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| DESPERATE over head-exhaust manifold leak https://slantsix.org/forum/viewtopic.php?t=68137 |
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| Author: | Daddiojoe [ Fri Mar 28, 2025 1:42 pm ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
Gentlemen: Thanks very much for your suggestions. My head has been shaved .10 and there is a boss on the block in my problem area. ALSO, witness marks on both of the exhaust manifolds I have tried. I have photos that I will post later. So I am cautiously optimistic that the problem was that my exhaust manifold was not able to seat properly due to running into that boss. So I have ground that down as well as grinding down the Dutra dual (plenty of room for grinding). I will let you know how things go when I get it re-assambled. Now my question is how did it ever work prior to all of these struggles? Thanks again, Joe |
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| Author: | ceej [ Fri Mar 28, 2025 6:17 pm ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
There are a couple ideas I have on that. 1. A thicker gasket 2. Luck!  I cut a bunch off the deck, so the issue became much more pronounced. Cutting the head can have the same effect. There was a super squishy gasket available a while back that may have handled a misalignment like that pretty well. Remflex? Can't remember, but that sounds close. Some folks double gasket. Not ideal, but in a pinch it'll work. For a while. Glad your making progress! CJ |
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| Author: | Rick Covalt [ Sat Mar 29, 2025 4:52 am ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
Glad you found your problem! Been there,done that! 
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| Author: | Dart270 [ Sun Mar 30, 2025 3:40 am ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
Sounds like you found it. Grind on block and/or head and/or exh manifold (block first) to fix it. Buy or borrow a good angle grinder (4 or 4.5" likely best). Fit up the manifolds first with no gasket and make sure they sit flat against head. Use feeler gauges and a flashlight. Leave bolts between int and exh manifolds loose also so there is room to move each while you get the exh/int nuts tightened. Lou |
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| Author: | Greg Ondayko [ Mon Mar 31, 2025 11:04 am ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
I always grind / cut off all the unnecessary Lumps of extra Cast Iron off the engine as per the "playing with blocks" article from Doc. I have never had one of the lumps cause issues, but It makes things much more simple and a few pounds lighter when they are gone. Greg |
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| Author: | Daddiojoe [ Thu Apr 03, 2025 3:54 pm ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
I ground off most of the boss at the rear of the block on the driver's side, and took some out of the Dutra Dual rear. Still had trouble installing. Might be hitting on the starter. Exhaust leak continues. I don't have money for the newer smaller starter recommended by Dan, so I went back to the cut-off stock manifold. It fits much easier, but still leaking. In the same place. However, I tried to re-use the RemFlex gasket. So as I have time am going to replace the gasket with a new one and take some more off of that boss. The exhaust manifold hitting something still makes the most sense as a cause of the problem. Still struggling. Joe |
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| Author: | Rick Covalt [ Thu Apr 03, 2025 4:47 pm ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
You have to tired of installing and removing by now! Just take a wafer disc or your favorite grinding tool and cut both lugs completely off. They serve no purpose. I would work with just the exhaust manifolds. Take the intake off completely and then make sure my exhaust sits flat against the head without a gasket. Then reinstall with a new gasket. |
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| Author: | Daddiojoe [ Thu May 15, 2025 7:44 am ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
PROBLEM SOLVED! Or at least properly diagnosed. After grinding off excess metal on the original exhaust manifold and on the block--a pretty big boss--I repainted part of the block. During the short time the engine ran, STILL exhibiting what I thought was an exhaust leak, the new red paint on the block showed lots of carbon right under the manifold bolt. So it WASN'T and exhaust leak, but a torn head gasket that the exhaust was escaping from. Confirmed by examination of the number six spark plug and 30 lbs of compression in the number six cylinder. Lucky that coolant never got into the combustion chambers. All of the exhaust problem came after I took the car to a garage for exhaust fab. The gasket somehow got sideways when the mechanic was working on it. So the only driving I did was from the shop to home. I feel like a dumbass. Worked on this for literally months. With this level of diagnostic skills, good thing I am not a physician. Thanks for your help and insight, everyone. |
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| Author: | SlantSixDan [ Thu May 15, 2025 9:51 am ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
Quote:
I feel like a dumbass.
Eh. You're in good company.
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| Author: | MDchanic [ Thu May 15, 2025 10:24 am ] |
| Post subject: | Re: DESPERATE over head-exhaust manifold leak |
Glad to hear, and thank you for posting the conclusion! I've chased a few problems around in circles for far too long before finding the answer was right in front of me, so I know how it feels. Let us know how it runs once you've got that head gasket changed. And remember, while you've got the head off, you may need to machine off a few thousandths to account for a taller modern head gasket, and once you're doing that you Might As Well... Let us know how the porting and polishing, combustion chamber cc-ing, and full rebuild go! - Eric |
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