ahofam123

After replacing the water pump with a rebuilt one and the thermastat with a new one, it seems as if my car isn't circulating the coolant. Ive already bled the system but the car is over heating and only the upper radiator hose is getting hot. The lower radiator hose, the radiator, and the coolant resevior all remain cold. Can the thermastat and the waterpump be the only culprits? I know that it is possible for rebuilt waterpumps to fail but how common is it? Thanks in advance.

IPSC

I just suffered through this and I can understand your frustration. When you say overheating is it actually overheating or is it just running hot? My car ran very hot after a recent water pump replacement. My problem was that the thermostat my mechanic acquired locally did not open at 180 degrees. Instead it opened at 210 degrees. The temp indicator was always at the top white mark and I lived in constant fear of overheating my engine. The method I used to trouble shoot the problem was to use a laser thermometer to measure temps at different points in the cooling system. It was from this that I deduced that the thermostat was not opening till the temp got very hot (210 and above). Then because it had been closed for so long the coolant in the radiator (which was usually about 130 degrees on the hot side 100 on the other) would rush into the system and hit the open thermostat and close it before any real cooling could occur. Then the vicious cycle would start again. If you can, borrow a laser thermometer and see if this is happening to you. The water pump housing was were I discovered this momentary opening of the thermostat. The lower hose would be as cool as 120 degrees while the housing would be as hot as 200 degrees. Then the thermostat would open and the bottom hose would be hot for about 10 seconds and then the thermostat would close again. You see the pump is so strong that it has a very high cyclic rate. In fact if you run a 944 with out a thermostat it will eventually overheat, as the coolant does not stay in the radiator long enough to do any cooling. My guess would be the thermostat. While not easy to change it is the first place I would start to look.


IPSC

Matt O.

So there is air getting in the system? Or is it just running hot?

Maybe the waterpump is bad. It could happen.

Also, try replacing the heater valve, I think it's only 20 or so dollars, but that was causing air to get in my system (at least that's what the mechanic told me).

-matt

ahofam123

The car isn't just getting hot it is overheating. I will pull the thermatstat sometime this week. I don't think that there is an air leak because after I let gravity bleed the coolant I let the car warm up with the heater on and when I open the bleeder bolt I have nothing but a stream of coolant come out at first, then it disappears to nothing. I'm thinking that this is because the thermastat isn't allowing any coolant to the waterpump.

Pilot Dave

If the thermostat does't fix it then you probably need a new radiator because it's clogged. I had the same problem. After a thermostat & water pump replacement the radiator was still cold. I changed it and problem solved.

Bad news, a new radiator costs $250-$300
Good news, it's easier to install than the F#%*&$ thermostat.

ahofam123

Thanks, I'll keep the radiator in mind but I believe that it is clear since I flushed it when I removed it to istall the water pump

Pilot Dave

Yup, mine flushed OK also. Problem was that only 2/3 of the radiator was clogged. The 1/3 that wasn't clogged ran a hose of water through it without a problem.

Its_Lobelt

[quote]Originally posted by Pilot Dave:
<strong>If the thermostat does't fix it then you probably need a new radiator because it's clogged. I had the same problem. After a thermostat & water pump replacement the radiator was still cold. I changed it and problem solved.

Bad news, a new radiator costs $250-$300
Good news, it's easier to install than the F#%*&$ thermostat.</strong><hr></blockquote>

Not really I bought mine from 944online.com for like 170 and its fine. Its aluminum and its made in Germany I like it and have no problems. That price is like from a dealer or somthin.

tdatk944+S4

Blead ,blead ,blead.

Pilot Dave

Robert_325i...ouch! I guess I could have saved $100 if I just shopped around a little. Lesson learned.

And tdatk944 is right. Make sure you have that system completely bled of all air. If 2 gallons of liquid did not go into your system then you have air in there.