GmanSC

For those good mechanics in this forum, see you can solve this simple problem.

BTW, the car involved is a 2007 Toyota Corolla. Sorry I have to borrow the SC forum for this.

Here it goes. My 2007 Corolla developed this weird problems for last couple weeks. First, the heater won't get hot, (well, it does, after one or two hours of driving). Second, for the first half hour, the temperature gauge would climb to almost the red H, but will come down to normal after one or two hours of driving ( everything is OK when the heater gets hot). And third, the car loss a glass of coolant every day.

My mechanic couldn't figure out why. He changed the thermostat, the radiator cap, check the heater valve control, radiator pressure but still didn't fix the problem. Finally, he suggested I change the head gasket (?) and quoted me the 700 dollars for the job. I said no thanks and took the car home.

Now, every morning, I have put in a glass of coolant, drove for an hour or two, and keep an eye on the temperature gauge and hope it does not pass the red H. I have been doing this for the week.

So what do you guys think?

isfdude

iTrader: (11)

If the head gasket was no good you would get a lot of white smoke and a burning plastic with ammonia smell. Have a pressure test done on the coolant to see if any leaks will push out under pressure. Also if it was a head gasket you would get a misfire code as well as smelling gas in the coolant.

Bgw70

Would you say about 8oz each morning?
Into the overflow plastic tank or directly into the radiator?

Are you sure he changed the thermostat and all of those other parts?

The symtoms are very strange...

I can tell you that driving in the red or near the red will certainly damage the engine and you will most likely need a head gasket.

http://repairpal.com/why-dont-i-have-any-heat

Coleroad

A head gasket leak doesn't have to be a leak into a cylinder,Just saying. It sounds like it is though, and creating air pockets in the cooling system. I want to know if the underside of the oil cap has the white film on it. A cup of coolant loss is relatively small amount. If it is leaking into a cylinder it probably wouldn't cause a miss because a cup over a couple hours wouldn't be more than a water injection system would put in. Pull the plugs. If it is going into a cylinder you will see the difference on the plug of that cylinder.

If you do need a new head gasket. Make sure they send the head out to the machine shop to be decked. If they don't odds are it will blow again sometime down the road.

Coleroad

You can go to autozone and get a cooling system pressure tester from their tool loan program. Your looking to see if the system holds a steady pressure or slowly bleeds down.

GmanSC

Thanks guys. The thermostat was replaced, I have the old one. The new one could be defective, though. The cooling system was checked and no leak. There is no white smoke or engine misfire,

I can understand the leakage, the engine over heating, but the heater? Seem like two different problems but actually they are related. The overheating problem goes away after an hour or two of driving when the heater gets hot.

The heater problem existed for sometime but the over heating happened right after the mechanic changed the thermostat.

I will replace the thermostat this weekend to see if anything changed.

texsexlex

iTrader: (3)

...do you know if it has a engine coolant temperature sensor ? If so, maybe this is the culprit. My wife's 2009 Malibu had an issue similar to this last year & it had basically the same symptoms. Some days she could drive all the way to work and the heater would not warm. The temp gauge would stay on cold, sometimes it would move to hot,but whenever it engaged, everything went back to normal. I put a couple of thermostats in it, then ran across a topic about the ECT sensor. I replaced it & no issues afterwards

isfdude

iTrader: (11)

When you are low on coolant the heater core is the first thing that will loose heat, because of poor circulation and air in the system. That's one of the symptoms that you could be low on antifreeze or a clogged heater core. A compression test or leak down test will show if any coolant is being sucked in by the cylinder has a leak down test measures air pressure not coolant and air is much thinner than liquid.

GmanSC

Guys,
The problem's fixed. I took the car to radiator shop this morning. They used high pressure to flush out the system, also replaced with OEM thermostat. It fixed the heating and overheating problems. However, It still showed a little bit of head gasket leak, you could see the coolant bubbled up with the cap open and the engine running. So it was the defective thermostat that cause overheating and the flushing of the system fixed the heating problem.
I took the car back to the mechanic and showed him the defective thermostat. He refunded my money also tightened all the bolts on the head. It fixed the leak.
Now everything is OK. Thank you all for your help.

ShawnOk

iTrader: (1)

Wow! That's awesome. Glad you got it fixed and got the refund for the part! Enjoy the nice weather in Cali with the your reinvigorated SC... we are right at freezing here in the Chicagoland. :-(

GmanSC

Shawn,
My SC was fine, there was no problem at all. The problem I had was for my 07 Toyota Corolla, which is my working vehicle. I am now a driving instructor (I used to be a Manufacturing Engineer), and driving in this Corolla eight hours a day with my student, doing 130 miles or so. I filled up the gas tank every other day and changed engine oil almost every month.
I am enjoying the SC on the weekend with top down and the lady in the passenger seat. Too bad for you guys in the East Coast. I can feel the freez.z.z.z..iiiing

ShawnOk

iTrader: (1)

Ohh sorry for my error. Should have read closer. In any case, glad things worked out. Enjoy both cars!

Coleroad

Awesome glad it's fixed.

isfdude

iTrader: (11)

The bubbling is perfectly normal as all the air has to come out. Plus with any car when you take the cap off the water pump will push out coolant, trust me if the head gasket was bad you could tighten the bolts until they are about to snap and it won't help. Glad you got it all taken care of and good luck with the car and hopefully nothing more will come up.