Brett Jenkins

No coolant on the garage floor, no obvious leaking hoses anywhere. Seems to be venting from the recessed indentation in the top of the reservoir, is this by design?

I tried to pressure test it, but the tester from AutoZone didn't fit the reservoir. I will track down a better pressure tester, but wanted to make sure the venting from the top of the reservoir wasn't indicating the obvious issue.

S4ordie

Check your oil.

blown 87

Do a chemical test on the cooling system to see if you are getting combustion chamber gasses in the cooling system, IE blown head gasket.

Mrmerlin

there are usually 3 failure points that are hard to find
the right hand side of the radiator on the top flange it cracks and coolant seeps out when its hot
The HCV it crumbles and leaks slowly and fails
the coolant bottle has a small crack in it and the water evaporates before you can find it..

Put a new HCV and short hose in and a new coolant cap, if your tank is tan or brown then just replace it.

insopect the radiator for crusty deposits on the top backside where the top rad hose connects

Brett Jenkins

Radiator end tank was replaced a couple months ago and remains dry. Radiator cap is new. Heater control valve and related hoses were replaced a couple months ago as well and visually are not leaking. No coolant in oil. I have attached a pic of a reservoir. The indentation in the top is where it was venting when it was hella hot the other day. Is that normal or is my obvious failure right there?

Leon Speed

Any coolant in the front valley?

daveo90s4

Brett,

Plastic reservoir is not meant to vent. If it is it has a hole in it that it shouldn't. If it has a hole in it it is either because it is simply old and brittle and was no longer able to withstand up to 14 psi (the pressure cap pressure rating) or excess pressure has caused it to fail (but the pressure cap has not yielded - strange). Excess pressure could be blown head gasket etc.

You could top it up, get all the air out of the system, and let the car idle for a while with the pressure cap off. Check for bubbles of air appearing. If so then that suggests head gasket problem. If not it suggests simply a cracked plastic bottle.

Tom. M

I had a similar issue a while back. ended up being coolant leaking from the waterpump shaft. Couldn't see it until I got it in the air and the front tbelt covers off. Replaced water pump and was good to go.

M. Requin

And check the coolant pressure sensor.

bd0nalds0n

Also check the breather lines. If the head bosses crack, you can weep coolant in a way that the steam vents through the breather lines without mixing in the oil.

SaciecSuitber

IE blown head gasket.

Bilal928S4

If coolant is in the middle of the bottle in the recess then it is either leaking there or there is a leak in the vicinity and coolant is ending up there.
Bilal

Brett Jenkins

When it was super hot/overheating, i could place my hand over the indentation in the top of the reservoir and feel the steam coming from it. I will pull the reservoir this weekend and inspect it.

blown 87

Go ahead and get one, you are going to need it, and test for gasses in your cooling system first.

jeff spahn

^^^^What he said