Dreaded LT1 intake manifold leak -- how hard to fix?
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Melting Slicks
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Dreaded LT1 intake manifold leak -- how hard to fix?
After performing the front crank seal repair this past weekend (for the 2nd time -- I used a Speedy Sleeve this time, so I think it will not leak again ;) ), I still have a leak from the front of the engine :rant:. I noticed that there was a ton of dirt collected on the top front of the intake and also a stream of oil running down the front cover from the RTV seal on the intake. Both of these conditions indicate an intake manifold leak (the 3rd one), I presume :mad. I would have fixed it then, but I did not have time as I need my car for work :smash: .
So, how hard of a job is it to repair this leak? I have done the water pump/Opti and the front cover seals and crank, so is this job easier or harder than those? Am I correct in assuming that the water pump does not have to come off? I am tired of draing the coolant and removing the water pump! :cuss
Parts I know I need are 1) intake gasket 2) Copper RTV or The Right Stuff. What else? Thanks for the help. ;)
So, how hard of a job is it to repair this leak? I have done the water pump/Opti and the front cover seals and crank, so is this job easier or harder than those? Am I correct in assuming that the water pump does not have to come off? I am tired of draing the coolant and removing the water pump! :cuss
Parts I know I need are 1) intake gasket 2) Copper RTV or The Right Stuff. What else? Thanks for the help. ;)
Race Director
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From: Texas
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (94vette)
Piece of Cake. The LT1 intake is dry...no coolant to worry about draining...so it's a no-brainer to pull it off and reinstall it.
You'll need gaskets, liquid teflon (for the intake bolt threads) and RTV (to seal the intake ends). There are a few keys...
- Clean all the bolt threads and apply the liquid teflon. This prevents the oil from leaching out
- Clean all the sealing surfaces and then clean them again for good measure
- After reinstallation of the intake, allow the engine to sit overnight before starting it so that the RTV fully cures.
You'll need gaskets, liquid teflon (for the intake bolt threads) and RTV (to seal the intake ends). There are a few keys...
- Clean all the bolt threads and apply the liquid teflon. This prevents the oil from leaching out
- Clean all the sealing surfaces and then clean them again for good measure
- After reinstallation of the intake, allow the engine to sit overnight before starting it so that the RTV fully cures.
Le Mans Master
Joined: Feb 2002
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Re: Dreaded LT1 intake manifold leak -- how hard to fix? (96GS#007)
Related question: Does the intake oil leak also mean that air can leak into the intake the same path? Or are air leaks only possible along the sides of the intake where the runners are located and the regular gaskets are used?
Race Director
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Re: Dreaded LT1 intake manifold leak -- how hard to fix? (Lone Ranger)
Related question: Does the intake oil leak also mean that air can leak into the intake the same path? Or are air leaks only possible along the sides of the intake where the runners are located and the regular gaskets are used?
Race Director
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From: Texas
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (kittmaster)
is there a step by step procedure to fix this ?? Tech tip?
On the LT1/4 it's not a big deal.
- Pull off the "CORVETTE" beauty covers.
- Disconnect the various electrical connectors
- Remove the nuts that hold the electrical harnesses to each side of the intake
- Move the harnesses out of the way
- Remove the 4 bolts that hold the fuel rail in place
- Remove the fuel rail/injector assembly from the intake (leave attached to fuel lines and simply set it on a towel on the windshield)
- Remove the throttle body and the throttle cable
- Remove throttle cable bracket
- Remove any misc items/hoses...PCV valve & hose, AIR connections, EGR (on the LT1), etc.
- Remove the intake manifold bolts
- Remove manifold & old gaskets
- Clean, clean, clean the sealing surfaces
- Clean intake bolt threads
- Install new gaskets
- Apply RTV sealer to the block for the end seals
- Set intake in place. Apply liquid teflon to the intake bolt threads and torque bolts per Factory Service Manual specs and sequence
- Reassemble the remainder in reverse of above
That pretty much covers the major stuff.
3 to 5 hour job. 2 or slightly more if you can really spin the wrenches and everything goes your way.
:cheers:
[Modified by 96GS#007, 7:26 AM 7/8/2003]
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Thread Starter
Melting Slicks
Joined: Oct 1999
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From: Houston, Texas FEAR THE BONES
2023 C5 of the Year Finalist - Modified
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (kittmaster)
that sounds like cake.......hell I should put a new cam while I'm that far down no??????.......
Racer
Joined: Feb 2002
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From: Fraser MI
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (96GS#007)
hmm...i may be inspired to change mine this weekend...it has a small oil leak in the back and i suspect a bad vacuum leak...can't hear it over my exhaust though!!
