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New motor mounts?

Posted: Tue Mar 23, 2021 7:06 pm
by Bertrand Daoust
Hi guys,

I'm thinking changing the oil pan gasket on my car to the new one Roger has right now.
The one I have right now (orange one) is leaking a bit.

My question is, should I change the motor mount while in there?
I changed the original ones in 2008 (or so) for what was available from Roger back then. Don't remember what they were exactly. Not Porsche ones for sure.

My thought is to change them as it's not much more work. I would put Volvo mounts. Porsche ones are way to expensive for me. Sorry...

What do you think?

Re: New motor mounts?

Posted: Tue Mar 23, 2021 7:32 pm
by worf
Selfish answer: leave’em on For Science (so that we have data on how long they last.)

Risk Management Answer: change’em.

Re: New motor mounts?

Posted: Tue Mar 23, 2021 7:44 pm
by Geza-aka-Zombo
After changing them, I recommend looking closely at the coolant and PS hoses. After I did mine, I found the lower rad hose was rubbing an alternator bolt head once pressurized and a PS reservoir hose was rubbing the PS pulley, all because the engine was sitting up higher.

Re: New motor mounts?

Posted: Tue Mar 23, 2021 8:01 pm
by Cymadesign
I just finished doing the same job after going through the same thought process. My oil pan cork gasket was leaking badly and the motor mounts were same vintage as yours. Seemed to be OK but... It is a lot of work to get the crossmember off for the OPG. And only a few minutes mor3 to change the motor mounts. So for me it was an easy decision since the Volvo mounts from Roger are pretty cheap.
Tony
1983 Euro S 5speed green/green

Re: New motor mounts?

Posted: Wed Mar 24, 2021 9:26 am
by SeanR
Change 'em. When doing the Volvo's keep the Volvo retaining strap attached and toss the lower hook plate.

Re: New motor mounts?

Posted: Wed Mar 24, 2021 6:33 pm
by ROG100
Now that the Porsche mounts are $500 each even more reason to use the Volvo Mounts.
Never had an issue in nearly 8 years and thousands of mounts.

Re: New motor mounts?

Posted: Wed Mar 24, 2021 8:05 pm
by Mrmerlin
I have installed many sets of Volvo mounts , and now with the metal strap on the mount it makes it easier without fitting the finger plate.

Re: New motor mounts?

Posted: Thu Mar 25, 2021 8:49 am
by oups59
Stan,

What is the finger plate? Is it what Porsche call a "stop" part #928-375-371-00 ? Number #3 in the picture?
Image

Re: New motor mounts?

Posted: Thu Mar 25, 2021 8:51 am
by oups59
Bertrand,

You can use my lift if you want. It will be a lot easier :cool:

Re: New motor mounts?

Posted: Thu Mar 25, 2021 9:55 am
by Geza-aka-Zombo
oups59 wrote: Thu Mar 25, 2021 8:49 am Stan,

What is the finger plate? Is it what Porsche call a "stop" part #928-375-371-00 ? Number #3 in the picture?
Image
I think that is what Stan was referring to, #3.

As I recall, #2 & 3 work together to limit engine movement to a degree if the MMs fail, like in a collision. I'm not familiar with the straps being discussed; is it possible these are electrical bonding straps for grounding across the rubber mount and not structural?

Re: New motor mounts?

Posted: Thu Mar 25, 2021 10:21 am
by Mrmerlin
yes part 3 is deleted, the metal straps appear to be strong enough to hold possibly and engine being flung

Re: New motor mounts?

Posted: Thu Mar 25, 2021 10:24 am
by SeanR
Geza-aka-Zombo wrote: Thu Mar 25, 2021 9:55 am
oups59 wrote: Thu Mar 25, 2021 8:49 am Stan,

What is the finger plate? Is it what Porsche call a "stop" part #928-375-371-00 ? Number #3 in the picture?
Image
I think that is what Stan was referring to, #3.

As I recall, #2 & 3 work together to limit engine movement to a degree if the MMs fail, like in a collision. I'm not familiar with the straps being discussed; is it possible these are electrical bonding straps for grounding across the rubber mount and not structural?
No, they are not grounding straps LOL.

Safety straps from Volvo.

Re: New motor mounts?

