I have a 96 Express van and I completely rebuild the engine. I originally had the intake sealed up tight but the lifters were defective so I had to pull it apart and reseal it. Then it leaked. I re sealed the intake again and now it leaks in the same area. leaks at the rear of the manifold where I applied RTV. I just got it together again and now it seeps from there. Any ideas on what is going on? it has the vortec style factory intake on it.

If you had it sealed up once before you had to tear it back down again, then you must be rushing yourself this time around getting aggravated and not getting it to seal up properly. JMO Relax clean it good and give it time to set-up before firing it up or so on. JMO



Cole
imp:

 

Very important to clean the mating surfaces with brake cleaner. Any oil and the silicone won't adhere.

 

I wasn't rushing. Whe I re did it the first time I did it myself (sitting in the van and trying to lift it into place and manuvering around components). I may have pushed the rtv out of place then. This time I did it with a friend and I triple checked and cleaned every surface! I was not in a hurry!! Believe me, I just want to get it running and it is just a toy, so no need to blast through repairs. I just don't understand? is applying a bead of rtv to the block and smearing rtv on the manifold ok to do? I think this will be my next method unless instructed otherwise.

 

If you have GOOD access to the offending area ,SOMETIMES you can clean the area and apply some more silicone [press it in ,your trying to fill a void] & it'll work !! CLEAN _CLEAN_CLEAN !!!
dave

 

I have always had good luck by dimpleing the intake and block surface with a center punch. I know its too late now, but if you pull the intake again, clean it good and dimple front and rear!!

 

I have a 96 Express van and I completely rebuild the engine. I originally had the intake sealed up tight but the lifters were defective so I had to pull it apart and reseal it. Then it leaked. I re sealed the intake again and now it leaks in the same area. leaks at the rear of the manifold where I applied RTV. I just got it together again and now it seeps from there. Any ideas on what is going on? it has the vortec style factory intake on it.

Are you using RTV as a gasket replacement on the china wall or is this just trying to get a seal with gaskets where they meet at the corners of the china wall, head, and intake?

By reseal do you mean the manifold came off each time and the sealing process repeated or at some point is the engine left assembled and you're putting RTV on the external joints?

Are you using RTV meant for engines rather than household plumbing?

Bogie

 

Are you using RTV as a gasket replacement on the china wall or is this just trying to get a seal with gaskets where they meet at the corners of the china wall, head, and intake?

By reseal do you mean the manifold came off each time and the sealing process repeated or at some point is the engine left assembled and you're putting RTV on the external joints?

Are you using RTV meant for engines rather than household plumbing?

Bogie

They don't sell the gasket kits with rubber seals for the china wall that I have seen. I am using rtv instead of a seal on the front and rear of the manifold. Yes I did pull the manifold off each time and replace the gaskets and rtv. Yes the rtv is for engines.
I think I will try to clean the crap out of the area and apply a thin coat of rtv to the outside of the existing rtv.

 

If you have GOOD access to the offending area ,SOMETIMES you can clean the area and apply some more silicone [press it in ,your trying to fill a void] & it'll work !! CLEAN _CLEAN_CLEAN !!!
dave

Would it be best to trim away the excess rtv that is there and then apply more rtv to it?

 

I'd only trim off what has squished out , then clean it w/ alcohol and put it on like you're grouting tile , you can always clean off any extra...
dave

 

I think I would pull it back off and do it right

 

Remove the intake..(Sorry) clean the china walls with brake clean and the bottom of the intake also, and then use Permatex" Right stuff " it comes in a cheese wiz can, make a good thick bead and immediately install the intake right stuff is far superior to regular junky RTV. Always use Right stiff on a engine, Oil will attack regular rtv and it will eventually leak.

 

Remove the intake..(Sorry) clean the china walls with brake clean and the bottom of the intake also, and then use Permatex" Right stuff " it comes in a cheese wiz can, make a good thick bead and immediately install the intake right stuff is far superior to regular junky RTV. Always use Right stiff on a engine, Oil will attack regular rtv and it will eventually leak.

+1 for the right stuff

 

suck it in.

My old neighbor used to build a lot of circle track cars. He would duct tape all the openings on the engine, hook up a vacuum source to the dip stick tube then get out his stethescope and check aroung for a whistle. He would dab on sealant until he got the leak stopped, the vacuum sucked in into the hole. too much vacuum would suck it all the way through.

 

Remove the intake..(Sorry) clean the china walls with brake clean and the bottom of the intake also, and then use Permatex" Right stuff " it comes in a cheese wiz can, make a good thick bead and immediately install the intake right stuff is far superior to regular junky RTV. Always use Right stiff on a engine, Oil will attack regular rtv and it will eventually leak.

X2 :thumbup:



Cole
imp:

 

Smearing rtv on a spot that is already leaking is a hack job...Its like painting over a prior paint job with out prepping the surface to bond the new paint.

 

I like the vacuum idea if you can keep from sucking sealer into the engine.

 

rtv

I think we all have had a leak after a fix at least once. You might think you had it clean but maybe not. After wiping with brake clean take a clean dry rag over it again. Then take a piece of blue painters tape and touch the mating surface, if the tape sticks your good to go with the 1/4 in bead of rtv. Don

 

Thanks for all of the great input and ideas. I think I will try the vacuum method first and if it persist then I will apply every remedy mentioned! All together. lol I just hate dropping $60 on a gasket set every time this happens! Not to mention that it is a pita (although I have gotten good at it) lol

 

There are different types of RTV. I use the High Temp adhesive type RTV, it's black and works very well.

 

You can cut a couple of long bolts of the proper thread and use them as alignment pins. I have done this in the past on hard to install intakes. In most instances you will only be able to put them on one side due to the angle the bolts go in at but it can really help, especially if you are working alone.

 

Brylcream ?

Like the old Ad, A Little dab will do you, His cars were always show quality when he sent them out, wipe off the excess when he couldn't hear the whistle with his stethescope

 

You can cut a couple of long bolts of the proper thread and use them as alignment pins. I have done this in the past on hard to install intakes. In most instances you will only be able to put them on one side due to the angle the bolts go in at but it can really help, especially if you are working alone.

Great idea! Man...The stuff you learn after the fact! Will ad this to my list of to do's when/if I end up pulling it again. Thanks

 

the vortec intake gaskets are reusable if they haven't been on the engine for 50k miles, Don't waste your time trying to suck RTV into the leak, you will never get the old RTV clean enough for it to stick, just pull the intake and do it right.

 

Funny , last time I put my intake on , I had a small leak at the back , cleaned the area w/ alcohol , forced a little silicone in the offending spot , stopped the leak [that was 2 years ago & it's still dry !!

dave

 

you got lucky.