coolant loss

FJK1954 · Jan 22, 2011

I am losing coolant,,strange thing is not all time ,,one time it will be down a gallon, then drive a thousand miles and still full..the fuel mileage around 9.5-10mpg,but just had oil analysis and it says some coolant in oil,check for leaks and retest...any suggestions?

btw--2004 fl-112 mercedes 4000-435 series with 905k miles. thanks frank

Refer Hauler · Jan 22, 2011

Has it been rebuilt? My first thoughts if not, is a pitted/cracked liner

layoutshooter · Jan 22, 2011

Do you have an APU that uses the main engine cooling system? If so, that could be leaking.

truckblue · Jan 22, 2011

EGR/Cooler leaking. If you are showing coolant in oil, that's where
I would look. You may have a pre-EGR motor, I think 2004 was first yr. I have the smaller MBE900 and thats what i was experiencing. Also found APU water pump leaking.

layoutshooter · Jan 22, 2011

truckblue said:
EGR/Cooler leaking. If you are showing coolant in oil, that's where
I would look. You may have a pre-EGR motor, I think 2004 was first yr. I have the smaller MBE900 and thats what i was experiencing. Also found APU water pump leaking.

Which APU? What did it cost to have that fixed?

truckblue · Jan 23, 2011

it's a carrier APU. When I got in the truck, the previous driver wasn't keeping up maintanance. The engine coolant was pure water. His answer to coolant leak was to just keep adding water. Because there wasn't any maintanence records, I had the unit checked out at a Carrier shop. It was a mess. New belts, oil, water pump, filters all came to a little over 400.00. I thought that fixed coolant leak problem, but it continued. That's when I had engine oil analysis done. Sure enough, coolant showed up. Typical EGR/Cooler leak. Went to detroit engine shop for repair.

layoutshooter · Jan 23, 2011

truckblue said:
it's a carrier APU. When I got in the truck, the previous driver wasn't keeping up maintanance. The engine coolant was pure water. His answer to coolant leak was to just keep adding water. Because there wasn't any maintanence records, I had the unit checked out at a Carrier shop. It was a mess. New belts, oil, water pump, filters all came to a little over 400.00. I thought that fixed coolant leak problem, but it continued. That's when I had engine oil analysis done. Sure enough, coolant showed up. Typical EGR/Cooler leak. Went to detroit engine shop for repair.

I have a ProHeat, from before the Carrier take over. I was having problems with hoses leaking. Took forever to find all the leaks. I just found the leak in the water pump. What joy!

I don't understand something. When I got coolant in my car engine I could see it on the dip stick. It would seem to me that if you were losing coolant a gallon at a pop it would show, what am I missing? Does diesel "hide" the coolant somehow?

FJK1954 · Jan 23, 2011

thanks everyone ill have the egr checked...cant be apu ...it is a rigmaster ...uses own coolant....i think maybe the fact that i use lucas in oil changes may help hide the coolant bubbles on dipstick. thanks again frank and no it has not been rebuilt yet..

davekc · Jan 23, 2011

Coolant in the oil could be coming from many places especially with 900k on the clock.

As mentioned, could be the EGR or cracked injector tube.
More serious items with coolant in the oil could be a cracked head, block, or leaking gasket. I would not continue to drive it as the coolant in the block is destroying your engine.