Strick

I can't believe we don't have a tech tip on removing the intake manifold and resealing it to stop oil leaks. I'd like the short version of a good procedures to accomplish this. The Helms is good, but usually there is a better way. We're talking 92 LT1. :flag :flag :flag

autotech

(Here ya go) Get to the intake first. Remove. Clean all surfaces well. Assuming the surfaces are in good shape. I use just a little weatherstrip adhesive to hold the gaskets in place. The writing will be up and more than likley the rear water jackets will be restricted with just a small hole in the gaskets. Put the front and rear gaskets in a small can and fill with lighter fluid. Use a good grade silicone and run a bead along the front and rear of the block where it meets the intake. Install the intake and torque to spec. Last but not least - light the can of fluid and burn the supplied front and rear gaskets to a crisp. They are useless. :thumbs:

JAKE

I just emailed you a file that I wrote and send to guys on sealing the intake manifold.

It was written primarily with the L98 in mind (also engines that have coolant circulating through the intake), but works equally well with other types.

Let me know how you make out.

Jake

Corvette Kid

Thanks, I'll be doing this soon. I especially like that last tip! :lolg:

Strick

It's been cold down here so the fire will be needed for heat. :lolg: :rofl: :lol: :lolg:

Hey Jake, put the article you sent me in the C4 Tech Tips. Your dimple idea is cool. :thumbs:


[Modified by Strick, 9:11 AM 2/2/2004]

Meloyelo90

Jake,

Can you please post the article you wrote ?

I'm in the process of installing a new manifold on an L98 right now and have some questions, maybe the article will help out. Thanks !

djhatz

http://www.firehawk.org/article.html?ID=1336
Ken Collings knows his LT1s.

Hey Strick, how's that new clutch coming along?
What happened, take off your bell housing and see all that oil? Same happened to me. I'm going to be doing the intake gasket when it warms up here in Detroit.

By the way guys, I don't think there is a rear and front gasket for the lt1 intake manifold. I think GM used sealant, surface is not flat enough for a gasket. Problem lies with the egr pipe coming to close to the intake after it leaves the passenger side exhaust manifold and wraps around the rear
of the engine- where the oil leak develops.

Jake, can u post your steps?

Hatz


[Modified by djhatz, 8:53 AM 2/3/2004]

Strick

dj, I have the clutch & flywheel off and inserting a new rear main seal just for preventive maintenance. No I didn't have a lot of oil inside, but there was some from the first oil leak I had which killed the disc and over heated the flywheel from slipping. These beam plates will make it so much easier to reinstall the C-beam bolts.

If jake doesn't post soon, I'll post what he sent me. It's interesting.

JAKE

It's already posted there guys. It's been posted on the forum for quite some time now.

Jake

USAsOnlyWay

Ok then I will step out and be the stupid one. All I can find is your tip on lifter lash adjustment. Under the cross generation section of tech tips. Where is this one at? :leaving:

JAKE

Fixing a Leaking Intake Manifold

One of the most common leak spots on both the BB and SB
Chevy engines is the end seals of the intake manifold, followed by
valve covers and then timing chain. Guess you could throw in rear
main seal too.

Here's the way I've been doing it for years and have prevented leaks in
the intake.

Remove the intake and thoroughly clean all the gasket sealing surfaces, I
mean clean!!!

No traces of gasket or silicone, or oil is acceptable. Use a coarse grit
sandpaper to scrub down both ends of the block and the underside of the
intake. Use a degreaser or carb cleaner to make sure all traces of oil or
silicone are removed.

Now take a fine point punch and hammer and punch a series of
dimples on both ends of the block and on both ends of the manifold.

You will end up with maybe 30 or more dimples on each end when you're
done.

They should be positioned about 1/8 to 1/4 inch apart. You don't have to
go deep, but make sure you've got dimples that you can catch with your
fingernail.

Be careful not to place the punch so close to the edges that you chip the
block or intake material. It's kinda hard to chip it but there's no need
to get closer than say 1/8th inch.

Now with every mating surface clean, clean, clean, use your finger to put
a very THIN layer of silicone sealant around each intake port and water
port on the heads. Place the intake gaskets in place and gently press the
gasket into the sealant.

