Extending the Life of Engine Mounts
03-21-2005, 04:07 PM
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Extending the Life of Engine Mounts
I know that replacing squished motor mounts is a very worthwhile (if messy)project and the Jager Engineering Speedmount is available as an interim measure for those not ready for the full meal deal replacement. I have been gearing up for the motor mount/steering rack/sump gasket wrenchfest for a while now, but still have a few things to get in place before taking the plunge.
Having some time to think about the situation always leads me to consider alternatives to the work. I have been able to stem the oil gushers from the sump gasket with my handy gear wrench, my rack does not leak much any more since adjusting the ride height, but the engine still sits wedged into the crossmember!
I am dogged with the thought that there must a way to recondition the motor mounts while in place. My idea is simple (in theory of course), elevate the motor, inject the rubber bladders with a suitable RTV silicone compound (or something else), let it harden, then release the engine's weight. I know there is more to it than this, but you get the idea. I'd be happy with these "solid" mounts compared to my reaqlly solid ones...at least for now. I recall a thread some time back that asked the same question.
I have a set of old mounts that I can practice on or even cut apart for inspection. I'd happily donate these to the cause. If it does not work, well, then I just go ahead and replace the mounts. Nothing ventured...nothing gained What would I be out? A few buck in materials and some of my time. I have lots of time invested in maintenance already, so a few more hours will not kill me. And I would throw a few $$ at the materials side of it too.
What I need is some help with the materials selection and implementation portions of the project. I'm a civil engineer, not a materials one. Anyone out there given this thought before? Obviously there are the basics of elasticity, tear resistance and compressive strength but we also have to deal with cure method, work time and injection process. Anyone out there with the knowledge or that has already investigated this?
I'd be interested in opinions pro and con on this idea. For now it is an academic discussion, but something in the back of my mind tells me that this is worth persuing. All views welcomed.
Regards,
SteveCo in St. John's
Having some time to think about the situation always leads me to consider alternatives to the work. I have been able to stem the oil gushers from the sump gasket with my handy gear wrench, my rack does not leak much any more since adjusting the ride height, but the engine still sits wedged into the crossmember!
I am dogged with the thought that there must a way to recondition the motor mounts while in place. My idea is simple (in theory of course), elevate the motor, inject the rubber bladders with a suitable RTV silicone compound (or something else), let it harden, then release the engine's weight. I know there is more to it than this, but you get the idea. I'd be happy with these "solid" mounts compared to my reaqlly solid ones...at least for now. I recall a thread some time back that asked the same question.
I have a set of old mounts that I can practice on or even cut apart for inspection. I'd happily donate these to the cause. If it does not work, well, then I just go ahead and replace the mounts. Nothing ventured...nothing gained What would I be out? A few buck in materials and some of my time. I have lots of time invested in maintenance already, so a few more hours will not kill me. And I would throw a few $$ at the materials side of it too.
What I need is some help with the materials selection and implementation portions of the project. I'm a civil engineer, not a materials one. Anyone out there given this thought before? Obviously there are the basics of elasticity, tear resistance and compressive strength but we also have to deal with cure method, work time and injection process. Anyone out there with the knowledge or that has already investigated this?
I'd be interested in opinions pro and con on this idea. For now it is an academic discussion, but something in the back of my mind tells me that this is worth persuing. All views welcomed.
Regards,
SteveCo in St. John's
03-21-2005, 04:45 PM
#2
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There is a post on this somewhere in here. I always thought about drilling the oil cavity w/ a hole for a zerk fitting and "inflating" the mount w/ grease from a grease gun. The grease being thicker than the oil that was there may hold up for awhile or require periodic refills. Never tried it, but it crossed my mind a few times.
Last edited by tresamore; 03-22-2005 at 10:44 PM.
03-21-2005, 05:39 PM
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Don't know what your spares look like, but If you have ever seen a totally flattened 20 year old 928 motor mount you would probably change your mind and just go ahead with the replacement.......yes, the thought of trying to pump one up may prove interesting but not very feasible. If you use the much talked about Ford mounts then cost really can't be an issue......just the job itself, and while not exactly fun it's really not *that* hard, just time consuming.......but very rewarding!
03-21-2005, 06:53 PM
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MikeN;
I agree that the motor mount R&R is very worthwhile. It's just a lot of work and cost (if you include the while-you-are-at-it items) to essentially "reinflate" the squashed mount.
I indeed do have a set of toasted mounts from an 85 Euro just like my car. In fact these are the real reason I started think about the idea of rejuvinating them. Seems to me the only thing wrong with these...and other ones I have seen pictures of...is the evacuation of the oil that filled them at one time. Other than that they seem to be fine.
Again, this is just a thought-provoking thread...if someone has done more investigation than I have, I just want to know about it. Hey, maybe this is the way the Kempf Timing Belt Tool came to be!
