NickD

Usually I am the guy answering these kinds of questions, but now I am confused myself

I am getting a serious amount of air in my coolant. I replaced my radiator ~5k miles ago and I replaced both of my headgaskets ~50k miles ago. The thermostat was also replaced 50k miles ago when I did the headgaskets.

I am getting so much air in my system that on my way into work this morning, stuck in 2 hours worth of traffic, I had to pull over on the shoulder and bleed the system twice!

So I am considering a bad radiator cap, I doubt it but maybe so I bought one when I went out for lunch. I will put it on before I leave from work this evening. The cap that is on there is the original radiator cap that came with the car, so it's 12years old and has been on 4 radiators now.

I am not leaking anti-freeze. My overflow bottle is actually getting quite full so air is getting in, anti-freeze is not leaking out. Makes me think headgasket (but @ 50k miles?!). Though the symptoms are slightly different from a headgasket problem. When my headgasket started to go the air in the system was an issue during warm-up. Once the engine was hot the air wouldn't expand anymore and everything worked. This problem seems more like a constant intake of air from within the engine bay, as opposed to from within in the engine.

Does anyone else have any ideas/suggestions?

 

Dave C ver2.0

Well considering your cooling system should be under pressure, I don't see any way you could be sucking it in. If your over flow bottle is filling up then I'd say radiator cap considering it's age.

When you did your head gaskets did you check the heads and deck for flatness? When you put the heads back on did you retorque after a few heat cycles? It is possible you're leaking a gasket again if you didn't (but I kinda think you did).

__________________
Started rebuilding IC engines in 1968 at the US Merchant Marine Academy. Don't think you know more than me about auto/IC/control systems unless you can document your education.

NickD

Dave, I agree with you on the radiator cap, the new one is sitting in my passenger seat waiting to be put on.

I had the heads milled and checked for cracks. The block I couldn't do because it was still in the car and I wasn't going to have it towed to the machine shop. We did a in-house "test" best we could and everything looked good.

I however did not re-torque the head bolts after a few heat cycles. If this were an issue wouldn't it have appeared earlier on and not after 50k? If the rad cap doesn't solve it then I will defiently look into re-torquing the head bolts.

Thanks for the info