Vibes at idle, motor mounts are suspect...need advice

speedfrk · speedfrk's Garage

Hello,

My car is a 88 944 turbo with balance shafts deleted. Just bought the car about a month ago and am starting to really go through it. It idled rough especially when cold, wide band is indicating a lean condition when cold af showing 16-17 and the car is missing. Running ok when warm though and the vibes quiet down after she gets warm and runs close to stoic no missing. I was told by a friend the motor mounts are the reason the car is vibrating. I got under her today and noticed something odd. See the photos, the mounts look to be separating, I can see threads for the bolts between the rubber mounts. Is this normal, are the mounts just loose? Not sure if they were bad. According to PO the mounts were replaced when the motor was rebuilt 10k miles ago.

Passenger side from in front of cross member:

Drivers side from in front of cross member:

pdxfj · 07-31-2015, 02:34 PM

Those are kaput.

I'm guessing they are sold rubber mounts and not the proper hydraulic (fluid filled) OE mounts.

Westy · 07-31-2015, 02:50 PM

Hmmm. That looks like a really FUN repair job!

Bradical · 07-31-2015, 03:50 PM

Super easy, see my thread.

New motor mounts

Westy · 07-31-2015, 03:54 PM

Yeah, I read that post a week or so ago. Nice job. But super easy to me is a fliptop beer can. Now that's super easy!!!!

Bradical · 07-31-2015, 05:51 PM

Well if thats the case you might swear alittle bit! Haha

sausagehacker · sausagehacker's Garage

I also have a balance shaft delete car and the AFR at idle should definitely be on rich side of stoic (true regardless of balance shafts). The motor mounts may be shot, but if you are running that lean, you should be hunting down another problem as well. Maybe a bad DME temp sensor, AFM, or FPR. My DME had it idling in the low 13s when up to temp. On Microsquirt is idles smooth between mid 12s and low 13s. Are you sure the wideband is accurate?

speedfrk · speedfrk's Garage

Well it looks like new motor mounts then. Actually have been planning a microsquirt install soon and have all the necessary sensors etc. I am dissapointed in the motor mounts but it's not the end of the world...read the clarks garage instructions and it seems straightforward. I'll post when I make some progress. Thanks for the advice guys.

pdxfj · 07-31-2015, 09:56 PM

Bad motor mounts are fairly common. My car had bad mounts when I bought it.

The correct mounts leak goo all over when they fail and just collapse. I think a PO went the cheap route and got the solid rubber mounts which are known not to last very long. Since I don't see any goo all over your mounts I'd bet they are not the right ones.

The OE Porsche mounts are not cheap, but worth it cost wise. It's not a terribly difficult job, just fiddly. I did mine in about 4 hours, but that was on a NA. Don't know if a Turbo car will take longer.

Good luck!

speedfrk · speedfrk's Garage

Sooo, I have been scouring the internet looking for replacement mounts and am not having much luck at all. I found this set on ebay

These are some brand named euroselect and have a porsche parts sticker on them that you would see on dealer parts. Is this an OEM part? At $224/side I am betting they are but are honestly out of my budget.

Then there are the LR ultra mounts. I am strongly considering these as the car is really set up for street/track anyhow.I have a solid Trans mount and have been thinking these might not be terrible.

From what I have read these are really the only good choices as the URO mounts are crap, so are the mahle mounts and you cannot even find the Rein mounts.

So I guess what I am beating around the bush here about is would you all recommend the ultra mounts for my application? What type of chassis vibes can I expect over stock? With the solid Trans mount and my currently shot motor mounts the car vibrates a good bit as is...hoping for less vibe at idle and through lower rpm range. Also hoping the LR mounts will last a good long while and give me the performance I want/need. Looking forward to your thoughts.

Bradical · 08-02-2015, 07:16 AM

FWIW those mounts on your car now appear to be the hydraulic corteco ones

Westy · 08-02-2015, 07:26 AM

I would be interested as well. When (IF!!) I finally get my car, it will most likely have old mounts. Would it be fair to say that if you want the ride to stay smooth, OEM is the only way to go? $224 bucks for a motor mount is ridiculous!

thomasryan · 08-02-2015, 10:19 AM

....and an engine that has an oil tube that doesn't crack from excess vibration....priceless.

The oP has a balance shaft delete car so whether he installs the cheapest aftermarket mount OR pays retail for the triangle stamped mount, the car is still going to vibrate with a higher amplitude.

I have cheap crp mounts in my car and in the words of Colin Hay, 'it's a mistake'. Lol

Westy · 08-02-2015, 10:39 AM

...just rolled a hundred and forty two bucks in coins from my beer growler, so I'm on my way.

thomasryan · 08-02-2015, 10:46 AM

Corteco is about 180 per....that's doable.

Using a gear wrench makes the job a lot easier....

Westy · 08-02-2015, 10:59 AM

Wife had $150 in quarters in her piggy. Afterall, the car will be half hers!

speedfrk · speedfrk's Garage

PO installed oil pan baffle and an extra oil pickup support welded in...hoping I don't have pickup tube issues but you just never know. Some people say the balance shaft delete with those mods is not as big of a deal but I'm not the expert here...so I welcome the input. Luckily the balance shafts are still there just the nensioner and belt were removed....so I may be able to put the Bs back in at some point. Regardless of all that though...

Quote:

Originally Posted by Bradical

FWIW those mounts on your car now appear to be the hydraulic corteco ones

So it looks like I had corteco mounts then, it looks like the split in half, is this how they normally fail? Knowing this, which do you all think will last longer the corteco mounts or the LR ultra mounts? Will the corteco mounts really absorb that much more engine vibration before it transfers into the chassis? Could really use input from someone who has used both or at least has felt the difference between the oem and the LR mounts. This car is a toy for me and not a daily driver...shoot it's got full ac delete so I don't take it on long trips as it is...

Bradical · 08-02-2015, 01:09 PM

If the balance shaft delete is actually just a balance belt delete, I would go ahead put a belt, tensioner and an idler pulley on it and save your future mounts!

Westy · 08-02-2015, 01:15 PM

^^^^Is that what this is about? They wear out prematurely because of the delete? Then what's the purpose of doing the delete? 1-2 HP? Or is there more to it?

thomasryan · 08-02-2015, 02:11 PM

Yes, free hp! As long as the pick up is stabilized, you can try throwing the belt back on and see what you think.

I took trip on the super slab (interstate) to Knoxville last night and forgot to drop my rear tire pressure. It was godawful! Nothing I would want to take a road trip in on the konis and the fuzion tires she is wearing.

That mount is definitely done. Aftermarket or the high dollar ones, there is some cost per mile which might work out close to the same....your labor being free of course. If it where my car, I would pop in some new cortecos, drive it, then throw on a cheap balance belt and see what you think.