said:

I hate intermittent leaks. Cooling system pressure tester is what I recommend to pinpoint the leaks.

 

Also this is what Cummins has to say about coolant. I myself use Fleetgaurd ES Compleat in both my 2nd gen Cummins powered trucks and tend to stay away from light duty automotive coolants such as Prestone.

Screenshot_20181021-113742.png

 

Then you would freak out to the thought I've been using "creek water" and "well water" for 16 years and the cooling system is perfect condition. I've NEVER used distilled water ever in my cooling system. 

 

 

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Mopar1973Man, could your creek water have contributed too the leak you had in rear portion of your head gasket?:sofa:

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34 minutes ago, Mopar1973Man said:

 

Then you would freak out to the thought I've been using "creek water" and "well water" for 16 years and the cooling system is perfect condition. I've NEVER used distilled water ever in my cooling system. 

 

 

As long as the chemical make up an hardness of the water is within Cummins specs I wouldn't have an issue with well water or creek water.

 

This DOES NOT meet Cummins specifications.

Screenshot_20181021-121651.png

 

 

This DOES meet Cummins specifications.

 

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Edited by 04Mach1

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 I have not checked that one out yet on my truck  (Lubricating oil pressure regulator), but I heard you guys mention that before. I did find some chunks of valve seals in my oil filter, when I redid my seals. Doesn't all the oil has to go through oil filter first before it gets to that port. But I guess being so close to the filter maybe it doesn't. 

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I always use distilled water.  Our county water has a high level of chlorine added. (kinda messes up the avoid chlorides part)  and our well water has a lot of sulphur (messes up the avoid sulfates part....) and other heavy metals and minerals.  so I am better off using distilled and watching Ph.  

 

Hag

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