Replacing water pump; use gasket sealant?
 

As soon as I have some free time I am going to replace the water pump and t-stat in my Carrera. I already have the OEM pump gasket and low temp t-stat ready to go. I've seen various DIY's here and elsewhere, and I have the Bentley manual. Also, last year I did this job on the 986 I used to own. Here's one issue where I'd like some opinions . . .

When I did this on the Boxster I put in the new pump with the metal gasket, and it leaked like a sieve. I took the pump and gasket back out, dried all the surfaces, and applied some Permatex gasket sealant. Put everything back together and all was good. In looking at all the info on pump replacement I've only seen one mention of using sealant.

What's the deal?

Was the Boxster water pump OE Porsche or aftermarket?

No sealant.

Boxster water pump was aftermarket, with metal impellers. Made that purchase after reading on Internet and in Excellence how the metal impellers were preferable to plastic. Now I'm back to OEM plastic!

Right, no sealant. You need to make sure the mating surfaces are flat, smooth, and clean.

You can use scotch pad to clean up any old gasket material on the engine block. I like using very fine sand paper.

agreed, no sealant when i replaced mine and no leaks

Use sealant if you want to increase your chances of a cracked head. Guess where the residual sealant goes? Inside the cylinder head capillaries. Guess what it blocks? Coolant passages.

Guess what that leads to? Localized hot spots... Guess what that increases the chances of?
Cracked heads.

I have one here now that cracked, inside the crack when we milled the crevice open we found RTV sealant blocking the capillary. That guy cost himself 11K.

No sealant but make sure you torque the bolts to specs.

I am not an expert DIY'er by any means but replaced my water pump myself a few months ago and did not use sealant. It has not leaked. I used a scotch pad to clean up the mating surface as best as I could and that was good enough.

I replaced mine Friday.

No sealant and no leaks. I used oem Porsche parts from Suncoast.

Make sure you have a new metal gasket for both the water pump and thermostat before you start.

There's one water pump bolt and two thermostat bolts that are tricky to reach. You'll need a 1" extension for the 10mm water pump bolt and a swivel and short extension for the 8mm thermostat bolts. Follow the instructions from the DIY guys on here.

Good luck!

I just did this myself with OEM pump and gasket. I did not use sealant and just tightened the bolts to the torque specs. However, I did tighten the bolts in a cross pattern similar to how you tighten lug nuts. So far there have been no leaks.

Thanks to all for the advice.

How about some suggestions for a torque wrench that will work for this project? I don't think my 1/2" drive torque wrench will work.

I use this one. Extremely well built.
The photo is not right. The torque wrench is fairly short at about 12 inch long.

Got the new water pump and thermostat in yesterday. I used no sealant! Just cleaned up the surfaces pretty good and put in the new metal gaskets. Used a new 3/8" torque wrench (as advertised by Ahsai) to set the proper torque, and let me tell you that 7 lb-ft sure doesn't seem very tight. Perhaps my problems with the Boxster were the result of overtightening?

Test drove the car yesterday evening, and drove the car to work today. No evidence of any leaks!!!

The pump I took out (which I assume was the original with 83K miles) looked in pretty good shape. All the plastic bits were intact. I installed an OEM pump from my local dealer and a low-temp thermostat from Pelican Parts.

Thanks again to all who chimed in!

Well done!

I had a leaking water-pump gasket. I removed the old pump and gasket. The pump didn't have a 996 number and the gasket was made of typical soft gasket material, so I think neither was Porsche OEM.
Got the new Porsche pump and Porsche metal gasket in. Due to the really tight space, none of my three torque wrenches fit, so I snugged down the bolts, probably tighter than 7 ft-lb.
Upon removing the jack stands and dropping down the rear of the car, coolant started leaking our what appears to be the joint between the top of the water pump and the engine block.
Maybe I tightened down the bolts too much. Has anyone reused the metal gasket, or is a new one needed?