'93 Sunbird - T-stat cap leaking?

[acidburn02zts]

Hey guys...

I'm working on a '93 sunbird... 2.0 w/ 135k on the clock. Its a neighbor's car that they picked up for $200... then was brought to me to get the bugs worked out.

I got the basic maintenance caught up... tune up + hoses, belts, t-stat, t-stat housing cap... and replaced the o2 sensor it was throwing a code for.

Car runs like a top at the moment... but as the cooling system builds pressure, the t-stat housing cap starts dripping and hissing.

The cooling fan isnt coming on as it should either... comes on when I pull codes but not when the car starts getting hot.

I thought about replacing the actual radaitor cap... thinking its stuck and not releasing pressure like it should. Not quite sure where to start on the cooling fan issue... is it a common problem?

Ideas?

Thanks guys
-Chris

 

[92 Sunbird LE]

Check the relay ( drivers side front fender ) You can use one of the other three on the other side ( but not the fuel pump one with purple wires because the car cant start)

If that doesnt work, test the coolant sensor on the drivers side of the head (easy to see 2 wires sticking out of it above the trans on the drivers side of the head) as it sends the signal to the computor to tell it to turn on the fan.

Worse case senario its the computer ( 80% of the time) so on the cheap, just hard wire it to run all the time when the ignition is on.

Diagram : ( crude pic sorry) CB = GM circurt breaker for p windows or p locks ACC = accessory on the fuse box LED = 12 volt led light mounted on the dash Triangles = ( black ) are grounds

Doug in P.R.

 

[acidburn02zts]

Lol... I like the diagram.

I assume the relay is ok since when I hooked up my obd1 box to pull codes, the fan comes on so I'm leaning towards sensor or ecu.

Couldnt one jumper the fuel pump relay trigger to the factory fan relay trigger so that anytime the pump is energized, the fan would be running? I was just wondering since both relays are close to each other.

As far as the leak goes which is the main concern at the moment, what are your thoughts? Its acting like the pressure cap on the side of the radiator isnt venting as it should... the overflow never gains or loses coolant even when the t-stat cap is hissing/leaking

-Chris

 

[92 Sunbird LE]

Couldnt one jumper the fuel pump relay trigger to the factory fan relay trigger so that anytime the pump is energized, the fan would be running? I was just wondering since both relays are close to each other.

As far as the leak goes which is the main concern at the moment, what are your thoughts? Its acting like the pressure cap on the side of the radiator isnt venting as it should... the overflow never gains or loses coolant even when the t-stat cap is hissing/leaking

The 3 relays on the passenger side does not include the fan relay , it is on the drivers side by itself, It could work but the fan sucks a lot of amps so that's why its a separate relay. Running the trigger wire to the other side may work but the fan has electrical feedback when its not powered and still spinning so that may not be a good idea without a led or other light in between , it may damage something.


Change it out if need be, if you have access to a cap pressure tester test it.
I took out my Tstat for safety reasons, ( not to cook the head many a 2.0 blown by this) not needed here in the tropics, even the heater core was disconnected when I got mine.



Overflow tube blocked or pinched ?

Doug in P.R.

______________________________

 

[acidburn02zts]

Not that I have seen...

I'll take a look at it tomorrow as the kid took it back the other day and has been driving it. He is keeping an eye on it but I told him not to drive it much as it could overheat... we'll see if he listened or not.

-Chris