Sign in to follow this  
graham73tii

need suggestions, valve cover leak above #4 plug

15 posts in this topic Last Reply

Recommended Posts

Alright folks, I'm working to get my car as leak free as possible before V@V and have made major progress replacing seals and gaskets.

Currently I've come back to the top of the motor to a problem encountered shortly after I acquired the car. The valve cover stud above plug #4 has "pulled loose" from the head casting (see picture). A couple years ago I pulled it out, cleaned everything up good, then used some JB Weld to epoxy the whole piece back into the head. This held for about a year and then I suppose the heat and vibration took it's toll.

I talked to some local mechanics and received the following options:

1) Clean and rough up the piece, use an epoxy metal weld that has a higher heat range than JB Weld to glue the piece back in (short term fix).

2) Use a "time-sert" insert to secure the stud into the head (similar to helicoil, but stronger).

3) Pull the head, take it to an experienced aluminum welder and have it fixed.

While pulling the head is probably the best choice, I really don't won't to go that route with V@V less than four weeks away. What solutions to this problem would anyone suggest ?

Thanks,

Garry

post-432-13667605292344_thumb.jpg

Share this post


Link to post
Share on other sites

This is just an opinion, I'm not a machinist or mechanic but I get around machine shops regularly as a mechanical engineer - that pulled out section looks bigger than a time-sert can repair.

I think I'd find out if the boss can be tapped to accept a larger thread, then have a stepped stud machined "special" to fit. Red Loctite that dude in and you're done forever. You'll need to have your machine shop give you the final opinion on feasibility, it's impossible to evaluate from a photo.

For a "better temporary fix" you might try tapping the existing stud hole before you put the JB Weld in there. It would give the epoxy more gripping "tooth".

Share this post


Link to post
Share on other sites

Hey Jerry,

Thanks for the suggestion. I hadn't thought of that and this is the reason I put it out here, to get some other options.

Garry

Share this post


Link to post
Share on other sites

I'm not sure what that is shown in the picture, can you clarify what we're looking at?

Specifically, the perfectly round washer looking thing at the base of the M6 stud. Is that a plug of epoxy that was pulled out? Or is that the parent metal of the cast aluminum head? If it's either of those, how did it get that shape? Did someone actually drill a 5/16" hole and try to pot the stud like a fence post in cement? I can't imagine the M6 stud ripping out a piece anything close to that size or shape.

It seems clear that even if the stud was not loose, that mystery washer-like bit would prevent the joint from sealing. The stud is M6, and the clearance hole in the cover is ~ 7.5mm, but the gasket hole is sized tighter.

To me, it kinda looks like the 'washer' shaped thing is a glob of epoxy that squeezed up into the stud clearance hole in the valve cover and was molded to shape in that process, but I'd like to hear it explained.

If that is a glue glob, and no one has already drilled a huge hole there, then it is a good candidate for a thread repair insert of your choice. Timesert or Helicoil, either would be plenty strong. Mostly depends on what size hole you could produce cleanly to take the repair tap.

Glue, epoxy, or Loctite will not be help you if the threads are shot.

Share this post


Link to post
Share on other sites

Hey John,

The "washer" like thing you are looking at is part of the aluminum casting. Yes, I agree it doesn't make sense that it would be stressed to the point of fracture, however it was like this when I aquired the car several years ago. Obviously I had an oil leak at the valve cover and once I pulled it off, what you see is what I found.

It does not appear to have been tapped previously, as the whole "washer" thing is actually a 3/4" long piece of the head casting which the stud is screwed into. Not sure you can tell in the pictures, but the hole is off center with a thinner wall toward the back of the motor (toward the distributor). It looks like it would be possible to thread a helicoil or time-sert into the hole. Then my question is how do you get the proper size for the stud? insert another helicoil?

Thanks,

Garry

Share this post


Link to post
Share on other sites
Hey John,

The "washer" like thing you are looking at is part of the aluminum casting. Yes, I agree it doesn't make sense that it would be stressed to the point of fracture, however it was like this when I aquired the car ............It does not appear to have been tapped previously, as the whole "washer" thing is actually a 3/4" long piece of the head casting which the stud is screwed into. ..................

question is how do you get the proper size for the stud? insert another helicoil?

Thanks,

Garry

I still can't imagine this to be a fracture, or a piece of the original casting, as it's appearance is too perfectly round. If you say it is 3/4" long, does it retain the shape over its length, so it has a cylindrical shape? Especially because it is not concentric with the stud. Maybe it's just the picture, but it really looks like a plug of sorts stuck in a drilled hole.

Regardless of how the large hole was formed, it is way too big now to use a thread insert, esp. with it off center like it shows.

Looks more like it will need a weld repair, or clean the hole out again & refill it with Devcon Aluminum Putty (Google for it).

Actually, the chunk of 'casting' that pulled out looks like what you'd get if someone had drilled a large hole then filled it with Devcon Aluminum Putty that later failed its bond to the casting. Are you sure it is a piece of the actual casting? Have a picture of the whole piece?

Share this post


Link to post
Share on other sites

Currently I do not have a picture of the entire piece. However your speculation could be correct in that the hole was previously drilled out and plugged. Currently the piece with stud still in it has been tapped back into the hole and it doesn't just slip out (tight).

Garry

Share this post


Link to post
Share on other sites

I assumed it was Devcon, JB Weld, or an aluminum plug that was pressed into the oversized hole in the casting. A casting would never fail like that, it would crack down the side or only the threads would pull out, and you'd not be able to push it back in with a few hammer taps.

Share this post


Link to post
Share on other sites

Guys,

Thanks for your advice and analogy, it all makes sense. Most likely what I have is a larger hole that has previously been filled with Devcon aluminum putty, then tapped and now has pulled loose.

Short of tearing everything back apart, for the short term I'll try to clean everything really well and go back with some Devcon, retap and insert the stud. If this fails again or next time I have the head off, I'll get this issue welded up properly.

I appreciate all the helpful tips and suggestions.

Garry

Share this post


Link to post
Share on other sites

make sure the valve cover itself is nice and flat. Lay it on a sheet of glass to see if it's warped--if a PO tightened those valve cover nuts down tight enough to strip the stud threads, he may have warped the cover.

If it's warped, you can either flatten it back with emery cloth taped to a sheet of glass, or have a machine shop mill the minimum amount off to get it flat again.

Then reinstall, and torque the nuts down to the proper amount--in order.

cheers

mike

Share this post


Link to post
Share on other sites

I took the valve cover to a machine shop, they checked the surface for warpage and found it to be relatively straight.

I used a Locktite metal epoxy with a higher operating temp than the JB Weld previously used. Filled the hole with it, drilled and tapped. It didn't hold, too brittle. The stud worked loose just driving the car around the block and back to the house.

I'm going to try and locate the Devcon Aluminum Putty to either fill the hole and tap, or "glue" the piece that came out back in. Welding is currently out of the question since the head is still on the engine in the car.

Garry

Share this post


Link to post
Share on other sites

Maybe you could thread the plug and the hole in the head and then screw all together with red loc tite.

Share this post


Link to post
Share on other sites

Thanks for the suggestion Marty. Actually the hole is about 10mm round and the stud is a M6. I've got some aluminum putty on the way to try over the weekend. I'm keeping my fingers crossed that this will work. If not, I'll have to re-clean the hole and JB weld the piece back again.

Garry

Share this post


Link to post
Share on other sites

I was thinking of threading the outside of 10 mm plug that was driven into the head and then threaded for the 6mm stud and the 10mm hole in the head

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this