New head gasket, now it's overheating...

PoisonDrop · Post by **PoisonDrop** » July 21st, 2007, 5:41 pm

Here's some background...

- Head gasket started leaking, oil in water, etc
- Put on a new gasket as well as a new cylinder head (to avoid warp-age)
- Spent some time cleaning things up, replacing some other gaskets, etc
- Replaced most water hoses as well as the thermostat
- Replaced the injector o-rings (just to be safe)

Today is the first time I've started it with all the new parts in place. It started on the third try and ran great. There was quite a bit of HLA noise, but it went away after awhile. There are no leaks or puddles on the ground, no white smoke at all, and the car is running smoothly, even when I rev it a little.

The problem is, it was fine for awhile after it reached normal operating temp. Then all of a sudden, the needle on the temp guage climbed to a little above half. Then it went back down to half. Then up again, then down again. Finally, it kept going up, so I turned the car off. All of this happened at idle (haven't gotten out of the driveway yet). The fan didn't come on, so I know I need a new fan switch, but the temp went above where it should be, with or without the fan. It started pouring rain here, so I had to stop working on it for now.

It sounds to me like there's air in the cooling system, but if anyone thinks different, I'd like to know. Wouldn't want to warp the new head and all. I guess I'm just looking for a second opinion here.

Thanks in advance!

Limegreen mx-3 · Post by **Limegreen mx-3** » July 21st, 2007, 9:19 pm

could be a big air bubble in ur coolant system or does it happen in stop and go traffic. A fan not working could get the temp to rise.

another think did u resurface the head when u replaced the old head gasket. if u did it could be still warp and the reason to why its over heating.

Shades · Post by **Shades** » July 21st, 2007, 9:23 pm

Air in the system there is...

To fix this, prepare your coolant mixture... then start the car with the rad cap off. Just let it idle (do not rev it) and watch for bubbles in the rad cap... keep filling up the rad with your mix. When it doesn't take anymore mix then put the cap on and watch the engine temp gauge again.

If it starts to spike again... then let the engine cool down, try this one more time. If it don't work then something is wrong.

Goodluck!

PoisonDrop · Post by **PoisonDrop** » July 21st, 2007, 9:27 pm

I got a new head instead of resurfacing the old one. I'll try getting all the air out of the system tomorrow after work.

Thanks for all the help!

shameem · Post by **shameem** » July 22nd, 2007, 2:58 pm

You have to have the heater going at full setting while removing air bubbles - they can be trapped in the heater core too.....

PoisonDrop · Post by **PoisonDrop** » July 22nd, 2007, 10:30 pm

That's a good idea. Thanks...

PoisonDrop · Post by **PoisonDrop** » July 24th, 2007, 11:18 am

Ok, so I got all the air out of the system and filled it with coolant. It held temperature for about 10 minutes at idle at normal operating temp. The radiator cap was still off, and there weren't any more air bubbles coming out. Then it started to overheat again. It got up to just below 3/4 on the temp gauge.

The fan never came on. I'm going to get a new fan switch today. The question is, does the fan make THAT much of a difference? I know it creates air flow when the car isn't moving, but would it overheat THAT much? Or could something else be wrong?

The thermostat IS opening (it's brand new), and the water pump is working fine, no water coming out of the fail safe hole. When it overheated a little, I turned the car off (with the radiator cap still off) and it shot coolant out of the radiator. Is this normal? At this point in time, I have no clue what could be wrong.

Limegreen mx-3 · Post by **Limegreen mx-3** » July 24th, 2007, 2:07 pm

A FAN not coming on can do that. LOL happen to me

Bumpysbro · Post by **Bumpysbro** » July 24th, 2007, 2:24 pm

same here, with mine it was the coolant fan relay which is under the coolant resevoir on the driver side. mine got water on it and the fan wasnt kicking on and caused my car to overheat.

PoisonDrop · Post by **PoisonDrop** » July 28th, 2007, 2:23 pm

My problem was that the fan (when it came on) was bringing the temp down at least 100 degrees. The issue was that I used the wrong temp sending unit, so the reading on the gauge was wrong. Funny, because I had the same problem when I installed the motor. I just didn't make the connection. So it wasn't really overheating, just appearing to overheat. It's fixed now, though, and running smooth as ever! Thanks for everyone's help!

PoisonDrop · Post by **PoisonDrop** » July 28th, 2007, 2:25 pm

I should add that anyone that has done the BP swap with an EGT motor from a SOHC 1.6 should use the tamp sending unit from the MX-3, not the EGT. The unit from the EGT has a different range, so the reading on the MX-3 gauge is wrong. Just some info for anyone else who may have my problem.

g0t_slack · Post by **g0t_slack** » August 6th, 2007, 9:25 am

Any update on this? I just scored another rs, and it's doing the same thing.

TREVO123 · Post by **TREVO123** » August 6th, 2007, 3:36 pm

What sender is that? the Square connecter one or the round one?

PoisonDrop · Post by **PoisonDrop** » August 15th, 2007, 1:38 pm

Sorry for the delayed reply...it's the one underneath the dissy on the front of the motor.

PoisonDrop · Post by **PoisonDrop** » August 15th, 2007, 1:39 pm

That only really applies if you have a BP under the hood. If you're using the stock motor then the normal temp sender should be fine.