: Exhaust leak '78 Deville 425



pompste
08-17-10, 10:51 PM
I hear a hissing sound where the main exhaust pipe attaches to the engine on my 425.
Could it be a bad gasket?
Thanks for any info.

YourMainParadox
08-18-10, 12:04 AM
broken bolts on the manifold seem to be the most common issue on the 425 472 and 500s. A hiss sounds more like something else thought. Exhaust would be loud popping ticking type sounds and very hot air coming our if you put your hand close.

sven914
08-18-10, 12:12 AM
Check the vacuum hoses around that area; one of them probably broke or split.

pompste
08-18-10, 01:10 AM
broken bolts on the manifold seem to be the most common issue on the 425 472 and 500s. A hiss sounds more like something else thought. Exhaust would be loud popping ticking type sounds and very hot air coming our if you put your hand close.

Now that i think of it,it does sound like popping,ticking sounds with a slight hiss.

pompste
08-18-10, 01:21 AM
If the bolts are broken-----is it pricey to get new bolts installed?

YourMainParadox
08-18-10, 08:32 AM
I am not sure. I still have to fix that on mine :( I need to find out what size bolts they are first before I try and get them out.... The best ways I have heard of trying to get them out is an air impact and lots of PB blaster over a couple days before hand.