Engine mount thread repair

TDIray

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I have a question. Both of my 18 mm vertical bolts fail to torque proper. Just finished a timing belt change. Can these the threads (Time Serts) be added with the motor mount bracket attached to the engine? If so, seams like a good alternative.

Thanks
 

turbovan+tdi

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I have a question. Both of my 18 mm vertical bolts fail to torque proper. Just finished a timing belt change. Can these the threads (Time Serts) be added with the motor mount bracket attached to the engine? If so, seams like a good alternative.
Thanks
If you can get straight in with a drill then yeah, they can be fixed on the car.
 

UhOh

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I have a question. Both of my 18 mm vertical bolts fail to torque proper. Just finished a timing belt change. Can these the threads (Time Serts) be added with the motor mount bracket attached to the engine? If so, seams like a good alternative.

Thanks
I did it this way. Wasn't fun, but I managed. Sadly, I didn't tap on hole far enough and I ended up having to cut the insert off (with a dremel), not a lot, but I wasn't happy I messed up. Been over a year and 25k+ miles and it's holding up so far. Take your time.
 

Metal Man

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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
One of the reasons this repair or a Heli coil repair is stronger than the original threads is that after the repair the load is now spread out over a much larger area.
 

TDIray

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I got the Time Sert installed. The install went well. I did file the insert tops just a little to make them flush with the mount bracket. This was a life saver. I did not have to redo my time belt this way.
Thanks a lot for this thread everyone.
 

MadScience

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Sorry the bing this thread back to life, I have have had issues with this lately. First on a 1.8T TB job the bracket threads came out with the bolts and yesterday the threads in one bracket hole let go right at the end of the 1/4 turn. I have had good results running a 1/2" 13 tap down the problem hole and drilling out and tapping the center hole. I then use 1/2" grade 8 bolts torqued to 44lbfts with thread lock and a spring washer. 3 bolts on total. Works fine and is a cheap fix.
 

UhOh

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Threadlocker and spring washer? That would be so the bolt doesn't back out. I'm not aware of any problems with the bolts backing out. The issue is with the threads on the mounts pulling out.

I suppose, however, that if the 1/2" grade 8 holds then that's good enough. Someone versed in bolt strengths can speak to this vs the stock bolts (which are higher grade, but a bit smaller).

Timeserts really work because their outer threads have a BIG bite in the mount and the steel hole threads contact with steel bolt threads is MUCH greater than stock. The ONLY issue/concern I'd have on any of this would be whether the intended collision break-away forces are adversely affected: I really don't want to test this out!
 

MadScience

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Yeah both thread lock and a spring washer are overkill but do no harm. But I see what you're saying in that the bolt will not back out with the engine hanging off the threads.

Timeserts look really nice, but are not that much cheaper than a new bracket...
 

Franko6

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We have been asked when installing a similar repair for glow plugs, why we don't use TimeSerts. The answer is, we do! But only if we find a HeliCoil will not work. The HeliCoil is much less expensive and if it were to fail, and we have done hundreds of Helicoil repairs for both the gp's and the engine mounts, you still can back up the Helicoil repair with a TimeSert.

We would need the Helicoil repair to fail before ever considering a TimeSert in a gp repair. For me,the first step hasn't failed yet.

I have had the Helicoil repair fail in the engine mount, but as you see, so does the TimeSert. There is a limit for what the 12mm bolt will hold in an aluminum hole and that is all you can do. Fortunately, the price of replacement engine mounts has come down. We can get new ones for under $120. Considering the replacement cost is why we have not particularly concentrated on repairing engine mounts. For me, the time to repair an engine mount compared to replacing has become quite close.

Years ago, we showed a thread repair in place, using a Helicoil, which would not have been possible with the TimeSert. The TimeSert would be too big to work. We stripped the front bolt, which at 1am in the morning, you either quit or find a workaround. We drilled out the hole(31/32nd drill) in place, and recoiled the hole inside of 15 minutes. That beat the alternative all to pieces.

