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Fredward · 06-30-2022, 06:39 AM

Hey gang an interesting project here. I always have an oil analysis done when I change oil. This last oil change there was Glycol detected in the oil. The usual cause on a C10-C12 is: Water pump, oil cooler, head gasket or cylinder liner O ring. So the easy thing to do first is replace the water pump. I got a new pump from Cat yesterday - $590.00 with $716.00 core! I guess they really want that core back. Also got a thermostat figured I replace that at the same time.

I'll be changing the pump next week after the July 4 holiday. Coach has 145,000 miles. Anyone have any experience to share ?

Xmcdog · 06-30-2022, 06:50 AM

Love those cats. You have travelled in that coach. Keep that kitty purring.

No experience in working on them but I don’t imagine it will be too difficult.
Excellent idea to have an oil analysis done. May have saved you a bundle.

birdhunter · 06-30-2022, 10:37 PM

I have a C12 with about 127k. Regular analysis by the CAT lab. Never any coolant in the oil. I would discuss the oil analysis with the cat lab. If you didn't have it done at the cat lab, I would have one done at the cat lab. I find them to be very helpful. I would think you might have other abnormalities such as metals etc. if it's a head gasket or an oil cooler, but I'm not sure. I would then discuss it with a cat service center. Maybe you already have.

Fredward · 07-01-2022, 06:13 AM

Hi Rich,
Yes this is the Cat lab here in Minnesota. And I talked with the technician on the phone who agreed that changing the pump is the place to start. Last year's analysis was normal. This spring there was a hint of coolant. I sampled again after our trip to Montana and that was the test that recommended taking action. And yes they are very helpful. Those water pumps are known for leaking into the oil.

birdhunter · 07-01-2022, 10:23 PM

Good to know Fred, thanks. Good luck! Let us know how it turns out.

Fredward · 07-15-2022, 08:25 AM

I changed out the pump replacing the old one with a new - rebuilt Cat pump. A pretty tedious project but totally doable for me anyway. Everything is back together and no leaks yet! We have a trip in a week so that will be the real test. But in the meantime and prior to leaving, I will change the oil and filter. Then we will get some miles on it and send another sample to the lab to verify that the pump was the source of the glycol in the oil.

(Knock on Wood!!!)
Fred

birdhunter · 07-15-2022, 10:36 PM

Good luck Fred! Could you see anything wrong with the old pump?

Fredward · 07-20-2022, 05:49 AM

No I could not see anything wrong. But after removing it and having it sit on the floor there was a little puddle of oil/water mixed. Sure hope the pump was the problem. My buddy has C10 and C12 in trucks and has seen the water pump be the source.

I changed oil and now all I can do is run it and sample the oil again. Several trips coming up here in July/August so I'll probably test the oil again after Labor Day.
Fred