Rear Main Seal

[Fuser1983]

So I got the truck up and running and it's doing fine. I had it listed on Craigslist here for $4900 obo, had some interesting trade offers, but one guy showed up with cash yesterday, and offered me $3500. I said I would not go any lower than $3900. He took it to Express Oil to get it looked, and came back saying that it needs the Rear Main Seal replaced and was quoted $600, and said he wouldn't go any more than $3500. So my questions are:

1. Was that a realistic quote for the job?
2. Am I getting a good deal from $3500-3900 or am I getting ripped off?

Thanks in advance!

 

[crazy4offroad]

I would stick hard at 3900 you already dropped 1k for him if he dont like it let him walk.

 

[dhamp]

Are you finding any oil droplets under the truck? He probably didn't snap any pics, did he? IMO, the guy was looking to ream you on the price and the mech was trying to make a buck. The seal could be starting to ooze a little, but could go for some years like that before it's a real issue. For an original truck in that condition, I wouldn't go that low unless you really need the money. Right now, it's just costing minimal insurance to keep it, so I wouldn't take an offer like that.

 

[Bagged Dually]

Call his bluff and tell him to hit the road and I bet he'll come back and buy it. If not you'll sell it in no time.

 

[Fuser1983]

Call his bluff and tell him to hit the road and I bet he'll come back and buy it. If not you'll sell it in no time.

Thanks! I stuck to my guns yesterday and told him I wouldn't take any less than $3900. It's an extra vehicle for me but I told him I don't mind keeping it. He really wants it, so it's not going anywhere unless he comes up on the offer.

There were couple of drops of oil under the truck, it's 25 years old so i'm not surprised it needs "something". But still, it's not a $600 fix.

 

[bucket]

A slightly leaky rear main (or anything else for that matter), doesn't change the value of an old truck. It just goes with the territory.

 

[19gmc84]

84 High Sierra 305 rear main seal

To replace rear main seal...I understand I should have two piece...it's an 84..so I can drop oil pan, remove oil pump and take off main cap.

Forgive me...I'm not a mechanic...i usually have help when I do these kinds of things...is this something I can do myself...I hear you have to jack engine up after loosening motor mounts to get oil pan out...but it appears to me the oil pan is prettty accessible.

What are the gotchas I need to know...we've put in the current engine ourselves but we're just shade tree kinda guys....so I'm not looking to have to pull tranny...or jack up engine...can I do this fairly easy? I got a quote of 450 to have shop do it...but I've been told if you don't do it exactly right...it will just start leaking again...so that's why I'm wondering if it's something I can do fairly easy I might just try it myself or should I pay the 450 and have shop do it.

 

[chengny]

Is that a 4WD? If so - it's not a hard job.

Get a Fel-Pro rear main seal kit # BS11829-1 and a Fel-Pro Permadry One Piece Oil Pan Gasket (if your dipstick is on the driver's side, be sure to get the right one)


Drain the oil, remove all the pan bolts and drop the pan.

Remove the oil pump bolt and pull the pump off the rear main cap.

Remove the rear main cap. Looks like this:

You must be registered for see images attach

You must be registered for see images attach

Roll the top half of the seal out of the housing - push up on one side with a screwdriver. The lower half will still be in the seal groove of the rear main bearing cap.

Clean up your oil pan rails and front seal groove with acetone/gasoline and a Scotchbrite pad.

Coat the lip seals with light motor oil - KEEP IT OFF THE MATING ENDS -
In your Felpro package you should find a small installation tool

This tool acts like a "shoehorn" to allow the seal to slide in its cavity without damaging it.

Be sure the lip seal is positioned towards the front of the engine

This seal CAN easily be installed backwards - all mating surfaces should be clean and free of oil

(NOTICE THE DESIGN: oil pressure is exerted against the lip forcing it to seal):

You must be registered for see images attach

Position the tip of the tool between the crankshaft and the seal seat in cylinder case
position the seal between the crankshaft and the tip of the tool so the seal bead contacts the tip of the tool.

Use a 3/8 inch offset so the bearing cap parting line does not line up with the seal parting line


Roll the seal around crankshaft using the tool as a "shoehorn"

Push seal up in cylinder case an extra 3/8 inch - this offset will be on the bearing cap half of the seal as well

Install the other seal half in the bearing cap

Apply sealant ( High Temp RTV Silicone ) to the butt seams. Note- the image below does not show the 3/8" offset between the seal butts and the bearing cap seam:

You must be registered for see images attach

Install the rear main cap and torque to specs.

Install the oil pump.

Install the oil pan using the Perma-dry gasket. Install this gasket dry - apply a tiny bit of silicone only in the corners - where the pan meets the front and rear seal housings.

 

[19gmc84]

Is that a 4WD? If so - it's not a hard job.

Get a Fel-Pro rear main seal kit # BS11829-1 and a Fel-Pro Permadry One Piece Oil Pan Gasket (if your dipstick is on the driver's side, be sure to get the right one)


Drain the oil, remove all the pan bolts and drop the pan.

Remove the oil pump bolt and pull the pump off the rear main cap.

Remove the rear main cap. Looks like this:

You must be registered for see images attach

You must be registered for see images attach

Roll the top half of the seal out of the housing - push up on one side with a screwdriver. The lower half will still be in the seal groove of the rear main bearing cap.

Clean up your oil pan rails and front seal groove with acetone/gasoline and a Scotchbrite pad.

Coat the lip seals with light motor oil - KEEP IT OFF THE MATING ENDS -
In your Felpro package you should find a small installation tool

This tool acts like a "shoehorn" to allow the seal to slide in its cavity without damaging it.

Be sure the lip seal is positioned towards the front of the engine

This seal CAN easily be installed backwards - all mating surfaces should be clean and free of oil

(NOTICE THE DESIGN: oil pressure is exerted against the lip forcing it to seal):

You must be registered for see images attach

Position the tip of the tool between the crankshaft and the seal seat in cylinder case
position the seal between the crankshaft and the tip of the tool so the seal bead contacts the tip of the tool.

Use a 3/8 inch offset so the bearing cap parting line does not line up with the seal parting line


Roll the seal around crankshaft using the tool as a "shoehorn"

Push seal up in cylinder case an extra 3/8 inch - this offset will be on the bearing cap half of the seal as well

Install the other seal half in the bearing cap

Apply sealant ( High Temp RTV Silicone ) to the butt seams. Note- the image below does not show the 3/8" offset between the seal butts and the bearing cap seam:

You must be registered for see images attach

Install the rear main cap and torque to specs.

Install the oil pump.

Install the oil pan using the Perma-dry gasket. Install this gasket dry - apply a tiny bit of silicone only in the corners - where the pan meets the front and rear seal housings.

Thanks so much...excellent details...think I'll try it...yes it is a 4WD and the dipstick is on the passenger side. The block number indicates if I remember correctly it being like an 84 engine...so with the year and the stick being on the passenger side...that should indicate it being a two piece correct. From what I've read...86 and above GM switched to the one piece and the dip stick didn't give an indication anymore after 86.

 

[chengny]

Anything prior to 86 will be a 2 piece rear main.

Also, if you can remember - when you changed the engine, did your flex plate not look like this:

You must be registered for see images attach

if so, you have a two piece rear main seal.

That medieval looking thing is an external counter weight and is only used with one piece sealed crankshafts.