Exhaust manifold still leaks! Hedder question

[duckdogwhiskey]

Hey guys. So here is the deal. After my truck went back to my mechanic this weekend, he has said he thought the tapping leak was coming from the egr valve on the truck rather than at the exhaust manifold because after he put in new manifold gaskets, the sound remained. You only hear it when accelerating. He put a weld around where he thought the leak was coming from on the egr tube, but still the sound. He cranked it up for me and put his hand over the exhaust pipe and back pressure immediately started hissing from my manifold. He now thinks that either the manifold has a crack or cracks that he could not see, or it is possibly warped from heating and cooling so many times with a sheared bolt. If this is the case, a new manifold costs about $99 and I could get hedders for about $199 and be done with it, which is what he is recommending. A buddy has some hedders that would not work on his 96 that were given to him, which he is offering to give to me. He has a 302 and I have a 351- 5.8, so I am hoping that since they don't fit his, they may fit mine. Does his assertion about a warped manifold make sense? I would have thought that the gasket set would have sealed it. He said he put quite a bit of torque on the manifold bolts, and someone else has suggested he may have either put too much or didn't follow the tightening pattern, which could cause it to continue leaking. Just don't want to keep shooting in the dark and wasting money. Your thoughts?

 

[Krafty]

I would have to say to try to get some serial numbers and brand off your buddy's headers and try to track down what they will actually fit on, then if thats a no go then drop the money on the headers if you still want to go that route.

 

[Bully Bob]

Hi Duck...,

What he said., but I'll add, I took out a pass. side exh. man. on a V/8 that was in three pieces..it was still work'n but hissed & ticked as well. It was nobody's fault...just old age., maybe a bad pour..who knows.

However., I went to the bone yard & picked up a used one for a couple $$ & it worked fine.

All you need is a straight edge...& for more comfort you can get a bottle of dye to check for cracks.

All my smog junk hooked right up & good to go.

Headers are fine... but you may need exh. tube extensions or other Exh. mods.

 

[Seabronc]

What they said /emoticons/[email protected] 2x" width="20" height="20" /> . You're telling me that your mechanic didn't know how much torque to use and what pattern to use in tightening it up? (Using anti-seize on the threads 15-22 ft lbs. Always work from the center out, snug first pass and then torque to spec on second pass, make one final pass to check, check again in about a week). It's not unusual to have a cracked exhaust manifold, just happens some times. Warp would not be high on the list suspect but like Bully Bob said, a long level or strait edge would answer that question.

If you want to make sure where the leak is, use a short piece of rubber hose as a stethoscope and move the end around till find it.

Good luck,

>-

 

[duckdogwhiskey]

Thanks guys! Bully Bob, Where would you put said dye? It should be easy enough to pull it back off now that he sheared and retapped 3 of the bolts over the weekend. They should come right off now. /emoticons/[email protected] 2x" width="20" height="20" /> Seabronc, the "mechanic" is just an ole shade tree guy that can usually make it work but doesn't seem to know the details on much, he just dives in. I'm not even sure he can read so a Hanes manual wouldn't help. Did I mention he is extremely cheap? Seriously, I knew that those bolts would shear and I figured it was worth paying him to go through the **** rather than spend my whole weekend cussing out back. I will try the stethoscope thing this weekend and see what I find before deciding how to proceed. I had him weld a flowmaster super 44 on while he was doing the work and it sounds good until you give it gas. Now that tick is REALLY bugging the **** out of me.

 

[Bully Bob]

"Bully Bob, Where would you put said dye?"

The name/proceedure escapes me at the moment....as I recall it's a red dye that you brush on any suspecious areas...a crack will then appear if, in fact one exists.

Don't want to scare ya but this prob. should have been done around the head exh. exit ports...just to be sure.

Magna-flux....?? I think that's what it's called....

"he sheared and retapped 3 of the bolts"

Hmmm, does this mean he cleaned out the existing threads...? OR did he actually "drill/oversize" & tap in "new" threads...?

HTH

B

 

[duckdogwhiskey]

He drilled them out and put in helicoils.