Monday, November 22, 2010

Cummins ISB Troubleshooting Coolant In The Lubricating Oil

The Cummins ISB diesel engine is one of my favorites in the fleet, simply because it's easy to work on and really does not cause a lot of problems in the long run. Every Mechanic knows that easy accessibility is key to a smooth repair and these models are great to work on even if the back 2 cylinders are under the firewall on a school bus.

However no diesel is perfect so follow me through this quick troubleshooting procedure if you experience coolant in the lubricating oil.

1. The first thing to check is the lubricating oil cooler. The engine oil is cooled by way of the coolant running through a sealed core inside the housing. If it develops a leak you're stuck with coolant getting in the oil. The coolant core can be tested and replaced.

2. The next possibility is the air compressor cylinder head is cracked, has a defective casting (porous) or the head gasket is defective. This is an overlooked cause, the cooling system from the engine is connected to the compressor running through the compressor cyl. head.

3. If  your cummins isb engine came with an aftercooler it can be pressure tested to see if there is any problems with the inner core leaking.

4. The engine cylinder head is the next possibility with a leaking core or defective expansion plugs. The head must be checked out with a pressure test and magniflux test to find any leaks or cracks.

5. Last but not least is the worst case scenario, the cylinder block. If it's cracked or porous you may  be looking for a replacement block or reman (remanufactured) engine.

These are mechanic tips that you can use to get you started finding the cause of coolant in your engine oil.

CHECK OUT ALL MY PREVIOUS POSTS ON THE CUMMINS ISB ENGINE

6 comments :

Branden said...

Hi John,
I've been checking your blog for awhile. I'm trying to understand what's going on in my 1981 35’ Bluebird All American FE. I've got a problem my local dealer/mechanic can't figure out and I thought I'd see if you had any ideas. I’ve also posted to a bus group I’m in. Your post got me thinking: my problem has to do with oil leaks, black smoky exhaust, and disappearing ATF.
It’s got a Cummins 555 9.1L with an Allison 545 and has been slowly leaking oil, and is now badly. On a trip in September to Nevada it lost 2 gal in 1500 miles. It was leaking a couple teaspoons in ten minutes of idling. Once shut down and cool it stopped dripping. It was also putting out major clouds of black smoke on a July trip to Montana when highway driving and letting off the accelerator (down a grade) and then stepping on it hard. I attributed it to very low oil and new diesel fuel treatments (FPPF injector cleaner and diesel additive). The smoke mostly cleared with an oil add/change.
In the last 150 miles home in September, an unlabeled red light on the dash came on, with a buzzer, for the first time in my ownership (5 yrs). It started coming on in the passes, particularly when going from slogging up to cresting and heading down. I thought it might be the automatic transmission fluid. The dipstick is hard to read (long and smears when withdrawing), so I'm not clear we were perfectly correct in our assessments of levels (very low, but red and clear) but the light turned off when we added two quarts. After about 75 miles, it all happened again-light, buzzer, refill transmission fluid. We went through 2 gal(!) of ATF in 150 miles. Up until the last 50 miles of the trip, the engine temp (water) and oil temp gauges were reading fine. Hot uphill, but cooled off right away. The last bit of the trip, though, the oil temp went near redline zone, I think around 390. I was able to keep it low enough (below redline) to get home and it's been in the shop ever since.
The oil is a leaking valve gasket (cover?). The ATF problem, though, is a mystery. Transmission shifts fine, and there are no signs of fluid leaks according to the mechanic. Their theory is that the radiator is not working well enough to keep the ATF cool, and it is vaporizing. This idea is supported by some vapor leakage evidence (unclear to me, just something the dealer mechanic said).
The radiator has been (now) diagnosed (with a heat sensor) to be only partially functional. 40 percent has some blockage, particularly at the bottom where the transmission cooler apparently is. They say radiator is too old to rod out (re-core?), apparently the metal is pretty thin. Thus, it seems like radiator replacement is the only solution. Does this sound like a plausible fix to the ATF problem?
The other question is about the huge clouds of black smoke. They were not the normal cold-engine smoke, nor were they light gray, or blue. They were black, and sooty. Maybe the problems are related, and I'm burning vaporized ATF? It's running and shifting like a top. The smoke clouds have mostly gone away, but I hate to not mention useful symptoms...
I wish I knew more about diesel engines so I could troubleshoot! Anyhow, if you've got time and an idea, great. If not, keep up the awesome blog! Thanks... Branden silvertrooper@gmail.com

Branden said...

