Guys, quick question. I just finish my 305 to 350 swap in my 85 Berlinetta. Other mods are in the sig. Anyway, after many ordeals, I've finally been able to start driving th car. Well I got home after about a 30 minute drive on the highway and I decided ti pop the hood to check out my high idle problem. Well while I was checking the throttle, I noticed bubbles in my coolant recovery tank. You could see the bubbles come from the connecting hose and float up. I turned the car off and the bubbles stopped. I was wondering what would cause these bubbles?

Some other info. The temp gauge is an autometer with the sensor in thermostat housing. It has a 180 thermostat. The gage has read 180 on the highway and only has gotten to about 200-210 when sitting in traffic.

Shoot me some ideas as to what could be causing this.

-
Dave

 

Probably just air coming up while the radiator is taking in water/coolant from the tank.

-Matt

 

head on over to the "cooling it down" post, they can give you some better info over there and there was a post about the exact same problem that was posted recently. Check that out

 

Thanks for the replies. And yes, I've found that other thread. Interesting nonetheless. I think my problem lies in my readiator cap. For one, there's no coolant in the oil. The oil is as clean and clear as it was when I put it in 150 miles ago. Second, the cooling system was still pressurized 1 day after I turned the car off and noticed the bubbles.

When I checked the coolant level today, there was a release of pressure when I took off the radiator cap. And to my surprise there was some antifreeze missing. But my recovery tank was completely full, up to the cap. I think my radiator cap (lever style) wasn't letting the antifreeze back into the cooling system. I'm going to try a new cap next week and see how it works.

Oh and keep the ideas coming.

-Dave

 

I did a head swap over the Winter correcting a blown head gasket (good opportunity to pop on a pair of AFR 190 heads) from last season. Symptoms were similar to yours...it would burp into the coolant bottle, no oil contamination, low rad level but full coolant bottle. What tipped me off was that my coolant smelled like exhaust. I picked up a test kit from NAPA (split the cost w/ my neighbor) and my car failed, both my wife's car and my truck passed...exhaust gasses present in the coolant.

#7 cyl was the culprit, it also contaminated the O2 sensor and caused it to over-report (rich) so the whole engine was running slightly lean...spark plugs looked like brand new, header primaries were spotless clean, etc.

Good luck.