Water pump leaking

[bowserdog1]

I noticed coolant pooling around the base of the water pump lately on my '82 928 (U.S.). In fact, I've been going through about a 1/2 gallon of coolant per week recently. The car has about 75,000 miles and I was going to replace the timing belt and then get at the water pump at the same time. Do you think I need to replace the water pump, or is it just the gasket between the pump and block?
One more question, do you think this is a weekend job for someone with some mechanical inclination? I can do most of the work I have tried on the engine but I have never attempted a timing belt change before.
Thanks.

Brian

[MPDano]

Originally Posted by bowserdog1

I noticed coolant pooling around the base of the water pump lately on my '82 928 (U.S.). In fact, I've been going through about a 1/2 gallon of coolant per week recently. The car has about 75,000 miles and I was going to replace the timing belt and then get at the water pump at the same time. Do you think I need to replace the water pump, or is it just the gasket between the pump and block?
One more question, do you think this is a weekend job for someone with some mechanical inclination? I can do most of the work I have tried on the engine but I have never attempted a timing belt change before.
Thanks.

Brian

75,000 with no history is an easy decision. Replace TB and WP at the same time. Also, be prepared to snap bolts in the process. There is write up somewhere which names the bolt sizes so you can buy new ones before starting the job. Your also going to inspect your tensioner as well. At a minimum, replace the rubber boot.

[Kiln_Red]

You need 14 new WP bolts. The ones that fasten the pump along the outside are shorter than the ones holding the pump in the center. You will have 5 longer bolts IIRC. To remove the bolts without damage, soak the hardware overnight in PB Blaster before trying to turn them. This has never failed me. You will probably need to smack the pump with a rubber mallet a few times to free it from the block. Be careful not to lose the locator pins. The gasket will probably have to be scraped off. In my experience, water pumps seep at the gasket at the most. They don't leak as much coolant as you've been adding unless the leak is at the shaft seal. DEFINITELY replace the WP.

I install the WP gasket dry, but Stan K. uses sealant. To each their own I guess.

[MPDano]

Originally Posted by Kiln_Red

I install the WP gasket dry, but Stan K. uses sealant. To each their own I guess.

..and I use Red RTV. Seals like a Frogs A$$

[bowserdog1]

Thanks for the advice. I guess I better start putting together a shopping list.

[Mrmerlin]

Thanks so much for your kind recognition Kiln. (Austin E.)

Yes infact using RTV is a great way to extend the sealing capability of the WP gasket.
I use the lite blue RTV sealant from Permatex.

Over time the coolant will work its way past the gasket around the bolt holes ,
To combat the corrosion that can happen to the WP bolts,
I also suggest to use a dab of Loctite PTFE non setting pipe sealant on the new bolts,
ACE hardware has new bolts.

Now is also a good time to replace the thermostat the rear sealing ring if you have one and the O ring as well as the heater control valve and the short hose and the coolant bottle cap.
Also consider swapping out the oil pump O rings use Dow Corning 111 on the O rings,
use STP oil treatment for priming the oil pump gear set, this will make sure you will have oil pressure when the engine is started
NOTE the dots on the gears they face the block.

I suggest to use Zerex GO5 coolant you need 2 gallons of coolant and 2 gallons of distilled water.
Make sure to drain the block prior to removing the water pump and installing the new coolant

[ROG100]

Water Pump - make sure you only use a NEW Laso or Porsche pump with a plastic impeller. Do NOT use a rebuild.

[stepson]

To reiterate: DO NOT USE A REBUILT WATERPUMP!!!

[topfuel67]

What's the issue with the rebuilt pumps?

[stepson]

You just never know who has rebuilt it. You just never know what was done to the pump during the rebuild. Were the bearing replaced or were they just mic'ed, greased, and reused? Do you really want to do this whole job all over again if the rebuild fails?

Better to take your chance with a new water pump IMO.

[Landseer]

Slam bam manufacture without restoring tolerances.

Rebuild requires the parts to be interference-fit together.

The impeller starts to move toward the block as the POS rebuild starts to fail.


Unlike a typical car, the water pump forms half the pump cavity plus the impeller.

Block forms the other half of cavity. Impeller acts like a milling bit and mills the block.

Then you have real trouble.

(too many folks have experienced this failure--- and the real enthusiasts amongst us figured out the issue, resulting in 928srus
to petition Laso to revise design on new pumps. With the internet, its possible to gather failure data as the cars age deep in their life cycle --- this is just one example of that with the 928, there are others.) Go to rennlist and search and read for a few hours if you don't believe.

[ROG100]

No reputable 928 parts supplier offers a rebuilt pump.
I also will not sell a rebuilt Porsche pump - nobody wants to pay the circa $500 anyway.

Buy a Laso new with a plastic impeller.

[Danglerb]

Due to the age of the cars and the limited production water pumps were getting rebuilt more than once, maybe the cost and difficulty in locating cores made rebuilders less likely to discard a core that should have been trashed, maybe the cheap Chinese water pumps forced them to shave costs or provided them with cheap low quality parts to use in a rebuild, but its a done deal now, NOBODY should be using anything but a current model Laso or better.

[topfuel67]

Now i see why the plastic impeller is recommended. Thanks for the advice. I am in the process of buying a new wp, tb and the tensioner. With the tensioner tool, flywheel lock and now wp bolts at riskits getting pricey to change a $20 timing belt!

[Fixer]

This turned out to be a great thread. I will CC Stan's advice on "to do while there"
Matt

[Landseer]

Whoa. The timing belt you need costs about $40. That's another story. Use only the Gates belt.

[harborman]

Yes, get a NEW pump, new LASO is what I put on, cost about $350. Take the advise of all above. There is a nice write up on doing the TB WP job with pictures and great directions. You will need to check other items while it's apart, like tensioner, etc. Also you will need a few special tools, fly wheel lock and tensioner guage. Relatively cheap, don't do a half a@@ job, get the right tools, sealants and TAKE YOUR TIME, not a rush job for a newbe. I also used a Gates TB, about $35 or so.

[topfuel67]

My car manufactured date is 3/81 (81 us version 4.5 auto). On rock auto they list 4 timing belts, 3 of those 4 say for 9/1/81 and newer, and the gates is one of those 3. The dayco is the only one available under the 1980 and the same as the other 1 of 4 under the 1981. Gates isnt listed here on pelican, or couple other sites i checked as being compatible for early 81s. As far as the other things I plan on taking my time and getting the right parts and tools. I plan on keeping this car.

[harborman]

Originally Posted by topfuel67

My car manufactured date is 3/81 (81 us version 4.5 auto). On rock auto they list 4 timing belts, 3 of those 4 say for 9/1/81 and newer, and the gates is one of those 3. The dayco is the only one available under the 1980 and the same as the other 1 of 4 under the 1981. Gates isnt listed here on pelican, or couple other sites i checked as being compatible for early 81s. As far as the other things I plan on taking my time and getting the right parts and tools. I plan on keeping this car.

I may have purchased the TB from Roger at 928rus or one of the other sites. Pelican is also a good place. I would stick with one of the Porsche 928 specialty suppliers and stay away from the run of the mill places around the corner. My car is an 86. Gates also makes a racing TB for around $130. I am no expert by any means. Stick with known 928 suppliers the guys on here use.

[Danglerb]

If you absolutely know exactly what you need, feel free to shop for a cheap price, otherwise stick with a vendor that knows the 928.