Hi John,
I've been checking your blog for awhile. I'm trying to understand what's going on in my 1981 35’ Bluebird All American FE. I've got a problem my local dealer/mechanic can't figure out and I thought I'd see if you had any ideas. I’ve also posted to a bus group I’m in. Your post got me thinking: my problem has to do with oil leaks, black smoky exhaust, and disappearing ATF.
It’s got a Cummins 555 9.1L with an Allison 545 and has been slowly leaking oil, and is now badly. On a trip in September to Nevada it lost 2 gal in 1500 miles. It was leaking a couple teaspoons in ten minutes of idling. Once shut down and cool it stopped dripping. It was also putting out major clouds of black smoke on a July trip to Montana when highway driving and letting off the accelerator (down a grade) and then stepping on it hard. I attributed it to very low oil and new diesel fuel treatments (FPPF injector cleaner and diesel additive). The smoke mostly cleared with an oil add/change.
In the last 150 miles home in September, an unlabeled red light on the dash came on, with a buzzer, for the first time in my ownership (5 yrs). It started coming on in the passes, particularly when going from slogging up to cresting and heading down. I thought it might be the automatic transmission fluid. The dipstick is hard to read (long and smears when withdrawing), so I'm not clear we were perfectly correct in our assessments of levels (very low, but red and clear) but the light turned off when we added two quarts. After about 75 miles, it all happened again-light, buzzer, refill transmission fluid. We went through 2 gal(!) of ATF in 150 miles. Up until the last 50 miles of the trip, the engine temp (water) and oil temp gauges were reading fine. Hot uphill, but cooled off right away. The last bit of the trip, though, the oil temp went near redline zone, I think around 390. I was able to keep it low enough (below redline) to get home and it's been in the shop ever since.
-continued-

Branden said...

-continuation-
The oil is a leaking valve gasket (cover?). The ATF problem, though, is a mystery. Transmission shifts fine, and there are no signs of fluid leaks according to the mechanic. Their theory is that the radiator is not working well enough to keep the ATF cool, and it is vaporizing. This idea is supported by some vapor leakage evidence (unclear to me, just something the dealer mechanic said).
The radiator has been (now) diagnosed (with a heat sensor) to be only partially functional. 40 percent has some blockage, particularly at the bottom where the transmission cooler apparently is. They say radiator is too old to rod out (re-core?), apparently the metal is pretty thin. Thus, it seems like radiator replacement is the only solution. Does this sound like a plausible fix to the ATF problem?
The other question is about the huge clouds of black smoke. They were not the normal cold-engine smoke, nor were they light gray, or blue. They were black, and sooty. Maybe the problems are related, and I'm burning vaporized ATF? It's running and shifting like a top. The smoke clouds have mostly gone away, but I hate to not mention useful symptoms...
I wish I knew more about diesel engines so I could troubleshoot! Anyhow, if you've got time and an idea, great. If not, keep up the awesome blog! Thanks... Branden silvertrooper@gmail.com

Robert said...

Didn't know where was best to ask a question. I have a 555 Cummins in a Versatile 555 tractor. It is leaking coolant into the oil. Used to be only in the spring or when it sat for long periods of time. Now it seems it is leaking more as it runs because it plugs the engine oil filter. The breather on the right side gets a lot of grey oil/coolant mix bypass. The left side is always clean. When i check the pan after a day of sitting rarely do I get more then a few coolant drops. What are my most likely problems and how do I find out. My email is bigsky888@hotmail.com

Robert

John Whelan said...

branden, Your rad is 40% percent blocked, I would repair that asap. That is directly affecting your trans temp... The trans will cook at 390 degrees which is extremely high. running at 250-280 is the absolute maximum. It could very well be vaporizing at that temp. and the trans oil will soon be smelling like burned popcorn.

John Whelan said...

Robert, The good old triple nickel...You most likely have failed cylinder liner seals. You can confirm by pulling the oil pan and pressuring up the cooling system while watching for leakage at the underside of the liners. I wouldn't run it too long with that condition.