Wierd vacuum leak issue

Posted By: moparmedic

Wierd vacuum leak issue - 06/05/13 06:40 AM

I have been dealing with a vacuum leak on a fresh 383. Thought the intake wasn't sealing properly and while looking for the leak with a can of carb cleaner found the leak was right around the exhaust crossover. When I spray carb cleaner directly in the opening in the head around the crossover, it will stall the engine. I will pull the head and check it later this week. Do the iron heads develop cracks in the heat riser/crossover area?
Seems like that may be whats going on...

Posted By: RapidRobert

Re: Wierd vacuum leak issue - 06/05/13 02:33 PM

that is a very high heat(ed) area. That's why that horse shoe cavity needs to be kept uncovered & sometime even that ain't enough. Holler what you find.

Posted By: screamindriver

Re: Wierd vacuum leak issue - 06/06/13 04:07 AM

Another common problem is the cross-over area of the intake warping enough to not seal using just the tin valley pan...Lay a straight edge across the sealing surface of the intake to rule that out...

Posted By: moparmedic

Re: Wierd vacuum leak issue - 06/11/13 04:14 AM

Took the head off it is at the machine shop. Didn't find anything obvious. They are going to pressure test it and see if they find anything.

Posted By: RapidRobert

Re: Wierd vacuum leak issue - 06/11/13 04:23 AM

Quote:

while looking for the leak with a can of carb cleaner found the leak was right around the exhaust crossover. When I spray carb cleaner directly in the opening in the head around the crossover, it will stall the engine.

What Screamin said, I'd be looking hard at the valley pan metal gasket, how it's sealing & possibly the intake itself (warped) but way less likely.

Posted By: moparmedic

Re: Wierd vacuum leak issue - 06/14/13 04:55 AM

Quote:

Quote:

while looking for the leak with a can of carb cleaner found the leak was right around the exhaust crossover. When I spray carb cleaner directly in the opening in the head around the crossover, it will stall the engine.

What Screamin said, I'd be looking hard at the valley pan metal gasket, how it's sealing & possibly the intake itself (warped) but way less likely.

Yeah, I did all of that. Everything looked good with a straight edge. I also reasealed the intake 3 times and used a different intake on the 3rd time. Also used the Fel Pro side gaskets and a new valley pan. I was down to getting the head checked and then I am out of ideas. Should know more by Monday.