mustangracer

I just put a new water pump on my 99 and have run into a weird problem. I let the car warm up to purge the air from system and it was running a little hot. At idle the car was running ~190* which isnt normal, the car usually runs 178-180.* I took it for a drive and through town it comes down to about 187 and wot it comes down to "normal." Now my thought is that the thermostat isnt fully opening and I know for a fact that this thermostat is good because it was on other water pump, so is it possible that this new water pump is an 04+ water pump that needs the separate housing and thermostat? The part number for water pump is ac delco 252-846, apparently both housings fit just the older style not properly. Thanks in advance.

Another note the lower radiator hose is cool to the touch so I know the thermostat isnt opening (or at least all the way) to circulate the coolant.

mustangracer

I did both methods, as soon as I cracked the ones on each head fluid came out and I let it run a few extra seconds just to be sure.

mustangracer

Heres a pic of thermostat mounted on new water pump, notice the huge gap there. Im almost certain that this is a new style pump that requires a 2 piece housing and thermostat, which would explain why its not fully opening.

pewter99

I thought the new pumps had the stat and everything in them and the old style was 2 piece. Maybe I am confused as I have changed a couple of them between the 99 and the 02.

TEXHAWK0

Water pumps used to come with the thermostat installed... Did that change?

mustangracer

I guess in my case yes

mustangracer

Im not sure if its a new style pump, i bolted my 1 piece housing on and started having weird temp problems (first post). Chevy never changed part numbers or anything so theres no way to tell if its old or new style, I was told this is old style but think someone was blowing sunshine up my a$$.

3boystoys

Still don't see a problem here with these numbers, still way below thresshold for fans to come on.

mustangracer

Cars tuned for a 160 thermostat and would consistently hold 180* no matter what until I intalled this pos water pump, so there is a problem.

Ordered a new housing so hope fully tomorrow I will have a resolution.

3boystoys

If you order the same pump, expect the same outcome. According to EvilTwin 190 is what you want anyway.

mustangracer

Well its what I thought the problem was, water pump is for an 04+. Bought a new housing and 160 thermostat and the car is rock steady 178 cruising.