stripped bolt, need help

[Scott_S]

I stripped the bolt on the front of the auto tensioner(bolt toward the front of the engine) and its leaking oil all over the place. I tried teflon tape and that didnt work. I figured it cracked the hole that it goes into exposing it to an oil galley. Anyone know how to fix this?

 

[Jingx284]

I'm not really good with this kind of stuff, but i've seen miracles done with jbweld or kwikweld. Once it hardens, it's just like metal. You could always just patch up the hole and redrill it.

 

[mopardwh]

At least you found your oil leak. That sucks though. So the hole is broke through the block? Are the threads stripped also? JB weld is not the best, but it shouldn't be that pressurized in that spot. Also use silicone, or some pipe dope. If you have to, drill the hole larger and tap vs. using helicoil. You can inlarge the hole on the tensioner just as easy.

 

[Scott_S]

Bolt is completly stripped so I will have to tap it no matter what I do. When I put it back together I'm going to use that marshmallow looking goo on the bolt and cross my fingers and hope it seals. This is all on the assumption that the crack is only on the bottom of the hole of course.

 

[toybreaker]

I was following your other thread...(please close that one out. ) I had a feeling this is where we going to end up on that. There's some oil passages on the back of the front cover. They are sandwiched between the front cover and the block, and they run right past the tensioner and if the tensioner thru bolts aren't tight the result is an oil leak out the tensioner hole.

I have some experience repairing cars for shops where this job has gone south on one of their mechanics, so I've seen several variations on this failure. In the other thread I asked you if anything felt funny during reassembly. Usually when something strips, you can feel it. For some reason, the tensioner bolt holes in the block seem to be one of the holes that is subject to mr murphys law.

It's getting tighter ...tighter..ummmm..it's still turning....and it didn't get any tighter.....

STOP!!!!

Just don't twist any further when it starts getting easier to turn...Pull the bolt back out and investigate. There's a good chance the block threads can be saved with a thread chaser, and a new, slightly longer bolt can save the day.

Please remember, this will most likely have to come apart again for a t-belt service, or for sure if you have to replace the tensioner. There is a way to compress the tensioner on the car, but I like to replace the tensioner every time when I do the t-belt.

So, needless to say, J-b weld in this application is rather permanent,...and I never use it where I'm going to even concievabally have to remove that piece of hardware. The bolt will break every time...and at that point you're seriously FUBAR.......

I've done this repair several different ways, and I prefer the helicoil, for this particular application. It's a major pain to drill it, but you can shorten up a drill bit, and grind it to fit a dremel chuck and use a 90* attachment. Be absolutely sure to drill it straight and not too deep.

You will also have to sacrifice a heli-coil tool set because of the close working quarters. Just cut the install tool down as required.

Follow the heli-coil instructions to the letter. You must break the drive tang off the heli coil, if you don't the tang can bend over and get caught up in the works at the end of the bolt, and start pulling the heli coil threads out/jam the bolt.

The good news is I've done this repair several times, and had good luck Several vehicles have even suffered thru a chain store t-belt/service without a return failure.

And, yes, it will cure your oil leak, permanentally.

Please let us know what you do, and how it turns out!

 

[mopardwh]

To toybreaker: Did you use any kind of thread sealer? Worst case scenario, can't you remove the front cover and repair the crack from behind?

 

[Scott_S]

I'm not worried about it being permanate or not because by the time I need a new belt I want to swap the whole motor. Good info though.
So are you saying that it is a wet hole and nothing is cracked?

 

[toybreaker]

I'm not completely sure about the 2g setup, but on the 1g cars, you can't pull the front cover without dropping the oil pan because the oil pump pick-up tube bolts to the front cover from behind. In addition, the one balance shaft that's driven by the oil pump needs to be addressed as well. Which is why I repair this problem on the car.

I prefer time serts for most thread repairs that are somewhat accessible, as I feel that they're stronger and more permanent. In the case of a front cover thread repair, there's just not enough access to assure the hole will be straight and etc....and helicoils are much more forgiving to hole irregularities...so I use heli-coils here. Just my personal preference.
When drilling and tapping the heli-coil hole, please install a bolt in the other tensioner hole to keep the front cover as snugly against the block as possible. We don't want any chips or burrs to work their way in between the cover and block...

I haven't seen one driven like this before, so we're in uncharted territory, but, I dont believe there's any issue here, except the front cover isn't being held against the block tightly enough to pinch the gasket and get a good seal. It's possible the gasket has torn due to being driven, but I believe in "easy", and there's really nothing to lose by trying to repair the threads without tearing the front cover off.

