96 LT4 Oil Leak
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,738
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From: Bogart GA
96 LT4 Oil Leak
My 96 has about 42,000 miles on it and it has an annoying oil leak that appears to be originating from the front of the engine and splashing back. Looks like it could be coming from the spark plug/crank pulley area. I haven't crawled under the car yet for a closer look. Are crank seals for the LT engines one piece or two?
Thanks.
Thanks.
Race Director
Joined: Apr 2000
Posts: 15,344
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From: Texas
My 96 has about 42,000 miles on it and it has an annoying oil leak that appears to be originating from the front of the engine and splashing back. Looks like it could be coming from the spark plug/crank pulley area. I haven't crawled under the car yet for a closer look. Are crank seals for the LT engines one piece or two?
Thanks.
Thanks.
The leak you describe typically comes from one of the following areas...
- intake manifold end seal (which is just RTV)
- water pump driveshaft seal in the timing chain (front) cover
- balancer seal in the front cover
- o-ring around the crankshaft position sensor
Every once in awhile the opti seal in the front cover will leak, but that's pretty rare.
All three seals in the front cover can be replaced with the front cover on the engine.
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
I would suspect the water pump drive shaft seal to be the cause.
And a bit of a PITA to replace as well.
Check the back side of the water pump for oil as well. If oil there then it is the drive shaft seal. Lots of posts on replacing it. Plan on several hours if you do your own work or a hefty bill to have a shop do it.
Good luck.
And a bit of a PITA to replace as well.
Check the back side of the water pump for oil as well. If oil there then it is the drive shaft seal. Lots of posts on replacing it. Plan on several hours if you do your own work or a hefty bill to have a shop do it.
Good luck.
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,738
Likes: 53
From: Bogart GA
Thanks guys for the help. I saw in a post they sell a tool for replacing the WP drive shaft seal. It looks like the tool they sell to replace the turbo 400 transmission shifter shaft seal, just a bigger version. Thread it around the shaft and withdraw seal, use other end to seat new seal. The biggest pain is finding the source. There is a lot "stuff" in the front of the engine. I may just replace them all and be done with it. Leaning over engine bays is also taking its toll on my aging back. 
Looks like at a minimum I will need to remove water pump?
How well does the rear main seal hold up?
Looks like at a minimum I will need to remove water pump?
How well does the rear main seal hold up?
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Thanks guys for the help. I saw in a post they sell a tool for replacing the WP drive shaft seal. It looks like the tool they sell to replace the turbo 400 transmission shifter shaft seal, just a bigger version. Thread it around the shaft and withdraw seal, use other end to seat new seal. The biggest pain is finding the source. There is a lot "stuff" in the front of the engine. I may just replace them all and be done with it. Leaning over engine bays is also taking its toll on my aging back.
Looks like at a minimum I will need to remove water pump?
How well does the rear main seal hold up?
Looks like at a minimum I will need to remove water pump?
How well does the rear main seal hold up?
You should also carefully check around the front and rear of the intake. When oil starts leaking past the end seals, it can make a heck of a mess. Wouldn't surprise me in the least if it's the end seal at the front of the intake. The intake takes about 90 minutes to r&r. If you're new at spinning wrenches assume 6-8 hours.
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,738
Likes: 53
From: Bogart GA
Thanks, not new to spinning wrenches but never been in a real rush and prefer to work slowly as to not forget I left the the darn rag in the lifter gallery after I finish torquing the last intake bolt. Beer and late nights don't mix well. I will see if someone can loan me the Kent Moore tool if it obvious that is the source of the leak. Thanks for your help.
Burning Brakes
Joined: Jan 2012
Posts: 1,191
Likes: 153
From: Gilbert AZ
2018 C1 of Year Finalis4
It also helps to drain the block by removing the knock sensors (both sides) along with draining the radiator. Otherwise you will have a hard time telling if you have a front seal leaking once the water pump comes off and fluid runs down the front of the motor.
