Exhaust: I6 manfold leak - second time around...(update with pics)

[62champ]

All this is on a 52K mile 60S-W4.

Finally got some time in August to put on the SS exhaust system I had picked up at York. In taking one of the nuts off the header pipe, snapped the bolt off in the manifold. With a local club member/good friends help, we were able to get he old bolt out and new studs in without problems.

Two weeks ago, I put everything together and started it up expecting to hear a nice mellow tone out the tailpipe - only to be disappointed by exhaust leaks from the manifold at the bottom of both central exhaust ports where they meet the block. I knew the mounting surface had looked kind of iffy, so off it came again to go to a machine shop for some "truing" up. They called yesterday to say it was finished.

Zipped everything up again this afternoon, double checked to see if anything was out of place - and almost threw a wrench through the wall of the garage when it was again leaking at the block/manifold - only this time it is leaking at both end exhaust ports.



I ordered a NOS gasket (one that is flat metal all the way across with a white material between that and a raised metal are). The orientation of the gasket was the same as the one that came off: Long flat side against the block with smaller raised area toward the manifold. Guy at the machine shop asked what kind of sealer I was going to use - then told about something some of the engine builders use that is good to 2500 degrees - but I thought those gasket always went on dry so I did not worry about it...

Just keep torquing it down might sound like the right thing to do, but the nut holding it on are brass - so there is a point of no return on that route.

So - for those who have fooled around with these motors, any ideas? When my wife was told what was wrong, she pointed to a 289 sitting in the garage and stated - "why don't you just put that thing in there..."

Thanks ahead.

[r1lark]

I had a similar issue with a Champion 6, but it was my fault. Pulled the intake to adjust the valves (carb was coming off anyway, so I figured what the heck.......). Got it all back together and I had an exhaust leak at a couple of places. When I pulled it back apart, found that the gasket had not been properly centered vertically on the ports. The stud holes in the gasket (at least the ones I used) had a lot of slop. Couldn't really see that with the manifolds on the studs. IIRC, the gasket was too high, and left just a small amount of gasket material to seal on the bottom. So, another new gasket, but this time I put just the gasket on the studs and made some match marks so it could be positioned corrrectly once the intake/exhaust was put on the studs. Worked for me........

Don't know if this is related to your issue, but wante to throw it out there.

[Alan]

Why don't you listen to the Ol' Lady for once?

[DEEPNHOCK]

While the intake/exhaust manifold is off....
Lay a straightedge along the intake manifold runner surface and check for uneven surfaces.
It should be flat (and mot high/low/high/low...)
That will cause problems (usually an intake vacuum leak).
I use Permatex 'Ultra Copper' on all my intake and exhaust gasket surfaces.
http://tinyurl.com/Permatex-Ultra-Copper
Someone will probably have a better suggestion, too....
Jeff

[62champ]

Why don't you listen to the Ol' Lady for once?

If she wants to pay for the rebuild, I would not want to put it in without an R1 cam and some other goodies...

[62champ]

I had a similar issue with a Champion 6, but it was my fault. Pulled the intake to adjust the valves (carb was coming off anyway, so I figured what the heck.......). Got it all back together and I had an exhaust leak at a couple of places. When I pulled it back apart, found that the gasket had not been properly centered vertically on the ports. The stud holes in the gasket (at least the ones I used) had a lot of slop. Couldn't really see that with the manifolds on the studs. IIRC, the gasket was too high, and left just a small amount of gasket material to seal on the bottom. So, another new gasket, but this time I put just the gasket on the studs and made some match marks so it could be positioned corrrectly once the intake/exhaust was put on the studs. Worked for me........

I think I have the opposite problem - the gasket fits pretty snugly on the studs, but the manifold has a eighth inch of play up and down. I actually loosened it up again and tried to center the manifold on the outside of the gasket with no changes in exhaust leaking.

[Skybolt]

I also found that one has to be careful of the bracket that hold the exhaust to the bell housing. I had similar problems and one of them was the when I tightened the clam to the bracket it wanted to pull the manifold away from the block, outwards, so I had to do some hole elongation. The other was what you found, the manifold has to be positioned correctly on the gasket. Took a few gaskets to find that out. Len.

[62champ]

This is the surface I am dealing with:



and the block looks just as good.

I found the supreme copper ATV and am going to give it a go. The gasket is from Victor and it is not necessarily "port matched" with the manifold. When I lined it up perfectly with one of the end ports, this is how it lined up with the other side:



I lined up everything as best I could and basically shot for the middle... Gasket sealer has to cure for 24 hrs - so home from work Monday will be the next test...

[DEEPNHOCK]

Did you lay a straightedge along the length to see if they are all at the same height?

[62champ]

Closest thing to a straight edge that I own is an old level - checked out fine - but that level should probably be checked as well...

[nvonada]

It took two tries to get mine to seal up. I used a Best gasket and copper coat the second time. It seems to be working just fine.

http://stude.vonadatech.com/wp/manifold-gasket-replacement/

[gordr]

Check the gasket, and see if it fits the port spacing on the block. If it fits the ports in the block perfectly, glue it to the block using 3M yellow trim cement, and coat the manifold with the gasket sealer of your choice, and bolt on the manifold, while trying to get it as well centered as possible.

If the gasket does not fit the block any better than it fits the manifold, maybe you should cut it into sections, and align each section independently, using cement as described above.

You might want to take a strip of paper or light cardboard, punch holes in it to exactly fit the studs in the block (no slop), and trace the outline of each port. Then transfer that pattern to the manifold and see that there is no point where the ports are misaligned enough to cause a leak. If the ports are badly misaligned, you may want to try another manifold.

[gordr]

Check the gasket, and see if it fits the port spacing on the block. If it fits the ports in the block perfectly, glue it to the block using 3M yellow trim cement, and coat the manifold with the gasket sealer of your choice, and bolt on the manifold, while trying to get it as well centered as possible.

If the gasket does not fit the block any better than it fits the manifold, maybe you should cut it into sections, and align each section independently, using cement as described above.

You might want to take a strip of paper or light cardboard, punch holes in it to exactly fit the studs in the block (no slop), and trace the outline of each port. Then transfer that pattern to the manifold and see that there is no point where the ports are misaligned enough to cause a leak. If the ports are badly misaligned, you may want to try another manifold.

[62champ]

Thanks Gordr - that might be the next go around...

Got everything back together late yesterday afternoon for it all to sit until after work today. Got home, made sure everything was tight and cranked it up. Definitely not the popping leaking sound as before, but could feel a little air coming out of the number one exhaust port....

I am going to let it ride and drive it until it gets too obnoxious. Might then try to find a composite gasket that others have talked about in some other treads. OH well, now have to see into the slight leak where the pipe goes into the muffler... Never have been sure how people can keep five or ten cars/trucks going without constantly working on something - or maybe they always are.

Thanks for all the suggestions and advice.

[Tom Bredehoft]

constantly working on something

That's why we do it. It beats watching the tube.