I am about a month after a thermostat change and a complete coolant flush/refill. Recently I wanted to check on the level of the coolant and noticed foam buildup in the reservoir. Is this anything I should be concerned with ? It doesn't look anything like the milky stuff when it mixes with the tranny oil.

When I took the pic the engine was at about 86F and it was-4F outside and the engine was running about 15 minutes.

Here's how it looks like:

 

Cant tell about the foam but for sure you got me envy with the -4 .. 70 in Miami ( Love cool )

By you comment about the tranny fluid I assume there is not an aftermarket cooler installed ... A must .. Dont wait till the problem is there . A $200 in the cooler will save you thousands on the tranny repair

 

Yeah it's a bit hard to get the parts here in PL that's why I've been delaying the job. Will have to put some thought into it once the weather clears. About the weather - believe me I'd take 70 over -4 anyday

 

I made a quick research online to found this :

It is either a blown head gasket or possibly a cracked head or cylinder block. The engine is pushing air into the cooling system somewhere during the compression stroke. Pull the spark plugs and take a look at them. You will probably find at least one is a lot cleaner than the others. This is due to coolant entering the cylinder and "steam cleaning" the inside of the cylinder when the engine is running.





------------------- I will guess the coolant entering a cylinder will cause misfire and rough engine idle ... Probably you found this info and already read it , let me know if you get to test the spark plugs ..



....Also another guy comment the bubbles could be due to a crack open thermostat .... I will relay more on this answer if engine is running smooth

 

Thanks for all the input. Wouldn't a blown head gasket throw a misfire code on the dash ? To be honest it is kinda rough but only when the engine is cold after that it evens out. The thermo was replaced 2 weeks back and the plugs and cables about 5 months ago. Is there anything in particular I can diagnose using a scan-tool to check if it is the head gasket ?

 

You can borrow a kit from an autoparts store to check for exhaust gas in the coolant, you just need to buy the special fluid the kit uses. Pretty simple, take off radiator cap, put the tester with fluid on and run the engine. If the fluid changes color, you have leaks.

Doesn't really sound like that to me though, sounds more like some kind of contaminant in the system. I'd drain the coolant, flush it out really good with straight water, then fill it back up.

 

My friend works as a mechanic in the VW dealership here maybe he can borrow that kit for a day and then we'll see. I guess I'll try to flush it one more time before I jump to the worst case scenario. I'll let you guys know if I find out anything.

 

Are you losing coolant? Any signs of overheating?

 

Overheating ? No. It's underheating I'd say the car reaches about 160-170 degrees F tops (checked with a scan-tool) after an hour drive. Maybe this could be related somehow to my issue ? It's a bit early to tell if I'm loosing coolant as it's been a bit over 2 weeks since the flush. I'll keep an eye out on it though.

 

Did you use a flush chemical of some kind? It could be some residual of that stuff.