Looking for a good Cummins mechanic

DKase · Aug 15, 2014

The 855 Big Cam 1 in my road tractor has me pulling out my hair. It is loosing about one gallon of antifreeze to 500 miles. No external leaks, no antifreeze in the oil, no compression in the radiator, no vapor from the breather or grey snot in the valve covers. I pressurized the after cooler to 15# and after 2 days no drips or signs at all in the intake. Pressurized the engine to 10# and no leaks after 3 days. Spin it with the starter with both manifolds off and no signs of any moisture. I plan to warm it up with both manifolds off today and see what happens. About all that is left is an injector cup. Any other thoughts?

Super Trucker · Aug 15, 2014

Check the intercooler on the engine. It's a mini rad that can go bad and put anti freeze directly into the intake . Had one do it until one morning it totally failed hydro locking the engine.

DKase · Aug 15, 2014

As I posted, I pressurized the intercooler to 15# for 2 days, and pressure held. Pulled the intake, and there are no signs of antifreeze in the intake. That is NOT the problem.

Bob Bancroft · Aug 15, 2014

I recall a new 5.9 that was losing coolant without a trace. Turned out the block was cracked(improperly cast) behind the exhaust manifold, and was only leaking when working hard, and the coolant sprayed onto the manifold and evaporated.

I had an engine here that was losing just a little coolant undetected, and finally when the water pump gave out and I replaced it, the leak stopped!

So I'm wondering if you have some similar oddity, where you can't duplicate the leak in a static condition?

John Saeli · Aug 15, 2014

An injector cup leak would allow compression into the rad. Does the rad have an expansion tank? If not, is the 1 gallon loss just normal expansion?

minnemoblb · Aug 15, 2014

I'm just thinking here does the truck have a trans cooler? If you haven't already checked that.

DKase · Aug 15, 2014

13 speed, no cooler. I have thought about the air compressor also. No antifreeze in the tanks, and no air dryer. No the heater core is not leaking. I think I pull the heads tomorrow and get them pressure tested, or replaced.

cnh · Aug 15, 2014

Take the belt off the water pump, pressurize the radiator to 15psi, turn and wiggle water pump by hand. Maybe it is loose and seeping.

DKase · Aug 16, 2014

Been there done that!

L.C.Gray · Aug 16, 2014

Put some water soluable flouresant dye in the coolant, run it and get out the black light at night. It'll show up somewhere.

ralph wilton · Aug 16, 2014

Replace the radiator cap

DKase · Aug 17, 2014

I know the antifreeze is going out the exhaust. I need to know how it is getting there without getting in the oil, or compression getting in the radiator!

casemagnum · Aug 17, 2014

I just had a JD mower with Kawasaki motor that had me pulling my hair out as well. Ended up being water pump that was seeping SLOW amount. Would only do it when running and was evaporating it as it leaked. As soon as I took water pump apart it was definitely evident. Fixed now. Don't know if this will be the same but just what I encountered.

Ol'TinBender · Aug 28, 2014

pin hole in one of the liners will do it everytime.

Looking for a good Cummins mechanic

DKase

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Super Trucker

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DKase

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Bob Bancroft

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John Saeli

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minnemoblb

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DKase

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cnh

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DKase

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ralph wilton

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Ol'TinBender

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