There seems to be a lot of people replacing head gaskets these days. I replaced all of my gaskets last weekand now I've got a major vacuum leak at the front of the lower intake. The directions for sealing it were a little sketchy. As best as I can remember this is what I did: I puta dab ofsealant (permatex 'the right-stuff') at the 4 corners of the intake in the small notch where the head meets the block, then put the rubber seals on the ends of the block pushing the seal ends into the notch, then the intakegasket, then the seal clamps, then tightened the intake manifoldon, then tightened the seal clamps. Clearly I did something wrong, I'm guessing I missed some more sealant somewhere???Any ideas?

 

When I did my head gasket last weekend, I clamped the seal clamps before I installed the lower intake. That way it pulled the gasket tight, and lined up the holes with the ports. I only permatexed around the 4 coolant passages, and the rubber seals. I wonder if there might be a leak somewhere else, like a vacuum line or pcv hose or something. Was this suspected from a rough idle? I know how it feels, its like "how many times will I have to redo this?" I remember my first motor swap in a K5 blazer about 10 years ago, I got a new crate 350 installed just about all the way, just to find out that my blazer isnt going to go anywhere with the torque converter still sitting in the back of the blazer.....lol Man was I fuming!

 

Oh man, that's some funny stuff - thanks for the laugh,I really don't feel like pulling this apart again. I am getting codes P0171/174/734/1172/1175 and I can hear a serious leak at the front of the intake seal, so I don't think thatthere is much else down there. The truck runs fine though. I have a feeling that I should have put more sealant on top of the rubber gasket, something seemed goofy at those notches between the heads and blockbut I was in a hurry and just following the directions.

 

I put a blob of RTV in those notches, just like a good ole chevy 350. It seemed to seal mine up good. I can only guess, but it may be pulling PCV vacuum through the crankcase, via the leak your finding in the intake rubber seal. It could be that your disco isbegging you to swap its motor out for a LS1. LOL Anyways, Im not sure if you have the GEMS engine or the Bosch engine, but If it were me Id take the lower intake loose and just move it up enough to look under it and see whats going on. Of course that involves a coolant drain. I know its frustrating.

 

Clamp bolts then intake bolts. However, it is possible that part of the intake gasket could have gotten folded, but that should result in misfires and misfire codes set accordingly. Check to make sure the intake duct is properly secured and sealed. Also make sure that your evap purge valve is connected(electrical connector and pipe to the intake) These to scenarios will probably not set a misfire fault as all cylinders will be firing just about the same causing no variation in the crankshaft rotational speed.

 

Well, I pulled the intake off tonight. One end on the front rubber sealhad gottenpushed out when I tightened the intake bolts leaving a nice gap inthe notch at the head. I guess that is why you tighten the clamp bolt first and then the intake bolts. I swear my directions told me otherwise. So sealant in the head/block notch, then the rubber gasket, maybe some more sealant on top of the rubbergasket, place themanifold gasket, then theend clamps, tighten the clamps and then the intake itself?

 

Pretty much, I siliconed the bottom of rubber gaskets lightly, then set the rubber gaskets in place, then a light layer of silicone over the top of the gasket, and then a nice blob in the notches, then silicone the coolant passages. then place the intake gasket in place, seal the tops of the intake gaskets at the coolant passages only. then put on clamps and tighten them down. Then set on intake and install.