The oil that's leaking out is actually coming fron an external oil passage formed between the front cover and block, so I don't believe a pipe dope/rtv/thread sealer would be much help because the leak is above the threads in the block. The passage is just a groove machined into the back of the front cover, and doesn't really have anything to do with the threads in the block, other than requiring the cover to be pulled up tightly against the block to pinch the gasket in place. (sorry, me no good with words.. you'd understand immediately if you could see the back of the front cover.)

I would think that a properly installed thread repair would make it all good again. I would caution against thread lockers on a helicoil'd female thread. If it locks the bolt onto the helicoil, the next time that bolt is removed, you could very easily pull the helicoil out of the block and destroy the threads in the proccess. That being said, there is a purple (low strength) thread locker that I use on Porsche carbs and such that is magic at providing a little extra resistance to seepage from multiple level joints. I would say put a very thin coat on the front cover face where the tensioner will mount to seal the tensioner body to the cover. Just use a q-tip or whatever to paint a thin coat on it, or the tensioner, and then put a schoshe on the bottom of the bolt head where it bears against the tensioner. That should be sufficient insurance against any oil migration, and still provide the ability to remove the hardware at a later date. Remember thread lockers are an anarobic (sp?) compound, meaning they cure in the absense of air. Just make sure the threads and surfaces are clean and dry, and assemble in a time efficient manner, and you'll be good to go. Just to be totally clear, that's no loc-tite on the threads, just on the tensioner/front cover joint, and the bottom of the bolt head where it bears against the tensioner body. The purple compound is pretty cool stuff, it's like a form in place plastic, and it works really well for curing seeps, and still allows for dissassembly at a later date.

Please use an accurate torque wrench on reassembly. If the bolt takes torque, I think you'll be good to go.

I wish you the best of luck in this repair! I've had pretty good luck returning this repair to service, so I'm hoping you will too. Please feel free to pm me for any additional questions.
John

 

[Scott_S]

Well here is the thing, for one, I'm really lazy and two I plan on (hopfully) building a destroker this summer/fall and swapping it in the winter so what is the easiest possible(even if its ghetto) way to seal up that leak?

 

[mopardwh]

what is the easiest possible(even if its ghetto) way to seal up that leak?

That would be JB weld!

 

[toybreaker]

I know mopardwh is just funnin ya...but just in case you're thinking about it...

In this particular case, I would strongly recommend against J.B. weld.

Seriously...think about it...you need to apply a clamping load to the front cover to pinch the gasket. Applying j.b.weld to it and reinstalling the bolt in the stripped hole won't do that, it will just lock the bolt in the hole, and make it impossible for a professional to repair this correctly, or maybe even at all.

The correct fix isn't that hard...and it's learning experience.

Jb is easy, and also a learning experience...you just won't like the lesson, trust me.

 

[mopardwh]

Absolutely. You can buy a cheap 90 angle drill or borrow one to drill it out. Or try removing the d-side mount and lowering it enough with a jack.
You never know, you may want to sell that motor to your buddy later.

 

[Scott_S]

I know mopardwh is just funnin ya...but just in case you're thinking about it...

In this particular case, I would strongly recommend against J.B. weld.

Seriously...think about it...you need to apply a clamping load to the front cover to pinch the gasket. Applying j.b.weld to it and reinstalling the bolt in the stripped hole won't do that, it will just lock the bolt in the hole, and make it impossible for a professional to repair this correctly, or maybe even at all.

The correct fix isn't that hard...and it's learning experience.

Jb is easy, and also a learning experience...you just won't like the lesson, trust me.

We are talking about the same bolt right? Because as far as I know the auto tensioner bolt doesnt have anything to do with clamping down any gaskets. Oh and fyi that professional that is going to fix it is me(I'm an auto tech) I'm just to lazy to go through the drilling and helicoiling because I know once I start taking things apart I'll take something else apart and it will get to the point where I just want to rebuild my whole motor. But just incase that is any confusion the leak it out of the left(if your looking at the motor from the drivers side) bolt on the auto tensioner and the oil is leaking out of that hole.

 

[toybreaker]

One last time....

The oil is coming from a passage on the backside of the front cover. It's an open channel...and only becomes a passage because it's sealed against the front of the block...by a gasket...which is pinched between the front cover and the block...by the thru bolts...several of which just happen to also retain the timing belt tensioner to the block...

Scott, please trust me on this. I knew what your problem was in your other thread...and it led us here. I've fixed this exact problem several time for shops here locally.

mopardwh has an excellent point. Try and explain to somebody that you're a professional tech after they have to drill out a jb welded bolt...because there's an oil leak....and see what they say...

.....that dog won't hunt...period....

Please, just get on with repairing this the correct way.