[Orangetxguy]

Originally Posted by Scottt

I thought the same thing when they pointed out my oil cooler to me. It bolts to the block and has your coolant flowing through it and I don't think air has anything to do with cooling the oil on a ISX.

I had oil in my coolant so I took it to the shop and they said the oil cooler has a hole in it so I asked how big a job. They pointed to the cooler and said about everything on this side of the engine has to come off..

I thought what a dumb place to put something you are trying to cool.

The oil thermostat is in the front of the block behind the ac compressor.......I never figured that one out either.

Just goes to show why you would not want me turning wrenches on a truck!!

[Maniac]

That's the trans oil cooler up in the front.

The engine oil coolers is actually water cooled, that's why I said the temp is usually close to what the water temp is, at least on my Cat it is.

There are no thermostats on the oil cooler that I know of, again that would be on a Cat

[Scottt]

Originally Posted by Maniac

That's the trans oil cooler up in the front.

The engine oil coolers is actually water cooled, that's why I said the temp is usually close to what the water temp is, at least on my Cat it is.

There are no thermostats on the oil cooler that I know of, again that would be on a Cat

He said he had a ISX 530hp

[Larry227]

Yes the ISX has an oil cooler thermostat which goes into the front of the oil cooler.
Here's a picture of it from the service manual.

[bob h]

The oil cooler uses the engine's cooling system to remove heat from the engine oil; that cooler is NEVER found out by the radiator, that I've ever heard of, always installed on the side of the engine block. It is normal for engine oil temp to run higher than engine coolant temp.

If oil temp is going out of range, and coolant temp is not; First thing to check is the oil level, and check oil for coolant contamination. Second, verify that the ECM is reading the oil temp correctly. If the oil is running too hot (and coolant is not), the oil thermostat could be the cause.

Keep in mind, engine oil degrades quickly in high temps.

[bob h]

Originally Posted by Scottt

I thought the same thing when they pointed out my oil cooler to me. It bolts to the block and has your coolant flowing through it and I don't think air has anything to do with cooling the oil on a ISX.

I had oil in my coolant so I took it to the shop and they said the oil cooler has a hole in it so I asked how big a job. They pointed to the cooler and said about everything on this side of the engine has to come off..

I thought what a dumb place to put something you are trying to cool.

The oil thermostat is in the front of the block behind the ac compressor.......I never figured that one out either.

The job of a thermostat (oil or coolant) is not simply to cool, it is to maintain temperature within a given range; too cold = bad, too hot = bad.

[LostSoul]

So far I have replaced the oil temp sensor ($150) and the oil thermostats ($802 at cummins). My oil still overheats on long or severe pulls. Coming back from Ohio with 43500 lbs in the box, I got alarms on the long steady pull up to Laramie WY and on Donner Pass. Both times near the top so I have significant capacity to pull, just not enough.

I do have a very small amount of coolant in my oil, not enough to make cream, but I have to add about a quart of coolant every three to four days.

I am really afraid this is going to get very expensive.

[Kranky]

How do you know that you have coolant in the oil?

Did you sample the oil and have it analyzed?

Just because you're adding a quart of coolant every 3 or 4 days doesn't mean the coolant is necessarily going into the oil.

If you do indeed have coolant in the oil (or vice versa), then have the oil cooler checked.

Since you've already tossed nearly a grand at it with no improvement, I'd recommend taking it back to the Cummins dealer and telling them you don't want to see it again until it's fixed right.

[COLT]

Starting to sound like my last truck... changed the oil cooler thermosats and ocasionaly it would still get a hot oil alarm and derate, it also used coolant but the oil samples must have been good still.

[Scottt]

Originally Posted by LostSoul

I do have a very small amount of coolant in my oil, not enough to make cream, but I have to add about a quart of coolant every three to four days.

When I had the hole in the oil cooler I would get oil on the cap of the coolant tank and when you would poke a hole in the oil filter before taking it off a small amount of coolant would run out first.

Before changing the cooler my oil would heat up to right where the buzzer goes off on a long pull.

Now my oil temp never moves off 230 degrees.