Replacing rear main seal 98 Suburban 2wd

**phoebeisis** · 02-16-2009, 10:01 AM

I changed the oil yesterday-1st time in about 8 months that I was under it(but it might have been leaking,I wouldn't always notice a leak)
I notice an oil drop on the filter,and oil kinda "around" that general area.
I don't think that the filter o-ring was leaking,and it was oil, not trans fluid.

Is this probably from the rear main seal-208,300 miles?

How difficult a driveway repair- jack stands etc- is this? How many hours-10-20?? for an amateur without air tools(but I might buy a compressor finally.

Thanks,
Charlie
PS I would be tempted to change out the motor( $2300 delivered for a new goodwrench GM motor), but this one gets such good mpg, and I'm broke(in debt, medical bills etc despite insurance), so I'll probably stay with this motor.I could credit card it-a new motor- probably.

**tbplus10** · 02-16-2009, 08:56 PM

A good possibility.
Why dont you clean the area up real good with some degreaser and keep an eye on it for a while.
This is a tough one, with that kinda mileage I dont think you'd find many people recommending replacing a rear main seal.
The engine has to be lifted at least a few inches to get the oil pan out to get at the rear seal.
Depending on the type seal your engine is using (1 piece or 2 piece) you may have to separate the engine and trans to get the new seal in.
Have you thought of a low mileage used engine?

**phoebeisis** · 02-17-2009, 08:42 AM

Tim,

Thanks for the response- not much forum response usually means it is an " oh, no" type question! Yeah, that would be a lot of work to fix a very old motor.

I will get under it today and really clean the area.

Just how will a leaking seal act? Will it just slowly increase the rate of leakage- OR will it suddenly become a gusher?

If the likelyhood is that it will just continue to slowly leak-1 qt per 2000 miles or so-than I'll just keep and eye on it, and replace oil until I can afford to replace the motor. If they suddenly become gushers, then it is a different story.

I'll clean it up once it gets a little warmer-coldish and wet today.

Thanks,
Charlie

**GaryL** · 02-17-2009, 10:15 AM

You will have to pull the transmission to get at the rear seal (1 piece). If it were me and only dripping a small amount (not covering the underside of the truck in oil) I would let it alone and just keep an eye on the oil level.

**phoebeisis** · 02-17-2009, 12:11 PM

Gary,

Thanks for the response. It used about 1 quart per 2500 miles on two 3000 mile roundtrips-all highway- last summer-maybe 2.5 quarts over 6000 miles of 68 mph travel.
I just assumed it was using-burning oil getting past the rings or the valve guide seals- for all I know it has been slowly leaking at that main rear seal for the entire 13000 miles I owned it.

The motor gets such great mpg I hate to just junk it.
Just eyeballing the dipstick and the drip-never noticed any under it, but I wouldn't notice the few drips it would make while off.

Yeah, just watch and wait might be the ticket for now.
Any idea if they -rear seal- just slowly increse in leak rate, or do they become gushers? Or is the answer-"sometimes they stay slow, sometimes they gush-no way to predict either way"

Thanks,
Charlie

**GaryL** · 02-17-2009, 01:34 PM

I've personally never seen one gush, but I'm sure it has happened to someone. Just keep an eye on it and you should be fine. I wouldn't junk a motor for a little oil usage. The 454 in my 78 has used a quart of oil every 3,000 miles since the day my Grandfather drove it off the lot new, but it never leaked.

**phoebeisis** · 02-17-2009, 04:58 PM

GaryL,

I like that plan. I mainly just drive it around the city,so if It breaks down,so what.Once or twice a year we drive to Flagstaff-3000 miles roundtrip, but that is at least 4 months off. So if it justs steady leaks 1 qt per 1000-1500 miles, so what.

The motor is really sweet otherwise gets great mpg-15 city 21 hy-so I would hate to dump it.Besides, we have big $$ problems right now. I would rather limp along for another 1.5 years when my $$ woes will be less.I would like to get a 2004 with 60,000 miles then.They are maybe $13000 now, but if gas goes up again, they will drop in price just like before.I won't care-I like the Suburban enough to keep it at $8 gal.

Thanks,
Charlie