: Overheating

08-17-11, 05:44 AM
Coolant boils after about 30 minutes.

I'll try a new thermostat in the morning.

Where exactly is it located?

Do I need any special tools to change it?

What else could it be, if the new thermostat doesn't fix the problem?

08-17-11, 07:51 AM
what car/engine?

usually the thermostat is on the top of the block, follow the top radiator hose. it's usually just 2 to 4 bolts holding the housing in place.

08-17-11, 09:12 PM
Follow this radiator hose?

Is it under the V8 fuel injector cover?

08-17-11, 09:15 PM
My fault. My car information used to be displayed under my username.. what happened to that feature?

Anyway, 1994 Cadillac Fleetwood Brougham.

08-17-11, 10:22 PM
It is probably not your thermostat. It is likely going to be a bad coolant reservoir cap, combined with air in the system. So, replace the cap, fill the reservoir, and bleed the system. The bleed screw is on top of the thermostat housing.

08-18-11, 07:23 AM
I'll get a new reservoir today (I need a new one since I can't see the fluid through it any longer).

I located the thermostat at the top of the water pump. Does that mean that anytime you purchase a water pump, it comes with a thermostat? Because if that's the case, then that thermostat is brand new.

I'll look for that bleed screw, also. I only saw 2 screws at the top when I removed the thermostat.

08-18-11, 07:55 AM
i'm not sure about the LT1 engine but I've never seen a thermostat as part of the water pump. it usually has it's own housing....I can look in the FSM for my 95 shortly and tell you though.

08-18-11, 11:24 AM
You don't get a new thermostat with a water pump. The LT1 uses a different stat than the old small blocks. Also, it needs to go in the correct way or it won't work.

08-18-11, 11:35 AM
directions from my 95's FSM:

Disconnect or remove:
1: battery negative cable
2: Air resonator and intake air duct
3: open coolant drain valve, located in left-hand radiator end tank and drain engine coolant
4: close coolant drain valve
5: radiator outlet hose and clamp from thermostat housing
6: two bolts holding thermostat housing to water pump top.
7: housing
8: thermostat and gasket.

Install or Connect:

1: Thermostat and Gasket
2: housing
3: bolts/screws (toque to 21 ft lbs)
4: radiator outlet hose and clamp to housing
5: air intake duct and air resonator
6: refill coolant
7: battery negative cable.

hope that helps. don't forget to bleed the system

08-19-11, 01:41 AM
I followed most of those directions;

But I don't know which is the bleed screw?;

And I also did not replace the thermostat, because I think it came with the water pump, and I just bought that water pump.

Are there any visual indications of a bad thermostat? And is the AC Delco thermostat (part #131-100) the new fail safe kind that stays open, even when it goes bad, enabling water to pass through the engine but causing the climate control to blow weak heat? Or do these contract when they go bad?

And that was one of the other reasons I was going to change it, because I hear a bad thermostat causes no heat, and my heater has been blowing semi hot air, so I figured this might help. What do y'all think?

Lastly Jay, I saw you mention that if you replace the thermostat in the wrong position, it will not function properly. I can't remember which way it was before I took it out. Horizontal?

Or diagonal with the top bar aligned the bolt holes?

I put it back diagonal for now, because there seems to be rivets here indicating the thermostat direction;

Is that correct?

Couldn't find a recovery tank, so I just ordered a tank cap instead. And don't forget to tell me where the bleed screw is located.

08-19-11, 07:39 AM
nice pictures...

as for not getting much heat did you try flushing the heater core? common problem that causes poor heat. I had to do mine last winter.

08-24-11, 02:25 AM
No, I haven't tried flushing the heater core.

So I bled the system by filling the reservoir with the bleed screw out. Once I got a clean flow of antifreeze, I put the bleed screw back, and topped off the reservoir until there were no bubbles coming out of the reserve tank. Is all that antifreeze still in my system, or will it come out some way? Where does it dispense?

Also, I noticed that my old reserve tank cap looks rusty;

Should I have drained the whole system? Or will it be fine? The inside of the reserve tank is very "rusty," also. Which is why I can't see how far up the liquid is filled..

08-24-11, 02:27 AM
I had also forgot to put the bleed screw back in the thermostat housing when I finished, and drove off spraying antifreeze everywhere..lol. Lesson learned.