Be sure to use silicone sealant that's "sensor safe". Fumes from the other
kind can kill the 02 sensor. I use VersaChem # 613 Super
Blue Silicone; comes in a 4 oz tube.

It has about 1/3rd more silicone than some other
brands. Other brands work just as well, just be sure it's 02 safe. Auto-
Zone, O'Reilly's, Pep Boys, NAPA, etc., all sell the good stuff.

Any sealant the oozes out into the port area is to be wiped away
with your finger. Now do the same thing to the intake gaskets; place
a very thin layer of sealant around each intake port and water port
on the gasket, even those with the sealant rings on 'em.

Smooth it out with a wetted finger tip (wetting your finger keeps the
sealant from sticking to your finger, but it's still kind a messy). When
your finished you'll have a thin layer of silicone sealant on both sides
of the gasket.

Keep the sealant about 1/4 inch from the port entry. If you apply it
thinly it won't squeeze into the port to obstruct airflow.

If a little does ooze into the airway, well if that small amount of
airflow restriction is enough to cause you to lose the race or hurt your
power you have some much more serious deficiencies. Using a thin
layer minimizes the chance of any leak.

Now the critical part:


RUN A CONTINUIOUS BEAD ABOUT 3/8 INCH thick, maybe even a hair
thicker, along both end seal areas. Make sure the bead extends onto the
head and that it is continuous with no gaps and as few hi/low places as
possible. 1/4 inch bead is too small.

CAREFULLY SET THE INTAKE MANIFOLD IN PLACE ON THE HEADS WHILE
THE SEALANT
IS STILL WET. SIT THE MANIFOLD STRAIGHT DOWN - DO NOT ALLOW
IT TO SHIFT FRONT TO BACK.

Some guys like to wait for the sealant to skin over, but I've found you
get a better seal by setting everything in place with it wet.

Proper alignment can be done by looking through one of the intake
manifold bolt holes and visually align it with the threaded hole in the head
as you lower it in place.


Remember, straight down. Take your time and do it slowly.


All the intake bolts should have been cleaned before you started the
gasket installation. Cleaned of any old sealant and crud. I use Anti-Seize
on my threads just for insurance against vacuum leaks; and it's
especially important when using aluminum heads to prevent the manifold
bolts from seizing.

Chasing the head bolt holes is a good idea but this can cause some crud
to fall into the lifter valley unless you take precautions to really cover it
well and pick every little piece of whatever that may fall into the
valley.

Hand start all the intake bolts and slowly torque them down following the
correct bolt sequence shown in any of the GM books that apply to your
engine. This can be tricky because the TPI intake calls for a peculiar
torque sequence. You may be able to get away with the old tried and
true cross pattern, but why take the chance. I guess GM had good
reasons for the recommended sequence shown in the Shop Manual.

Torque them down in very small increments, 5 lbs at a time is what I
use. I have to make more passes, but you're only dealing with 12 bolts
so what's the big deal, right?

PUT A TORQUE WRENCH ON THEM TOO. There's no substitute for proper
torque.
Too much and you can distort the manifold and/or pull threads; too little
and the manifold bolts will loosen when it goes through heating and
cooling cycles.

Wait about an hour or preferably longer, then go back and re-torque the
manifold bolts again.
Letting manifold sit for an hour or more will allow the gasket to take a
set. This "set" has the effect of loosening the bolts. On occasion I've
had to re-torque them a second or even a third time. The more
compressible or thick the gasket, the more it will compress and need to
be re-torqued.

Be sure to torque all the bolts in place while the silicone sealant is
still wet.

Resist the temptation to wipe away any sealant that may ooze from
between the intake and block/heads. If you're so inclined, you can cut it
away with a very sharp razor blade after waiting for it to FULLY cure -
about 24 hours.


The dimples in the block and manifold will give the sealant something to
bite into and you'll be leak free until you decide to change cams, then ya
gotta do it all over again.

Do Not, Do Not use the end seals that come with the new intake manifold
gaskets. If you do you've got better than a 50/50 chance of having the
same leak again in time.


Like many other things, there's always more than one way to do
something, but I've used this technique on many, many engines with
complete success.

