T-stat issues?

[dipsamt]

I think this an easy problem and fixing it shouldn't be hard. But I'm curious as to *why* it's happening.

A few weeks ago, my engine started running hotter and I was losing water. Water pump gasket - replaced it and the water pump. Now the engine still runs hotter but it dips down so I know I'm getting water because of that and the obvious lack of leakage. But - the heat in my car is really cold. Then it gets warm, then cold, then warm again. It does this for about 10 minutes (after warming up the car for 5) and then it stays warm.

My guess is the T-stat is starting to go so that's my plan right now. But why is the heat bouncing up and down? Is the t-stat spontaneously opening and closing?

[FB71]

you're getting steam pockets in the heater circuit. Sounds like you possibly have a blown headgasket.

[dipsamt]

Great. Not exactly what I was hoping for. Not trying to get out of changing the head gasket or anything, but why would it stop after the 10 minutes?

[DuritzCrows17]

if this is the case I recomend just swapping a used engine in from the jy, head gaskets are such a pain.

[FB71]

??? a head gasket can be swapped out in 30-45 minutes...

[DuritzCrows17]

??? a head gasket can be swapped out in 30-45 minutes...

I'v had bad luck with them, i guess your right.

[Dave G]

??? a head gasket can be swapped out in 30-45 minutes...

Maybe if you have a team of mechanics and plenty of cocaine... :-). I'd say more like 4 or 5 hours for mere mortals.

[FB71]

sorry, I keep forgetting I've been doing this for a long time.... (since god was a boy and dirt was clean!)

you're correct. For someone who's never done it before, it will be an all-day job. But, an engine swap will be an all-weekend job for the same person.

[DuritzCrows17]

??? a head gasket can be swapped out in 30-45 minutes...

Maybe if you have a team of mechanics and plenty of cocaine... :-). I'd say more like 4 or 5 hours for mere mortals.

Lol I was hoping I wasn't the only one that couldnt get it done in under 2 hours.

[dipsamt]

Ok, I'd like to be more clear if I can. I don't have a huge cache of tools (although I can borrow some if I need to) so I only want to change out the head gasket if I really need to.

The temp gauge is normal. It used to be barely rising above the min. mark but I think reseating the radiator cap is what happened with that. Now it goes about half-way which is normal. That was a month ago.

There's no oil in the coolant. It's nice and clear. There's no smoke coming out the back. There's no sweet smell. If it *is* the head gasket, I'll do what I have to, but I'd really like to avoid another all-night episode (my last project was the water pump. Took me 19 hours because I didn't think about lowering the engine and I didn't have the right tools. The best thing out of that was that I was right - it was the water pump and also finding this forum). Since I've changed the water pump, that's when I'm getting the hot air/lukewarm air. And, like I said, it only goes for about 10 minutes and then it's fine.

[freshtiva]

What happens if you start the car with the radiator cap off ?

[Dave G]

Sorry for veering off topic :-) I'd concur with your original plan - pop in a new thermostat & see if that fixes it. I'll bet it will.

[25Horseplay]

Make sure you get the proper 2 stage T stat.

[FB71]

I still go with steam pockets, but it may be as simple as burping the system after opening it for service. Jack up the front of the car as high as you safely can, remove the rad cap, and run until it reaches operating temp. When the tstat opens, the coolant level will drop. When it does, quickly fill the rad and cap it. Shut off the engine, let 'er down, and see what happens with the heat.

[dipsamt]

Yeah, I read about the 2 stage t-stats.

Jim, that actually might be it! I was going to do that when I replaced the water pump but it was late and decided to do later. I never did and didn't remember until now.

So, I'll burp it first. T-stat second. Head-gasket third. I'll keep you guys updated. Thank you very much!!