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Can't figure this out! Cooling issues


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JD_1990_GTS
New User

Jun 20, 2011, 7:00 AM

Post #1 of 10 (1431 views)
Can't figure this out! Cooling issues Sign In

Cliffs at bottom...

Ok, I have a 1990 Celica GTS that is about to drive me crazy. The first symptom I noticed was that the gauge was not warming up like it used to, it began reading slightly lower and the heater was less hot. I drove it like that for a couple months with no problems. One morning on way to work I noticed the gauge didn't move at all for several minutes, I was kind of alarmed and then saw it shoot up to almost 3/4 way and it started to overheat. I watched it it slowly cooled back down once onhighway. From that point on, it kept doing the same thing. It would NOT warm up quickly at all, but once it started warming up, it would QUICKLY overheat. This makes no sense to me. Shortly after that, i noticed coolant leaks from a rear freeze plug, and the coolant bypass by the thermostat. The leaks DID NOT start until after all the overheating symptoms. It's almost as if pressure in the engine built up and created these leaks.
Out of ideas, I went ahead and changed thermostat and topped coolant off. I tested old thermostat, and it opened up in boiling water. It is now overheating less, but is still taking a LONG time for the needle on the gauge to move and it still rarely gets to where it used to be (which was dead in the middle for years). Can anyone shed some insight?

There is NO smoke from exhaust, no coolant in oil, and no oil in coolant. Car purrs like a kitten and runs flawlessly except for the crazy leaks and overheating. When I say it's leaking, I mean it's an extreme leak. I was pouring some water into radiator and as soon as I started pouring it in, it was dripping very fast and constant from freeze plug.

I'm also confused about how this cooling system works. I always thought the radiator inlet was on top and hot water from the thermostat hose ran DOWN the radiator and cooled and entered the engine from the bottom hose of radiator. This one is backwards?
The top hose gets very very hot, while the bottom one stays cool. Shouldn't the hot water from the engine make the bottom hose attatched to the thermostat housing hot?

Sorry for the length. I'll try and sum this up.

Car taking longer to warm up. 2 year old radiator and good coolant. fan works fine too.
Takes long to warm up then overheats VERY quickly.
Soon after develops weird leaks from bypass hose and freeze plug (seems like pressure built up in engine and blew through weak spots)
Continues to overheat very quickly.
Change thermostat, and radiator cap seems better although still takes forever to warm up.
Began to overheat again yesterday.
Still leaking like crazy although it is intermittent. Will leak ferociously sometimes and sometimes not at all.....


(hyperlinks removed - not allowed)


(This post was edited by Tom Greenleaf on Jun 20, 2011, 7:04 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 20, 2011, 7:19 AM

Post #2 of 10 (1426 views)
Re: Can't figure this out! Cooling issues Sign In

Pressure test the cooling system and fix all the leaks. Could and probably does have air in it and holds no pressure. Bypass hose is there to mix all engine coolant to a uniform temp and might be failing if air in it from leaks.

Is thermostat in the right direction? Pressure didn't push out a freeze plug as pressure is limited to radiator cap's rating.

If one freeze plug goes expect more too - usually corrosion caused not pressure. Some are so hard to get at you need to pull an engine to do them all!

How much time and money do you want to invest in this car?

T



JD_1990_GTS
New User

Jun 20, 2011, 7:27 AM

Post #3 of 10 (1421 views)
Re: Can't figure this out! Cooling issues Sign In

Thermostat is in the right way. I have flushed and burped it. I just think it's weird that both leaks (Freeze plug and bypass) started at same time after the overheating occurred. The freeze plug is in a difficult spot. I am going to TRY to clean it up and jb weld it. I love this car but don't want to put any more significant money into it.
It runs very very well. Good power, no smoke, and idles flawlessly. Just turned over 190,000 miles and could go much longer if maintained.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 20, 2011, 7:44 AM

Post #4 of 10 (1417 views)
Re: Can't figure this out! Cooling issues Sign In

They make freeze plugs that might fit inside original one like rubber or a copper one like this........... Hope pic shows,



If at a real parts store get a new on the counter and see if you can find one that is snug to go inside it or do it right. Not sure JB Weld will work and could make the real fix harder. As said, if one went others probably will too.

The one you know leaks and the overheat could easily have stressed out an older bypass hose.

Car may run great but this needs tending to in a manner that really works or get a quote from shop that may have tons of tools for hard to get to ones,


T



JD_1990_GTS
New User

Jun 20, 2011, 8:00 AM

Post #5 of 10 (1411 views)
Re: Can't figure this out! Cooling issues Sign In

Ok, I will check into that. Thank you.
Also, the upper radiator hose is soft. I can easily completely compress it (with gloves since it's so hot) while the car is running. Same with the bottom one. Does this mean anything?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 20, 2011, 8:03 AM

Post #6 of 10 (1410 views)
Re: Can't figure this out! Cooling issues Sign In

Of course you can easily compress it as system isn't holding pressure while leaking,


T



JD_1990_GTS
New User

Jun 20, 2011, 8:18 AM

Post #7 of 10 (1406 views)
Re: Can't figure this out! Cooling issues Sign In

Makes sense. I guess I'll try fixing freeze plug leak first and go from there. I have 2 other cars so I have time to fix it.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 20, 2011, 1:52 PM

Post #8 of 10 (1398 views)
Re: Can't figure this out! Cooling issues Sign In

JB weld will definately not work on a freeze plug. A new plug is the only answer and you can expect more of them to leak in the near future.



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chickenhouse
Enthusiast

Jun 20, 2011, 2:21 PM

Post #9 of 10 (1392 views)
Re: Can't figure this out! Cooling issues Sign In

I want to be a buttinski. When engine is cold, can you easily remove the hose (top) and see if it has collapsed internally?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 20, 2011, 2:51 PM

Post #10 of 10 (1390 views)
Re: Can't figure this out! Cooling issues Sign In

You can but in anytime CH. At the age of this car the hoses should probably be replaced if it's going to get fixed up,

T







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