Camshaft bolts >:(

[Fordlover96]

So, this evening I was changing out a noisy timing chain tensioner and I had to take one of the camshafts out to get the tensioner out. While putting the bolts back in, I made the rookie mistake of putting the bolts in while the engine was slightly warm and two of bolt holes got stripped. The bolt holes for the camshaft bolts.

What do I do?!?!

I've never really dealt with stripped bolts that go into the head.

Any advice would be appreciated.

 

[Devin]

Do you mean you took a camshaft sprocket out? It's two of those little bolts that stripped out?

 

[Fordlover96]

Not the sprocket. The camshaft caps. Sorry!

 

[rubydist]

you will need to drill out and tap those holes the correct larger size so you can put in a helicoil or other threaded insert in there to repair it.

 

[sperold]

You could look into a heli-coil insert after you figure out what thread size you are dealing with.

Do you know the torque that is expected on this fastener?

If the clamping force to hold this cap down is not too great, you might get away with a very crude fix (that I only mention if you are Totally in a bind).

You could research the thread size, and go to a stud from an alternative system (metric to imperial) that is slightly larger with roughly the same threads per inch.
With brute force alone, you may be able to auger the stud into the damaged tapped hole. It will never come out, and your tightening effort will be from the nut on the top of the stud.

It is a long shot, and very unsophisticated, but it might save the day.

Review the thread sizes that are available in the Machinerys Handbook and you will be astounded by the number of similar thread forms to your damaged ones.

If this should fail, you are still eligible for the helicoil treatment, as the insert has a comparatively large outer dimension

 

[pjtoledo]

did you put the wrong bolts in the caps? those bolts are 7mm diameter and 1mm pitch.
due to the locating dowels it may be difficult to enlarge the holes.

 

[sperold]

If you repair this with a stud, there may be threads remaining at the bottom of the tapped hole that have not been stripped out by the original bolt. The stud will reach those remaining threads if the hole was bottom tapped.

If it is a M7 X 1 coarse bolt, there are 3 categories of fit (close-4H, medium 6G, and free 8G) each one with a different outside diameter. For the stud, get the 4H as it is a full 7 mm diameter. That is .2755 inch diameter.

There is a M8 (.3149 inch) stud but it switches to 1.25 pitch which is 20.32 threads per inch as apposed to 25.4 threads per inch for the 1.00 pitch.
Although that is a tempting choice, the imperial system has one a bit better.

A 5/16 inch stud is .3125 in diameter, and the fine thread model has a pitch of 24 thread per inch. 5/16 x 24 UNF
The diameter is uncomfortably large (.3125 to .2755) but the pitch is very close (25.4 to 24).

Consider tapping the hole to the .3125 diameter size ( 5/16 x 24 UNF) if the M7 X1 stud doesnot sound feasible. But install a stud as you can't mess with these threads in the future.

 

[pjtoledo]

do not try to cut different pitch threads.
there are 8 x 1 mm taps available, perhaps a longer 8 x 1 bolt?
its in soft aluminum, you won't need a hardened bolt.

8mm is extremely close to 5/16. only about .0024 " difference.


bad news, just checked a head. the bushings are only 7.55 mm, or 19/64".
that's not quite enough for 8mm or 5/16".
it will be difficult to drill the holes deeper, outer ones will break out the side, most inner ones may hit the springs.

 

[yamahaSHO]

I've stripped out so many of those... After many helicoils, I bought new heads and had studs made for them. As for preventing stripping, I found completely cleaning out all the oil with carb cleaner allows you to torque to spec, however, I do it off of feel anymore. The thread pitch on those is so narrow that they are easy to strip out.

I think I still have a helicoil kit for those somewhere.

 

[black92]

I just went through this.
You need to remove the hollow locating pin prior to taping the hole for a Heli-Coil. Tip for removing them. Insert a snug drill bit and gently grab with a vice grip. drill bit will keep the locating pin from distorting.
My ordered my M7-1.00 Heli-Coil kit from Fastenal, however they can be had online also. Maybe Amazon.

 

[Fordlover96]

Thank you so much all you guys. I really appreciate it. Like I said, this is the first time I've honestly ever dealt with a stripped threads in the head and its scary as shit at first lol

I just went through this.
You need to remove the hollow locating pin prior to taping the hole for a Heli-Coil. Tip for removing them. Insert a snug drill bit and gently grab with a vice grip. drill bit will keep the locating pin from distorting.
My ordered my M7-1.00 Heli-Coil kit from Fastenal, however they can be had online also. Maybe Amazon.

Is M7-1.00 compatible with the original bolts? Aka is that the thread of the bolt?

I've stripped out so many of those... After many helicoils, I bought new heads and had studs made for them. As for preventing stripping, I found completely cleaning out all the oil with carb cleaner allows you to torque to spec, however, I do it off of feel anymore. The thread pitch on those is so narrow that they are easy to strip out.

I think I still have a helicoil kit for those somewhere.

Would you mind seeing what helicoil kit you used?

THANKS AGAIN EVERYONE! Ill keep you updated!

 

[black92]

You need Helicoil # 5546-7
M7x1.00

 

[yamahaSHO]

It was over 10 years ago when I did this and I'm not sure where mine are after the recent move.

 

[Fordlover96]

Alright so he helicoil was pretty easy. Cleaned up one of the other thread while I was in there.

Here's my question. Do you have an good tips for cleaning all the shavings out of the head?

I did my best covering everything with shop towels but some still shot around.

Thanks!

 

[black92]

With the engine in the car out will be difficult. Cover the cylinder and clean the hole with compressed air.

I did mine on a engine stand. I tipped it over to clean it.

 

[rubydist]

the good news is the aluminum shavings aren't going to cause huge problems. I would wash them down into the pan as best as possible and then drain the oil.

 

[Fordlover96]

So, got all the shaving out. Changed oil. Started car only to figure out I must have put the cam shaft one or two teeth off bc the car runs like crapppp. Timing is off. How is the chain side of the camshaft supposed to be positioned? I'm talking about the exhaust cam on the front of engine. The other camshaft has a little dimple on the gear, but I couldn't seem to find anything on the chain that indicates where the cam and chain should be positioned. Thanks again so much you guys!!!!

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[black92]

There should be 2 chain links that are painted or different colored that you line up the dimples on the sprockets.

http://alfitz.com/SHO_Engine_Book.pdf See page 89 of the book (page 59 of download) for install instructions

 

[Fordlover96]

Alright so, got it taken apart. I had painted little white lines on the end of the camshaft before I intially took it apart so I figured I put it back right on those little marks but I guess not. I aligned the marks with what I'm pretty sure is correct. The cams is totally in a different position then when it was running bad. Does it look correct?

 

[black92]

Cant tell from the pictures. There is a tool designed to fit over the pair of cams to insure they are properly lined up. The manual I posted goes over this. I recommend reading the cylinder head assembly section. Take a close look at the chain. look for two links that are different from the rest.