7.3 oil in the coolant, o-rings, now what?

[TomsBeast]

Originally Posted by arctictraveller

It's always satisfying when you are trouble shooting and get a positive indication you have found the problem. I do wonder why the tube section corroded enough to leak, perhaps at some time the coolant was compromised? Or was it a bad solder joint or weld? Anyway, glad you found the problem...........

I talked to a couple of mechanics that work on the 7.3 in trucks mostly, they both said once in a while it's the cooler. Funny, there is no visually discernible difference between the old one, no corrosion, no physical damage, and the inside of the new one.

I tested both twice, reusing the o-rings. Old cooler leaked both times, new cooler never leaked, 30psi.

[Bbasso]

Well done.












The message you have entered is too short. Please lengthen your message to at least 10 characters

[arctictraveller]

Originally Posted by TomsBeast

Funny, there is no visually discernible difference between the old one, no corrosion, no physical damage, and the inside of the new one..

Most likely it would take a bore scope down the tubes to find the small pin hole deep inside.

[TomsBeast]

Originally Posted by arctictraveller

Most likely it would take a bore scope down the tubes to find the small pin hole deep inside.

I wonder how many oil coolers get changed out needlessly, when it's just brittle o-rings? We may never know...

[TomsBeast]

The last piece of the puzzle arrived at my doorstep last evening, a replacement thermostat housing to replace my bent one.

I must have bent my old one while over tightening it 3 weeks ago on my Seattle trip, when the cooling system first started acting up. Guys that work on their own vehicles know the drill, 11pm at a truck stop on my way to Seattle, thermostat stuck closed, oil pan hot, radiator cold. I had my all my niece's worldly belonging in my trailer, and it's raining, I've got 1000 miles more to go, 3 days to get it done. I removed the thermostat and replaced the housing using RTV. It leaked. Cold, wet, tired and in the state of denial, I tightened it more. It still leaked. Don't try this by the way, run without a thermostat on a 7.3 Diesel. The housing to front cover connection relies on the thermostat's channel o-ring to keep the coolant from escaping. I wound up cutting the innards out of the thermostat, reinstalling it with just the outer ring part and channel o-ring, to seal it. Things are so much clearer while turning wrenches at home, in daylight, near all your tools and creature comforts nearby. Awe, the things you learn while trying a roadside fix. Nothing good happens at a truck stop after 11pm

Last night, I did one more soapy water flush, a clear water flush, new thermostat and housing, new overflow/gas bottle cap, took it for a 10mile test drive.

The lower hose popped off while on the road. Turns out, just like my coveralls, the inside of the hose is still slippery from the residual oil. At the smallest pressure increase the hose popped off the lower radiator nipple. My pressure was kept at bay knowing my GF was cooking up a nice meal, and had a glass of sparkling waiting. Simple fix, I cleaned the inside of the hose with brake kleen, scrubbed it with a wire brush, and added a second hose clamp for good measure.

Added 50/50 coolant mix and went on a second 10mile test drive, coolant temp coming up as expected, engine running smoother as a result, no longer in 'cold start mod' I suspect, the system is holding pressure

[marret]

Lots of trials and tribulations, but great you were able to work through it to find a solution.