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Rear Housing At Crankcase Centerline Oil Leak
Posted by: JimBrandberg ()
Date: October 25, 2017 05:41AM

I'm working on a 66 140 with an oil leak I'm having trouble with. It's at the gasket between the rear housing and crankcase right at the centerline for the crankcase. It pretty much only leaks when it's running. With the skid plate removed and the engine running you can wipe the oil away and see it gather from the gasket.
I wasn't sure if it was the gasket or the crankcase split. I replaced the gasket and checked the torque on 7 of the crankcase bolts, missing the front top one due to shrouding in the way. A few of the center bolts were a little loose but not either of the rear ones.
I thought maybe it was okay at first but don't know for sure because I had installed the skid plate and lost the view, oil did gather in the skidplate after perhaps 15 minutes of running. I'm only running it a few minutes at a time because of no shrouding or fan installed.
I installed a different rear housing and although the leak is still there, it's a little different. The first housing seemed like the leak was perhaps 1/8" wide gathering into a single drop, the second housing seems like perhaps 3/8" wide gathering into a single drop. Right at the centerline.
The gasket surfaces on crankcase and rear housing seem good with a straightedge.
The gallery inside the rear housing at this place is a large area for oil return, the distributor shaft passes through this "room".
Since it pretty much only leaks when running I would be inclined to suspect the rear housing area. It seems like if the crankcase split was the problem, it would be oil coming from the sump and would leak all the time. Maybe my thinking is off.
Since the leak pattern changed a bit with the different housings, I'm thinking about another gasket with black silicone applied with my finger to both sides of the entire gasket. I'm not much for the silicone thing but I'm at a bit of a loss. My two previous attempts were with SylGlyde grease on the gasket. I've shied away from adhesives since it takes so long to scrape this gasket if adhesive has been applied but I'm looking for suggestions.
You can imagine my apprehension in removing and splitting the crankcase without it being necessary.
I've saved the real kicker for last. This Corsa convertible was rear ended by a city bus and sat for 15 years. It was at the Body Shop before coming here. I just don't see any cracks or damage to the engine.
Perhaps I should try Gaskacinch or something instead of black silicone. I've avoided Permatex Aviation Form-A-Gasket like the plague as I've spent many hours scraping old gaskets in my lifetime.
Sorry to be so long and thanks in advance for advice.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: JimBrandberg ()
Date: October 25, 2017 06:40AM

When searcing for Gaskacinch I see 440A and 440B. What's the difference?
Edelbrock Gaskacinch seems easir to find. Is it the same?
Is Permatex High Tack Gasket Sealant the same?
What about using The Right stuff for this application? Sounds expensive, used for intake manifolds. What about a thin layer applied with a finger to both sides of a gasket?
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: cnicol ()
Date: October 25, 2017 07:17AM

I'd give it a try with "The Right Stuff". Yes it's expensive but the dispenser will last and last if you're applying the "Right Amount". I aim for a 1/16" continuous bead. The trick for re-use of the dispenser is to let it sit for at least a week to allow the product in the nozzle to completely solidify.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: corventure Dave ()
Date: October 25, 2017 07:33AM

I have found that a straightedge may be deceiving when checking the rear housing gasket surface. I have made a practice of putting the rear housing on a flat surface... I use a piece of plate glass. On this I have a sheet of 400 wet-dry sandpaper wetted with WD-40. I hand mill or sand the gasket surface this way. It is amazing how uneven the housing gasket surface is. Just a few passes will show high and low spots.
With the rear housing trued, I have eliminated most oil leaks in this area. This came in really handy when I competed in concourse!
You may try this on the rear housing you removed, to see if this surface is the issue.

Corventure Dave

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: JimBrandberg ()
Date: October 25, 2017 07:34AM

Is there a difference between gray and black with The Right Stuff?
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: vairmech ()
Date: October 25, 2017 08:40AM

Use the black stuff. You only need to put it on the lower half, side bolt to side bolt, of the outer gasket area and then do only a film spread with your finger.

BTW, the gray stuff is way harder and bonds to the gasket and parts and is very hard to get apart later.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: 1STLM ()
Date: October 25, 2017 09:02AM

I have limited experience with High Tack but so far it has worked wonders, including on the rear cover gasket. It is supposed to be soluble with lacquer thinner and is also with gasket dissolver. I have used dissolver by wiping it on with a Q tip rather than spraying onto an engine.

