Head bolt hole stripped!

[mtskibum16]

Hey guys. Well, the title says most of it.

 

I was installing my newly surfaced/pressure tested heads. I had put oil on the threads and washer surface and torqued each bolt to 22 ft-lbs in the proper sequence. I "warmed up" my torque wrench on 51 ft-lbs on a wheel lugnut to make sure it was clicking correctly. Started turning the first bolt to torque it to 51. It felt like I should be getting pretty close but no click. Stopped and went back to the wheel and it clicked perfect. Went back to the head and turned it about 45 more degrees and the threads gave!!!

 

I'm not sure what could have caused this. The most likely thing I can figure is that I had the block at 45 degrees on the engine stand and maybe I had the wrench out of square enough the it didn't click properly. Maybe the threads were weak from being over tightened in the past, etc....really I don't know.

 

All I'm wondering now is how do I fix this? One recommendation I got was to use a helicoil. I've never used this product but I know lots of people have. Anyone have any other thoughts? I'm going to ask the machine shop tomorrow. Has anyone heard of this happening before? Seems strange as I couldn't have been much over 51. Also, the head gasket should be fine to use still right? As I said all bolts were to 22 ft-lbs and then one to 51+ ft-lbs. Is it still fine to use after I fix the threads?

 

Thanks for the help!!!

[Fairtax4me]

I'd get a new gasket for good measure. Those things are picky about how they seat. Once they compress they don't go back to the same as their previously uncompressed state.

 

The threads can be helicoiled, or some other form of insert. There are quite a few out there that should work fine.

 

There was one that several people here touted as very easy to use and very reliable that popped up in a thread not long ago. I wanna say it was Time-Sert... ? The thread was about spark plug holes though. Not sure how well or if it would work for a cylinder head bolt.

[eppoh]

That really stinks.

 

As far as a helicoil... I thought these blocks had multiple level of threads for the head bolts.

 

I stuck a curved pick down the head bolt holes in mine and though I felt three distinct sets of threads, separated by maybe am eighth inch of smooth bore in between.

 

Maybe I am mistaken.

 

In case you are wondering why I did that... I am doing heads with the engine in the car, never again... anyway I was thinking about shortening the lower rear bolt a little to make it easier to install, and was wondering if the threads in the block were as long as the threads on the head bolts. They are very long. Now I know why.

[rxleone]

Oh. Wow. That's a bit of a problem. I'm not sure if you can re-thread them.

 

Best bet would be to go to a machine shop (not a mechanics - no doubt they'd say you can't and try to charge you up a new block) and see what they can do. I wouldn't trust myself helicoiling a hole of importance like that - more trouble then its worth.

 

Let us know how you get on.

[Qman]

Heli-coil the block. I would consider doing them all if you have some that are bad. The gasket will be fine as you never achieved full torque. I did a head job once that I had pulled the threads on no less than 5 holes. Very frustrating. I feel your pain. But, all repairs held up fine as far as I know. Never heard of any problems later on.

[eppoh]

What year/model is the car?

[mtskibum16]

Thanks for the comments guys.

 

Qman, it's good to hear from someone that has done it. That's crazy that you had 5 pull out! So did you just use the spring type helicoil insert? I thought the gasket would be fine to since I never fully torqued it. I'd hate to have to go buy another one when this is brand new!

 

eppoh - It's a 98 LGT wagon but I'm pretty sure it's a 97 MY motor. So you mean there are threads, then a space, then more threads etc? Either way, it doesn't matter now since I don't have any threads left

 

After doing a little research yesterday I'm feeling pretty good about the helicoil. I just want to make sure I get it drilled/tapped square to the block! Since I only have to drill out a little bit of metal and there's already a hole I'm sure it will be easy to drill straight.

 

Anyone else have an idea on the gasket?

[Gloyale]

You need to use a new gasket. This engine in particular needs to have the best possible gasket or it will come back to bite you.

 

dealerships sell the gaskets individually.

 

just replace the one side that you are removing.

[Qman]

You need to use a new gasket. This engine in particular needs to have the best possible gasket or it will come back to bite you.

 

dealerships sell the gaskets individually.

 

just replace the one side that you are removing.

 

If it had seen heat I would agree. It did not nor did it achieve final torque. The gasket will be fine. If you have a dealer local to you and can get one without a lot of delay I would consider it. If not, run with it.

[Qman]

Thanks for the comments guys.

 

Qman, it's good to hear from someone that has done it. That's crazy that you had 5 pull out! So did you just use the spring type helicoil insert? I thought the gasket would be fine to since I never fully torqued it. I'd hate to have to go buy another one when this is brand new!

 

eppoh - It's a 98 LGT wagon but I'm pretty sure it's a 97 MY motor. So you mean there are threads, then a space, then more threads etc? Either way, it doesn't matter now since I don't have any threads left

 

After doing a little research yesterday I'm feeling pretty good about the helicoil. I just want to make sure I get it drilled/tapped square to the block! Since I only have to drill out a little bit of metal and there's already a hole I'm sure it will be easy to drill straight.

 

Anyone else have an idea on the gasket?

 

Yes, coil type thread insert. The existing hole will keep you straight as long as you do not use a lot of force when drilling. Put a little grease on the flutes to hold the chips from drilling and threading.

