Coolant Leak Around Water Pump

After going out for a run in my 996 C2 and getting stuck in heavy traffic on a hill where I had a lot of stop/ start in hot weather, I got home and noticed there was coolant leaking from the rear left of the car. It's never lost coolant up to this point and I assume the it got quite hot and found a weak spot. Can't tell for sure but looks like it's leaking around the water pump gasket. I have ordered a replacement pierberg pump and also a thermostat. It seems harder to get the full range of brands in the UK and had to order from Germany. I watched a few videos and trawled the forums and it appears to be a reasonably straightforward job though I'm sure I will come across the usual challenges! More confusing seems to be the subject of coolant, I've read conflicting forum comments on what's best to use. But Prestone seems like a good option and I believe that's what in the car currently as its a luminous yellow/ green colour. The recommendation seems to be to be to use a compressor to flush the cooling system which I don't have so many need to borrow one for that job. I also can't seem to find the correct hose clamps to replace the current ones. Again, a lot of forum posts state that the original type should be used and not screw clamps. Any thoughts or recommendations before I start would be much appreciated! ​​​

Use Pentosin red if you can get it. Or Porsche stuff. Use the Airlift system to fill it.

You could look for screw/bolt hose clamps. They won't cut into the hose. Also agree with yelcab. Get the Pentosin and mix with distilled water. The suggestion to get an airlift system to fill it requires an air compressor, but maybe this is a good reason to get the air compressor. Comes in handy for a lot of things.

Quotes source post: 18976675

Porsche moved to a newer screw-type hose clamp. You can use that as long as it�s the Porsche clamp. Porsche went this route because it�s a slight improvement. The old clamps can lose clamping force over time. That seems like the only downside besides having to use a different tool to properly remove and install them. Do not use the cheap screw clamps found elsewhere. They are either crap metal or rust-prone, and can deform (out of round) and even leak or crack a metal hose. These are actually worse than the original tension-style clamps. But the best ones are the newer style Porsche screw clamps.

Quotes source post: 18976859

Nothing is worse than the tension type clamps. The two ears always face the wrong direction. Or they spring to the wrong direction when your pliers slip off. Even when they face the right direction and you have reused them, they lose enough tension that they leak at working pressure ... leading to you having to do the job over again. Remove that piece of crap of a clamp and replace with screw type clam of good quality. The Oreily's ones have always worked for me. Norma clamps are also good. When I remove any of those tension clamps, they go right into the garbage. There is one thing that is worse, the Otinger one time use clamps. You have to cut them off, they cannot be reused, and you cannot readily get them at the autoparts store.

Thanks all that helps with the clamps, I'd got it into my head from reading other posts that the screw type clamps were a bad idea but I see the Porsche ones are readily available on the design911 website (I guess the closest to pelican parts we have in the UK). There do seem to be some differences of availability of brands. Pentosin doesn't seem to be readily available in the UK.

The benefit of the spring clamps is that they maintain clamping force even though the rubber will creep (the indentation you see in the rubber left by the clamp after its removal) over the years and reduce the diameter of the hose where the clamp sits. The screw style clamps otoh loose clamping force over the years thereby increasing the risk of a leak. If that is enough of an advantage to outway their disadvantage and stick with them, is a personal choice.

My personal experience with the spring clamp is on a Cayman, one of those clamps (re-used) started to leak 2 weeks after the waterpump replacement. I had to pay a visit to the customer's garage to find it, having it towed to my place, performed a pressure test to find the leak at the old clamp, and replaced it. There was no more profit in that job. Eversince then, every one of those clamps when removed gets thrown away, immediately -- no second guessing. I have never had to replace a screw clamp when done right. As for indentation of a hose by the screw clamp, that is why hoses get replaced pre-emptively before they leak. They do not last forever.

When I refreshed my cooling system, I ordered all new clamps from the dealer - they were all superseded to screw type clamps.

If you can't find Pentosin, Prestone makes a pink European coolant that masy work as well.

Why are you so inclined on it being pink color?

I use the Porsche stuff. its just not that much more and its always in stock and I don't like mixing brands.. My simple view of the cosmos... LOL

Pentosin also doesn't seem to be common in the UK, so having done some further research I have gone for Comma G30 as this seems to be good quality and readily available. I have delivery of the Pierberg pump, Metzger thermostat and replacement aux belt, just awaiting some coolant hoses and OEM clips and will be giving it a go.​​​​ One other thing I have noticed is there are two metal pipes that appear to connect to lower inlet manifold (I think). They are quite rusty and the plate they connect to is very corroded. I can't work out from any diagrams what they are. Below is an image from the internet I found and have highlighted what I am referring to. Any ideas?

