spessx

I have a 2005 C2S with 98k miles that I just purchased a month ago. I don’t have records as to whether the water pump has been replaced. I’ve currently got the serpentine belt off right now because I’m replacing the alternator and AOS. When I spin the water pump by hand it’s completely smooth and doesn’t have any leaks.

After I get the AOS buttoned up it’s going into the shop for a new IMS/Clutch/Rms. It’s an extra $1,400 to do the water pump and 160 degree thermostat at the same time.

So I have two questions:

1. Do these water pumps start to make noise before they fail (similar to how the idler pulleys will)?

2. Should I bite the bullet on the water pump and replace it now? Or wait for it or the engine to fail (whichever comes first) and just have it replaced?

ronvanr

Bite the bullet! If the water pump hasn't been replaced. The price feels about right.

jchapura

1. Sometimes. Sometimes they fail catastrophically and without warning, leaving you stranded. With the belt off, check the shaft radial movement. There should be very, very little movement. Also look for pink "crust" as a sign of (coolant) weeping.
2. I would. Better safe than sorry. I'd also replace the thermostat with a "low temp" (160degF) thermostat to reduce the chance/severity of bore scoring. And since much of the coolant is drained, assess the condition of the hoses and replace those also.
If you're doing the cooling system work yourself, get an UView AirLift to be able to pull most of the air out of the system when you start refilling it.

spessx

I won’t be doing this work myself. I’ve watched a few videos on how to change out the water pump and I’ve got less productive ways to spend a weekend. But I’ll definitely be adding the 160 degree thermostat.

ATX_Native

Have you done the IMS Solution yet or are you considering?

(Assuming you don’t have a large IMS bearing engine already)

bheit1

With 100k miles, yes I would replace the water pump. I would also replace the coolant reservoir as they tend to dry out and crack.

I don't understand the 160 degree thermostat thing unless you're racing. Seems to me you want the engine to warm up as quickly
as possible to prevent bore scoring, and change oil every 5k mi. I've been in Austin when the temp dropped to zero.

jchapura

It's my understanding the low temp t-stat is meant to allow for more uniform block temperature (between the hottest and coolest areas) during the warmup cycle.

bheit1

From my way of thinking, the warmer thermostat should get the block up closer to the hotter cylinder temp. sooner. I would also think Porsche would be using the cooler one if there was an advantage.

jchapura

It's my understanding that because the low temp t-stat opens earlier, coolant is flowing earlier and then tending to more uniformly heat the areas that had no flow and cool the hot areas that had no flow, especially in the early stage of warmup. It seems coolant flow is especially important for this system and in regards to minimizing one or more of the root causes of bore scoring.

spessx

I’m having the IMS solution done. I have the earlier smaller bearing in my car.

spessx

I think this is the reason. Cylinder 4/5/6 don’t have as good of cooling as 1/2/3 and opening the thermostat earlier during warmup prevents them from getting too hot and damaging the coating on the pistons over time. Once the coating starts coming off of the pistons it gets wedged between the pistons and cylinders and causes scoring.

groovzilla

Replace Water Pump, Thermostat, Idler Pulleys and Belt.

sandwedge

With a 2005 I think it's safe to say you don't have any kind of extended warranty that would cover a failure. So unless you have evidence that it's been replaced I would probably go ahead and have it replaced since at your mileage you may be on borrowed time and will have to pay out of pocket sooner or later for replacement. I say this since the water pump on my -09 C4S failed at 43,000 miles and took the serpentine belt with it.

No pink fluid leak on the garage floor or any kind of noise or warnings otherwise of the failure. It just seized up without warning, hence the serpentine coming apart as well. Total cost for all of it came to around $1,200 as I recall it but this was 6 or 7 years ago. And as jchapura pointed out, if it fails while your out on the road, you're stranded. One of relatively few failures I can think of....especially relatively inexpensive ones that will leave you stranded.

I have 72,000 miles on the original pump on my GTS and keep debating on whether to preemptively replace it out of pocket or wait for it to fail and have it covered by my extended Fidelity warranty like the one on the -09 C4S. Having to pull over roadside calling for a wrecker no matter where you are is not a great experience.

yelcab

For a 997.1 car, I would replace the water pump and thermostat at 60K miles whether it fails or not. I do practice what i preach on my own 997. New waterpump at 60K and again at 120K.

Petza914

This is correct and why it works to prevent scoring. The other advantage is that it's fully open by 180 to help keep the engine cooler earlier vs theb180 thermostat that's not fully open until over 200.degrees which means the amount of coolant flowing to the last cylinder in the flow path (#6) is getting hotter than the others...which cylinder almost always scores...#6.