Car problem - expert help needed

[Zenmervolt]

Originally posted by: Eli
What exactly do you mean by jumping? Does the needle literally flick from cold, to hot? Or is it a gradual increase, within a 10 second range, as Roger stated?

My girlfriends' mom's Toyota Camry would do that. We never did find the problem.. I always figured there was just a short somewhere... lol

The slow back-and forth can be normal on some cars, especially in the city. My 924S moves between roughly 1/2 (89 degrees C) and 3/4 (97 degrees C) in the city. Thermostat opens at 3/4 and trips the fan, then closes at 1/2 and shuts the fan off. The car will take about 10 minutes to go from 89 degrees to 97 degrees, and about a minute to go back to 89 degrees once the fans kick in. On the freeway it's fairly stable at what I'm interpolating to be about 94 degrees C or so.

ZV

EDIT: And now that I've converted those to Fahrenheit, I think I'll be checking my sender for accuracy since the thermostat is supposed to be 180 degree and not 205! If the sender's accurate I'll be in for an expensive thermostat replacement (have to pull the water pump to get at it, have to pull the belts to get at the water pump, have to have a $600 tool to re-tension the belts). Hopefully my sender's just reading high because everything else seems to be spot-on with how the car's running.

 

[The Sauce]

The needle literally flickers from warm to cold...less than a second...back and forth. When I get it up and running on the highway it stays cold. If I slow down then it jumps back and forth.

The long heat up times (Interior heat) results from either a bad thermostat, low coolant or a blown head gasket.

Well this requires a somewhat longer story. The head gasket blew about 15 months ago and Toyota fixed it, sent the deck out to be resurfaced and cracks filled, etc... Cost me $3600 total with much of the cooling system replaced once all was said and done. As of late (~ 12,000 miles later) it has been consuming coolant again. No smoke out the tailpipe (of the car, that is), but adding coolant every couple of weeks. And then the above stated thermostat and heater problems. Took the car to a BP Procare and they replaced the thermostat and found high hydrocarbons in the coolant (like 2000 PPM or something) and concluded that it was a blown head gasket. I took it back to Toyota and they pressure-tested the cooling system again and found no leak - concluded that the head gasket was OK and gave me back the car. Even if it is the head gasket, they said that they would not warrantee the prior repairs, and I'm in no mood to pay to have that done again on a 16 year old, 135,000 mile car. So that's the full story. Does that change anything? Is Toyota fibbin?

 

They filled the cracks in the cylinder head ?

Impossible, even a good welder often fails when it comes to repairing cracks in a cylinder head, I hate to be the one to tell you but the reason why you are having problems with your cooling system is because exhaust gas is forcing it's way through he cracks in the cylinder head into your cooling system causing the temp Gage sensor to be momentarily uncovered which causes the rapid fluctuations, poor heat in the interior cabin and most likely the high idle when cold.
(Contamination of various sensors with coolant and exhaust by products)

 

[The Sauce]

Well I'm not 100% certain about the cracks thing. Honestly, I wasn't as involved in the repairs as I probably should have been...it was a busy time. They did mention something about a crack but it did not seem certain by any means...maybe they were speculating prior to taking everything apart. Anyhoo, I am expecting bad news with this car and already have a new one lined up and ready to buy when this one finally explodes...which seems to be getting closer by the minute I'm just trying to figure out what I can do to stall the inevitable here and postpone the new purchase.