Oil Leak coming from flywheel cover

Grannie86

New Member
Mar 2, 2019
27
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Deptford, NJ
Yes, purchased a 86' Grand National this week ( New Member signing on) with 28k on Odometer. Drove over 175 miles to my home after purchase. Inspect condition of car ect..Test drove Ok. Examined also underside of car. Did notice small oil drip from flywheel cover? But was informed by Seller, oil was just changed and spilled some down from oil fill. Well when I got home I had fresh oil from flywheel cover,onto cross over pipe- header thru-out trannie pan ect. Guess buyer be Were? Possibly a rope-seal at crank worn-out? Sounds expensive right to deal with, just need peace of mind idea, of ballpark cost to repair by mechanic? Thanks for
 

NY Twin Turbo

All the good stuff.....Times 2.
Dec 10, 2014
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Westchester NY
Yes, purchased a 86' Grand National this week ( New Member signing on) with 28k on Odometer. Drove over 175 miles to my home after purchase. Inspect condition of car ect..Test drove Ok. Examined also underside of car. Did notice small oil drip from flywheel cover? But was informed by Seller, oil was just changed and spilled some down from oil fill. Well when I got home I had fresh oil from flywheel cover,onto cross over pipe- header thru-out trannie pan ect. Guess buyer be Were? Possibly a rope-seal at crank worn-out? Sounds expensive right to deal with, just need peace of mind idea, of ballpark cost to repair by mechanic? Thanks for
Yes, purchased a 86' Grand National this week ( New Member signing on) with 28k on Odometer. Drove over 175 miles to my home after purchase. Inspect condition of car ect..Test drove Ok. Examined also underside of car. Did notice small oil drip from flywheel cover? But was informed by Seller, oil was just changed and spilled some down from oil fill. Well when I got home I had fresh oil from flywheel cover,onto cross over pipe- header thru-out trannie pan ect. Guess buyer be Were? Possibly a rope-seal at crank worn-out? Sounds expensive right to deal with, just need peace of mind idea, of ballpark cost to repair by mechanic? Thanks for
Don't ask how much. Ask who.

For your own sake, from this point on you will never take your car to a "mechanic" ever again.

Welcome to the world of Turbo Buicks.
 

dank GN

BlackArts Automotive (661)993-8277
Jan 11, 2009
3,595
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SoCal the high desert
Well the replacement seal is like $10 and it’s possible to do it in the driveway with a decent set of tools and a torque wrench . I’m going to take a guess and say it would cost around 4-500 if u take it to someone to rio you off . Save the cash and do it yourself
 

1KWIKSIX

Well-Known Member
Sep 29, 2007
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Mississauga, Ontario, Canada

No disintegrations

Active Member
Dec 27, 2015
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Imo Someone doing for him isn't a rip off. Over the years cars have wrong bolts in the cross over, and everywhere else and don't come apart like a 5 year old car.
Some fellas have the skills but some just don't and a little money now on experienced help is worth it. PS is prob the rear main seal but could just be valve cover gaskets or something simple.
 

MikeS

Member
Oct 30, 2012
85
22
8
Wipe off all the oil you see. Put oil dye in the oil and go for a drive. Then get under it with a black light. The source of the oil could be a leak at the Pcv, rear of the intake manifold, valve cover gasket, etc....guessing gets expensive fast.
 
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captndave737

Active Member
Feb 14, 2006
994
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Raleigh, NC
it seems all leaks look like they're coming from the rear main. I have a leak coming from the front corner of my Passenger side valve cover but all the oil is by the flywheel cover. Dye and a black light showed where it"s coming from.
 
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raregn

Addicted to BOOST
Jul 20, 2010
82
14
8
Winnipeg, Mb. Canada
Like it has been said, most likely a rear crank seal.
But on a 33 year old low mileage car it could be literally leaking from everywhere and running down the back of the motor.
Valve cover gaskets, PCV grommet, rear of intake manifold, oil pan gasket.
Unless you have a fresh engine if it is not leaking oil, that means there is no oil in it to leak.
 

Nick Micale

Tech Advisor
Staff member
May 26, 2001
8,543
1,532
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Phoenix, AZ
www.ArizonaGN.com
The first thing you must do is to remove the converter shield and check the flexplate on the front side, and look for oil tracks streaming from the crankshaft to verify the leak from the rear main seal.

Next, check if the oil is synthetic, as it will leak from the rear main seal, and other places as well.

I recently "fixed" a rear main seal leak on a 7000 mile GNX by dumping the Mobil I and used Valvoline ZR-1!
 
