I have been talking to Dave about a problem with my coolant system. The buzzer keeps going off for the first few seconds when I start my car but then goes away. It has never come on while the car is being driven. Already we ruled out seal failure. However I just took my car apart and discovered something. IN order to find a bad hose I put in orange coolant instead of the usual green stuff. Wehn I disconected the hose coming the the resevoir to the AST it had green coolant still. It wasn't mixed either. It was a rich green. Anyways...What could cause(i guess) a vacuum failure that would cause the coolant to not flow. Also when I opened my AST it only had water in it and was barely full. Can some one give me advice on what I should do next. Thanks



Oh.....I have an aftermarket Radiator that might be a factor.

 

I'm not sure I totally understand your question and you probably know all of this already, but just in case, here goes. I do know that even a pinhole in the line running from the AST to the overflow will be enough to break the vacuum and not pull the coolant back into the engine as it cools and contracts. In order for the coolant to mix in the line between the AST and the overflow, the system would need to get hot enough and build enough pressure (.9 Bar) to be able to flow into the line between the AST and the overflow. Good luck sorting it out. I'm glad to hear that you have ruled out coolant $eal$!



Dennis

 

Yeah you are on the right track. Sorry if I was confusing. I checked the hoses going to the AST and they are good. How is the vacuum created? Maybe that is the question to ask....

 

If the system is full at ambient temperature and then you run the engine up to normal running temp, the coolant gets hot, expands, and is sent into the overflow once the pressure in the system becomes greater then the pressure rating of the cap on the AST (assuming the cap is good). Just the opposite happens when you shut the engine off and everything cools down. As everything cools, it contracts or returns to it's original volume and this is what causes the vacuum needed to pull the coolant back into the engine through the one way valve in the cap on the AST.



If the coolant never mixed in the hose from the AST then I have to ask:



1) Was the system full at the AST AND the Filler neck before your started the car?

2) Did you let the car fully warm up enough to let the thermostat open?



It seems to me, and maybe I'm wrong on this, but even if the water pump was bad, if the cooling system was full when you started and you let the car warm up fully then some of the orange cooland "should" have been pushed out of the AST into the hose in question.



Another thought is are you sure that he system has been properly burped? I guess that if you had alot of air trapped in the engine that perhaps it could cause some problems.



Dennis

 

The AST was never full. I opend it and their was only what seemed to be water. How do I burp the system. I might as well do that while everything is out! Thanks for the goood advise though!

 

I had a problem very similar to that, and what the problem was the hose used to connect to the overflow tank wasn't stiff enough so the vacuum created would collapse the hose and the coolant couldn't get back from the overflow tank.

 

Take the cap off the filler neck, fill it up with the car running and leave the cap off for a min or two to let the air bubbles escape.

Top it off once you see that last of the bubbles and cap it back off. You can do the same in the AST.

 

I doubt it also but check to see that your water pump is not leaking.





http://www.fd3boost.com/waterpump_HT.php





Also i dont know so I'll ask. How can you tell if a thermostat is bad? Besides overheating the car of coarse.

 

You beat me to it......



I am putting everything back together so we will see what happens

 

Take the thermostat out and put it in a pot of boiling water and see if it opens all the way.