legacycentral bbs

So my radiator cracked this past week and I installed a new one. I let the car run for a good period of time adding coolant as needed. When I started to drive it it went from cold to over heating in a matter of minutes. The heat is blowing cold. Any thoughts. Oh and if I drive it long enough in the over heating it will start to blow hot air through the heat and will cool down. Thanks for any help. Sorry forgot to mention my car is a 1990 Subaru Legacy L. Has awd, manual transmission, and air conditioning that works when it wants.

need to bleed the system, there is a plug on the passenger side of the radiator that has to be removed when filling, as well as a plug on the engine. Not sure of the exact location for the engine plug, hopefully someone else will chime in....

Thanks I didnt know about the plug makes since though. Ill search the engine for a plug as well. It has to be easy to find. I mean they would want it to be visible for when fluid was coming out ... right? But then again we are talking about engineers.

I would have replaced the coolant temp sensor and the thermostat also if possible.

But it sounds like you have a lot of air in the system.

I would burp it = run it for quite a bit with the cap off and just slowly add coolant.

I bleed it for a long time allthough I didnt do it with the bleeders out so I will do that when I get home tonight.

You need to take that bleeder off on the passenger side of the radiator, or you're wasting your time.

Is there a bleeder on the block? I thought the only one was the one on the radiator.

The bleeder should be on the radiator as suggested.
The radiators crack when the motors overheat so it is quite possible that you have had an overheating problem anyway.

You should change the thermostat.

If the radiator is a second hand on then you should probably get it checked by a radiator specialist who will probably pull the top or bottom tank off to clean the tubes. That being the case, you could have got the old one repaired with a new top tank and a clean-out probably. A bit late now to hear it but for next time perhaps.
If you are sure the thermostat and radiator are both good then you should warm it up and then with the cap off see if you can see the water circulating in the top of the radiator. If you can't actually see the water swirling around when you rev it up, you should at least notice a drop in the level when you rev it a little. If the water doesn't swirl or drop a bit when you rev it then it is possible the water pump is not pumping.

Aother thing when getting the air out is to make the front of the car as high as possible,or make the cap be the high point in the system.I have a gravel pit behind my shop,when i refill coolant i will literally park the car on a slope at like a 45 degree angle lol.Makes things a lot easier.

Thanks for the advice. She is now running like a champ... with enough oil leaks to keep her underside rust free . But shes running smooth again. Ill get started on making her run good when i get back from mob. Again thanks for the advice.

glad you got it burped. I my race cars I used to drill a 1/8" hole in the T-stat and place it at the highest point (or point that would be highest with it on jackstands) so it would bleed the air thru.


Haven't tried it on a Subie yet though.....

Subaru tstats already have a hole with a "jiggle" piece through it to allow air to pass by.

^^^ Awesome, I always wondered what that was for *duh*. I guess I should probably check make sure it's at the top of the T-stat housing.

Wonder if its possible to shove an STI drive train into it when i get back. That would make for a fun project and I can get it okayed by the wife she knows its leaking oil.