I broke the timing chain the other day. Replaced the timing chain, not water pump as it is only about a year old. Pretty sure everything is back together right, as I always do all my own work. Starts and runs fine, and with the radiator cap off, after a couple minutes it starts overflowing all over the floor. Not a little, but alot. I've had coolant in and out of the car numerous times due to previous radiator replacement and coolant flush, etc.... Those times I was able to burp it fine, and it did not overflow. No big deal really. Has run great for months w/o problems.
I usually figure these things out, but I've never had a car pump that much coolant on the floor. When it was overflowing the first time, I put the cap on and then a few minutes it over heated and released pressure from the cap. I'm thinking this has to be something simple, and I'm not catching it. Any suggestions would be appreciated.

 

Try getting a heater hose loose to bleed the air out.

 

Thats all you changed? hmm. weird.

 

Thanks for the replies. I did take one hose offf the throttle body and got coolant to flow from there. I still think something is amiss. Water pump sarted to squeel after running for a bit, and the water level in the radiator started to rise and overflow. The heater hoses warm up but not the hoses to the radiator. Could be the pump ate it I suppose, given the noise. More pressing issues to address, so she will have to wait a day or so.

 

What I generally do, and have recommended to others, is to pull one of the 2 coolant temp units by the thermostat, put a funnel in there, and fill the engine through that hole before topping off the radiator. For some reason, getting that air bubble out from under the thermostat is the biggest PITA in these V6s.

 

Maverick, that sounds like a great idea. I always look for the scientific reason behind problems, and if there is a large air pocket in the top-end, that could be the reason the coolant gets pushed out when the engine heats up. See about checking that out tonight. Thanks.

I've read about others having issues refilling the coolant, but in the 3-4 times I've done it on this car, I've never had an issue. Until now.

 

Have to ask.

Did you have the thermostat out when you were doing the timing chain?

 

IDK why, but it seems that our replacement thermostats don't like to release the air trapped underneath them like they do in other cars. I used to try to squeeze both hoses to try to force the air out of the top of the radiator, and then I just decided "Screw this, I'm going to get the coolant right into the engine where it belongs. Looks like I need to take out the CTS to do it, but it's got to be done."

 

I always drill a small hole in the t-stat lip to let out trapped air.

 

Very clever improvised solution!

I'm trying real hard to think of a reason why to not do this.
So far, can't think of one.

Anybody else want to weigh in on the pinhole airtrap solution?

 

A hole can make warm up time take longer.
You can wedge an asprin in the t stat, fill it up, & the pill will dissolve away.
If you can get the air out, try raising the front of the car.

 

I always do it, just a 1/16" to 3/32" hole is required. The _old OEM_ SBC thermostats had a notch stamped out of the lip where the center section seals to do the same thing.

RBob.

 

Fo' shizzle?!!!

So there is SUPPOSED TO BE a hole in the darn thing in the first place?

 

THanks guys. Got it finally sorted out today. Ended up pulling a sensor on the intake and filled it up w/ coolant there, works great to get the air bubble out. Never had this problem before on this car. Kind of kicked my butt, especially when it seemed like everytime I touch a vacuum line, it breaks. Need to replace that mess some day. That plastic crap is a pain. Any way, thanks for all the input. Think I was overthinking it a bit. Baby is back on the road.

 

From what I understand, most older thermostats had something called a "poppet valve" that would open and let out the trapped air as the system was filled. I guess they stopped doing that and decided that a screw in the upper portion of the thermostat housing or radiator hose pipe (FWD, mostly) would work to the same effect. But, if the thermostat doesn't have a way to let the air out, it's kind of pointless, isn't it?

for the suggestions to drill a hole in the thermostat. Going to have to try that at some point.