Posted: Thu Mar 25, 2021 12:17 pm
by Geza-aka-Zombo
Strap on left looks suspect to me, structurally; cable on right, I can see doing the job. I suppose it's just a design evolution.

Image

I did the attached write-up a while back on engine mounts for anyone interested.

Re: New motor mounts?

Posted: Thu Mar 25, 2021 12:19 pm
by Bertrand Daoust
Thanks guys ! :thumbup:

So the only thing to remember is to not use #3. That's it.
Right?

Luc, a lift would be great but you would have to feed me and find me a bed for few days! :roflmao:

Now just need to order the parts via Roger.

Thanks again! :rockon:

Re: New motor mounts?

Posted: Thu Mar 25, 2021 2:23 pm
by oups59
Bertrand Daoust wrote: Thu Mar 25, 2021 12:19 pm Thanks guys ! :thumbup:

So the only thing to remember is to not use #3. That's it.
Right?

Luc, a lift would be great but you would have to feed me and find me a bed for few days! :roflmao:

Now just need to order the parts via Roger.

Thanks again! :rockon:
Beer and wine also included :beerchug:

Re: New motor mounts?

Posted: Thu Mar 25, 2021 2:24 pm
by oups59
Mrmerlin wrote: Thu Mar 25, 2021 10:21 am yes part 3 is deleted, the metal straps appear to be strong enough to hold possibly and engine being flung
When I did mine, I kept the plates....Do I have to remove them?

Re: New motor mounts?

Posted: Thu Mar 25, 2021 2:53 pm
by Don Smith
Aw, geez, do we have to go back in there? It looks like we’ll all be sleeping over. I’ll bring the beer!!

Re: New motor mounts?

Posted: Thu Mar 25, 2021 2:55 pm
by SeanR
oups59 wrote: Thu Mar 25, 2021 2:24 pm
Mrmerlin wrote: Thu Mar 25, 2021 10:21 am yes part 3 is deleted, the metal straps appear to be strong enough to hold possibly and engine being flung
When I did mine, I kept the plates....Do I have to remove them?
Nope. I still have them on mine and a lot of customers cars w/o the straps. I just liked the way the engine sits with out the plate, and the ease of installation with out that damn thing. Never had any issues with vibrations like some have said they had but I tend to pay attention to the details most days.

Re: New motor mounts?

Posted: Thu Mar 25, 2021 4:28 pm
by h2pmr
Geza-aka-Zombo wrote:After changing them, I recommend looking closely at the coolant and PS hoses. After I did mine, I found the lower rad hose was rubbing an alternator bolt head once pressurized and a PS reservoir hose was rubbing the PS pulley, all because the engine was sitting up higher.
the orange one has metal braided covers over the hoses under the bonnet, just for show, but the alt bolt head had rubbed right through the braiding, quite surprising how much the hoses can expand.
although my Rad is an alloy version so that might also contribute.

cheers
Phil

Re: New motor mounts?

Posted: Thu Mar 25, 2021 5:01 pm
by worf
There is an accommodation on the S4 fan shroud (and I think also the S3 shroud) for a big zip-tie to retain the lower radiator hose against the shroud.

Re: New motor mounts?

Posted: Thu Mar 25, 2021 6:33 pm
by MFranke
I've kept the plates, with the straps as well.

If you delete the plates, won't that affect height and the ability to gauge wear?

Re: New motor mounts?

Posted: Fri Mar 26, 2021 11:10 am
by Mrmerlin
you use the MM strap with no plate,
or remove the strap and use the plate.
not both as that will lift the engine even higher,
2mm more or so?

Re: New motor mounts?

Posted: Fri Mar 26, 2021 6:06 pm
by MFranke
Image
Image

Hopefully these pics may help. I couldn't find a plate to measure, but found a mount bracket, which I think is about the same thickness.

Assuming bracket and plate are the same thickness, it appears that a plate delete would lower the engine net by about 1.5mm. Whereas leaving the plate and strap would raise it a net 1mm. This is all assuming the Volvo mounts compress about the same as the original mounts. All that said, I have installed a couple sets of these with the straps, and plates, and the engine height was fine. It looked correct relative to the lower crossmember. I would not worry too much either way.

Re: New motor mounts?

Posted: Fri Mar 26, 2021 6:11 pm
by Bertrand Daoust
Parts ordered!

