Protostar1

Hi All,

I recently performed a timing/ balance/ rollers/ water pump job on my '92 968. Not long after, I noticed a small coolant puddle under the passenger side of the car. Obviously I am less than pleased to see a leak after performing the long and arduous task. I am 95% convinced this is leak is coming from the block to pump joint (where there is a paper gasket). See the two droplets below; if anyone sees something that points to another leak location PLEASE say so:



I know the pump was torqued correctly to the Porsche service manual spec (I want to say 6-8ftlbs?) as I checked it with a low torque wrench with an overcheck in a cross pattern. My suspicion, as is often the case, that the $4 paper gasket is the weak link here.

My primary reason for posting is to get an idea of the best way to ensure if I go through this pain of a job again, I will not get a return leak. When I originally installed the pump, I did a bit of searching around and saw about a 50-50 split between "install it as the manual states; dry" and "smear some RTV on the gasket". Having done this job to the best of my ability, I am regretting not using RTV. Is the consensus that RTV is a good route if used sparingly? What kind of RTV is best? Just standard black silicone?

One final question set: having performed this job now about 6 months/ 1,000 miles ago and not remembering it in great detail, am I missing any necessary parts aside from a new gasket and likely a new timing belt (had to cut the last one off and for $25 for a Gates item, seems dumb not to just do a fresh one; not planning to do a balance belt however)? Does anyone have a good method for compressing the timing belt tensioner aside from a big C clamp? It was a PITA to get compressed last time.

Would love some feedback on this, thank you guys!

- Nate

jeffrsmith

Permatex Hylomar is a great sealant for these types of joints and it does not harden. I used it on my 944 water pump and many other vehicles and have never had a problem. If you use regular RTV you can get little ***** of the stuff floating around in you system if it squeezes out to the inside, and if you ever need to do the pump again you will have to deal with removing the remaining product.

thomasmryan

+1 on the hylomar...thin coats on both parts and a dry gasket. Awesome stuff.

Protostar1

Thanks guys, this is the feedback I was looking for. Any reason to put it on the pump/ block versus just a thin smear on the gasket itself?

You are in agreement the drips shown in my photo indicate a pump to block joint leak and not something else I am totally missing?

Any thoughts on parts I should be replacing just for this pump reinstallation? Everything is new so still thinking gasket and timing belt only.

- Nate

EDIT: What Hylomar do you guys use? Universal Blue or Advanced Formula (or any number of others Permatex makes)?

konakat

I'm not as familiar with the layout of the 968, but on the 944 there is a coolant hose directly above the belt area. If you have a leak there from the clamp not being on correctly, etc, the coolant will fall down and look like a water pump leak.

Devia

Did you replace the hose that the clamp's on? My rule of thumb is to always replace the hoses, as they're not expensive, are exposed to high heat every time I replace the thermostat/waterpump.

968 GUY

Check to make sure the clamps are tight. I am guessing you put new hoses on. There is a black plastic cover that has an o-ring seal, you can just see it at the upper part of your photo, on the 951, it is the turbo thermostat housing, on the 968, i believe it is just there to keep a good flow.
I had one warp slightly and cause a small leak. I thought it was the o-ring, but after replacing it, there was still a leak.

Checked for cracks and noticed it was warped at the sealing flange. was replacing some belts and other things on one of the 968's so I swapped it and ordered a new one. think it was less than 10 bucks.

odurandina

the hoses take an absolute beating.

mhr

You don't need to use sealant with the green gasket. You do with the other. Apparently the green gasket has sealant impregnated in it.

I don't think the 968 has the same belt tensioner but on the S2 you loosent the locking bolts and then use the special spanner or in my case some very large angled needle nose pliers into the holes on either side of the tensioner and you turn against the spring to slacken the belt and then lock it down with the locking bolts in that position. At that point you can get the belt off without cutting or damaging it.

Good luck
Mark

Protostar1

I did NOT replace any hoses when I did the water pump job. Until I pulled the undertray, I was thinking (hoping) the same as you that the old hoses might be the source of the leak. However, I did not think there was any observable leak path from any of the hoses to the bottom of the pump, only the drop shown which I am assuming then came from the pump to block face.

Of the three connection points, is there a suspected leak point? With this concern, I am going to get some dye and a blacklight tonight to see if I can really confirm the leak path. Still thinking it is the block face unfortunately...

Protostar1

Hi Mark,

Yes, I believe the S2 and 968 tensioners are different. This is what mine looks like:



Not sure how it is possible to reduce tension on this without cutting the belt, pulling the tensioner arm away from the tensioner, then using something like a C-clamp to compress it until it can be pinned with a nail.

- Nate

EDIT: Not sure what is going on with the belts in that above pic, just pulled it from google.

968 GUY

Yeah looks like either the BS belt broke and wadded up or someone is trying to drive the WP with the BS belt(swapped).

I did remove the hydraulic tensioner when I changed belts but for the lifr of me I cant remember if I just unbolted it and was able to pull it off, or what.

Did have to pull the crank pulley I remember.

Do check that plastic water outlet neck on the pump though.

Protostar1

So I did a little disassembly and poking around... found this little streak of fluid. If this tube was leaking, along this path, it would certainly drip where shown in the original post's photo!:



I set up some paper towels behind this joint and below the pump to see if I can confirm this is indeed a leak, and the only one. However, 24 hours later, the pump still appears to be dry... Car is on jack stands in the front only. If the leak is on the heater box feed, I suppose that joint could now be dry in the position the car is in...

RajDatta

You can undo the old tensioner mounting bolts and remove it. You can then compress it on a Wise for installation.