Those 2 tubes and rusty plates make up the bracket for the exhaust silencer. One on each side, part 17 and 18 in the diagram. What you're referring to as intake manifold is actually the exhaust manifold (#1 and 2)

Those are the supports for the muffler.. Steel tube welded to a flat plate, no real corrosion protection and its not helped by the heat from the headers. While I had my motor off being rebuilt I sanded them and repainted with 1500 degree silver paint.. They are NLA from Porsche. You have to pull the exhaust system to get them out, and fair warning,, I "only" broke 1 header bolt when I pulled my engine, the guys at flat 6 and the guy that did the heads were impressed.. They said the average was 1/2 of them.. If you want to take them out,,, slow and steady, the one I broke was the last one and I got in a hurry.. heat, pb blaster heat pbblaster gently tug with wrench, then I used small round drift punch and tapped in the middle of the bolt with a tiny tiny ball peen,, heat pb blaster. test repeat... About 10 min a bolt.. I used a small tip MAPP gas torch so I could get the heat in the bolt quickly, I also used a small impact driver with the clutch all the way loose so I could put some vibration in a couple of them. But the heat cool cycle won the race.

Quotes source post: 18986642

I have never broken any of those header bolts ...

That's great thanks for confirming what it is, I thought at first it was a pipe carrying some sort of fluid so at least it's not about to leak! I think I'll reassess that job for now and treat it with a bit of rust converter if it doesn't appear too bad on closer inspection for now.

Quotes source post: 18986821

LUCKY! Mine had never been off I'm pretty sure, Hoffman was the head guy that told me almost all the heads he gets have broken bolts. I tracked down some Iconel bolts that I used to put mine back on.. And used never seize on them...

Quotes source post: 18986821

Same. One Indy said I should expect at least one to fail, but none of mine did.

I now have all parts except the hoses and clamps and had booked the day off tomorrow to do the work. Hoses should arrive in a few days. just wondering if I could put the engine flush in with some distilled water and get the system cleaned out and emptied, swap the thermostat and pump ready, leaving the cooling system empty for a few days. Then replace hoses once they arrive and vacuum fill with coolant. Would it be bad to have the system empty for a few days? If so I'll leave it, but would be good to get most of the work done if possible. I do sometimes feel like I overthink everything with this car! ​​​ ​​​​

I see no problem with that. Had my engine out and coolant system empty for about 6 months and that had no detrimental effects.

Thanks, I've made a start. So far I'm glad to say no issues, I sprayed all the bolts a few days ago and so far all have come off quite easily. Coolant coming out looks very clean. I thought I'd do an experiment and mix some of the old with the new coolant to see if they react to form a gel. The old is luminous green/ yellow and the new is red/pink. Not sure how quick they will react if they are going to at all but so far nothing. ​​​ ​​​​​​ ​​​​​

Porsche had a green coolant that was used in the "early 99 996", it was a carry over from the 944-968-928 water-cooled cars. It was soon replaced by the newer coolant but they sent out a TSB saying the newer coolant was compatible with "thier" older green coolant..( not to say that it was compatible with any ole green coolant) So if you are a die-hard "purest" with an early car, you may want to search for some NOS Genuine Official Porsche Green coolant for your car...

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Was at another forum members garage and he showed me a sump plate that was jacked up like yours. It had a large crack in it from being jacked/supported just like in your pic. Maybe he'll chime in..? I know, many do this, but... Those sump covers are not thick and from what I've seen, not a good jacking point...

Quotes source post: 18993299

I certainly take your point on this, in my defence it's actually right on the edge so there is sump casing above, rather than it being jacked in the middle of the cover where I understand it would potentially crack. out of interest where should it be supported for future reference? The job went pretty smoothly, though took me a lot of fiddling to get the pump out and I broke 3 of the impeller veins doing it, but recovered all the broken pieces. I was naturally more careful getting the new pump in! The old pump appeared to be in visibly good condition, but there was a tiny amount of play which I expect is all that's needed to produce a leak, so hopefully that's definitely the cause. The pump had a year stamp of 07 and the thermostat shows 01. Since the car is 03, looks like the stat is original and the pump has been replaced once before. Also getting the replacement belt on was extremely difficult, it was a Febi and I think I would try another brand next time. Just awaiting replacement hoses so I can finish the job now ​​​​​​ ​​​​​​

To update on progress- I've now completed the work. I got the replacement hoses on yesterday. I used the vacuum method having bought an eBay lit and borrowed a compressor. It seemed to work fine but couldn't get the pressure as low as the recommended level, but close to it. Held it for 20 mins and no sign of leaks. Refilled using the siphon hose and topped up to max, ran the car and topped up again. Took it for another drive and checked the water pump housing which is completely dry. So far so good! Thanks to all who have helped and I would echo what I have read on several posts- it might seem like a daunting job, but follow the posts and videos others have made, take your time and it's not too tricky if you are reasonably confident. Also very rewarding to do. ​​​​​ ​​​​​I now have an AC compressor magnetic clutch to replace on my A4 B8, hopefully that goes as smoothly as this job!

FWIW, the engine lift point is the steel mount at the rear of the engine that the motor mounts hook to. Otherwise a 3/4 inch thick piece of plywood thats bigger than the sump cover with a pad of a couple layers of cardboard will spread the load. That engine is WAY heavier than most people realize.. Its heavier than my 5.3 chevy aluminum V8 in my other toy.