As a footnote, we stopped using the torque + 1/4 turn method for engine mounts years ago. I think it's a bit absurd method anyway. The 10mm bolts are a direct 45 ft lbs torque. The 12mm, we use 65 ft lbs. The body mount is 35 ft lbs. It causes less problems and we have never had an engine fall or strip a mount when using those numbers, unless the mounts were previously damaged anyway, then we either fix it or replace it. Of course, we use a torque wrench that is calibrated, which is really quite easy to do.
 
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UhOh

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Great info, Frank!

I'll note that on my use of the Timeserts that I went that way only because I didn't want to pull the old mount (I'd had the TB all set- it was my first job and I didn't want to risk messing the TB up). But I agree with Frank in that the time that it takes to do repairs is generally not worth it when compared to the price of a new mount: this is especially true for professionals (which I am not)!
 

GallowayChicago

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There are basically three ways to fix a stripped motor mount:
- (1) Replace it with a new one [expensive]
- (2) drill, tap and pray [lots of labor]
- (3) make it work 100% by using nuts [never worry about mount again]

038 199 207 H - Repair aluminum thread failure by cutting a slot for a nut. Works wonderfully. Permanent Fix





full youtube videohttp://www.youtube.com/watch?v=D_SO3SSK1RI
 
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UhOh

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^^ Cool idea!

If one can get the mount out that's a good way to go. I couldn't get mine out: rather, I refused to undo my new TB install to remove the mount- my first TB job and I was confident that I had the TB perfectly set (which it turned out it was) and didn't want to risk my luck in undoing everything.
 

GallowayChicago

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I was able to get the 038-199-207-H passenger side motor mount off my 2000 ALH MK4 Golf 1.9L TDI only by removing the middle black Turbo intake tube (not the lower one coming from the intercooler), but the only other way is to remove the large Camshaft sprocket and this will require removal of the timing belt. By taking the time to remove the black turbo intake I did not have to mess with the Timing, but it was a game of twister. Luckily I actually caught the mount just before it was going to fail.Lots of aluminum shavings and a 1/4" gap was seen on both bolts. These little diesels are powerful and really hard on all three motor mount dampeners.

The real trick in doing this repair was grinding down the nuts with the top-hat rings down so that they both had a key that stopped them from being able to rotate. Once done I tightened the assembly nuts and bolts and filled the slots with black RTV. This would reduce the likelihood of oxidation to either the aluminum or the steel nuts. Final note: when I did the on car assembly I used black RTV again as thread-lock. While it is wet it acts like a lubricant but when it hardens it holds the bolt and fills the voids where water can degrade the fitting.

By doing this you change the raw physics of how you are securing your motor mount. You are going from Pulling to Clamping. I call the OEM setup Pulling because the force that can be exerted on the aluminum threads is much less than the force that can be sustained by the all steel nuts.


note: To remove the upper black tube from the turbo you need good light and a hoes-clamp puller. Credit: someone else's photo.
 
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UhOh

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Not sure if I'd mentioned it previously, but there was a reason why the mounts were designed like they were (highly questionable as it may appear), and that's for safety, for engine breakaway in collisions. I don't have the capacity (resources, including mental) to figure out what changes a changed mount like this presents to the breakaway function, but for sure it's altered. Mind you, I prefer the strategy of not testing, of not hitting anything in order to find out how either this "design" OR VW's operates!;)
 

jokila

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Not sure if I'd mentioned it previously, but there was a reason why the mounts were designed like they were (highly questionable as it may appear), and that's for safety, for engine breakaway in collisions. I don't have the capacity (resources, including mental) to figure out what changes a changed mount like this presents to the breakaway function, but for sure it's altered. Mind you, I prefer the strategy of not testing, of not hitting anything in order to find out how either this "design" OR VW's operates!;)
Yeah. I have wondered that myself.
 

Wingnut

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There are basically three ways to fix a stripped motor mount:
- (1) Replace it with a new one [expensive]
- (2) drill, tap and pray [lots of labor]
- (3) make it work 100% by using nuts [never worry about mount again]

038 199 207 H - Repair aluminum thread failure by cutting a slot for a nut. Works wonderfully. Permanent Fix





full youtube videohttp://www.youtube.com/watch?v=D_SO3SSK1RI
How do you get a tool in there to hold the bottom nuts while torquing the bolts? Can maybe be done on a bench, but not in the car.