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1KWIKSIX

Well-Known Member
Sep 29, 2007
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Mississauga, Ontario, Canada
The first thing you must do is to remove the converter shield and check the flexplate on the front side, and look for oil tracks streaming from the crankshaft to verify the leak from the rear main seal.

Next, check if the oil is synthetic, as it will leak from the rear main seal, and other places as well.

I recently "fixed" a rear main seal leak on a 7000 mile GNX by dumping the Mobil I and used Valvoline ZR-1!

I share the same experience as Nick did....got rid of the Mobil 1 and switched to Brad Penn and voila....no more leaks (at least at the rear main seal anyways) LOL
 

Turbo6inKY

Short Guy
Jun 18, 2001
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Louisville, KY
blog.andrewdscott.com
Yes, purchased a 86' Grand National this week ( New Member signing on) with 28k on Odometer. Drove over 175 miles to my home after purchase. Inspect condition of car ect..Test drove Ok. Examined also underside of car. Did notice small oil drip from flywheel cover? But was informed by Seller, oil was just changed and spilled some down from oil fill. Well when I got home I had fresh oil from flywheel cover,onto cross over pipe- header thru-out trannie pan ect. Guess buyer be Were? Possibly a rope-seal at crank worn-out? Sounds expensive right to deal with, just need peace of mind idea, of ballpark cost to repair by mechanic? Thanks for

Valve cover gasket leaks also present in the same location. Pull the cover and check. If the back of the engine between the block and the flexplate is dry, move upward.
 

Grannie86

New Member
Mar 2, 2019
27
2
3
60
Deptford, NJ
Thanks for replies, did vertify the crank seal is leaking and will look into that down the road to repair? But first I like the SpoolProof idea. Um making up a ShadeTree vision using the orginal metal flexplate-cover and see How it works to collect leaking oil
 

TurboBuRick

Moderator
Staff member
Feb 18, 2006
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The rear seal is a shit design. Even if the rope seal is replaced with neoprene it still never 100% leak free. Try not to over fill the oil. Keep the level a tad below the full mark.
That can help trmendioualy.
 
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raregn

Addicted to BOOST
Jul 20, 2010
82
14
8
Winnipeg, Mb. Canada
I actually keep a large drip pan on my garage floor under my engine.
Right now I have no leaks as my engine is only 2 years old with about 6000km on it.
But it's a turbocharged Buick, it will start leaking eventually.
Before I had the engine rebuilt it would leak bad in the spring after pulling out of winter storage. Would clear up after the first few heat cycles.
 

87WE4!!

Active Member
Jul 2, 2018
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Don't ask how much. Ask who.

For your own sake, from this point on you will never take your car to a "mechanic" ever again.

Welcome to the world of Turbo Buicks.
Truest post I’ve ever read on here. I’ve been a TB owner for 32 years and you absolutely either have to learn the car yourself or take it to the Turbo Buick shop in your area. Trust me, find the right person. The wrong mechanic can very easily F—- your car up and create new issues. Even with a simple job like a rear main seal.
 

Grannie86

New Member
Mar 2, 2019
27
2
3
60
Deptford, NJ
The rear seal is a shit design. Even if the rope seal is replaced with neoprene it still never 100% leak free. Try not to over fill the oil. Keep the level a tad below the full mark.
That can help trmendioualy.
Thanks for your reply, will most definity use your idea for oil level below full
 

GNICETRY

Cat&wife post starter
May 26, 2001
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Grannie86 welcome to the site. Not sure if you did research or not but these cars will leak 99% of the time if not stock and about 90% of the time stock. If you plan on having a bone dry undercarriage I would contemplate another vehicle. That being said you have a VERY high percentage that your rear main will leak. Even if you weld it (Don't do that). The SpoolFool Drip Lip is a well designed piece from a Buick nut and fanatic to details. It would be a welcome addition to ANY car because your rear main WILL leak. A very good start is to clean it off well and then check with the dye (or have a Buick guru take a look at it). Some people like Mobil 1 (synthetic) and some don't. I use Mobil 1 15-50W. When I put in Mobil 1 10-30W=Exxon Valdez. You really can't go wrong with dino heavier weight racing oil either.
A lot of guys on this site are pretty handy and like dong work themselves. A lot of guys on this site are cheap too and still have their Confirmation $$. You have to discern your abilities/time/finances and be guided by that. But don't cheap out on your Buick. It is one of the best musclecars made, treat it accordingly :)
 
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