Repairing Cracked BB Valve Cover

[Mark E.]

A PO (honestly, it was not me) installed an improperly clocked alternator on my '70 454 which caused its ground bolt to dig into the front corner of the valve cover. This caused a dent and small hairline crack ~1/2" long in the VC.

I removed the dent, and cosmetically the VC looks almost perfect (plus the damaged spot is hidden behind the alternator when installed). But the crack remains which weeps oil. I've lived with it this way for years, but it's time to fix it.

How can this be repaired? The VCs are original so I'd like to keep them.

[Terry M.]

Re: Repairing Cracked BB Valve Cover

A PO (honestly, it was not me) installed an improperly clocked alternator on my '70 454 which caused its ground bolt to dig into the front corner of the valve cover. This caused a dent and small hairline crack ~1/2" long in the VC.

I removed the dent, and cosmetically the VC looks almost perfect (plus the damaged spot is hidden behind the alternator when installed). But the crack remains which weeps oil. I've lived with it this way for years, but it's time to fix it.

How can this be repaired? The VCs are original so I'd like to keep them.

Mark
Two thoughts come to mind, depending on the state of the current finish on the rocker covers.

If you wish to preserve the current finish: Clean them very well and use JB Weld on the inside to cover the crack.

If the current finish doesn't matter: Weld the crack closed from the inside and refinish the exterior as one would do any sheet metal part. Then refinish the exterior as you wish.

[Mark E.]

Re: Repairing Cracked BB Valve Cover

Thanks Terry. The original flash chrome finish is in good shape, and would be hard to duplicate.

What's the risk of JB Weld coming loose and circulating around the engine? If sealing the crack from inside is safe, is JB Weld the best product?

[Terry M.]

Re: Repairing Cracked BB Valve Cover

Thanks Terry. The original flash chrome finish is in good shape, and would be hard to duplicate.

What's the risk of JB Weld coming loose and circulating around the engine? If sealing the crack from inside is safe, is JB Weld the best product?

I have no personal experience with JB Weld, but it is well regarded by others here and on other automotive boards. I am sure, like any other product that depends on bonding with a surface, cleanliness is extremely important. Even if it were to come lose, I would not expect it to go far given the position it is in. See what others have to say about it.

[Gene M.]

Re: Repairing Cracked BB Valve Cover

I would go with Terry's permeant solution and tig weld it on the inside. After all the alternator covers it up. The weld is as permeant as one is going to get. Buff out the chrome as good as one can and call it done. I would put function over pretty.

[Mark E.]

Re: Repairing Cracked BB Valve Cover

Why TIG? Is that method of welding the least harmful to the surrounding area/finish?

[Bob R.]

Re: Repairing Cracked BB Valve Cover

I had a pin hole from corrosion in the tin valve cover of my 63 300 hp cleaned the area well and and coated the inside of the cover with clear epoxy cement. It held up for several years with no leaks, eventually I replaced with another cover.

[Joe L.]

Re: Repairing Cracked BB Valve Cover

A PO (honestly, it was not me) installed an improperly clocked alternator on my '70 454 which caused its ground bolt to dig into the front corner of the valve cover. This caused a dent and small hairline crack ~1/2" long in the VC.

I removed the dent, and cosmetically the VC looks almost perfect (plus the damaged spot is hidden behind the alternator when installed). But the crack remains which weeps oil. I've lived with it this way for years, but it's time to fix it.

How can this be repaired? The VCs are original so I'd like to keep them.

Mark-----


I agree with Terry's first suggestion. This is a PERFECT situation for the use of JB Weld. First, make sure that you roughen the surface on the inside of the cover where the JB Weld is to be applied. I'd use very coarse grit emory cloth for this. Next, clean the surface thoroughly of all grease and grit. Use Brakeclean for this purpose. Then, apply the JB Weld to the crack and the area surrounding it. Use regular cure-time JB Weld, not the fast curing variety.

You'll have a repair that will last a lot longer than you will.

As an alternative, you could use a brazed repair. This does not require as much heat as a weld and will serve the same purpose. However, if it were me, I'd use the JB Weld.

[Gene M.]

Re: Repairing Cracked BB Valve Cover

Why TIG? Is that method of welding the least harmful to the surrounding area/finish?

Mark
One could do it with MIG but the TIG is more precise for delicate work.

[Douglas L.]

Re: Repairing Cracked BB Valve Cover

TIG for sure if you do go the weld route and wish to maintain the finish. Its going to discolor it regardless but TIG would minimize the discoloration. But I agree with the JB weld solution, thats what I'd do.

[Joe L.]

Re: Repairing Cracked BB Valve Cover

Thanks Terry. The original flash chrome finish is in good shape, and would be hard to duplicate.

What's the risk of JB Weld coming loose and circulating around the engine? If sealing the crack from inside is safe, is JB Weld the best product?

Mark-------

If you do any welding, it's going to negatively affect the flash chrome on the other side of the weld and there may even be some distortion of the cover. I would not risk it. The JB Weld will do fine. Actually, JB Weld is very strong and impervious to engine oil but, in this case, it doesn't even need to be strong.

[Jim D.]

Re: Repairing Cracked BB Valve Cover

Mark-------

If you do any welding, it's going to negatively affect the flash chrome on the other side of the weld and there may even be some distortion of the cover. I would not risk it. The JB Weld will do fine. Actually, JB Weld is very strong and impervious to engine oil but, in this case, it doesn't even need to be strong.

I agree 100%. JB Weld is the way to go. Just use the original formula. I've heard the Quikweld formula isn't as good. Make sure everything is clean (use acetone or lacquer thinner) and roughen up the surface. There will be zero chance that it will come off without a hammer and chisel.

[Terry M.]

Re: Repairing Cracked BB Valve Cover

Why TIG? Is that method of welding the least harmful to the surrounding area/finish?

Gene and Douglas are right about TIG. One can control the heat far better with TIG, but it does require a higher degree of skill than MIG welding and more expensive equipment.

One thing about the JB Weld -- if it fails in a year or five you can always go for welding. I doubt it will come lose before it starts leaking. If it leaks after JB, get the cover welded.

[Mark E.]

Re: Repairing Cracked BB Valve Cover

Thanks for the advice guys; I appreciate it.

From your input, I feel more confident about trying JB Weld without causing more problems. Welding/brazing is plan B.

I'll let you know how it goes.

[Jerry K.]

Re: Repairing Cracked BB Valve Cover

Silver solder worked on my 62 with small pin holes. Have a hobby shop soldering iron. Filed, sanded, primed and painted in no time.