dkontz6234 Report post Posted October 17, 2018 I have a Cummins 400 diesel engine and I have coolant in the oil. I had the oil cooler replaced and it happened again. Any ideas on what else could cause this? Share this post Link to post Share on other sites
sstgermain Report post Posted October 17, 2018 Egr cooler comes to mind. Really need to do a pressure test. Dont run it as antifreeze will eat the bearings real quick like. Share this post Link to post Share on other sites
dickandlois Report post Posted October 17, 2018 4 hours ago, dkontz6234 said: I have a Cummins 400 diesel engine and I have coolant in the oil. I had the oil cooler replaced and it happened again. Any ideas on what else could cause this? There is a possibility of a blown head gasket, cracked head. Engine running Rough or white smoke in the exhaust? What year is the Coach / Engine ? Rich. Share this post Link to post Share on other sites
wolfe10 Report post Posted October 17, 2018 As suggested, DON'T guess. Do a pressure test and verify exactly where the leak is. Could be minor or major, but, as Steve said, it needs to be handled before you do significant engine damage. Share this post Link to post Share on other sites
dkontz6234 Report post Posted October 17, 2018 The coach is a 2008. After they replaced the oil cooler they did a pressure test and everything checked out They took out for a test drive and checked it again, and there were no problems. I drove it 32 to miles to a park where we are staying. I didn't check anything when I got here, but 3 weeks later I started the engine and the low coolant light came on. I checked the oil and it was a milky grey color. I have an appointment to have it towed back to Frieghtliner next week. Share this post Link to post Share on other sites
manholt Report post Posted October 17, 2018 Where are you staying? Ambient temp? Share this post Link to post Share on other sites
dickandlois Report post Posted October 18, 2018 dekontz6234 3 weeks later I started the engine and the low coolant light came on. I checked the oil and it was a milky grey color. From the time you parked the coach at the park, was the engine ever restarted? Like Carl asked, What was the ambient temperature swing from cool morning to the high point during the day; over the 21 days? Rich. Share this post Link to post Share on other sites
cmarq Report post Posted October 18, 2018 Find the leak before any repairs, I had 40 years at Cummins Ct. There are many places coolant can get into the oil. If you do any disassembly before finding the leak you have are playing the guessing game. Share this post Link to post Share on other sites
manholt Report post Posted October 18, 2018 Personally, MHO, I would take the coach to Cummins. It's their engine! If I had a chassis problem, then Freightliner or Spartan! Share this post Link to post Share on other sites
hermanmullins Report post Posted October 18, 2018 There are times when do it yourself is the way to go and times for the pros. Carl is correct this is time for the Pros. Herman Share this post Link to post Share on other sites
dickandlois Report post Posted October 18, 2018 dekontz6234 I do not disagree with Carl, cmarq or Herman. When the Engine is running - oil pressure is higher then the coolant pressure and when the engine is hot and not running - The coolant pressure is higher then the oil pressure. From your information / there is no oil in the coolant - only coolant in the oil. One way cross barrier transfer from coolant to oil? Water pump issue? Engines are setup different for different applications - Water cooled air compressor? Good luck ! Rich. Share this post Link to post Share on other sites
jleamont Report post Posted October 18, 2018 I have seen everything from Cylinder cavitation, multiple oil coolers fail, Air Compressor leaking, all ended up with coolant into the crankcase and sadly all long before 100,000 miles. As Carl Mentioned, Cummins dealer would be my 1st choice, 2nd would be a Freightliner dealer with the Cummins licensing. Share this post Link to post Share on other sites
manholt Report post Posted October 18, 2018 Joe. You would be my first choice, then the rest in order! I smell an engine Ernie in Texas, on 5 ac. Share this post Link to post Share on other sites
dkontz6234 Report post Posted October 19, 2018 There is also oil in the coolant. We are staying in Phoenix, AZ. Share this post Link to post Share on other sites
rsbilledwards Report post Posted October 20, 2018 Pressure test! Find the leak then act Share this post Link to post Share on other sites
dkontz6234 Report post Posted October 20, 2018 It was pressure tested when the oil cooler was replaced, it held for 45 minutes. It was pressure tested again after the test drive, and it held. Share this post Link to post Share on other sites
wolfe10 Report post Posted October 20, 2018 And, now??? Share this post Link to post Share on other sites
rsbilledwards Report post Posted October 21, 2018 Pressure test the entire cooling system in order to find where the coolant is entering the oiling system. You know the oil cooler is fine. The coolant system is not. It could be a number of places. Apparently you need a real mechanic...just sayin...maybe What you learned from the oil cooler check is that it is not your issue... Share this post Link to post Share on other sites
dkontz6234 Report post Posted October 21, 2018 And now I have Coolant in the oil and oil in the coolant. Share this post Link to post Share on other sites
dkontz6234 Report post Posted October 21, 2018 " Apparently you need a real mechanic...just sayin." The coach was at a certified Cummins service center. They have worked on my coach since I bought it in 2013. Share this post Link to post Share on other sites
richard5933 Report post Posted October 21, 2018 Not every problem which causes oil-coolant crossover can be found with a pressure test, especially problems which happen only when the engine is being operated. They did a pressure test - no problem found. Yet, you still have a problem. Not many choices here - either take it back to them to have another crack at it or find another shop to get a second opinion. No matter how good a shop is, there are times they miss things. As already mentioned, there is a long list of things which can cause the problem. Many of the possibilities in this situation are expensive to repair, so hopefully it will turn out to be something external which can be easily repaired. Share this post Link to post Share on other sites
hermanmullins Report post Posted October 21, 2018 dk, Not being a smart alex but everyone agrees that you had it pressured tested and it checked out good. But thing happen over time or in the blink of the eye. Please take it back to the shop you trust and tell them what has happened since they tested it before. That is the best advice I and everyone else can give you. Herman Share this post Link to post Share on other sites
manholt Report post Posted October 21, 2018 Herman, Richard. You got my vote! dk. After the pressure test, how far, long and under what conditions was the test drive, before the next test...did it sit & cool off or was it done right away? Share this post Link to post Share on other sites
dkontz6234 Report post Posted October 22, 2018 Not sure if the pressure test was done right after the test drive or after it sat for awhile. Does that make a difference? Share this post Link to post Share on other sites
wolfe10 Report post Posted October 22, 2018 34 minutes ago, dkontz6234 said: Not sure if the pressure test was done right after the test drive or after it sat for awhile. Does that make a difference? The answer is "it could" (make a difference). Heat expands/cold contracts. So cold can cause some things to leak worse. But, more pressure in both oil and coolant systems with engine running, so somethings leak worse then (not related to pressure test, but very relevant for when you are driving). Share this post Link to post Share on other sites
