Need immediate advice - stripped front engine mount yoke stud holes - 986 Forum - The Community for Porsche Boxster & Cayman Owners

JoeFromPA · 03-20-2011, 08:03 PM

Hi all,

Pulled my old engine mount out tonight and installed the new one. All was going well as I bolt the new mount up to the engine, tightened it, then lined up the yoke bolt holes with the matching holes on my 99 boxster's chassis.

I put 2 studs in no problem, tightened moderately with the nuts until it helped line up the others.

Put the next stud & nut in....tightened it....bam. Stud was tight and is now fully loose and pops out. Same thing happened with the one afterwards. Studs are slightly stripped and WILL NOT re-engage in the chassis. I spent 30 minutes trying to get them to re-thread, no luck.

What I need to know immediately is: can I take this to my mechanic and get him to tap out a new, larger (I'm guessing m12) threaded hole in the chassis and yoke?

Joe

P.s. Gently started and drove the car to test if I needed to flatbed it to mechanic - car drives fine with only 2 studs holding the yoke to the chassis. I felt safe with this considering how little real weight that front yoke carries. No ugly vibrations either.

AndyA6 · 03-20-2011, 08:27 PM

I am sure you can drive carefully to the shop.

JoeFromPA · 03-20-2011, 08:42 PM

Thanks Andy, I'm confident in that too. I'm mainly wanting to make sure that new holes can be tapped into the yoke and chassis at that point. If not, I'm wondering about alternative solutions.

The boxster hadn't been started in 45 days and it absolutely purred to life within 1 second of twisting the key. Never started smoother than with this new engine mount

Lil bastard · 03-20-2011, 08:55 PM

One thing you can do is insert a Timecert - http://www.timesert.com/ .

These are pretty easily installed and are approved and used by Porsche.

They are plenty strong as this is Porsche's approved method of repairing stripped cylinder head stud taps on the block - if they can hold the cylinder head torques, they'll definitely work in this case.

Depending upon what you pay your mechanic, it may well pay you to buy a repair kit and do it yourself. Afterward, you can either add the tool to your toolbox - there are several other areas on the Boxster which benefit from timecert repair, or do what I did - get the kit, make the repair (in my case a stripped swaybar mount tap) and then resell the kit on eBay (I sold mine for the same price I paid, so essentially a free repair).

Cheers!

JoeFromPA · 03-20-2011, 09:10 PM

Nice. Mechanic will probably charge me $50 for an hour of his time fixing this (it'll take him 30 minutes, but his hourly is so low it's great). He's a great guy - I've seen him fixing up $500 dodge caravans from the late 1800s and replacing oil pans on ferarris. Car's going in for an emissions and inspection anyway, so this is just gravy.

Really like that timesert stuff...a comprehensive kit (for more than one job) seems pretty expensive, but i'd order this for the future honestly next time this comes up. For now, I want my baby on the road....the weather is nice, insurance kicked back in on March 1st (3 months garaged rates), and it's time to start redlining again...

Joe

clickman · 03-20-2011, 09:45 PM

I'm looking at replacing my motor mount this spring, and your problem is something I definitely want to avoid. In all the other threads I've seen on doing this job, I haven't seen this mentioned once. What exactly happened? Did you overtorque the bolts?

eightsandaces · 03-21-2011, 02:15 AM

Quote:

Originally Posted by Lil bastard

One thing you can do is insert a Timecert - http://www.timesert.com/ .

These are pretty easily installed and are approved and used by Porsche.

They are plenty strong as this is Porsche's approved method of repairing stripped cylinder head stud taps on the block - if they can hold the cylinder head torques, they'll definitely work in this case.

Depending upon what you pay your mechanic, it may well pay you to buy a repair kit and do it yourself. Afterward, you can either add the tool to your toolbox - there are several other areas on the Boxster which benefit from timecert repair, or do what I did - get the kit, make the repair (in my case a stripped swaybar mount tap) and then resell the kit on eBay (I sold mine for the same price I paid, so essentially a free repair).

Cheers!

These work very well, the key is to drill very perpendicular and perfectly square, like a human drill press, into the damaged surface.

insite · 03-21-2011, 06:01 AM

you'd need an M10x1.5 helicoil kit. you would drill oversized with a 13/32 bit, tap it with an M10 STI tap, and thread in the helicoil.

since you stripped not one, but TWO of these during your DIY, i recommend you NOT attempt this yourself, as you really only get one shot with these.

and yes, your mechanic may charge $50 an hour, but do do this yourself, you'd need to spend about $60 - $80 in tools & equipment anyway.

EDIT: BTW, this will take your guy 2-3 hrs

Gilles · 03-21-2011, 11:14 AM

Quote:

Originally Posted by eightsandaces

These work very well, the key is to drill very perpendicular and perfectly square, like a human drill press, into the damaged surface.

+ 1 "the key is to drill very perpendicular and perfectly square"

The question here is, do you have enough room to position your drill in front of the engine..???