[mtskibum16]

It seems reasonable that since the gasket is going back in the same exact spot, on the same exact mating surfaces, and was never fully compressed that it should be fine. However, I would hate to have to redo this because I skimped on a $50 part. It just seems logical that it would be fine though.

[mtskibum16]

Just thought of something and thought I'd throw it out there.

 

I think the gasket can be reused without issue. If you recall, the torque sequence is 22 ft-lbs, then 51, then back off 180 degrees, then 180 degrees again, then torque to 11/25 (or something like that), then 90 degrees then 90 again. So after a torque to 51 ft-lbs you release the tension back to near zero (or at least under 11 ft-lbs) before you torque again. This leads me to believe that the gaskets are designed to be compressed then released then compressed again and that they are reusable at least to the point that final torque is reached.

 

Thoughts?

[ericem]

Makes complete sense. People are just being extra cautious on advice, but it does not make sense that the gasket would be garbage unless as mentioned it hit full torque.

[eppoh]

Thanks for the comments guys.

 

 

 

eppoh - It's a 98 LGT wagon but I'm pretty sure it's a 97 MY motor. So you mean there are threads, then a space, then more threads etc? Either way, it doesn't matter now since I don't have any threads left

 

 

Anyone else have an idea on the gasket?

 

Yes, that is what I mean.

 

Don't know how you would helicoil that, but there must be a way.

 

Mine is a Phase 2 2.2. If you have a 2.5 maybe it is different.

Edited March 30, 2010 by eppoh

[Qman]

Just thought of something and thought I'd throw it out there.

 

I think the gasket can be reused without issue. If you recall, the torque sequence is 22 ft-lbs, then 51, then back off 180 degrees, then 180 degrees again, then torque to 11/25 (or something like that), then 90 degrees then 90 again. So after a torque to 51 ft-lbs you release the tension back to near zero (or at least under 11 ft-lbs) before you torque again. This leads me to believe that the gaskets are designed to be compressed then released then compressed again and that they are reusable at least to the point that final torque is reached.

 

Thoughts?

 

That is the thoughts I used to come up with my advice.

[mtskibum16]

Qman - How long were the helicoil inserts you used? The ones my local store carry are only 15mm long (.59"). I measured the stock length of threads and they're 44.1mm (1.74").

 

I don't have a thread gauge. Does anyone know off the top of their head what pitch the head bolts are? I'll take the bolt with me tomorrow if need be.

[Fairtax4me]

I think you can put in as many inserts as you need to make up the difference. Just thread one in to the bottom, then the next and so on. Might have to use 3 or 4 that way but it should work just the same.

[mtskibum16]

I've never used them so I wasn't sure if you could stack them or not. It makes sense that you could since they will be "timed" by the threads the helicoil is going in to. Has anyone done that? Thread pitch? Need to run to the store I guess.

[Qman]

I've never used them so I wasn't sure if you could stack them or not. It makes sense that you could since they will be "timed" by the threads the helicoil is going in to. Has anyone done that? Thread pitch? Need to run to the store I guess.

 

1 Helicoil is all you need. Any more and you run the risk of dislodging them or causing thread mismatch.

[mtskibum16]

Well, I over analyze everything (mechanical engineer ) and I've done some research and based on the parent material (aluminum), the bolt strength, and the Heli-coil selection guide, it looks like I need their insert that is 2-3 times the nominal bolt diameter (20-30mm) to match the strength of the holes' thread to the ultimate strength of the bolt. Since the final torque on the bolt is no where near reaching the ultimate strength of the bolt I think the 15mm insert would be fine. However, I'm going to try and find a 20 or 30mm length one.

[Qman]

Yep, you're right over analyzed it for sure.

 

Steel vs aluminum threads need to be accounted for as well. Not just diameter and length. I have done several of these and one is enough. But, if you feel better about it see if they are available and at what cost.

[Scottbaru]

I regularly put helicoils in new machines my shop designs and builds, it's a much stronger thread than just tapped threads in aluminum or mild steel. The longer the better of course. Multiple helicoils would all align with the threads tapped by the single helicoil tap, so multiples wouldn't be a problem, but would be a little silly. 2.5 times the diameter is normally the most you need.

 

I like Time-Serts mentioned earlier in this thread, but they have a top flange that might not work without slightly countersinking the block. Helicoils are everywhere, and most mechanics and machinists are familiar with them.

 

I just did my head gaskets, scary noises when torquing those bolts. Gotta use oil on the bolts, don't forget that.

[johnceggleston]

Gotta use oil on the bolts, don't forget that.

 

 

is 10w30 ok or is there a better, job specific product out there?

[Qman]

is 10w30 ok or is there a better, job specific product out there?

 

From my experiences 10w30 should be fine. I also have used a small amount of anti-sieze when putting steel bolts into aluminum threads.

[mtskibum16]

I'm wondering if the taps/install tool from these kits are long enough to get down into the block. It's around 4" to the bottom of the threads in the block.

 

Scott, 2.5x the diameter would be great. The problem is the standard around town seems to be the 1x diameter which seems too short. It looks like I'm going to have to order something anyways. There is no M11x1.25 around town. I think I'm going to use my other block and deal with later.

 

I definitely used/will use oil on the threads and washers.