Tresamore;
I like the grease idea, but I expect the actual rubber bladder would be compromised...this would have been at least part of the problem with the initial failure of the mounts. Great idea, though.
Regards,
SteveCo in St. John's
I agree that the motor mount R&R is very worthwhile. It's just a lot of work and cost (if you include the while-you-are-at-it items) to essentially "reinflate" the squashed mount.
I indeed do have a set of toasted mounts from an 85 Euro just like my car. In fact these are the real reason I started think about the idea of rejuvinating them. Seems to me the only thing wrong with these...and other ones I have seen pictures of...is the evacuation of the oil that filled them at one time. Other than that they seem to be fine.
Again, this is just a thought-provoking thread...if someone has done more investigation than I have, I just want to know about it. Hey, maybe this is the way the Kempf Timing Belt Tool came to be!
Tresamore;
I like the grease idea, but I expect the actual rubber bladder would be compromised...this would have been at least part of the problem with the initial failure of the mounts. Great idea, though.
Regards,
SteveCo in St. John's
03-21-2005, 07:47 PM
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Steve,
I really don't think any amount of internal pressure will "inflate" crushed mounts. If you want a simple solution get the Jaeger inserts, udderwise get off yer **** an' do 'er right b'y.
I really don't think any amount of internal pressure will "inflate" crushed mounts. If you want a simple solution get the Jaeger inserts, udderwise get off yer **** an' do 'er right b'y.
03-21-2005, 09:04 PM
#6
Why Porsche chose to give these cars udders and not proper mounts is beyond me although the words "German engineering'' come to mind. No doubt it still makes perfect sense to all concerned. I have new udders on my shark, and I hope they stick around a while. I seem to recall the jaeger solution as being quite affordable. I wouldn't feel too comfortable racking up miles without doing something. As to recycling the old mounts, I have a whole barn full of parts that are too good to throw out and too poor to use, ''just in case''. The biggest problem I see with 928s is if you let them go and don't keep up with them it makes it harder and harder to justify bringing them back up to snuff and they become cheap bangers, degrade to projects and then become parts cars. So I use new parts or good used parts, and angst over whether I should throw out perfectly good trash or keep it. The bladders have already broken. So assuming you could fill them with something and get the gel to set up, how long will the bladders hold it all together? Put another way, if you had them out of the car and you had them in your hands, would you recondition them or replace them? It kind of makes Jaeger seem like a pretty sharp cookie. New parts without the installation hassle. Less time in the garage and more time to angst. I mean drive. PS. I once put 3 used water pumps in a car in a month because they were free.
03-21-2005, 10:12 PM
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Steve.............to get at the nuts that hold the MMs in place you have to remove the steering rack. With the rack removed access to the mounts is still very limited so you have to remove the x-member. If you've gone this far the next steps to R&R the mounts are not that bad.
I bought the Ford equivalent MMs at my local NAPA store and they are made by Anchor for $70CDN........not sure what if any material you could fill the inplace 20 year old mounts with but I'd be prepared to clean the residue off of the block and underside of the car and then do the mount replacement soon thereafter.
I bought the Ford equivalent MMs at my local NAPA store and they are made by Anchor for $70CDN........not sure what if any material you could fill the inplace 20 year old mounts with but I'd be prepared to clean the residue off of the block and underside of the car and then do the mount replacement soon thereafter.
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03-22-2005, 02:37 AM
#8
Three Wheelin'
SteveCo,
Don't get discouraged! Reinflating the mounts would be a really cool thing if you could devise a viable way to do it!
Do you think you can get enough vertical lift on the engine while it is in situ to allow the mounts to refill satisfactorily? I like the idea of using a silicone or gel that sets up hard.
Good luck!
Don't get discouraged! Reinflating the mounts would be a really cool thing if you could devise a viable way to do it!
Do you think you can get enough vertical lift on the engine while it is in situ to allow the mounts to refill satisfactorily? I like the idea of using a silicone or gel that sets up hard.
Good luck!
03-22-2005, 03:05 AM
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Take a look where the original "fill port" is on your motor mounts. To get to those' you'd first need to remove them, remove the little ball that's swaged in there to seal the port, add a fitting of some kind... All the while the mount is out of the car on your workbench. Save yourself the aggravation and install either new Porsche mounts or the Anchor replacements. That way, you won't have to do the job again when the hose from the fitting on the fender liner melts due to exhaust heat.
The factory used the hydraulic mounts for a pretty good reason: they dampen cyclical vibrations as well as hold the motor up. If you want rock-hard mounts filled with grease or silicone, don't bother doing anything and you know what they will feel like already. Pumping them up will add the half-inch of height back, but you could do the same thing with a few thick washers as spacers after yoy pull the crossmember.
Starting to see where I'm coming from? The cost of the mounts is insignificant after you factor in the labor.
