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Username Post: Rear oil seal or not?        (Topic#181078)
Forum Newbie
Posts: 59

Reg: 02-01-08
02-01-08 02:30 PM - Post#1356268    

I am new to this forum. I went from Chevys to Pontiacs in 1967 and I can build a 389-455 Pontiac engine blindfolded.

Now my problem. My daughter gave me a 1993 Chevy Blazer with a V6 engine and the engine has a serious oil leak. It has been determined by others that it is not in the oil filter area so apparently the culprit is the rear main seal, rear intake gasket or pan gaskets. A rear oil seal leak is a a real sore spot with 1955-1979 Pontiac V8 engines and you must remove the engine to install a new seal. However I have never had such a problem with the rear seal when I worked on 1955-1970 small-block Chevy V8 enginess. I only have experience with 1955-1970 265-350 Chevy V-8 engines and I understand the seal is different in design on those engines compared to the seal the later model Chevy V8 and V6 engines.

What should I look for before I look at the rear seal on the 1993 Chevy Blazer V6? Does the engine have to come out to fix the rear seal? If the engine has to come out to fix the rear seal, I may install a completely rebuilt engine and be done with it.

LMC Truck
"13th Year" Gold Supporting Member
Posts: 16147

Loc: Colorado Springs, CO
Reg: 08-08-04
02-01-08 03:31 PM - Post#1356306    
    In response to Duntov

Look at the oil sender on top of the motor. If it is a 4.3 v-8, it will be next to the distributor. Often, the oil pressure switch will start leaking here - and it looks just like a rear main seal leak. It is a lot easier to change the oil pressure sender than the rear main seal.

If it is a 4.3 93, it should have a one piece rear main seal, which is more resistant to failures. If you have to change it, you will have to separate the engine and trans - it's your choice on whether to pull the engine or the trans.

Forum Newbie
Posts: 59

Reg: 02-01-08
02-01-08 07:38 PM - Post#1356490    
    In response to Vaughn

Thanks .. The oil pressure sending unit is the next place I will look. I hope it is not the rear main seal. I don't know how the Chevy one piece seal works and don't know how to replace it at least not yet. I assume a '93 Chevy V6 with the one piece main seal is external and does not require removing the oil pan. Just removal of the bellhousing, clutch assembly and transmission.

The Pontiac V8 engine must be raised at least 10" in order to detach and slide the pan back past the oil pump pick-up screen and remove it. The bellhousing and transmission must also be removed in order to slide the pan back far enough to remove it. You might as well pull the engine since you have it nearly out by that time.

Dedicated Enthusiast
Posts: 6446
Age: 53
Loc: Kansas
Reg: 02-16-03
02-01-08 08:06 PM - Post#1356512    
    In response to Duntov

Done my share of rear mains on the Olds 5.7 Diesels. What a PITA!

No need to remove pan. It is just a big seal on the end of the crank. Your are correct in removing items stated + flywheel.

Regards, Jeff
1998 K1500 6.5 Coal burner
1965 C10 with 498 BBC AFR Heads
1964 C10 Ran 348W for 6 years, now SBC.

Corvettes owned: '74 '77 '78 L82 Silver Anniversary, 2002 LS1

Don't have a nervous come together!

"13th Year" Gold Supporting Member
Posts: 16147

Loc: Colorado Springs, CO
Reg: 08-08-04
02-02-08 08:57 AM - Post#1356781    
    In response to fritz1990

Jeff is right. No need to remove oil pan. The seal bolts to the outside rear of the block - so you remove (or move backwards) the trans and then remove flywheel/flexplate.

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