1 or 2 piece rear main seal help please! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cckutchma · 06-30-2006, 06:50 AM

I am a newbie 1984 C-20 owner. It has a swapped 350 cid engine with a 4 speed manual transmission. Icannot find any VIN numbers on it. (the engine) As much as I have been told it is a 1985 engine. Is there any other way without stripping the motor down to tell the year. 80-85 2 piece 86 up one piece and how critical is the difference

greg0380 · 06-30-2006, 08:06 AM

to the best of my knowledge, going to a 1 piece seal the oil pan, crankshaft, flywheel and transmission dust cover was changed.

Slonaker · 06-30-2006, 09:14 AM

The two piece is supposed to seal better. On mine ('86 305) it did use a different pan and flexplate than my new 350. I reused the dust cover without any issues.

You aren't going to notice any difference unless you start pulling stuff apart. Are you trying to do something to it, or are you just curious?

Slonaker

cckutchma · 07-02-2006, 09:53 AM

Sorry about that been down with a shoulder injury. Yeah I am planning on dressing the engine up with a chrome oil pan and am not sure if theres a difference with the oil pans designs 1985-1986.

Slonaker · 07-02-2006, 12:40 PM

Yes, the '85 and '86 pans are different. When you look in the catalogs, the '86 pans are a different part number, and usually more expensive.

Slonaker

piecesparts · 07-02-2006, 12:51 PM

Not ALL 86 engines were a one piece seal. I pulled the 305 out of my son's 86 and it was a two piece setup. I replaced it with a GM direct replacement 350 and scrapped the whole 305 mess. All of the accessories swapped over---I did not use the pan or any of those items.

cckutchma · 07-03-2006, 08:28 AM

Geez I hope it doesnt matter So other than tear-down there isnt any other way of telling the difference. What if I just pulled the oil pan could I tell then

Slonaker · 07-03-2006, 08:54 AM

I assume it is possible to tell the difference by looking at it, but I don't know how.

The numbers should be on the back of the block near where it attaches to the transmission. If you can find those, you can google them or look them up on www.mortec.com.

Slonaker

Slonaker

cckutchma · 07-03-2006, 10:06 AM

thanks for the input. I will check for those #s when this shoulder gets a little more healed up.

piecesparts · 07-03-2006, 10:19 AM

IF you pull the shield of of the flywheel area, you will be able to see if there is a difference in the design. A one piece seal is designed to install on the rear of the motor and it is bolted on, where the standard two piece seal is an integeral part of the motor. It will be evident, when you look.

06-30-2006, 06:50 AM	#1
cckutchma Junior Member Join Date: May 2006 Location: Springfield, IL Posts: 36	1 or 2 piece rear main seal help please! I am a newbie 1984 C-20 owner. It has a swapped 350 cid engine with a 4 speed manual transmission. Icannot find any VIN numbers on it. (the engine) As much as I have been told it is a 1985 engine. Is there any other way without stripping the motor down to tell the year. 80-85 2 piece 86 up one piece and how critical is the difference

06-30-2006, 08:06 AM	#2
greg0380 Registered User Join Date: Dec 2003 Location: CT Posts: 454	Re: 1 or 2 piece rear main seal help please! to the best of my knowledge, going to a 1 piece seal the oil pan, crankshaft, flywheel and transmission dust cover was changed. __________________ 1985 GMC Sierra 1500, 1/2 ton, 2WD, LWB, TBI 305 5 speed, 3.42 rear 2007 GMC Sierra 1500, xtended cab, 4X4, flexfuel 5.3L 1999 BMW 528i Last edited by greg0380; 06-30-2006 at 08:07 AM.

06-30-2006, 09:14 AM	#3
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	Re: 1 or 2 piece rear main seal help please! The two piece is supposed to seal better. On mine ('86 305) it did use a different pan and flexplate than my new 350. I reused the dust cover without any issues. You aren't going to notice any difference unless you start pulling stuff apart. Are you trying to do something to it, or are you just curious? Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

07-02-2006, 09:53 AM	#4
cckutchma Junior Member Join Date: May 2006 Location: Springfield, IL Posts: 36	Re: 1 or 2 piece rear main seal help please! Sorry about that been down with a shoulder injury. Yeah I am planning on dressing the engine up with a chrome oil pan and am not sure if theres a difference with the oil pans designs 1985-1986. Last edited by cckutchma; 07-02-2006 at 09:55 AM.

07-02-2006, 12:40 PM	#5
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	Re: 1 or 2 piece rear main seal help please! Yes, the '85 and '86 pans are different. When you look in the catalogs, the '86 pans are a different part number, and usually more expensive. Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

07-02-2006, 12:51 PM	#6
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: 1 or 2 piece rear main seal help please! Not ALL 86 engines were a one piece seal. I pulled the 305 out of my son's 86 and it was a two piece setup. I replaced it with a GM direct replacement 350 and scrapped the whole 305 mess. All of the accessories swapped over---I did not use the pan or any of those items.

07-03-2006, 08:28 AM	#7
cckutchma Junior Member Join Date: May 2006 Location: Springfield, IL Posts: 36	Re: 1 or 2 piece rear main seal help please! Geez I hope it doesnt matter So other than tear-down there isnt any other way of telling the difference. What if I just pulled the oil pan could I tell then

07-03-2006, 08:54 AM	#8
Slonaker Insert Witty Text Here Join Date: Oct 2002 Location: San Antonio, TX Posts: 3,415	Re: 1 or 2 piece rear main seal help please! I assume it is possible to tell the difference by looking at it, but I don't know how. The numbers should be on the back of the block near where it attaches to the transmission. If you can find those, you can google them or look them up on www.mortec.com. Slonaker Slonaker __________________ '86 Chevy C10 (Sold 04/19/13 ) Stock '01 Silverado

07-03-2006, 10:06 AM	#9
cckutchma Junior Member Join Date: May 2006 Location: Springfield, IL Posts: 36	Re: 1 or 2 piece rear main seal help please! thanks for the input. I will check for those #s when this shoulder gets a little more healed up.

07-03-2006, 10:19 AM	#10
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: 1 or 2 piece rear main seal help please! IF you pull the shield of of the flywheel area, you will be able to see if there is a difference in the design. A one piece seal is designed to install on the rear of the motor and it is bolted on, where the standard two piece seal is an integeral part of the motor. It will be evident, when you look.

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