The first time I did this job, I did it on a friend lift (not Luc!) 10 minutes from my place.
This time I'm gone do it on my back with the car on jack stands and now 58 years old!
Wish me good luck... :)

I'll take all the time it needs.
No rush so it should be good.
I hope... :smile:

Thanks again.

Re: New motor mounts?

Posted: Sat Apr 03, 2021 8:18 am
by JBRob007
We’ve done so many MMs & Oil Pan Gaskets in the last 6 months we’ve got it down pat. A lift would be nice though - getting a little old to be lying on the floor and it’s a MESSY job! The Volvo MMs work great and we discard the lower plate. I assume the tensile strength of the strap is pretty hefty 😎

Re: New motor mounts?

Posted: Sat Apr 03, 2021 9:46 am
by Bertrand Daoust
Thanks for the encouragement words Joel.

Not started yet but maybe I'll lift the car today!
I may go as far as removing the belly pan... :tongue:
Need to start somewhere...

Re: New motor mounts?

Posted: Sat Apr 03, 2021 9:54 am
by Geza-aka-Zombo
I'm sure that POS 0.020 thick strap would work fine keeping the engine in place during a MIL-STD-810 40g crash safety shock test.

Re: New motor mounts?

Posted: Sat Apr 03, 2021 10:20 am
by SeanR
Geza-aka-Zombo wrote: Sat Apr 03, 2021 9:54 am I'm sure that POS 0.020 thick strap would work fine keeping the engine in place during a MIL-STD-810 40g crash safety shock test.
Considering that Volvo is renown for their safety record in designs over the decades I'm not going to worry about it. If you are in a 40g crash I think what that strap is doing is the least of your worries.

Re: New motor mounts?

Posted: Sat Apr 03, 2021 11:31 am
by Geza-aka-Zombo
Let's not mix up 40g shock with 40g acceleration. Personally, I kept the Porsche plate and ditched the strap.

Back in the early '90s, I designed the avionics rack (best pic I can find below) for an F/A-18 System. It was designed to meet the standard at the time 20g functional and 40g crash safety shock (crash safety shock can fail, just not come dislodged from its mounting). Out in the field, cracks were developing on the rack (which held 300 lbs of electronics). Navy wired it up with accelerometers and recorded data during Cat launches. Turns out it was seeing over 100g shock when the Cat disengaged with the landing gear - Pilot sees this same shock - not the same as acceleration as it only lasts milliseconds. See video below how pilot head jerks forward at the end on launch. But long enough to crack a structure, and maybe dislodge and engine. I went out to a Lab in Texas, that had a large enough shaker head to test the system to that level - we took high speed footage - you'd be surprised what can happed in 10msec.

https://www.youtube.com/watch?v=8rAWViXFv8A

Image

Re: New motor mounts?

Posted: Sat Apr 03, 2021 2:16 pm
by JBRob007
I’ll worry about it when someone catapults a 928 off an aircraft carrier. Otherwise, I’m sure the POS strap will do the job of keeping the engine in the engine bay.

Re: New motor mounts?

Posted: Sat Apr 03, 2021 2:53 pm
by MFranke
Thinking about this more, I may be one those people falling on the side of keeping the factory plate going forward. When I first encountered the Volvo strap, it seemed too flimsy for me to consider it as a crash restraint.. at least for a 928 engine, figuring it maybe as an extra ground, or maybe some kind of travel limit should it or the other side let loose. Looking at the Volvo mounting bolts and hardware, they appear less robust than factory. I wonder if the Volvo mount is originally designed for a smaller engine.

The factory setup appears stronger and, given the finger clearances, appears may limit lash movement more that that strap. Not sure how this factors in to real world or design basis events, or how much it really matters, but I'm assuming Porsche did their testing and had their reasons.

Another thing I think about is that I have used mounts before that did not come with any strap. It is just the mount and the factor plate/bracket setup in that case.

Re: New motor mounts?

Posted: Sat Apr 03, 2021 7:04 pm
by Bertrand Daoust
- Car lifted;
- belly pans removed;
- oil dropped;
- all 13 and 17 mm steering rack bolts loosen;
- Beer time! :beerchug:

Re: New motor mounts?

Posted: Sun Apr 04, 2021 10:02 am
by oups59
Good job Bertrand.....

Re: New motor mounts?

