Rear Main Seal Replace

[BBGMC]

Ok so I officially need to replace my rear main seal does anyone know how hard it would be to accomplish this with the engine still in the truck? its a 2wd big block 402 out of a 71 truck with a th400. Also would it be more cost effective and time wise to pay a shop to do the work? does anyone know of a trustworthy shop in the Sacramento Area that can do this for a reasonable price?

[BCOWANWHEELS]

if your engine is hi milage and has alot of blow by then a seal wont fix it

[Beatcoaster]

I got a quote for this back when I first got my truck and a shop wanted $500 to do the work...This was for a 2 piece SBC seal, where they would have had to drop the driveline, tranny, flexplate, oilpan, etc and hope that there wasn't a burr on the crankshaft causing it. For that much you are halfway to a rebuild, might as well just pull the engine and replace all the seals and do some other maintenance/rebuild on it. It's doing things more expensive, but right, and giving you that peace of mind about your engine...Anytime a rear main goes out, I think you need to really inspect things to make sure the cause is age, not something chewing away at it...just my $.02

[airdale94]

If it's a rope seal it can be done but it's not for the feint of heart. It's not going to be cost effective to pay a shop. Unless it's pouring out or it's a perfectly running low mileage engine I would leave it till you can pull it with the intention of refreshening/rebuilding it. If it's a 2 piece rubber steel seel, it's easier, not sure what the BBC have. You still have to drop the pan.

[geezer#99]

Just replaced the rear main seal on my 67 gmc 250 6 banger yesterday. It's a 2 piece rubber seal. Jacked truck up in the driveway, put jackstands under it, pulled the pan and replaced the seal. Lots more fun laying on your back on cold concrete.
Just follow the instructions in the seal box. Top half of seal I pushed out with the end of my pen so I wouldn't scratch the crank surface. Lubed the new seal and slipped it back in. I've done several this way. 396 and 454 bbc were hardest to do. Only cause I had to remove 4 speed and bellhousing to get pan out in 70 Chevelle. This can be a daunting job if you've never done one before. Maybe find a friendly mechanic that you can watch while he changes it for you. Pan gasket and seal cost about 30 bucks at NAPA. Rest is labour cost. Depends on what needs to be removed could be a 3-4 hour job or more so 400-500 bucks would be normal.

[czarcaustic]

Wow I can't believe I logged on today and this thread was here -

I walked into my garage this morning and noticed there was a large amount of oil pooled where it shouldn't be - on my floor.

Since I don't know jack about engines - I just taught myself how to rebuild brakes and clean up the fuel system - I called my Father in Law over to tell me what the hell was going on. He got on the creeper and slid under the truck this is what he said:

"No oil from the front of your block or down the sides - oil pan is covered - must be your rear main. I don't think you need to pull the engine to fix it, these 350 small blocks are pretty easy once you pull the pan, we could probably do it on Saturday morning for about 25 bucks. You should head over to the parts house and get a rear main seal and another cork gasket for your pan." and slid out.

Is it as easy as the old man says it is or should I be seeking professional help?

[geezer#99]

Yup the old man is right. I know. I'm an old man too!! LOL. It's time consuming. Depends what you need to move or remove though. Did you check the rear of the intake manifold too. Or the back of a valve cover too. The gaskets back there can leak a bunch too. Could save some work even though the pan and seal job is good to learn. I had no oil on my pan but lots inside the bellhousing so I new it was rear main seal time and new clutch time too. Do some more checking first for leak source then get messy.

[myoldchevytruck]

Was watching Two Guys Garage the other day and they showed this product for repairing your Rear Main Seal. Those guys are normally pretty good about things. Maybe worth looking in to. Seems you can get it at your local Auto Zone or Advanced Auto. Here's the product link:

http://www.barsproducts.com/1050.htm

[myoldchevytruck]

Was watching Two Guys Garage the other day and they showed this product for repairing your Rear Main Seal. Those guys are normally pretty good about things. Maybe worth looking in to. Seems you can get it at your local Auto Zone or Advanced Auto. Here's the product link:

http://www.barsproducts.com/1050.htm

[BBGMC]

ok heres a little bit more info when I got the truck back in 2007 the guy told my dad that he and his dad had rebuilt the engine 5 years ago. now to my knowledge and after driving it everyday since I got it that statement was a lie it burns oil so valve seals are bad it has really good compression so that tells me that maybe just maybe they did a re ring job and cam now its always had a small drip of oil since getting it so in august I finally decided to see if the oil pan was loose which it was and so I snugged it up then noticed a larger drip and after about a hundred miles it went back to a slow drip a few spots here and there until yesterday I noticed it smoking bad but not running rough from oil in the combustion chamber so then I look and my exhaust system is covered in fresh oil I look on the ground at autozone and a huge running puddle is under my truck like it goes from the back of the engine to right under the rear axle so I have a Fel Pro 1 piece oil pan gasket with a cam lifters valve covers and fel pro ultra seal gaskets just dont have the rest of the parts or money to do it

[airdale94]

It might just need a pan gasket. If you tightened it up and it got worse for a while I would say it's your pan gasket.