Thunder32

here's the situation-
the port motor (500EFI) has an excessive vacuum pressure. I can remove the air breather tube, and it is sucking air in at an alarming rate. With the air breather tubes installed, it pulls so hard that it actually "whistles".
The oil pressure, oil temperature, water temps are all fine.
The starboard motor does not do this at all.
so....
is it a bad PVC valve??
leak in intake manifold??

please help

Adam

articfriends

iTrader: (1)

i would be confident that you have a intake leak,it should also be pulling some oil into the intake ports and burning it out exhaust. You cant get a vacuum like that into crankcase anyother way. When you pull intake manifold,look at your gasket imprint,you should have one side that is either wet with oil or has poor port alignment or a imprint that isn't good,could even have a piece missing. We see this quite often on the 96-99 gm vortecs in the chevy 1/2 ton trucks. It is remotely possible you could have a loose intake bolt or bolts,you may want to try snugging them down before you ripp it all apart,Smitty

Thunder32

Thanks Smitty- I'll try that first. The PVC valve was ok.
Oh, by the way, it's a 2003 500EFI motor w/ 72 hours on it.

Any input is greatly appreciated.

Adam

dukenrock

I just posted a forum for the same thing and then I noticed you hasve a similar problem. I have a 2001 382 fastech with 500 EFI's and my starboard motor has an extermely loud vacuum his. Could you let me know what you found out on yours? Thanks!

MESABALANCING

I WOULD THINK IF THE INTAKE WAS LOOSE THE VACUM WOULD BE LOWER AND NOT THAT STRONG OF A SIGNAL I WOULD BE CURIOUS AS TO WHAT YOU FIND.DOES THAT ENGINE IDLE ANY DIFFERENT THAN THE OTHER AND IS THERE A CHANCE THAT YOU MAY HAVE SOMETHING OBSTRUCTING THE TUBE THAT WOULD MAKE THE HOLE SMALLER AND CREATE A STRONGER SIGNAL. KEEP ME ADVISED AS TO WHAT YOU FIND THANKS LAZ MESA WWW.MESABALANCING.COM

Thunder32

I do not have a scan tool but after much debate from "merc" mechanics, I going to replace the IAC motor assembly, and start there. I actually get better information on this site than my local mechanic. Thanks everyone.
I'll keep you posted..

Adam

Thunder32

and Mesa, both engines idle the same, no loss of power, no obstructions, and all temps, and pressure within normal....just that excessive vacuum

dukenrock

Let me know if the IAC fixes it...I believe that's where my problem is...Thanks

Thunder32

ok, problem fixed. Had a friend that is a merc mechanic look at it Friday, and it was the intake manifold gasket. Installed new Fel Pro gasket, and problem solved. The IAC motor was not the problem. Three hours to fix and 20 beers afterwards.

Adam

robyw1

If it don't start I bet I know why