Water pump going out? Radiator?

[buck531]

I'm been trying to figure this out for the past few summers. In the summer (or even now for that matter) the temp in my turd gets to around 200. Yes I know that's within spec and what not but I have my fans coming on at 176 and I have a drilled 180 t-stat. It only used to get up to that temp when the a/c was on in the summer. Now yesterday (70 degrees) I didn't have the a/c on and sitting at a light the temp started climbing. After the light turns green I go on my way and the temp starts going down.

Now last year or the year before the temp only got up to 184 and pretty much stayed there. It only seems to do it when I'm going slow or idling for a long period of time. I do have a FMHE on the car for the i/c and I'm not sure if that's causing the issue. I wouldn't think because when the temp rises the car is idling, not driving.

Nothing leaks. It has good pressure. I just swapped the t-stat last night and that didn't change anything.

I really don't want to just start replacing parts and not fix it. I'm tired of doing that crap. Any ideas?

[Scottydoggs]

they can still get hot even with the fans tuned and a cooler t stat.

i got my fans tuned to 185, run a 195 t stat, and generally the engine runs around 180, now if i stop and idle for a long time, temps will pass 200 on a hot day.

adding the ic and fmhe has changed nothing so far either. i can feel the fans pulling air through the fmhe too. so my guess is when moving theres really no restriction there.

[SubwayGuy]

Are you sure the system is bled properly?

[buck531]

Uhh yeah? I know there's a "special" way to bleed it but I've never done it in all of my years on working on 3800's.

[Scottydoggs]

if you have a drilled t stat you dont "have" to bleed it. it will self bleed as its ran, just check the coolant level the next morning and top off if need be.

but the bleeder is a top the t stat housing in case your not joking lol

[buck531]

uhh.. yeah scotty I know.

[buck531]

I've never had this issue in the last 6 years I've owned the car. It just came up last year and this year. All the previous times the temp has always sat at 185 and really hasn't moved.

[CHI2000GTP]

Try rev'ing the engine when you're idling and the trans is in Park. Keep your foot on the gas with RPM's around 2500. After 15-20 seconds, does the needle start to drop like a rock? If so, water pump time. Means that you have better flow when pump is spinning faster, meaning that the impellers are worn down. Was happening to me. Water pump was completely eaten/dissolved. See pic in link below, post #64.

http://www.grandprixforums.net/threa...88#post1427488

[buck531]

Try rev'ing the engine when you're idling and the trans is in Park. Keep your foot on the gas with RPM's around 2500. After 15-20 seconds, does the needle start to drop like a rock? If so, water pump time. Means that you have better flow when pump is spinning faster, meaning that the impellers are worn down. Was happening to me. Water pump was completely eaten/dissolved. See pic in link below, post #64.

http://www.grandprixforums.net/threa...88#post1427488

holy crap! lol. wow. I'll let it get up to temp and try it when I get home. That does make more sense. The temp does go down after driving it but that's at 2500-3k rpm's compared to sitting in traffic at idle at 800.

[Scottydoggs]

lmao, even a good water pump will cool your engine down if you hold the gas at a higher rpm. its spinning faster of course it will cool the engine down.


i used to do this all the time in my trucks when i had the plow on, if i went to fast, or gave it to much gas on the hwy the plow blade blocked the rad's air flow and it would get hot.

id pull over, hold the gas @ 1500 to 2000 rpm and watch the needle drop like a rock.

[CHI2000GTP]

True there Scotty. I suppose that line of thinking won't directly diagnose the water pump as the culprit. But still, I feel like if the overheating is way past the 210 mark, and speeding up the water pump drops is right away... likely the water pump, IMO. But, I'm no expert by any means, LOL

[Scottydoggs]

i hit 200 in traffic today, 80 degrees out today.


side note, still kr free lol

[CHI2000GTP]

Nice! I will be buying a ODB tool to monitor my KR, although I'm running all stock at the moment.

[buck531]

Well I just got home. Roughly 75-80 degree out. Temp got up to 214 in traffic. Got home and revved to 2k (took a video) and it went from 212 to 214. Something isn't right.

https://www.youtube.com/watch?v=FBsJyb26AOg

[Scottydoggs]

flow issue i bet, like the title says, w/p or rad is the question.