rnixon

You seem to have done your research, but just in case, it's also the ideal time to replace the oil sump gasket with a more modern one.

Dan87951

I could be wrong, but Roger is probably asking owners to support the forum sponsors instead of the dealer, as they too can get "genuine Porsche" parts if you so desire.

The real point of my post was to point out I have had good luck with three out of the four vendors...

Schocki

That is exactly the point! Porsche is not doing a lot for their former "flagship" and I don't see any changes on the horizon.
This forum here and also the equivalent in Germany (PFF) is packed with help, support and advice. The 928 owner is a different breed and all of us love our cars and want to keep them on the road. Even if they are 20 plus years old and we want to drive them! We are not discussing which interior carbon package suits our new 911 better. Most of us work on our cars and know them very well.
Our parts suppliers support us way beyond what Porsche dealership provide, THANK YOU FOR THAT!

Everybody can install the part that he wants on his 928, no questions asked. But just because "Porsche" is printed on the package does not mean that this part is the better choice (reagardless of the price).
Why should I replace a faulty hybrid LH-ECU with the same part from the dealership that has been stored in a warehouse for the last 15 years? Installing another ticking bomb in my car that is kown to fail one day? No, thank you!

I'd rather support a Rennlists sponsor that supplies a refurbished unit with an upgraded chip.
Leaky oil pan gasket? What is better silicone or 60's cork technology?

Heater valve from Porsche or the same part from MB? If you don't need the bling of the package go with MB.

Replacement motor for the interior fan or new unit from Porsche for five times the price?
I could continue the list...........

Who comes up with ideas and alternatives like this? Our vendors who not only sell parts but share the same passion for the 928 !

bureau13

There's a chance it was done previously, but then again, there's so much gunk on the underside of my engine right now, I half suspect maybe that's what's keeping my oil inside lol. It does sound like a consensus while-you're-at-it item though...thanks.

Imo000

Changing only the mounts is pretty easy and is not really and doing the pan gasket will make the work a lot more complicated. It's not a while you are in there deal.

bureau13

Maybe it's more of a "while you've begged or borrowed lift time from a friend, you may as well make the most of it" deal?

ROG100

I guess you missed my point totally - I will try again - you advised 928 Owners to buy from a Porsche dealer when you can buy the same product from 928 International, 928 Specialists or 928sRus. We all sell Porsche parts direct from Porsche. You also advertised a Porsche dealer who is not even a site sponsor here on Rennlist. Support the people who support you the 928 Owner. Yes it may cost a couple of $ more but it goes to supporting the 928 which is what I thought this forum was about. As you do not state your name, with respect, I do not know you from Adam - however even if I knew your name and you were a passed customer I would have still made the same statement as I firmly believe in supporting the 928 community. Withholding your business from my company is your prerogative but will not blackmail me into stopping my 110% support for the suppliers and sponsors here on Rennlist. I pay for the privilege to be a sponsor here and I am proud of it.

Just my opinion.

Carl Fausett

Bureau 13 - thanks for straightening me out. I read your initial post and got from i that you thought your car had our rubber mounts and you thought they were bad. I would be very interested in that as it would be our first failure for this part.

A useful direction for this thread to now take: "how to tell if your motor mounts are bad"

With the hydraulic mounts (OEM) we used to be able to tell if the engine was sitting too low compared to the crossbrace, then we new the oil had leaked out and the motor had settled.

Speaking as an old mechanic, on AT cars, one could put the car in D and R and hold the brake and torque the motor a bit with the gas peddle while another mechanic watched the engine roll. That's how we would quickly check for a broken mount back in the day. But on 928's. the limit hooks on its motor mounts prevent it from rolling very far. Still, from underneath the car you can see if there is separation between the rubber and the steel as the engine torques.

Sean and others: what other techniques have you used to determine that a all-rubber after-market replacement mount is bad?

ROG100

On the 87 to 95 cars check the level of the top of the intake manifold with the top of the cross brace. If it is below the cross brace then they are collapsed.
Also - similar to what Carl said - rev the engine to 4k and see if it moves side to side. If it moves there is still life in the mounts but if the engine does not move they are toast. This works for 83 to 86 cars - both 16v & 32v.
By far the best way is to look at the oil pan and its relation to the cross member - if it is touching or very close they are collapsed.
78 to 82 cars rarely have any issue with the solid rubber mounts from the factory. Sometimes the rubber parts from the metal frame but you would not know that until you remove the mount. The biggest failure with the early 78 to 82 cars is the engine shock absorbers - most are shot and replacing them can make a big difference.

Wisconsin Joe

I thought that the distance between the oil pan and the crossmember was the best indicator.

When I replaced mine (original ones AFAIK), there was barely enough room to get a piece of paper in the gap.
After replacement, there's easily enough room for a finger.

Also, these mounts are supposed to have some give to them. I also read that if the motor doesn't rock back and forth a noticeable amount either when revving or on startup, then the mounts are no good.

Edit to add: Roger beat me to it, but it's nice to see he agreed with what I said.

antsmands

I don't think that is what Roger is saying at all! I can vouch that he is definitely one of the "Stand Up" guys and I am glad that he has taken on the task of suppling quality parts at affordable prices to keep these cars on the road! Don't forget that 928's are no longer in production so Porsche is not going to focus their attention on in my case a 31yr old car. We have to have guys like these 928 suppliers to keep us alive!

SeanR

All I do is pop the hood, get in the drivers seat, watch the top of the engine as I start it. If the motor doesn't rock back and forth on the starter, then the mounts are collapsed.

bureau13

I've been basing my opinion that I likely need new mounts on the fact that I get a bit more vibration at idle than I should, but I will definitely try the "watch for engine rocking" method to be sure.

dr bob

Digging through my picture archives, here's a look at intake manifold height relative to crossbar with Porsche mounts in for a year or so. The straightedge is sitting on the forward roll of the top of the S4 intake. Folks with newly-installed aftermarket mounts will likely find the intake higher by 6-10mm.

ROG100

Over the years we have done a lot of tests and trials with MM's.

Here is a cross section of a failed Porsche hydraulic MM. Top picture.
Next picture is a cross section of an aftermarket Hydraulic MM
Next picture a cross section of a Ford Ranger solid MM
And for those that have never seen one the last picture is a 78 to 82 solid rubber mount that works along with two mini shock absorbers.