It agree with Dave above that a straight edge may be deceiving. I used a straight edge but also used a thin feeler gauge to get a better idea of flatness. With the housing on plate glass I probed around with a .002" blade looking for high spots. You can also place the blade under the gasket surface to judge the tension. Using the edges and corners of the glass I was able to check out all of the inside gasket surfaces and did find some high area. After more hand milling I went back to those areas with the feeler gauge and was happy with the results.

Brice

66 Corsa Turbo Convertible

Bozeman, Montana

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: JimBrandberg ()
Date: October 25, 2017 10:37AM

I have a bench with 3/8 plate steel which I think is pretty flat. I did a little hand sanding with the rear housing but not much cecking. Perhaps I will go over the surfaces with a Magic Marker or something to check it out better.
Thanks for the replies.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: corventure Dave ()
Date: October 25, 2017 10:48AM

Just a couple old shots of same process, checking and sanding on plate glass to improve gasket sealing surface on carburetor cluster.

Corventure Dave

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: TIBCO ()
Date: October 25, 2017 11:30AM

Dave beat me to it. I also use a flat surface, in my case, a 12" round sanding disc backing plate. Jim, do as you suggested, coat the entire gasket surface area with a magic marker, then sand till flat. I think a lot of these covers get warped by folks over-tightening the lower, 3/8" studs for the engine mount.

Cliff Tibbitts
Lexington, KY
CORSA, CKCE
66 Monza, 140/4sp

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: Brizo ()
Date: October 25, 2017 11:01PM

JimBrandberg, Since you've resealed the rear housing once already,its sounds to me like it may be coming from the crankcase split. There is oil pressure at the cam bearing only an inch away. Before you remove the rear housing again, I would try compressing the aluminum on each side of the split in that small area with an 1/8"pin punch and retest it.

Dan Brizendine,
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: JimBrandberg ()
Date: October 26, 2017 05:30PM

I let the "Right Stuff" silicone set overnight and then jacked the engine up and secured to the mount. I started it and let it run for a few minutes, seemed okay, hard to tell with the skid plate on. Tried it again and could see it was still leaking.
I supported it on the jack and removed the motor mount plate and skidplate. With the engine running, I could see it still leaking. I took the 1/8" punch and whacked the crankcase on each side of the split and the leak stopped right before my eyes. After several hours messing with the rear housing 3 times, it semed too good to be true. I had also previously checked the crankcase bolts which is not easily accomplished.
I think Dan Brizendine is a genius and has my vote for man of the year. I'm so glad I asked here, I just wouldn't have thought of it. Thank you so much.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: MattNall ()
Date: October 26, 2017 05:35PM

That is a great tip!





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: Frog ()
Date: October 27, 2017 06:32PM

Jim Brandberg wrote: "I took the 1/8" punch and whacked the crankcase on each side of the split and the leak stopped right before my eyes."

I would really like to see exactly WHERE you whacked the case seam with that 1/8-inch punch, and at what angle. It sounds like some great advice for the future.

Thank you.

Frog

Rob Lane
Clayton, in the Northeast Georgia Mountains.
1964 500 Coupe
Purchased by me in April of 1964.

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: MattNall ()
Date: October 27, 2017 10:22PM

You don't have much choice on the angle... on aVair in that area..

I'd say as far away as 1/4". Harder metals you NEED to be closer..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: davemotohead ()
Date: October 27, 2017 10:40PM

Hammers can fix anything!





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: JimBrandberg ()
Date: October 28, 2017 08:19AM

I just hit it dead on with the 1/8" punch about 3/16" away from the split. It's a compressing the metal sort of thing rather than a staking it over sort of thing.
Dan also said in PM that if it changed but didn't quite stop, I might remove the oilpan and do some more inside. I imagine perhaps doing it up inside beyond the oilpan surface.
There's only about 1/4" of the split visible below the rear housing with the skidplate removed. When I removed the skidplate, I replaced the 4 nuts with some thick washers for testing purposes.
Of course I had checked the crankcase bolts previously.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: Frog ()
Date: October 28, 2017 08:47AM

Excellent.
Thank you.
Frog

Rob Lane
Clayton, in the Northeast Georgia Mountains.
1964 500 Coupe
Purchased by me in April of 1964.

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Re: Rear Housing At Crankcase Centerline Oil Leak
Posted by: Timothy Shortle ()
Date: October 28, 2017 10:12AM

Glad you got it fixed Jim. I was going to suggest a thicker gasket. I have bought (pink) gaskets from John Sweet that have fixed a similar issue for me. This of course after having taken it apart a couple of times trying to solve an oil leak.

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