I have to disagree with your claim that the drill & tap repair is "lots of labor" It's a 10 minute job. There certainly is a lot more labor time to cut those slots in the mount to accept the nuts.

I agree that the cost of the time sert tool is expensive and if you are just doing 1 mount, the cost to buy a new mount makes sense. But there are options after buying and using the tool. Repair more mounts at $5 worth of inserts each. Or sell the tool to recoup some $$$.
 

GallowayChicago

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How do you get a tool in there to hold the bottom nuts while torquing the bolts? Can maybe be done on a bench, but not in the car.

I have to disagree with your claim that the drill & tap repair is "lots of labor" It's a 10 minute job. There certainly is a lot more labor time to cut those slots in the mount to accept the nuts.

I agree that the cost of the time sert tool is expensive and if you are just doing 1 mount, the cost to buy a new mount makes sense. But there are options after buying and using the tool. Repair more mounts at $5 worth of inserts each. Or sell the tool to recoup some $$$.
Wingnut; There seems to be a miscommunication for which I do apologize. The YouTube video would answer all your questions and it is only 8-mins long (I made it to better show the assembly).

The slot for the nut, in the motor mount, is cut as a snug box and the nut that is used is one of the types with a large ring or hat brim on it. The ring is ground down to form a key or elongated area. This key is what stops the nut from turning in the slot. The slot, with the nut in it, was then sealed with black RTV to stop oxidation. When you finally go to install the mount on the auto you do not need to insert any tools in the nut hold to keep it from rotating and you can torque down to the OEM requires specs without being concerned that it will ever strip. You are correct about the cost vs labor aspect of doing this repair, but over all other repairs or even replacement, this one is MOST SECURE.

closed up of nut from video

full youtube video http://www.youtube.com/watch?v=D_SO3SSK1RI
 
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jokila

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How do you get a tool in there to hold the bottom nuts while torquing the bolts? Can maybe be done on a bench, but not in the car.

I have to disagree with your claim that the drill & tap repair is "lots of labor" It's a 10 minute job. There certainly is a lot more labor time to cut those slots in the mount to accept the nuts.

I agree that the cost of the time sert tool is expensive and if you are just doing 1 mount, the cost to buy a new mount makes sense. But there are options after buying and using the tool. Repair more mounts at $5 worth of inserts each. Or sell the tool to recoup some $$$.
I agree with all your points.

I also changed my method when torquing those two 18mm bolts. I use several stages to get to final instead of the two in the past. I had one bolt let go when after I had torqued the other bolt which left me in a tough jam if i were to undo the bolt to make more room to install the timesert. There was enough room, but it was involved to say the least.
 
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MadScience

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Great thread. With the newer vertical engine mount bolts requiring 74ftlbs and no 1/4 turn, does that mean they are not TTY bolts? Can they be reused?
 

Shello

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@ Franko6 would you suggest stopping the 1/4 turn process on the 3 horizontal 16mm bolts on the transmission mount bracket after the suggested 37 ft lbs?
 

Franko6

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Shello,

Sorry, but I just saw this question. There seems to be a bit of confusion, as bolt head is not the way to identify a bolt. It's shaft size, thread pitch and length. I will identify shaft size.

The only bolt I torque to 35 ft lbs are the vertical 10mm(?) 2 bolts (16mm bolt head) that hold the body mount to the body itself. The three 10mm bolts (also 16mm bolt heads..) for the engine mount, I torque to a straight 45 ft lbs. The Vertical 12mm bolts (18mm head) I torque to 65 ft lbs.

I realize there is some who will cry 'FOUL!' for going against the grain on 'spec', but we particularly do not like stripping engine mount bolts. We also do not like over-tightening what is in all intents and purposes, NOT a torque to yield bolt.

