Mystery coolant leak stops vacaton

Well, after a call from the local Cummins shop, the problem is a coolant leak in the air compressor. Bill est $3,300. Engine warranty went out last year, go figure. Only 23K miles on the coach. Between the shop and myself, we are going back to Cummins to see if they will consider helping with the cost due to the low mileage. Fingers crossed. Has anyone else gotten help from Cummins with a slightly out of warranty repair?

It might be funny to some of you about the use of 'Stop Leak' but it has it's place and it's worked for me several times over the years.

Once drove from LA to Portland Oregon with a coolant leak, stopping every 70 odd miles to add stop leak. It was exciting struggling to the top of the grapevine nursing that Lincoln engine along, but the downhill saved it as it cooled right down since I coasted nearly 10 miles downhill.

Another time drove my DP 35' Class A from Valdez up Highway 4 on a 6% grade for miles puking ATF from the tranni. Found some tranni stop leak here and there at convenience stores along the way and limped at 55 MPH all the way almost 2,000 miles to Prince George before I found a hydraulic shop that could make a new hose for me. Sold the rig 8 years later still running fine.

So the stop leak products do help in certain cases. I do not know why it's not allowed in a diesel engine with a rad leak...but I respect the advice of many here so don't expect I'd ever add a stop leak myself in future. With Coachnet, don't really have to either.

Or just add bananas. Oh, wait a minute bananas are for transmission noise!
Moisheh

Yeah.....lets take a $35000.00 diesel engine and throw a $2.00 can of stop leak in it.

Ok. That is good news. One more check to rule out internal engine damage. Drain a pint or so of oil into a clear jar. Let it sit. If there is coolant in the oil, it will settle to the bottom of the jar and will be visible. If you have any coolant in the oil do not run the engine. Coolant in thr oil will cause the bearings to seize.

No pressure coming out of the overflow....

With my 5.9 Cummins, turned out the mystery leak was way up front from one of the coolant lines to the dash heater. Turning off the two brass valves (one down low on the engine, the other up a foot or two) solved the leak issue temporarily. A couple years later, got around to fixing it and it turned out to be a rusted through short piece of steel tubing near the front of the rig. Cutting it back past the leak and adding new hose made a permanent fix.

Does the coolant overflow bubble when the engine is running? If so you have a breach between the coolant and the cylinders.

RedRollingRoadblock wrote:
Good chance that using a leak stop product will clog the coolant filter.

Dennis12 wrote:
Dike radiator and system sealer. Made by Conklin. Tried the rest. I put it in my V8 7 years ago for a head gasket leak. Still running with no problem.

I have had several diesel pushers and have not had one yet with a coolant filter. Only my 6.0 Ford had one. Know some of the earlier Cummins had them in 2000 but not in 2012.

. do NOT use stop leak in a diesel engine.

And why not??)