Compression Problems 426 Hemi

Discussion about the Hemi in general.

Moderator: scottm

allen
Posts: 21
Joined: Mon Feb 18, 2008 6:27 pm

Compression Problems 426 Hemi

Postby allen » Tue Sep 21, 2010 8:10 pm

Just checked the compression on my 426 Hemi. Drivers side each cylinder is about 150.
The passenger side each cylinder is 115. Big difference especially since the engine has just been
done and has less than 100 miles on it. Any suggestions on what might be the problem or cause.

mart
Posts: 536
Joined: Tue Mar 22, 2005 2:06 pm

Re: Compression Problems 426 Hemi

Postby mart » Wed Sep 22, 2010 5:26 am

allen wrote:Just checked the compression on my 426 Hemi. Drivers side each cylinder is about 150. The passenger side each cylinder is 115. Big difference especially since the engine has just been done and has less than 100 miles on it. Any suggestions on what
might be the problem or cause.

----------------
If the problem is in all the cylinders just on one side, it sounds like it's *probably* a valve problem on that side. It could be (best case scenario) that that the valves are just improperly adjusted causing them not seat...or (worst case scenario) that you've burned or bent a bunch of valves. As a start, try doing a "dry" and then a "wet" compression test on the bad cylinders and then compare the results to tell whether the problem is valves or rings. A "dry compression check is just a normal compression test ,done by cranking the engine over with the compression gauge screwed into the spark plug hole. A "wet" test is the same, but involves squirting some motor oil into the cylinder first. If the problem is rings, the oil will temporarily cause the rings to seal, giving a near normal, or at least, substantially higher compression reading. If you have a burned, bent, stuck, improperly adjusted, or otherwise leaking valve, the oil won't cause a higher reading.

mart
=====================================

NE57
Posts: 192
Joined: Fri Mar 27, 2009 12:54 pm

Re: Compression Problems 426 Hemi

Postby NE57 » Wed Sep 22, 2010 9:54 am

Could the passenger side head gasket have been installed incorrectly or accidentally damaged? Since its all the cylinders on only one side, I'd look at the one thing that all low cyls have in common. If your compression tests show rings are good and valves are good, what's the one thing left?

NE57
Posts: 192
Joined: Fri Mar 27, 2009 12:54 pm

Re: Compression Problems 426 Hemi

Postby NE57 » Wed Sep 22, 2010 9:55 am

yeah well a vaccum test too.

Goran
Posts: 25
Joined: Thu Jan 17, 2008 2:01 am
Contact:

Re: Compression Problems 426 Hemi

Postby Goran » Wed Sep 22, 2010 11:53 am

A shot in the dark, how about different thickness head gaskete?
Goran
I am a 69 years old sportscar freak living in Sweden with a Hemi equipped Pantera.

allen
Posts: 21
Joined: Mon Feb 18, 2008 6:27 pm

Re: Compression Problems 426 Hemi

Postby allen » Wed Sep 22, 2010 7:50 pm

I will try placing a liitle oil into each cylinder to see if it is a valve seating problem . The head gaskets are the same and I hope installed properly. I will also try to see what kind of vacuum Will post back by the weekend and let you know


Return to “General Hemi Discussion”

Who is online

Users browsing this forum: No registered users and 2 guests