Re: IML:440 exhaust manifold question...

["Andrew A." <canafornia@xxxxxxxxxxxx>]

that was my second guess...and I tried to pinpoint from exactly where the sound is coming from with my stethoscope, but I can't for sure..It definetely is coming from the center of the manifold area in towards the engine block but although I hear some sound and leakage when I try to get the scope end near the block/manifold joint, but it doesn't seem to be of the magnitude that would cause such a large noise. So my suspicion is that it could be a crack on the inside of the manifold and what I hear in the stethoscope is just an echo or a "bounce" near the manifold engine joint...hard to say and impossible to see due to the awkward way the manifold arches upwards making a visual inspection next to impossible...I'm going to try with a little mirror and an LED light maybe to see if I can get a glimmer of any crack...the other thing is that I don't really see any exhaust residue anywhere near the manifold/engine joint, and with a leak this bad, you would definetely expect some if it where coming from a blown manifold gasket....

----- Original Message -----

From: sosmi@xxxxxxxxxxx

To: mailing-list@xxxxxxxxxxxxxxxx

Sent: Tuesday, January 09, 2007 6:48 PM

Subject: Re: IML:440 exhaust manifold question...

Andrew, the exhaust leak, could be a gasket failure between the manifold and cylinder head.If the manifold was removed for freeze plug, or valve job reasons, most people install a gasket at that time. The factory assembly uses no gasket, as the new machined surfaces are so true, they seal fine.The other factor is, the metal to metal contact transfers heat from the manifold to the head better.Installing the gasket, can result in poor heat transfer, and the chance for manifold distortion from improper torquing of the bolts.Add to that, sudden thermal shock (drive through a puddle)And you end up with a cracked manifold.I don't think the manifold is necessarily at fault, but rather how its abused.Ya'll have a nice day, Dave.

 

-------------- Original message --------------
From: "Andrew A." <canafornia@xxxxxxxxxxxx>

Another problem my 75 Imperial has is that there is a severe exhaust leak from the drivers side. I thought it was the "doughnut" gasket but feeling around the joint with my hand while the engine is running from underneath I feel no air escaping so I don't think it's that...someone told me that these manifolds have a tendency to crack and that almost certainly that will be my problem once I take it off and see.......Is this true, that these manifolds like to crack on the inside?...If so I would like to get one ahead of time so as not to be waiting for it in the spring when I redo the exhaust to dual and deal with this leak....I tried to spot a part number on it but I don't really see any exept a very blury unreadable one towards the front of the manifold which looks more like some kind of casting code rather than a part number....Does anyone know what the part number would be for this drivers side manifold and where to get one other than ebay..also from what years and mode ls of cars did they use this same manifold?..thanks for any help in advance!