As for how we use Recoils, we use a double depth recoil, that goes from the very top, to the very bottom of the bolt hole for the vertical engine mount repair. They do not make a single recoil that fits, so we bought 'specials' that are 15mm length. The bolt hole is drilled as far as we can without breaking through to the bottom of the hole. I wish I had a 'bottoming tap' for the weird size recoil thread, so we could use the recoil at full depth, but we have to stop where the recoil binds with the first recoil, then stack the next on top of it.

As a matter of threading principle, aluminum threads should be a minimum of 2x the length compared to the diameter of the threads; i.e., 12mm x 2 = 24mm and we use a 30mm depth. Not really overkill... If you stick to my torques, they will not pull out.

I like the idea of sealing the threads. We use a aluminum wiring paste that has anti-corrosion grease in a nickel base. It stays put and keeps out corrosion. We use the same stuff for glow plugs, wheel nuts, acorn grounding nuts, etc.

What is interesting is later model engine mounts come with Timeserts, which are quite deep. Still, if you over-stress them and they will pull out.

Engineering of these 'systems' is quite remarkable. I can honestly say, I'm alive today because a Jetta sacrificed it's life to save mine. The point being, don't mess with a connection whose design is to fail in a catastrophic incident and in a way that may save your butt.
 
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Vince Waldon

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Engineering of these 'systems' is quite remarkable. I can honestly say, I'm alive today because a Jetta sacrificed it's life to save mine. The point being, don't mess with a connection whose design is to fail in a catastrophic incident and in a way that may save your butt.
This. A thousand times this. :)

Although it's true that engineers are constantly weighing cost in their designs... and thus sometimes they do things to save a penny across the millions of cars that roll off the assembly lines... they almost always think safety first (and then argue with the accountants later if need be. :) )

So, one man's "wow this is a crappy flimsy design" could be another man's "thank gawd it sacrificed itself to save my life". And we weekend warriors are not always in full possession of the design goals...so worth thinking about as we do our various "improvements". :) :)

That said, not sure what was up with their door module designer and their armrest latch designer and their fender foam designer and their rear brake caliper designer and their... :D
 
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When I had the motorcycle shop we used Keen-serts, as used in aerospace applications, for most thread repairs, with never a failure. Still use them on the odd occasion when repairs are needed, though the similarly designed Acme inserts seem beefier still and may be worth further investigation...
 
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vincej

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As Helicoil inserts can be quite short I have occasionally successfully used two in the same hole, one on top of the other. The solid insert repair looks really good though.

To maintain the integrity a part that requires removal of bolts over numerous repairs VW should have designed them with inserts out of the factory. Of course if they had a chain rather than a belt not so many repairs would be needed.
 

turbovan+tdi

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Not sure if I'd mentioned it previously, but there was a reason why the mounts were designed like they were (highly questionable as it may appear), and that's for safety, for engine breakaway in collisions. I don't have the capacity (resources, including mental) to figure out what changes a changed mount like this presents to the breakaway function, but for sure it's altered. Mind you, I prefer the strategy of not testing, of not hitting anything in order to find out how either this "design" OR VW's operates!;)
You are correct, the mounts actually break, not the bracket. I have an 03 Wagon with a 1.8T engine, hit hard in the front, it broke off both side motor mounts, the brackets are intact. :eek:
 

Franko6

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Strangerfaces, there are several things about that thread repair and the reason we don't use them. 1) They are more expensive 2) They don't come in 30mm length as far as I can see. This is important, as the thread contact to the aluminum will pull out if it's not long enough, And 3) we have repaired many, and as I have already pointed out, vincej, we specifically use a 15mm recoils and put in two. They do stack nicely.

In the collision I had, the mount broke at the transmission side at the body. Smaller bolts gave out first. The body to engine connection was wrecked also where the bent and pulled out. What really did me service was the door curtain and the seat air bag. It was a sideways strike. The steering wheel bag never went off, which was a surprise.
 

turbovan+tdi

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What really did me service was the door curtain and the seat air bag. It was a sideways strike. The steering wheel bag never went off, which was a surprise.
Its weird, some accidents you'd swear the air bags should have gone off but don't and vice versa, :confused: ;)
 

Golf2K

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Wow these Timeserts are expensive, $266 CDN amazon, my HeliCoil set had a m12x1.75, I suppose that will not work?
 
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