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Discussion Starter · #1 ·
Hey Guys, could use some help.

Couple of days ago I was driving around town for about 1 hour, and I saw the check engine light come on. So I pulled over, and checked what was wrong. Car was overheating, and was leeking antifreeze (it was boiling).

So then I started reading up on it (yeah I used search), and I saw the a couple of you guys had the same problem.

The fan on the radiator is supposed to come on when the temp gauge is around 50% right? I checked it out today, it was at around 60% and the fan did not come on. I read that some of you have your fans always running, could someone tell me how could I make that happen? I read that I gotta connect a wire to the battery or something, but not sure. Also anyone have any ideas what might be the problem? Bad Thermostat???

Thanx for any help guys!
 

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The second smaller fan only comes on when using the air conditioning. You can wire it up to come on with the radiator fan if you wish but thats not your problem with the car overheating. The large fan in the engine bay should be on when the car is that warm but the little fan wont. I'd check your thermostat.
 
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I would rent a coolant pressure tester from Napa, and check to see if your losing pressure from your coolant system, pressurize it up to whatever your radiator cap is rated to, and watch the needle, if its starts dropping, look for antifreeze leaking out of lines, or inbetween the head and the block.

If you can't see any, assume the worst and do a compression and leakdown test, you may be leaking coolant into the cylinders from a blown headgasket.

Other than that, Replace the T-stat, top off the coolant and away you go.
 
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A siezed water pump will result in a snapped Timing belt, so thats not an option.

I had my water pump start leaking on me before though, was a huge very obvious drip the moment the car turned on.
 

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The cooling fan should be on if the temperature gauge is past half way. You can temporarily wire your 90-92 radiator fan to come on with the ignition this way: just remove the connector from the thermoswitch on the thermostat housing (auto trans cars actually have two of these thermoswitches; either connector will work) and connect a jumper wire between the wiring harness part of the connector and any ground (i.e. the negative battery cable). If your fan isn't coming on, suspect a broken thermoswitch (check to see if it's intact) or a bad relay/wiring (one of 2 relays located near the battery, closest to the back of the car.)
 

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just throwing out things here..... is there a chance that the radiator is blocked (like the coolant flow is blocked)? (somehow? I've heard of this happening to car in the past, but I don't know how exactly it would happen?)
 

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Discussion Starter · #8 ·
If you can't see any, assume the worst and do a compression and leakdown test, you may be leaking coolant into the cylinders from a blown headgasket.
If I had a blown headgasket, then wouldn't my car be blowing out white smoke?
 

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pitt
listen to majik.

if cooling fan does not come on i beleive pressure cap will releive the boil pressure for a while and you will have coolant that area.

your thermoswitch is likely toast. ok, it could be fan.

my '88 auto has 3 sensors or switches on thermostat housing. the red one with single vertical bayonet male fitting is the fan thermoswitch.
when mine fails the fan runs from cold when i turn on ignition switch and i beleive it runs even if i seperate the lead. the switch is not designed to activate the fan until it senses about 200 degrees F.
so pull yours while engine in running and observe what fan does. if fan comes on i would replace thermoswitch.
otherwise test fan by applying 12 v to its 2 leads.
 

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jamin said:

so pull yours while engine in running and observe what fan does. if fan comes on i would replace thermoswitch.
otherwise test fan by applying 12 v to its 2 leads.
The 90-92 cars are slightly different than the 88-89's in this respect. On the 88-89's, you can simply unplug a thermoswitch on the thermostat housing and the fan will come on. On the 90-92's, you need to unplug and ground the connector for the fan to come on.
 

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overheating

As mentioned, the rad cap, t-stat, fan t-sensor, coolant level & ratio, possible flow blockage, trapped air, etc......can all cause related symptons of overheating.
Clean, check, r & r suspect cooling system components......before the overheating situation causes bigger problems to the head & or gasket.
 

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PiTT said:
If I had a blown headgasket, then wouldn't my car be blowing out white smoke?
Yes and no....when the head gasket blows there is a few things that could happen depending on where the gasket blows. The coolant could leak into you cylinder and burn up causing the "white smoke", but it could also leak into you oil. Or like what happened when my head gasket blew, the coolant will appear to be boiling into the overflow bottle, but actually its air escaping from the coolant system the only way it can, which is out the puke bottle.
Now IMHO it sounds like you headgasket is blowen (or at the very worst a cracked head), the common symptoms of a blowen headgasket/cracked head are.

-Loss of coolant- either burning up in the cylinders, or overflowing out the puke bottle, or leaking into your oil.

-Overheating

-Rough Running- bogging on take off in first gear, backfiring and if you have a BOV the backfiring will just be way more often.

-loss of power or boost droping off- the loss of compression will cause power loss and I think it could cause you boost to fall.

-whistling noise- you can sometimes hear the compression escaping

Do a compression test, and make sure you test ever cylinder, as you may get a perfect reading in every cylinder but one, depending on where the headgasket is blowen. A leak down test is also a good idea.
Once you do a compression test, study the results, did you get the same/close to the same reading in every cylinder? Did the compression leak out in any cylinder, wether it be slowly or fast?
If your answer to the first question is "yes", and the second one "no", then your compression is fine and your headgasket may actualy be ok. Now go ahead and let you engine warm up to operating temp then do a compression test again. If your readings are the same or close to the same in every cylinder and the compression didn't leak out again then your head may be ok also.
If, however, your compression readings were quite different in one or more of the cylinders, and/or the compression dropped of slowly or fast on the cold engine compression test. Then your headgasket is probley blowen...in which case you would have to remove the head and have it sent to a machine shop to be planed and be pressure tested for cracks, the simply get a new headgasket and put your head back on once you get it back from the shop.
If your cold compression test was good, but the readings were off or the compression leaked out when you did the test on a warm engine, then there is a good chance that your head is cracked but your headgasket is ok. Because the cracks in the head will expand and open up when the car warms up.

Do these tests before you do anything else, that way you can atleast rule out a cracked head or blowen headgasket, but you symptoms seem to indacate a blowen headgasket/cracked head.

methman
 
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good post methman, except for the metal expanding part.

Generally, heat will cause a crack to seal shut, not open wider.
 

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I just went thru a month long battle w/overheating. I've personally found that our cooling systems are VERY sensitive to air pockets. I need to jack-up the front of my car, idle with the cap off and the A/C on with full heat. Only until I did this did my temp guage stay just left of center.

Rich.
 
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