The factory used the hydraulic mounts for a pretty good reason: they dampen cyclical vibrations as well as hold the motor up. If you want rock-hard mounts filled with grease or silicone, don't bother doing anything and you know what they will feel like already. Pumping them up will add the half-inch of height back, but you could do the same thing with a few thick washers as spacers after yoy pull the crossmember.
Starting to see where I'm coming from? The cost of the mounts is insignificant after you factor in the labor.
03-22-2005, 01:03 PM
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These are all good points...and points of view. Just to be clear, I plan on replacing my mounts with new ones as part of the larger maintenance effort on the rack, tie rod ends and sump gasket. This thread was aimed at finding an interim and easy way to restore reasonable operation of the mounts while preparing for the larger effort.
If there was any mount rehabilitation senario that involved removing them, I would definitely opt to replace them with new. I have not yet decided whether OEM or the Anchor mounts will go back in...I'm having a hard time with new OEM mounts in terms of cost coupled with the knowledge that they will probably only last 10 years. Anyway, it's a decision that I will eventually have to make.
I actually have a Jegar Speedmount in my possession (thanks to a fellow Rennlister for passing it on), but have had mixed thoughts about using it. Since effectively fixing the sump gasket leaks, the thought of resting most of the weight of the engine on the pan gasket has not had much appeal. Maybe I should just use it and replace the gasket later as planned.
I've already cleaned the area around the engine support. Man, what a mess of grease and sand! I must have taken 10lbs of dirt out of there. I have to deal with a replacement rack before I do more in this area. Since all has been good in the rack department for the past year, I have been postponing things...maybe too long. I still have to bite the bullet and fork out $500+Cdn for a rebuilt rack...or find one to rebuild myself first. Either way there's hassle or $$$...no wonder I'm looking for ways to avoid the inevitable!
I still think that it is possible to inject the old mounts with something that would effective support the engine and reduce major vibration...similar to the early model solid mounts. This would not be perfect, but I think it would be worth the effort to0 try. All I need to do is find out what to inject. Without that, I'm dead in the water.
This is not an issue of cost avoidance...nor one of those critical areas like the water pump or timeing belt where the best answer is to stick with the OEM parts. I just think a good repair can be made here...this type of effort may be something we will need more of as the years continue to tick by...
Regards,
SteveCo in St. John's
If there was any mount rehabilitation senario that involved removing them, I would definitely opt to replace them with new. I have not yet decided whether OEM or the Anchor mounts will go back in...I'm having a hard time with new OEM mounts in terms of cost coupled with the knowledge that they will probably only last 10 years. Anyway, it's a decision that I will eventually have to make.
I actually have a Jegar Speedmount in my possession (thanks to a fellow Rennlister for passing it on), but have had mixed thoughts about using it. Since effectively fixing the sump gasket leaks, the thought of resting most of the weight of the engine on the pan gasket has not had much appeal. Maybe I should just use it and replace the gasket later as planned.
I've already cleaned the area around the engine support. Man, what a mess of grease and sand! I must have taken 10lbs of dirt out of there. I have to deal with a replacement rack before I do more in this area. Since all has been good in the rack department for the past year, I have been postponing things...maybe too long. I still have to bite the bullet and fork out $500+Cdn for a rebuilt rack...or find one to rebuild myself first. Either way there's hassle or $$$...no wonder I'm looking for ways to avoid the inevitable!
I still think that it is possible to inject the old mounts with something that would effective support the engine and reduce major vibration...similar to the early model solid mounts. This would not be perfect, but I think it would be worth the effort to0 try. All I need to do is find out what to inject. Without that, I'm dead in the water.
This is not an issue of cost avoidance...nor one of those critical areas like the water pump or timeing belt where the best answer is to stick with the OEM parts. I just think a good repair can be made here...this type of effort may be something we will need more of as the years continue to tick by...
Regards,
SteveCo in St. John's
03-22-2005, 01:42 PM
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Hi Steve,
Looking at my old OEM mounts ( that still had some life), pumping them up would be unlikely: adding 10mm of spacers would have yielded a taller, quite vibration prone mount - and all the work was done anyway in order to access them just to have that moment of intimacy . So, .....
One of the best tips ever to flood the throngs of Rennlisters has been the #2698 'Ford' mount deal IMHO. Join the many of us who have done this, and still have hundreds of $$ left in the secret 928 stash. They appear to be at least equal to the OEM units - we'll know in a decade or more ...
Locally ( north of the 49th), CarQuest and NAPA both supply them: Rock Auto in the US has an unbeatable price at ~$50/pr. Grab a pair, and once the rack is out, 'tis a breeze.
