welding exhaust manifolds.

[OldSkool]

I have cracks on the outside of each exhaust manifold on my 5.0. They run from the petcock holes up about 1.5 inches. There is no water intrusion into the engine so I think they are freeze related from 2 years ago. Year before last they were very small leaks however during the last couple times out this season they really opened up.

Question is can these cracks be welded or are the manifold done for? There is a new cast iron welding rod that does not shrink after welding eliminating the need to post heat the repair. Has anyone had experience with this?

I would get picture however the cover is on and ain’t coming off for a little while.

 

[fwebster]

Yes, they can be repaired. However, the trick is getting the entire manifold hot enough so that the heat from welding doesn't do more damage that you already have. I've seen cast iron manifolds crack and break like glass when they were not pre-heated. Also, you will never get them hot enough while they are attached to the engine, so plan to take everything off the boat and all the plugs out before starting to apply heat. Heat the cast iron uniformly over the entire piece and get when the cracked area is hot enough to change colors, it should be safe to use a cast iron electrode to weld up the crack.

Be sure to grind the crack into a "V" at least half the depth of the casting where the crack is before you try welding.

Lots of work for questionable results and savings...........it might be easier to replace the manifolds and elbows/risers now.

 

[BonBini]

Hey OldSchooler: Back in the day when I had to do sht jobs like welding up junk... nickle rod worked pretty good. The cast needs to be preheated and then its just welding the rod in. Now you've got an alloy. Weve sent out a few bull gear housings from some old d6's. The guys just heated in brass and that seemed to mix in well with the cast too.... When welding any crack, one needs to stop the crack before heating, drilling a hole always seem to work good.

I'm thinking if it were me... I'de just get a set of new ones. I'm also thinking new ones may have been on your x-mass list?

no spell checking for me tonight... I've started my safe drinking

 

[OldSkool]

I hear you on the questionable results. I have weld cast before with varied results. I'll remove them and try it with the idea that nothing venture nothing gained. I will start looking for them on e-bay again. Found a set last year for 500 bucks but I'm leary of buying used.
They are 300 a side plus shipping new without the risers.

 

[BonBini]

And one more thing. It"ll (new word) most likely be warped afterwards.

 

[chrissrv195]

Hey Bill, I think I agree with the guys on this one too. I think I would also look for some good used manifolds or find a good deal on new ones. You could take them to a good welding shop & see what they could do with them....but I bet it would cost the price of 1 new manifold to have them fixed & the welds may not hold in the end.

You've got all winter to snoop around for good used or new manifolds. I'd use this time to really do some research & find the best prices!

HAPPY NEW YEAR BILL !!!!!!!!

 

[FireIsland1]

I would bet big money you can't weld them to stop the leaks. it's not your ability,it's the base metal. it's crap cast iron that varies in thickness and is rusted very bad inside. yes fwebster idea is the prefered method of welding cast, but the odds are against you. in our shop we do major cast repairs on high end pump housings $5k+ . We never weld. instead we stitch them with studs. no distortion , no damage, and no failure. You drill, tap and insert studs along the crack, overlaping each one, grind flush and your done.

 

[66pony]

Old Skool, One trick I have found is to use a gas grill to heat the entire casting before welding and then using it to temper the weld. Good cheap oven. Should keep you from having the warping and shattering if you tried to weld a cold piece of cast. Also tempering will most likely assure a good take on the weld.

 

[OldSkool]

Thanks all for the information and responses. I have done cast stitching and welding (wouldn't call myself an expert in it) however the cast is pretty thin and for this same reason I may just blow holes in the thing trying to weld it and end up with junk anyhow. If I have them welded the price will be about the same as buying used with no guarantee of longevity. Haven't used the gas grill to warm cast up but it seems like it would work, on small pieces especially on post cool down. Warping is another concern that you mention it.

One thing I just thought about was internal cracking that may allow water into the head. Better to not chance this repair.

Again, thanks to all of you.

 

[390x]

+1 on what FireIsland said. Pin 'em. This is done on engine blocks all the time as they tend to get hairline cracks around the block drains for some reason.