Engine mount thread repair

Wingnut

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I know I have seen this posted before, but after a short search, I couldn't find it, so I thought I would post up my quick repair of an engine mount with stripped threads.

As you know, aluminum is softer than steel. With the engine mount bolts requiring a significant amount of torque, the threads can get damaged in these mounts after repeated removal & re-installation of the vertical mount bolts. My car is now on its 3rd timing belt and I didn't want to spend $150 on a new mount when I can make my old mount stronger by putting a steel insert in place of the aluminum threads.

On a scale of 1-10, this is about a 2 in difficulty. Other than than the kit itself, the only other tool you need is a tap handle and some cutting oil.

This is the kit I used. It is a Time-Sert kit number 1215 (m12 x 1.50). I went with this kit over a helicoil because it is a solid insert and much better IMHO.



The kit comes with 5 inserts, but they are only 16mm long and I wanted a more solid repair, so I bought extra inserts. They are 24mm long and will hold more of the bolt.

Here is the stripped threads in the mount. Its hard to see as the picture is blurry. But I did not feel that there was enough material left to feel confident it would hold up to another torque and another 160k km of holding the engine up.



Using the supplied drill bit, drill out the old threads. A drill is not required. I used the tap handle:



Then, use the ream tool to make a lip at the top of the hole for the shoulder of the insert. this prevents it from threading below the top of the hole and keeps it flush when inserted.



Then, tap the hole for the insert (cutting oil is recommended):



here are the finished holes to accept the inserts. You can see the lip more clearly in this picture that you made with the ream tool:



Once it is tapped, clean out the hole to remove the shavings. Then use some brake cleaner or similar to clean the threads in the hole. By removing the oil residue from the holes, the threadlock wil hold the insert better.

Apply some Loctite thread lock on the insert:



Use the insert tool to thread the insert into the hole. You must use oil on the insert tool for this step.



As it gets closer to the bottom, it will grab and thread the insert all the way to the bottom and make the repair flush. Its so easy, an 8 year old can do it:



And here is the finished product. The steel inserts are far stronger than the original aluminum threads and you can feel confident about applying the required torque on the new engine mount bolts.




Thanks for looking.
 
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Another great time and money saver from Wingnut. Thanks! This one will be saved for future use. :cool::cool::cool:
 

Wingnut

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Helicoils are fine for many applications. But when it comes to holding up my engine, I wanted to make sure the product was the best possible. Heli coils are cheaper and require less tools (basically just a drill & tap), but are not as strong IMHO. Especially when repairing aluminum threads. The kit and extra inserts cost just over $100 in the US (I paid almost $150 once shipping & taxes were added to get it to me in Canada). Thats still cheaper than a new mount and will be stronger than a new mount.

I got my kit from E-bay: http://www.ebay.ca/itm/300688868626

Extra inserts: http://www.ebay.ca/itm/300692096789
 
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Curious Chris

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Nice write up. I know on my next timing belt (it will the third one) I will need to do this as my mount had some missing threads at the top on the second change.
 

visionlogic

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Excellent wingnut. I've used helicoils in the past but will probably use the timeserts in the future. Good idea to always look closely at the TTY bolts that are removed. Any aluminum caught in the threads means trouble.
 

volmaniac

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... But when it comes to holding up my engine, I wanted to make sure the product was the best possible. ...http://www.ebay.ca/itm/300692096789
Great point! I successfully used helicoils for repairing stripped out threads for the coolant flange, but those are small low torque threads. Makes sense to install the heavy duty steel inserts for the motor mount.
 

PDJetta

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Yes. TimeSerts are the way to go. I install them now whenever I remove the engine or transaxle mount bolts.

A couble of years ago I read about TimeSerts on this list. It was said to use the 30 mm length 12 X 1.5 mm inserts. Since then I have determined that you need to use either a 24 mm or 30 mm long insert, depending on the type of VW mount you have. I've noticed that there are two styles of threaded VW mount holes, both 30 mm long--open hole and blind hole. The transaxle mount on my son's 2.5 liter A5 Jetta has an open hole and I used a 30 mm insert and the insert filled the hole perfectly. Later, I threaded an ALH engine mount that HermTDI sent me and it had blind holes. Although the hole was a little over 30 mm deep, I could not drill any deeper because the drill bit would punch out the end of the mount. I tapped the hole and the tap supplied in the TimeSert kit bottomed out in the hole. I used a 30 mm insert and screwed it in until it reached the end of the tapped threads and it would not go in any deeper. About 3 mm of the insert was sticking out the top of the hole. Herm had to grind the insert down.

I have now concluded that for the blind hole mount, even though the thread depth is 30 mm, you need to use a 24 mm threaded insert (as pictured by Wingnut). The slightly shorter thread area should not matter, since the steel threads are a lot stronger.

I do not know if the open-hole mounts are specific to the transaxle mount, or if they are specific to the A5 Jetta, but for those, use the 30 mm long 12 X 1.5 mm insert.

Supposidly you don't need to use thread locker on the insert, since the insert tool rolls the threads and locks the insert in place, but it can't hurt.

Here is the transaxle mount with the open holes that I put 30 mm inserts in:







--Nate
 
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Wingnut

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Remember that the end of the mount bolt has a few mm of material that is not threaded:



So no need to have threads go all the way down into the hole. 24mm is plenty long enough.
 

ymz

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And once in a while, even a TimeSert won't help... :(



Started to pull out of the mount bracket around 60 Ft*Lbs... So I got to practice on another bracket... good thing I had a spare sitting around...

