What causes coolant level to go up?

[Lurch]

I flushed it a week or two ago and it was steady for a week or so, then noticed it went up in the reservoir about an inch yesterday. What's up with that?

 

[Drew99GT]

Did you check it when the engine was hot now, compared to when you flushed it (when the engine was cold)?

 

[gathermewool]

+1 for thermal expansion

 

[Lurch]

Originally Posted By: Drew99GT
Did you check it when the engine was hot now, compared to when you flushed it (when the engine was cold)?


I've been watching it often (when hot and cold) and it seemed to always be right on the max level line in the reservoir but yesterday it was 1" above it.

Am thinking about doing an OC so I can send in a new UOA to see if Thermagasket fixed my small head gasket leak. I kind of hate to waste 3 qts of good PP 5-30 but I suppose I should.

 

[Drew99GT]

Oh, I forgot that you're the one who tried Thermogasket. Did you check the fluid at the radiator? Might try running the engine with the rad cap off and see if you're getting a lot of bubbles. Perhaps the gasket is still compromised and pushing exhaust gases into the cooling system - hence the rise in fluid level.

 

[Lurch]

Originally Posted By: Drew99GT
Oh, I forgot that you're the one who tried Thermogasket. Did you check the fluid at the radiator? Might try running the engine with the rad cap off and see if you're getting a lot of bubbles. Perhaps the gasket is still compromised and pushing exhaust gases into the cooling system - hence the rise in fluid level.


I didn't check radiator level lately but it was right up there the last I knew. I'll check it Friday and reply back to this thread. Thank you.

 

[another Todd]

Maybe the previously lost coolant came back.

 

[Lurch]

I checked it Friday and both the radiator and reservoir coolant levels were right at the mark. I'll keep a close eye on it and let you all know how it turns out.