Cummins Oil Cooler Trouble Anyone?

[afrank1971]

Has anyone else had oil cooler troubles? I have a Cummins ISL 400, at 6,350 miles, in Sundance, Wyoming, I discovered oil in my coolant (dripping out the coolant overflow tube). I was able to limp it in to Cummins Rocky Mountain in Gillette, where it spent the next 3 to 4 days of our trip having the oil cooler replaced and coolant system flushed. Our next trip out, to our local desert, when we got home our trailer was splattered with oil, oil in the coolant again, and dripping out the coolant overflow tube, again. So at 8,159 miles it went in to Cummins Cal Pacific, who said it was just leftover residual oil from the previously replaced oil cooler problem, and said it simply needed to be reflushed again. Now I've driven a whole 96 miles, mileage at 8,255 miles, and I found this morning a new layer of oil in my coolant. Not yet leaking out the overflow, but certainly more than when I checked it at Cummins Cal Pacific when I picked it up.

So, question to everyone is, how long does it take to get all the oil out? I can't help but feel I'm getting the run around. Like it's not that they know it's the oil cooler so much as they don't want to rip into the engine to figure out what's really pumping oil into the coolant system. If anyone has any experience with this issue, and how patient I should be, any advice would be greatly appreciated.

Thanks,
Alan

[justlou]

If it really is residual oil, you should not see a drop in transmission oil level. However, I don't think there would be that much oil remaining in the system. I would check the transmission level to see if it is remaining full. If not you still have a problem.

[afrank1971]

My thoughts as well, there shouldn't be that much if it's just residual. It's engine oil, not transmission, but it indeed does drop. This latest "residual" amount is not yet a detectable amount to register lower on the engine dipstick, but I'm sure it won't be long. I think I'm giong to have to go run it a while to build up some more oil in order to convince them I guess.

[Lug_Nut]

Were they sure that the oil cooler was the issue? Did they pressure test it to determine it definately was it? A leaking head gasket could also cause similar.

Peter

[afrank1971]

Thats really the question I've been asking as well, whether or not they're sure it's the oil cooler. In WY, the guy came out, looked in the reservoir, and said "yup, it's the oil cooler". I don't know what they did at Cal Pacific, but the previous work order from WY stated that it needed another flush, so I don't think they looked any further. They just flushed it. Luckily I have a buddy thats a Cummins/Daimler diesel mechanic who last night set me up with how we can test it to verify that in fact the oil is still pumping through. Once I complete that test, I'll know for sure if there's still something wrong and hopefully be able to get someting to happen. Will keep you all posted.
Thanks,
Alan

[Rick & Hope]

I don't have any experience with rv Cummins but our semi with isx had the oil cooler go out. The dealer flushed it 5 or 6 times to get all the oil out. This was done at the time of the oil cooler replacement. Never saw any more evidence of oil in the coolant.

[afrank1971]

Thanks Rick, thats the kind of experience I'm looking for, and about what I thought. I know they flushed it several times, all day they said, in Wyoming, and then again once or twice here at Cal Pacific. It should be a done deal by now. Just need to convince them now. Thanks!

[Roadwander]

If they are using only water to flush the cooling system it might be a long time before all the oil gets removed. When oil gets into a cooling system, it gets everywhere - - inside the engine, the radiator and don't forget the heater core along with its associated plumbing and lengthy hoses. My experience with Diesels is severely limited but with passenger cars we had to use a cooling system flushing compound (soap or perhaps a solvent) that would break down the oil to make it "water soluble" so it could be flushed out. Interestingly enough, the stronger the flushing compound, the better it worked but the harder it was on the water pump seal.

On a related note, when oil-to-water coolers leak, they leak oil into the cooling system when the engine is running because there is probably 40-60 PSIG engine oil presure and only 16 PSIG in the cooling system. But, when the engine is shut down and the oil pressure drops to zero, there is still about 16 PSIG in the cooling system and the engine coolant will then be forced into the engine oiling system - - ie; you get coolant in the oil.

It might be prudent to test your engine oil for gylcol to see if any coolant has leaked into the oil - - if it has, you might want to change it along with the oil filters.

[Roadwander]

I read your post a second time and it triggered some additional thoughts so I'm back again.

Regardless if you have oil in the coolant or not, the coolant will not blow out the overflow tube unless the cooling system pressure exceeds the relief pressure of the radiator cap. Something is pressuring your cooling system and if you are finding oil in the coolant, then there is a path somewhere for the oil to get into the coolant. Make sure the radiator cap is ok and that there is not any debris where the rubber seal on the cap meets the radiator neck.

Also, it seems like you are experiencing identical symptoms after the cooler was replaced so the chances that you have (or even had) a cooler leak are seemingly quite remote.

[afrank1971]

Okay, ran the engine for a total of 7 hours, 4 hours and then another 3 hours. Started out by cleaning out the oil from the coolant reservoir with paper towels and placing them in a plastic bag, and checking the oil level. Then ran it for 4 hours at 1,600 RPM, let it cool down and checked things out. Coolant reservoir had oil in it again, and the oil level was slightly down. Cleaned it out and saved the paper towels again, then ran it another 3 hours. Let it cool down and found yet more oil in the reservoir, and the oil level down yet a bit more. This should be more evidence than they need, and certainly more than I should have had to do myself. Trained Cummins technicians should have been able to figure this out. So, now back to Cummins to see if these test results can convince them that something is still wrong. We'll see, and will let you all know.
Alan

[RVDude]

We are talking engine oil and NOT tranny right? Me thinks lug_nut has the rational cause....
oil levels keep going down, oil keeps showing up in the coolant, something pressurizing the coolant system beyond 15lbs...
Only a sustained pressure test will determine what/where... Are you seeing any whitish foam in the oil or on the dipstick? I am surprised there is not a reverse drip of coolant into the oil when not running - the whitish foam is a telltale.

[afrank1971]

To be honest, I have been surprised as well to not see any coolant in the oil, but there does not seem to be. In my experience that's usualy a two way street. Seems that the oil going into the coolant system simply keeps filling it up until there's too much overall fluid and then it spills out the overflow. And yes, it's engine oil, not tranny fluid. Hopefully I can convince Cummins to properly test and diagnose it this time, I believe I have the proof I need to show that there is still a problem.

[FleetMan]

When the oil cooler on my International engine (Ford PSD pickup) failed, the higher oil pressure, engine running, forced oil into the coolant but apparently the 15 to 16 PSI in the cooling system was not enough to force coolant into the oil when the engine was not running. You may have a similar situation. The continuous drop in oil level and appearance in the coolant should be enough to get Cummins to react. Don't let them attempt to brush you off!

Can Newmar intercede for you and apply some leverage on Cummins on your behalf?

[afrank1971]

Coach is back at Cummins now. At least the tech I dropped it off with agreed there must still be a problem. We'll see what they come up with, and I'll be keeping my fingers crossed.