Yuri
 

Seatman

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Just a little bit of info that might help someone. I got a couple of these inserts from a garage for cheap, a lot of garages keep kits for obvious reasons so might be worth checking if you don't want to buy a whole kit.
 

wrenchman30

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while these thread repairs are nice your assuming they are stronger, your screwing them into aluminum which is the weakness in the first place
 

Dimitri16V

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It is designed that way so the engine drops during a front end collision
 

Wingnut

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while these thread repairs are nice your assuming they are stronger, your screwing them into aluminum which is the weakness in the first place
Yes, the aluminum is the weak point. However, it is the repeated removal & re-installation of the vertical mount bolts that strips the threads in the mount. The steel insert now takes the stress of the bolt threads, meaning it will stand up to the repeated re & re of the bolts better than the softer aluminum Since there is no movement between the insert and the aluminum, it doesn't wear out.
 

phaser

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I have nearly 360k on my 04, and intend to keep driving it until it dies.

Should this be thread repair be done now as preventive maintenance, or just wait?

.
 
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ymz

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Should this be thread repair be done now as preventive maintenance, or just wait?
What prompted me to install the inserts was the amount of "wiggle" when I partially inserted the bolts into the mount bracket... (keep in mind that the engine had quite a high number of miles on it - meaning that the threads had been "exercised" quite a number of times for timing belt changes...)

Yuri
 

UhOh

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while these thread repairs are nice your assuming they are stronger, your screwing them into aluminum which is the weakness in the first place
Two things not mentioned is that the insert has courser and larger threads AND it is to be installed using red thread-locker.

Check back with me on how well they work. I partially botched the installation of one of them, didn't get the tap all the way down (I had thought I had, but when I went to install the insert it stopped before the top was seated:eek:) and ended up dremmeling a bit of it off: it's effectively less strong, so if a less-strong install ends up working for me then a proper install will surely be fine! It's been holding together now for 6k miles.
 

jokila

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Two things not mentioned is that the insert has courser and larger threads AND it is to be installed using red thread-locker.

Check back with me on how well they work. I partially botched the installation of one of them, didn't get the tap all the way down (I had thought I had, but when I went to install the insert it stopped before the top was seated:eek:) and ended up dremmeling a bit of it off: it's effectively less strong, so if a less-strong install ends up working for me then a proper install will surely be fine! It's been holding together now for 6k miles.
I did one of my mount's bolts with this. I agree the aluminum is weak after repeated reinstallation. It was my third timing belt.

There is nothing worse than being at the point in the timing belt process and realizing the threads are disintegrating as you torque down. I was able to cut the threads right through the other motor mount and seat the timesert. It was a lifesaver to having to wait another day and buy more TTY bolts.
 

UhOh

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I did one of my mount's bolts with this. I agree the aluminum is weak after repeated reinstallation. It was my third timing belt.

There is nothing worse than being at the point in the timing belt process and realizing the threads are disintegrating as you torque down. I was able to cut the threads right through the other motor mount and seat the timesert. It was a lifesaver to having to wait another day and buy more TTY bolts.
All in all the cost was slightly less than had I bought a new motor mount. BUT, now I have the tool bits and a couple of additional serts for use elsewhere (I have two of these cars). For me it was a matter of not wanting to tear things back apart to swap in a new mount: I was tired and I didn't want to undo any of my TB work (adds increased risk of messing something else up!).
 

jokila

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All in all the cost was slightly less than had I bought a new motor mount. BUT, now I have the tool bits and a couple of additional serts for use elsewhere (I have two of these cars). For me it was a matter of not wanting to tear things back apart to swap in a new mount: I was tired and I didn't want to undo any of my TB work (adds increased risk of messing something else up!).
That was exactly my situation and the cost. I ended up ordering it because I do timing belt work for others and it happened once before to a customer. He ended up ordering a new mount and me having to wait another day or two to finish it. I wanted to be prepared in case it happened again and it happened to me during my last TB work.
 

Dimitri16V

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I did one of my mount's bolts with this. I agree the aluminum is weak after repeated reinstallation. It was my third timing belt.

There is nothing worse than being at the point in the timing belt process and realizing the threads are disintegrating as you torque down. I was able to cut the threads right through the other motor mount and seat the timesert. It was a lifesaver to having to wait another day and buy more TTY bolts.
Those are not TTY bolts .
 

jokila

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Those are not TTY bolts .
I think you must not be following which bolts I am referring to as they most certainly are TTY bolts.

The aluminum mount that is attached to the side of the engine uses what I believe are three 16mm, non TTY bolts to the engine, but most everyone replaces them. It is the two large bolts that attach to it that are definitely TTY. The threads of this mount get weak and can disintegrate.

The torque on those 18mm bolts is 75 ft lbs, or if you follow the Bentley, it is 44 ft lbs + 1/4 turn.
 

wrenchman30

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tty bolts feel like you strip them out when torqued properly, these bolts and many on vw are specified as tty bolts but in reality there just bolts with thread sealer on them, place a new bolt and a old bolt head to thread and the threads will be same length (head will touch each end of bolt)
 

ymz

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tthese bolts and many on vw are specified as tty bolts but in reality there just bolts with thread sealer on them
not always... sometimes (such as in the case of these vertical engine mount bolts) they're just bolts with an anti-corrosion coating on them... not thread locker...

Yuri
 
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