I recently replaced the water pump. It wasn't overheating or anything, just developed a leak. Never really payed that much attention to specific temps that much since there was nothing unusual. After replacing the water pump, I've been watching the temps carefully. Just cruising around or some spirited mountain roads it likes 196 degrees, maybe up to 198. As soon as I get on the interstate and cruise about 80-85 with about 2,000 rpm, the temp goes up to 201-203. Soon as I get back on surface streets it drops to 196....it seems to like 196. All my experiences with other cars and motorcycles, the temps drop at higher speeds and goes up at lower speeds. I guess I just don't get what the C5 is doing. Nothing bad, just odd to me.

 

make sure you have all the air out of system ????

 

203 degrees is absolutely nothing to be concerned about, on these cars.

 

What was the part number of the water pump you used?

 

Pounder- I did a burp procedure when I replaced the water pump. I'll do the procedure you posted, thanks.

Ed- I can look up the part number, but it was the stock AC Delco replacement pump and stock AC Delco replacement Thermostat.

Thanks for the replies.

 

I checked the AC Delco part number.... 252-846, but also lists the OEM #19195105

 

FWIW, last month I experienced exactly the same odd high temps at low rpm, low temps at high rpm (the exact opposite of anything I had ever experienced before with any of my cars...and I have owned dozens) and outside temperatures were below freezing. My coolant level was low (so I obviously have a leak somewhere; and it is a very slow leak and a failing water pump is my prime suspect). When I filled the coolant tank up, everything behaved normally again. I'm no mechanic; but I suspect that the higher rpm had my water pump spooled up and it was able to drive the low level coolant through the system and/or make the thermostat behave as it should. I can't explain exactly what is going on with my car or yours - but I can vouch for the fact that your symptoms mirrored those of my car. Air in the system and low coolant in the case of your car, you appear to have ruled out- getting the coolant level up with my car solved the problem. Using my car as a baseline, that may leave the new water pump or possibly the thermostat as prime suspects in the case of your car. Your issue arose after the new water pump installed, so as painful as it may be to face- perhaps your new water pump is defective; or not working as well as the old one. But for my car temperatures hovering around 200 is pretty normal.

 

Hey Doug- Thanks for the reply. My coolant level is good and no leaks. I will go though the process to make sure there is no air in the system again. My temps aren't concerning right now, just seems a little odd. I'll see how things go this Summer. If you change your water pump, it's a real contortion to get it done, but I got through it. Hope yours goes well.

 

You are most welcome. So far topping off my coolant has the problem solved- the leak is a very slow one; and I'm thinking I'll be good through the winter. From what information I found on line the water pump replace appears to be a reasonable DIY job and the complete kit affordable; so I am considered doing the job DIY when our weather warms up. But most likely, I'll end up chickening out and I'll source the parts and have my mechanic diagnose and tackle it. I've done that with a number of things on my car (plugs, wires, brakes & exhaust work). Their labor charges are reasonable and cost me less than a trip to the emergency room!

 

The actual replacement is simple in concept. I think there were 6 bolts. Draining the fluid can be a real mess, but the hoses were not a problem. I did get the hose clamp tool....definitely needed. The worst part is getting the new pump on. It's in an awkward position. You can't actually see all the bolts, so you have to fumble around. The bolt holes are clear drilled, so just a slight tilt and they fall out and the gaskets on the other side fall off. A little silicone grease held things in place enough to get it in place. You will need a little luck... So far, no leaks on mine. If you get a good price from a shop, it might be worth it. Let us know if that solves the odd temps.

 

252846 is the professional replacement that they have fitting from 97-04. People are going to come across issues with that one, especially if they have an 04, or they upgrade to the 2 piece thermostat and housing.

The best one for 97-04 is 251-744 and the 2 piece thermostat and housing. I also suspect some people may use the 252846 with a one piece thermostat/housing and be plagued by mysterious overheating. It all has to do with a few tolerances - I can explain in detail if someone reads this and has an issue.

 

Moved to C5 Tech.

 

I realize this thread is 5 years old but I'm curious, why would someone have issues if using 252846 and a 2-piece thermostat and housing, or have overheating issues if using 252846 and a one-piece housing? What would one use then with a 252846?
If 251-744 and 15-11057 / 12600172 (2 piece) are compatible then 252846 and 15-11057 / 12600172 (2 piece) should also be compatible since both part numbers pull up as correct for the application, no?

Has anyone actually measured that the inlet holes between the two are different and confirmed that "251-744 will NOT accept a one-piece t-stat and housing"

252846 comes with these instructions:



Per instructions, the one-piece design 12571261 (also labeled ACDelco 15-10412) or 15-11057 / 12600172 design can be used with the 252846.

I've seen from someone "The earlier thermostat and housing will not fit the later pump because the hole in the later pump is slightly smaller even though they look the same"
I've read Gates 33910 Integrated Housing Engine Coolant Thermostat and 252846 was a success.
Could it be there was a revision to 252846 enabling both 1-piece and 2-piece to work?

252846 is the later pump. 89018053 is the early pump from what I read.
Here's a video of someone installing the 1 peice t-stat into a 252846 at 12 min into the video:
LPE Thermostats List.pdf

 

Yes I measured holes in each pump. The universal pump with a different size (larger) hole had issues in addition to the hole. I still have my 2004 OE pump in the shed if you need measurements. I sent you a PM as well.

I remember that the universal pump had a larger hole to accommodate the 1-piece thermostat/housing and it was not a good seal with the 2004 2-piece. I wound up using the gasket and rubber o-ring until I got the 2004 specific pump. The rubber ring did not seal well to the universal pump, but was needed to retain the thermostat in the housing. The paper gasket was needed to seal it as best as possible but it was hokey. I also noticed that the length of the thermostat was an issue with the universal pump - the thermostat in my 04 was designed to reach down and block off a bypass until it came up to temp - the measurements here were off as well. This was what I personally experienced. Then, when getting a 2004 specific pump that has the smaller hole, the thermostat sat correctly depth wise and also sealer properly and all issues went away.

This was 5 years ago - there is no telling if the aftermarket has made any changes to for any of this.

 

Measuring the 2 piece (12600172) vs the 1 piece (12571261), the distance from the top of the thermostat to the gasket surface is the same, so if there is an issue, it would be with the machining depth of the universal 252846 pump.
Hopefully it's been resolved since 5 years ago.

I will pay close attention to the depth of the thermostat in relation to the universal 252846 pump. If it's a problem, I may use a spacer or get a 251-744 pump. Thanks!

 

Straight from Summit review on the 251-744, the review confirms that the 1 piece integrated T-stat will not fit in the 251-744. Written 8 months ago.
I'll report back if the 252-846 works with the 1 piece.