bureau13

This is where the Guardian pump shines, IMO...in conjunction with the PK Tensioner. Yes, I lose the warning system, but I also lose the number one killer of timing belts, namely, a seized water pump causing the belt to break.

Jfrahm

The core is worth a good bit, if it's a good one. As for why it is not generally done, it adds cost and complexity to the process, shouldn't be necessary, and makes the part non-rebuildable. The one I had fail with a spun impeller was at over 110K miles, 10 years. I'd been told the water pump had been replaced so I left it when I did the timing belt (944S2). At that age and mileage, fair enough.

There are also considerations about tacking on a cadmium plated part (don't!) and some impeller types would not be compatible. I only did it because it was easy and more or less free peace of mind. I'm not sure how much of a problem it really is from an OEM supplier's point of view.

I dug out a Porsche-marked 928S4 water pump core. The INA-sourced shaft is some sort of carbon steel and a dull file does not cut it, but an HSS Dremel bit cut into it easily (not a carbide bit).

The casting looks like this:
http://jenniskens.livedsl.nl/Technic...umps%20005.jpg

Lots of Porsche arrowheads, bushing on the composite impeller, cadmium plated pulley, 92 casting mark. I thought it was the 1987 original, probably not with a 92 in the target.

I like the idea of flow welding the shaft ends a wee bit to bell them out, but staking is probably a lot smarter and easier.

Bertrand Daoust

Same here.



From Ed's web site: http://perfexmfg.com/EGDS_water_pump.php

The EGDS includes a removable cover to allow inspection/ replacement of the coupler at anytime. The removable cover also allows the inspection of the water pump shaft and drive bearing play at service intervals. The EGDS impeller is drilled and pinned to the shaft as an added measure to assure no migration into the engine block.

BTW, very happy with my setup.

Captain_Slow

OK...I'm buying a Porkensioner and a Guardian pump for my next change. The posts from Imo000, polecat, John, and now Bertrand (at first I thought you pulled your pump for that pic!) have convinced me that the modern design advantages will allow me to let go of the warning system (though I will miss it at least for awhile).

Another thought I have is of Ed painstakingly rebuilding and testing each and every one of the pumps himself, and knowing that from year to year this continues. I don't know what quality control is like at an aftermarket manufacturer's factory, or what the worker turnover is like. I think I can reasonably assume that Ed is a perfectionist. I like that.

MainePorsche

It would be good if Perfex Manufacturing Inc. (Guardian pump) would come on here to comment. I sent them an email about the discussion here. Would be in there interest to do so.

polecat702

I don't think Ed has posted any thing in years. When the pump was first introduced, he had some failures, and got beat up pretty bad.

He hung tuff, and perfected his coupler/bearing package. I spoke with him once before I bought my Guardian. He told me that he loves these cars, and money really wasn't the driving force to engineer the EGDS. He really wants these cars to continue to be driven, and enjoyed.

MainePorsche

Joe,
Ed sounds like a stand up guy. Stand up guys do the good work. Sorry to hear he got grief here, but it sounds like now he can complete the circle. Would be good for us to hear from him. Sounds like he'd get a good amount of support now.

Captain_Slow

There will always be Apollo 1 moments when trying to make innovative improvements or new and original designs. Nothing is learned when things seem to be going right. The failures are inevitable and necessary (unfortunately) to achieve the goal. The coupler on Ed's pump gets all the attention, but reading his site I was really impressed with the improved bearing.

jcorenman

I think we're making a lot of assumptions here, based on not much data.

First, PKTs:
I don't think this is a good assumption. While it is probably correct that the static tension is lower with the PKT, remember that the Audi/NTN tensioner only knows how to do one thing: increase tension when the belt flutters. It's literally a spring-loaded hydraulic piston with a check-valve. And flutter is the nature of belts over with long unsupported spans. So when the belt flutters the tensioner tightens the belt, which stops the flutter by raising the frequency of the flutter. When it flutters again, it gets tightened again.

So the dynamic tension with the engine running will certainly be higher. I don't think it is possible to know how much higher, it can't be easily calculated and there is no reported data. Just lots of speculation.

I appreciate that Greg Nettles reported zero wear after 60K miles on new cam gears. Our S4 had zero wear at 69K miles when I fit a PKT, and at 84K when I pulled it off the gears were scrap. That's partially the nature of the coating on the earlier cam gears: Stays perfect for a long time and then goes away, but not in 15K miles. Statistical samples of one mean nothing.

The good news is that we have choices, not many but more than zero. For the price of a PKT I bought a used 9201 tool instead. I also don't believe a water pump needs to be arbitrarily trashed just because it gets to be five years old, as long as it is a good pump and gets used periodically. I expect a factory pump to go 60K-80K miles or more, however many years that is. Which makes paying stupid prices slightly more palatable, but more importantly I think I've done the best I can to try to make sure we don't get stranded alongside some lonely highway.

Just my two cents. Your priorities may be different, your mileage will vary, and your choices won't be the same.

jcorenman

The bearing is terrific, the coupler left scars. The impellers are far less risk than a piece of rubber.

MainePorsche

Yes, but there is at least one difference that the Guardian offers that is not available elsewhere - if the pump fails it disengages thereby saving the belt and consequently the valves. I don't think that those of us here would ever consider a knock off pump on Ebay, but the issue that I think is central is what happens if a pump failure occurs even on the best of pumps. The Guardian is the only one that essentially offers the belt and valve protection. By looking at their site and comments from members that have detailed its fabrication on their inspection, this pump appears to be engineered by engineers and is of quality construction. The effects of the PkT on belt action and gear status is outside of the design, fabrication, and utility of this pump.

Just my 2¢

NoVector

I think you nailed it, Roger. Endurance/longevity of the pump aside, there’s no way I’d leave water pump bolts more than ~5 years. I snapped a couple bolt heads off on the 84 the first time I replaced the pump. I don't know how long they were in the block, but what a pita that was.

I think my owner's manual says to replace the belt at 60K miles; so popping the water pump off, checking it out and then putting on a new gasket and bolts every 5 years when I do the belt sounds like a good plan to me.

Mrmerlin

FWIW when fitting new WP bolts I suggest to use PTFE sealant on the threads,
this will stop fluid migration and thus prevent the bolts from corroding into the block.

Go Go Joe

Still wondering about the GMB water pump for a '89 S4? It is supposedly new manufacture not rebuilt. Made in China with a metal impeller. $129.99 on Amazon. I emailed a rep at GMB who initially thought it had a plastic impeller as that was how it was advertised on GMB's website, But it's actually metal. He did say that it's possible they could switch to plastic if there is enough interest. I told him that there could be more demand if the impeller was plastic and as long as it was new manufacture, not rebuilt from old cores. Any thought on this specifically? Thanks, Joe

Go Go Joe

Still wondering about the GMB water pump for a '89 S4? It is supposedly new manufacture not rebuilt. Made in China with a metal impeller. I emailed a rep at GMB who initially thought it had a plastic impeller as that was how it was advertised on GMB's website, But it's actually metal. He did say that it's possible they could switch to plastic if there is enough interest. I told him that there could be more demand if the impeller was plastic and as long as it was new manufacture, not rebuilt from old cores. Any thought on this specifically? Thanks, Joe