If your steering wheel or bodywork noticeably vibrates when your 944 is idling (sometimes the rev counter will see-saw at idle too) then it is more than likely that your engine mounts need replacing. There are two mounts and the mount on the drivers side is particularly vulnerable and is usually the first to go.
When I first had both my engine mounts replaced I'd not had the car long (2-3 months) and being the middle of winter I didn't fancy doing it myself, so I had the local general motor mechanic do it. Not being a Porsche specialist and because of the age of the car he wasn't sure how much the mounts would cost, so I said I'd source them from somewhere on the internet.
Not having had any quality problems with third party parts before I sourced some brand new mounts from a place in the states through Ebay. They were cheaper than the OEM (Original Equipment Manufacturer) equivalent so I ordered them and they arrived in a few days. I gave them to the mechanic who then fitted them. He showed me the old mounts and especially the drivers side one was noticeably crushed down more than the other and the rubber had split.
So, nearly a year and a half on I'm writing this post to clear up some things I've found out since.
HERE'S WHAT I KNOW NOW
1. Symptoms of worn engine mounts (Click images for larger versions)
2. Engine mount modifications (OLD Version on Left, NEW Version on Right)
3. How to remove and install engine mounts (Click image for larger version)
As further reference you can use these guides to remove the engine mounts
4. The Engine Mount Heat Protection Plate
If you refer to point 5 in the removal instructions above you will notice it mentions removing the shield for the right engine mount. This is in fact known at the 'heat protection plate' (See part No.19 in the diagram below)
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I would recommend that every 944 owner checks that they have one as upon checking my own car after the 2nd set of engine mounts were recently installed I found that mine was missing. This may explain why the previous 3rd Party engine mount on this side deteriorated (about 15 months) so quickly due to it being cooked by the heat from the engine manifold.
Here's what to look for on the right side of the engine by the exhaust manifold. The orange arrow points to upper one of two mounting posts for the heat protection plate.
Here's the same shot but a wider view showing a missing heat protection plate
And now here's the same shot again but showing the heat protection plate correctly attached
Her are a couple of photos of the heat protection plate itself
The heat protection plate costs about £23 direct from Porsche and has the following part numbers depending on your version of the 944 (right/left hand drive).
944-341-107-01 LL
951-341-108-02 LL
945-341-107-01 RL > My right hand drive 1984 944 (In the photos above)
952-341-108-02 RL
5. Even though OEM Porsche engine mounts and some third party mounts look the same they are NOT.
Third party mount (solid rubber)
OEM Porsche mount (hydraulic)
6. Genuine OEM Porsche engine mounts for a 944 or 944 Turbo WILL ALWAYS BE 'hydraulic'. This means that the black rubber middle is filled with fluid. When these mounts wear out the rubber will often split and the fluid escapes. When you buy 944 mounts from Porsche they will be the uprated 944 Turbo ones (Product code 951 375 042 04) and are roughly £130 each.
7. Solid rubber mounts I have been informed by Porsche are actually only meant for the 924 even though they have exactly the same fitting as the 944. I did not know this when I purchased mine from Ebay and having looked on various Porsche parts sites since and inquired about the hydraulic version it seems that actually a lot of people are only selling the solid rubber ones. My 1st pair of Third Party solid rubber mounts from Ebay cost about £55 each, my 2nd pair of Genuine Porsche Hydraulic mounts cost £127 each.
I initially replaced the engine mounts in December 2008 with the Third Party Solid Rubber variant and then when I noticed engine vibration 18 months later I had them replaced with Genuine Porsche Hydraulic mounts.
Below are the Third Party solid rubber mounts once they were removed from the car.
Notice the mount on the right (UK Drivers Side) is considerably crushed down more than the one on the left. I measured the heights of the detensioned mounts and found that the one on the right was at 63mm which is 2mm below the recommended level. The one on the left measured at 68mm which is OK and is between the 65-70mm tolerance recommended by Porche (See point 1 at the beginning of the post)
(63mm mount)
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(68mm mount)
Here's a couple of photos of one of the brand new Genuine Porsche engine mounts (Left) alongside one of the Third Party ones (Right)
8. Third party mounts DON'T always look the same, here's some others.
CONCLUSION
In my opinion and based on my experiences I would only consider using the 3rd Party solid rubber mounts in two instances. In the first instance I would use them if you intend selling the car within 6-12 months as a means of solving engine vibration that could affect the sale price of the vehicle. And in the second instance I think you could probably use the solid rubber variety on the left side only (as this takes less weight and heat from the engine) if you are trying to save a few quid, but would always use the more expensive hydraulic ones on the right. Therefore if you intend keeping the car for the long term ie. 2 years+ then it would be wiser to go for the more durable genuine Hydraulic mounts from Porsche because the awkwardness and cost of doing the job is something you would want to avoid repeating too often.
