Heat gets hot, goes cold, gets hot again

[skeeter123]

And I hate to bring up the Dexcool issue, but Dexcool works great until it gets a little air in the system, then it can create some oily/greasy residue. It also cant' be mixed with other (green) coolants. You say it's done this as long as you've had it, but how long is that? Are you still running Dexcool in it? Is there a lot of brown/yellow sludgy stuff in the reservoir?
When I got mine, it was clear that the prevous owner had mixed green coolant in with the original Dexcool. I switched to regular green coolant and also went with a 180-deg thermostat to keep things cooler. If you decide to switch from Dexcool, you have to really flush the system out pretty good, and clear out the reservoir as well.

[thephantom1492]

I would suggest to be carefull about drilling holes in the thermostat as it could also damage it and also leave metal parts.

Using a lower temperature thermostat is also not a so great idea, it may make the engine stay cold and the "choke" can stay on, increasing the fuel consumption.

As for the water pump, it's not because that it do not leak that it's in good shape, you could have broken impalers or a broken shaft or loose one (basically they press fit the pulley, shaft and impalers).

As for the mix of different kind of coolant, some are incompatible and do make a mess.

Your car need dexcool coolant, I would NOT suggest to move to the green one. Yes the green is cheaper, but is incompatible partially with the cooling system, mainly dissimilar metal used around the system. Dexcool has been designed to not have issues, while the old green stuff has not. The result can be an accelerated corosion of the heater core.

The fact that your coolant rise when you open the bottle indicate a good air pocket in the system, which when you depressurise expend, and push away the coolant.

But in short, if you bleed the system, that everything work well and later on it still have air, then it mean that you have a leak.

[diem]

When I got the car, the coolant was a little dirty but it was dexcool. I've only had the car 2 months.

I'm using Dexcool and it's as orange as it should be, with no sludge anywhere. What would symptoms of a bad water pump thats not leaking be? I have no overheating issues.

Right, it seems like air getting in would cause the coolant to drop when I remove the cap, not rise. Once I put the cap back on and do a cold startup, the coolant then returns to it's correct level. I'm leaning towards doing a chemical flush tomorrow.

[thephantom1492]

chemical or back flush with plently of water... some say to use hot water. I personally didn't had to do that so can't suggest anything

[diem]

I replaced the water pump as I already had a new one laying around. The old one was a GM part and looked to be much heavier duty than the replacement. It seemed very old but appeared to be in tip top shape. I couldn't turn the propeller by hand, not sure if it's suppose to be like that.

Flushed the system with tap water. I'm going to pick up the prestone materials tomorrow and do a nice chemical back flush

[doctorhrdware]

If I remember correctly you should not be able to spin the shaft on the water pump. But I might be wrong.

[GregGP]

Originally Posted by doctorhrdware

If I remember correctly you should not be able to spin the shaft on the water pump. But I might be wrong.

You should be able to turn the water pump by hand, it just won't spin freely.

[skeeter123]

get ur check yet?

http://www.topclassactions.com/close...engine-coolant

[diem]

It's definitely not right. Not sure if it's a head gasket or maybe a warped head.

It doesn't completely overheat but will go up to about 220 at times. Even with a 195 thermostat in, the steady temp is 205 even when 30 degrees outside.

Thinking I'm just going to tear it down, take both heads in to the local machine shop and have them checked. I'll be sure to have someone else do the angle torquing. That was a very weird procedure having to hold the dial while turning.

[skeeter123]

FYI, the cooling fans (both) turn on at low speed at 220-deg, and go to high speed when ECT hits 230-deg. However, they also come on whenever A/C is on....

[diem]

Got it all apart in 3 hours. The rear head gasket looked suspect. The heads have been dropped off at the local machine shop.

There was coolant in several cylinder. Not sure if it got there when removing the head or if it was already there. The walls are not scored or marked.