Hope this helps,

Jake

BTW, I use the dimple technique on the blocks of BB Chevys between the
cylinders that don't have head bolt holes to give the head gasket
something to bite into also. When you're running 14.1 CR without "O"
rings you need all the help you can get.






[Modified by JAKE, 12:37 PM 2/5/2004]

JAKE

Sorry! I thought for sure I'd posted that some time back. Guess I didn't.

I just posted it now though; with a couple of little additions.

I've become a little reluctant to post tips like those because there's always someone to come along to criticize/disagree and then offer an alternate way of doing it. Example, setting lifter preload: One guy advocated doing it with a dial indicator.

Most of the tips I give now are through private emails. My fighting days are over; I've become a devout pacifist in my old age. Fightin's too stressful. LOL

Hope it helps though.

Jake


[Modified by JAKE, 1:43 AM 2/4/2004]

87SAM

I can vouch for the procedure that Jake has. I used it 2 –3 years ago and it was invaluable, works like a charm and still leak free! Thanks again Jake! :thumbs: :thumbs: :thumbs:

Aggravated4life

Well,Jake ,I HAVE to disagree with you or at least add my cents...you didnt include one very important PART when redoing the intake,you never mentioned the BEER!This is defintely a 12 pack job!
:D :jester

J/k buddy...thats a great write up and its probably the best Ive seen.Chilton or Haynes,or even the GM manuals couldnt pay you enough to re write their books.
:cheers:

tblt44

Repzard

My buddy has a 92 that's leaking also.
Doesn't seem to be a real big job.But it would be nice to have some info or maybe a sticky .

Repzard

Thank You !!!

Sticky

floridamale

6 & 1/2 years old the dust is so thick I can't see to read

GREGGPENN

The one thing I found controversial is the use of a sealer on the gaskets. Some people use other agents to hold the gasket in place (most commonly High-Tac spray adhesive). Others think ANY sealer is a bad idea. That's because fuel and fuel fumes running into the port can "erode" the sealer -- leaving a gap in it's place.

Because I note none of the silicones I've looked at say fuel resistance, I was reluctant to (and did not) do this step. Instead, I placed the thin layer around the water ports ONLY and let it setup/glue to the heads overnight. Nothing went on the other side of the gaskets. I did use the touted "Right Stuff" sealer to seal the China walls. I also used the dimpling method described here.

I debated the issue of using silicone (or other sealer) on the intake. I also pointed out that the injector squirts its fuel slightly below the intake-to-head seal where little (if any) fuel would come in contact with the gaskets. The couple of people who were adamently against the use of sealer were so emphatic, that I conceeded to that option. Had I found silicone to be fuel resistant, I would have gone the other way.

I'm still not convinced it's harmful, but I am convinced that good intake gaskets look "substantial" enough that I see why some people believe thats ALL that's necessary to seal your intake. Plus, when I removed the old gaskets, GM didn't appear to use anything like silicone that I could find.

JAKE

GEEZZZ! You went back to 2004 to dig this up?? What's up with THAT! Motivation?? Is it because I questioned your LSA claim in another thread?? Seems that way to me.

More to the point, Here's one example: A big, beautiful photo of an engine builder applying SSS to the intake gaskets intake ports appears in one of the Performance Building the SBC Vol. II(or some such wording) manuals which dates well over a decade ago. This is "Old School" stuff which we "Old Guys" have known and been doing since Hector was a Pup.

My advice, Try not to get too **** over this stuff - over-thinking, overly concerned, overly this and overly that. Suspecting faults and flaws when none actually exist. Too stressful doing things that way. Either follow the procedure I posted or don't'; no skin off my nose if you don't.

BTW it's also posted as a STICKY on LS1LT1.COM and a few other Forums (Third Gen/CamaroZ28/others) as well and I regularly get feed-back on how well it works and grateful thanks from the Forum members. One Forum Administrator emailed me asking my permission to cut and paste it to HIS Forum after he came across it on a competing Forum - naturally I consented. So your concerns are unfounded.

As I wrote, (what was it six years ago?), there's always someone who comes along and disagrees or whatever. Never fails - sooner or later. Either accept the procedures or don't.

My only goal is to try, as best I can, to help others - HELP being the operative word.

As I regularly say, feel free to do as you please.

Jake