5.7 Bubbles in Overflow Tank

[landtoy80]

Is there anything other than a blown head gasket that will make the radiator overflow tank look like a fish tank with a bubble maker in it?
On a test drive I saw a few bubbles coming from overflow tank. After a run up I70 Denver to Evergreen the bubbles got worse. No CEL,
temp was fine, coolant level good, engine runs strong and sounded good, has 300,000 mi on it.

 

[bloc]

On gas engines anyway, I can’t think of another cause. But modern diesels have EGR coolers that can do this..

Combustion gas detectors for coolant aren’t too expensive.. might be worth looking into and testing to confirm.

Any other signs of head gasket issues? Sweet smelling exhaust? Puff of white smoke/water vapor and/or stumbling on cold start?

 

[landtoy80]

I have a 10 year old combustion gas detector chemical kit u you out put on the radiator.( I would guess the chemical is no longer effective by now.) It only works if the engine is cool or you drain some coolant prior to using. It’s not something that is friendly to use at a used car lot. I have wondered if the kit worked off the overflow tank? I guess it would only work when the rad cap was opening to the overflow tank.

 

[bloc]

It’s not something that is friendly to use at a used car lot.

Good point, I hadn’t used one but have seen them around.

Maybe a good PPI could accomplish the same thing in a more formal setting, and shouldn’t be too much to ask.

 

[LTSR]

Check underneath the oil cap to see if there's any signs of coolant mixing with the oil