All Heated up

dmcollazo · 03-27-2005, 10:24 AM

96 t & c lxi 3.8...Wasn't getting hot air changed t-stat...everything fine for a day or so....stopped at the bank and idling for about 5 min...norm temp..went to go and the temp gauge shot up very fast..turned heater on high..after about a min temp went back down to norm...stayed normal...all of a sudden(while driving) temp shot up again...getting very annoyed

.....Sound like a block somewhere....or water pump possibly?
Would appreciate any help from anywhere right about now.Thanks!

Bye the way it has done this several times....no bucking or snorting or anything else for symptoms.

yogi_123rd · 03-27-2005, 12:41 PM

Two possibilities:
1. The thermostat could be bad or installed backwards. Usually it causes problems within 5 minutes of when you first start up. Acts like it is sticking shut.
2. The coolings fans are not coming on when they should. This case would sound like a marginally bad cooling fan temperature sensor switch. Lesser probable is a bad relay. The temp switch somewhere by the thermostat (two wire connector).

If possible, verify the fans are coming on at the correct temperature by idling the vehicle and noting the needle on the temperature gauge when the temperature drops. Should be somewhere near the midmark on the gauge.

dmcollazo · 03-27-2005, 01:45 PM

thanks for the reply! The fans are turning on when this happens, because I can hear them come on...I turn the heater on high and it blows HOT air..this seems to be enough to bring the temp back down to normal...

yogi_123rd · 03-27-2005, 11:28 PM

Since the fans come on, the problem is blockage or water not circulating (pump). If this problem began after replacing the thermostat, I'd say that where the problem lies. The thermostat should have been installed with the round brass heat sensor (short end) down and the two or three sided steel tower side (taller end) pointed into the gooseneck coupling.

dmcollazo · 03-28-2005, 09:51 AM

thanks!!!I got a pump and will replace today,,,if weather permits...thanks again!

dmcollazo · 03-28-2005, 07:07 PM

drove today for a while...did not change water pump yet..weather was to bad....had heat on almost whole entire time and it never overheated...does that sound more like a block in the heater core? cause the heater was on almost the whole time and wasn't able to block? Any help would be appreciated!?!?!?!

yogi_123rd · 03-29-2005, 07:53 AM

I don't think it is your water pump because your heater is working (water must be circulating). Usually the bearing in them goes and they make noises and leak.
The next question is are the cooling fans coming on at the proper temperature. It should be just a bit higher than your normal operating temperature on the temp. gauge. The fans should come on for about 5-10 seconds which is enough time to lower the temperature back into the normal range.
If for the most part it operates in this way, but occationally spikes high, then:
1. Something is blocking the flow, probably at the thermostat because it has the narrowest opening. I've seen problems like this when silicon sealant was used and beads of it gummed up the thermostat shut. I've also seen where scale rust from the inside of the engine was so bad chunks floated around in the system. You should try a flush of the cooling system first to eliminate this possibility..
2. Another possibility is that you have a blown head gasket and water is being superheated. The symptoms are you randomly boil over for no reason or over time, you would notice a drop in the water level, but wouldn't be able to find any leaks.

I would try flushing the system first.

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