Posted: Mon Apr 05, 2021 7:11 pm
by Bertrand Daoust
- Sway bar removed;
- Steering rack plate removed;
- Steering rack pulled down;
- Motor mount lower bolts loosen...

Nothing seized yet. :thumbup:
The last time I did the job, I put anti-seize everywhere.
Very happy I did.
And will again on every bolts...

Re: New motor mounts?

Posted: Fri Apr 09, 2021 9:42 am
by Bertrand Daoust
- Steering rack removed. Need to machine and install an external bushing on the passenger side to reduce some radial play;
- Cross member removed;
- Cleaning time before painting or powder coating. Not sure yet wich way I'll go;
- Should get the parts today. Thanks Roger. :thumbup:

Edit: Checked with the powder coating place I've done business with in the past and they don't take inviduals parts right now because of Covid-19 so...
I also need to remove the oil pan.
Parts are in. :thumbup:

Need to do something with this.
The plate is a bit rusty but salvable.
Any suggestion for the insulation pad replacement?
Image

Empty spaces...
Image

Re: New motor mounts?

Posted: Sun Apr 25, 2021 9:58 am
by Bertrand Daoust
Got a question this morning.

I need to lower the engine to install the front oil pan bolts.

How much can I lower it without causing any problem?

Can I go 1 or even 2 inches bellow the cross brace?

The lower I can go, the easier it is to get those front bolts in.

Thank you.

Re: New motor mounts?

Posted: Sun Apr 25, 2021 10:08 am
by SeanR
Don't bother moving the engine, just contort you body, arms and hands so you can put the bolts in blindly with your finger tips. It's a PITA but doable.

Re: New motor mounts?

Posted: Sun Apr 25, 2021 1:33 pm
by worf
Yeah —^ don’t see how lowering will make much difference.

The only way the front bolts are easy is if the motor is upside down on an engine stand.

Re: New motor mounts?

Posted: Sun Apr 25, 2021 3:35 pm
by MFranke
Caution to not to mix up the long and short screw locations, or mix in any longer screws by mistake. Worth double checking if you start to feel a screw starts giving some resistance to ensure it is not bottoming out. Some of the lower block threads for the pan screws are closed end or have block castings above them.

Re: New motor mounts?

Posted: Wed Apr 28, 2021 8:20 am
by Bertrand Daoust
The pan is reinstalled.

Finally I didn't have to lower the engine more than where it was sitting on the old mounts to reinstall the front bolts.
A bit of contorsion like Sean said but it worked. Good chance I have small hands...
I had to ''play'' a bit with the gasket holes on the last few bolts as they were not perfectly aligned.
No big deal as I made sure first to finish with the easiest accessible ones!
Torqued all accessible bolts to 72 inch/pounds. All the others by feel. Anti seize on all bolts.
The pan has 5 recess locations for the short bolts. I made sure to put the right ones at the right place!

Thanks for the replies guys. :thumbup:

Should get the ''Form-A-Shield'' material today (thanks Dave).
Next step is the cross member...

Re: New motor mounts?

Posted: Wed Apr 28, 2021 6:46 pm
by Bertrand Daoust
Better...
Image

Re: New motor mounts?

Posted: Wed Apr 28, 2021 7:10 pm
by Bertrand Daoust
A question on mounting the new mounts to the cross member.

Should I install both mounts on the cross member before putting the cross member in place?
I'm asking because I read on one other thread to put the left one one the cross member and the right one on the engine first.
Not sure I understand well...

What is the best (easiest) way?

Thank you.

Re: New motor mounts?

Posted: Wed Apr 28, 2021 7:43 pm
by worf
Bertrand Daoust wrote: Wed Apr 28, 2021 7:10 pm Should I install both mounts on the cross member before putting the cross member in place?
Yes. Unless you have extra-long fingers with an eyeball on each tip.

Re: New motor mounts?

Posted: Wed Apr 28, 2021 8:20 pm
by Bertrand Daoust
That's what I tought too but just wanted to make sure.

Thanks Dave.

Re: New motor mounts?

Posted: Fri Apr 30, 2021 6:39 pm
by Bertrand Daoust
Cross member is in place.

Engine is back sitting where it belongs. :)

About 3 cm higher than before. It will sit a bit I think when I'll drive the car which is good.
1 cm or so would be perfect!

Next step is the steering rack.
Should go well...