Team Owner
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Re: Dreaded LT1 intake manifold leak -- how hard to fix? (konroh)
One more thing. Make sure your intake gasket kit (I got the one from Fel-Pro) contains the injector O-rings as you'll want to swap all eight of those out while you're in there and you have the intake off.
Also, be sure to protect the exposed areas of the engine from dirt, old pieces of gasket material, etc, as you don't want any contaminants getting into your oil, the lifeblood of your engine.
When the guys repaired my intake at CI-IV, I actually went ahead and changed the oil and filter, too, just to be on the safe side. :thumbs:
Also, be sure to protect the exposed areas of the engine from dirt, old pieces of gasket material, etc, as you don't want any contaminants getting into your oil, the lifeblood of your engine.
When the guys repaired my intake at CI-IV, I actually went ahead and changed the oil and filter, too, just to be on the safe side. :thumbs:
Race Director
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From: Texas
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (kittmaster)
If you want to see what it takes to do a cam swap, here's a link to my write-up that details my installation of the HOT Cam in my GS:
http://www.hashmarks.com/techtips/hot_cam.htm
LOTS of pics (thumbnails so it'll load pretty quickly even if you're using dial-up)
http://www.hashmarks.com/techtips/hot_cam.htm
LOTS of pics (thumbnails so it'll load pretty quickly even if you're using dial-up)
Burning Brakes
Joined: Jan 2003
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From: Arlington TN
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (96GS#007)
I had it done at the dealership here in town for around $300.00 a few years ago. I didn't think that was a bad price. I was told by the service writer that is was cheaper to get the LT-1 done then the L98. Said there was more labor time on the L98.
[Modified by Corvette1996LT1, 1:05 PM 7/8/2003]
[Modified by Corvette1996LT1, 1:05 PM 7/8/2003]
Instructor
Joined: Jan 2001
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From: Portsmouth RI
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (94vette)
Flat rate Chevy dealer $65/hour book time + parts. Total was $219 to get it fixed with them to stand behind it.
Really good price, took them 5 hours (I think they milked it) but only charged the 3.something book time.
Really good price, took them 5 hours (I think they milked it) but only charged the 3.something book time.
Le Mans Master
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Re: Dreaded LT1 intake manifold leak -- how hard to fix? (burked3)
Starting mine this weekend. Two things I would recommend in addition to the liquid teflon and dry time....
1. Buy a new EGR valve gasket. They get hard and brittle from the heat.
2. Buy new injector O-rings. On the 92 and 93 LT1, there is no need to remove the injectors from the fuel rails ~ but you will need to pop the rails and injectors out of the intake as an assembly and lay back while performing surgery. Lower o-rings seal the intake vacuum ~ it doesn't take much of a leak to cause performance problems.
~ Purp
1. Buy a new EGR valve gasket. They get hard and brittle from the heat.
2. Buy new injector O-rings. On the 92 and 93 LT1, there is no need to remove the injectors from the fuel rails ~ but you will need to pop the rails and injectors out of the intake as an assembly and lay back while performing surgery. Lower o-rings seal the intake vacuum ~ it doesn't take much of a leak to cause performance problems.
~ Purp
Racer
Joined: Feb 2002
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From: Fraser MI
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (PurpleC4)
anyone have a good way to check for a vacuum leak before tackling this job? i don't want to do it if it isn't the problem. i have heard if i hook up a vacuum guage it will bounce around at idle if you have a leak, but what if the leak is constant? The problem i have is low BLM's and not a lot of power off the line until about 2k rpms...
Le Mans Master
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Re: Dreaded LT1 intake manifold leak -- how hard to fix? (konroh)
Konroh ~ There are numerous ways to check for vacuum leaks, some work better than others. Some people actually take a propane torch and attach an 1/8" or 3/16" diameter plastic hose to the head unit and run the open end of the hose (unlit of course) around all of the potential vacuum leak sources while the engine is at idle. When you reach the source of the vacuum leak the idle will increase and smooth out.
Some actually take 3 in 1 oil and squirt it around all possible leak sources. When the leak seals up from the oil, the idle speeds up. This is messy and doen't work well on vertical surfaces.
~ Purp
Some actually take 3 in 1 oil and squirt it around all possible leak sources. When the leak seals up from the oil, the idle speeds up. This is messy and doen't work well on vertical surfaces.
~ Purp
Burning Brakes
Joined: May 2002
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From: Sierra Foothills, State of Jefferson
Re: Dreaded LT1 intake manifold leak -- how hard to fix? (94vette)
My next project for the Vette- I'm tired of smelling hot/burnt oil :rolleyes:
And thanks for the reminder about the O-rings and EGR gasket!
And thanks for the reminder about the O-rings and EGR gasket!