For the rack, I removed mine and dropped it off at Maritime Battery, located in Burnside Industrial Park. They sent it out to TO on a week turnaround, rebuilt w. a years warranty - all for <$350 Canuck. A seal kit was ~$125, so a no-brainer. Something to consider when you next fly in to Halifax; however, you may have to convince Air Canada that a steering rack is not an AK-47 ..
Looking at my old OEM mounts ( that still had some life), pumping them up would be unlikely: adding 10mm of spacers would have yielded a taller, quite vibration prone mount - and all the work was done anyway in order to access them just to have that moment of intimacy . So, .....
One of the best tips ever to flood the throngs of Rennlisters has been the #2698 'Ford' mount deal IMHO. Join the many of us who have done this, and still have hundreds of $$ left in the secret 928 stash. They appear to be at least equal to the OEM units - we'll know in a decade or more ...
Locally ( north of the 49th), CarQuest and NAPA both supply them: Rock Auto in the US has an unbeatable price at ~$50/pr. Grab a pair, and once the rack is out, 'tis a breeze.
For the rack, I removed mine and dropped it off at Maritime Battery, located in Burnside Industrial Park. They sent it out to TO on a week turnaround, rebuilt w. a years warranty - all for <$350 Canuck. A seal kit was ~$125, so a no-brainer. Something to consider when you next fly in to Halifax; however, you may have to convince Air Canada that a steering rack is not an AK-47 ..
03-22-2005, 02:00 PM
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Garth;
I hear you and agree that the Anchor alternative is an excellent one. I had been leaning that way already.
Thanks for the info on the rack rebuild. Maybe I can find the outfit in TO that did the work for Maritime Battery and deal with them directly. I'm still planning to get a core rack to rebuild to reduce the downtime. While I have a garage to store my car, it's not suitable to use for the swap process...need to do this outside during the driving season (or with the help of the local mechanics shop).
Regards,
SteveCo in St. John's
I hear you and agree that the Anchor alternative is an excellent one. I had been leaning that way already.
Thanks for the info on the rack rebuild. Maybe I can find the outfit in TO that did the work for Maritime Battery and deal with them directly. I'm still planning to get a core rack to rebuild to reduce the downtime. While I have a garage to store my car, it's not suitable to use for the swap process...need to do this outside during the driving season (or with the help of the local mechanics shop).
Regards,
SteveCo in St. John's
03-22-2005, 02:16 PM
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Inflation of flattened motor mounts
Hi Steve,
I have had thoughts of the same thing, the mounts on my car are getting to the point of replacement too. I was thinking if a valve stem could be inserted into the rubber( tapped ) then using the handy dandy cans of tire sealant the inside could be coated. Presurization could be an issue, however there is a new system that shoots sealant first then allows inflation air...
If the rubber could be sealed the insertion of oil/ grease would also be more effective, no or less leaks.
I have seen a product that reports to stop leaks and would require just a small hole to allow it sprayed inside, then if a grease fitting was threaded into the hole and the mount pumped up this may give a tired mount an extended life.
Maybe Garth would also be willing to donate one of the used ones for an experiment? we'll talk...
Richard
Oh, If you decide not to use the Jager mount let me know and I may try it.
Good luck
I have had thoughts of the same thing, the mounts on my car are getting to the point of replacement too. I was thinking if a valve stem could be inserted into the rubber( tapped ) then using the handy dandy cans of tire sealant the inside could be coated. Presurization could be an issue, however there is a new system that shoots sealant first then allows inflation air...
If the rubber could be sealed the insertion of oil/ grease would also be more effective, no or less leaks.
I have seen a product that reports to stop leaks and would require just a small hole to allow it sprayed inside, then if a grease fitting was threaded into the hole and the mount pumped up this may give a tired mount an extended life.
Maybe Garth would also be willing to donate one of the used ones for an experiment? we'll talk...
Richard
Oh, If you decide not to use the Jager mount let me know and I may try it.
Good luck
03-22-2005, 02:34 PM
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Richard;
Interesting idea with the valve tap. I'm not sure that gass presure would work in this application, but I'm not an expert by any means. Certainly easy to try on a bench...I have two mounts available for experimentation already.
PM me if you want to discuss your idea some more.
On the Speedmount, I'd be happy to pass it along to you as soon as I make final determination whether or not to use it.
Regards,
SteveCo in St. John's
Interesting idea with the valve tap. I'm not sure that gass presure would work in this application, but I'm not an expert by any means. Certainly easy to try on a bench...I have two mounts available for experimentation already.
PM me if you want to discuss your idea some more.
On the Speedmount, I'd be happy to pass it along to you as soon as I make final determination whether or not to use it.
Regards,
SteveCo in St. John's
03-22-2005, 02:58 PM
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When I replaced my motor mounts I also installed the Speedmount. I figured that it would help to displace some of the weight and make the motor mounts last longer...small price to pay compared to the cost of new motor mounts and the hasstle of putting them in.