Oil Pump & Rear Main Seal ( long )

[peter brandt]

> "are you absolutely sure it is leaking from the rear seal? You should be
able to look into the torque converter inspection hole and see the leak or
at least the oil on the converter.
>" tom

Tom,

Looking straight up between engine and transmission, I can see the end of
the crank sticking out of the block, and the flange the flexplate is bolted
to. Oil is leaking right from that area, I guess it could be the rubber seal
at the back of the pan, but the crank gets oily, too. If George's tranny
story is a thriller, my oil leak seems to turn into a mystery. I drove the
coach home from the shop last night ( 10 miles ), no leak. No oil stains
under it this morning, no leak after driving it to the storage lot. When it
leaks, oil runs down the inspection cover next to and into the starter.

">This almost sounds like you are pressurizing the crank case.Did you check
the PCV valve to see whether you have suction or pressure? I think I would
also check with a vacuum gauge on the intake manifold and then check
cylinder commpression to see if you may have a broken ring or hole in a
piston."<

Vacuum reading is 15" @ idle ( altitude about 6500ft ), 16" @ 2000 RPM ( no
load ), strong suction at PCV valve, no noticeable "blowby".
I did a compression test, 125psi cyl. # 2 & 4, 140 - 145 psi all others,
cold engine. The spark plugs that came out looked clean, no signs of oil
fouling, the engine didn't seem to use a lot of oil before it started
leaking - it starts and runs really well.

After cleaning things up I noticed red RTV all around the pan, so it has
been off before - I didn't find anything in the PO's records for the last 10
years, though. I have no way of knowing what kind of seal is in there - is
this a typical failure for a rope seal?

>"If this does not find the problem then you have a rather big job."<

"Big job" meaning the rear main seal, or worse?

I apologize for the long post, I know how difficult it is to diagnose a
problem over the phone or the net, so I'm trying to give as many details as
possible.

Thanks again,

Peter
77 Eleganza II
Colorado

 

[peter brandt]

> Peter,
> It really doesn't matter. Assuming you have eliminated any possibility
of
> oil running down from the intake manifold or distributor, and any problem
> with crankcase pressure, your leak is somewhere inside the bell housing,
It
> could be rear main seal, leaking oil gallery plugs, leaking cam bore plug,
> oil pan gasket, whatever. In any of these cases, you must pull the
> transmission for access, so do whatever it needs.
>
> Rick Staples
> '75 Eleganza
> Louisville, CO

Rick,

You're right - I've looked at this long enough, it's time to "just do it".
Since I don't have much experience working on big old V8s, I just wanted to
make sure I didn't miss something obvious.

Thanks for your advice,

Peter
77 Eleganza II
Colorado

 

[peter brandt]

> Peter,
> Are you sure the dip stick is calibrated right and the crankcase is not
being
> overfilled? Hope I'm not insulting you if this is too obvious. It seems
> strange that on your last time out it stopped leaking. Has the leak
resumed?
> Dave

Dave,

Thank you for your reply. I checked the dipstick last time I changed the oil
and filter, with 6 quarts it was pretty close to the full mark. I've added
oil since then, of course, and when it started leaking again on Saturday the
level was right between the add and full marks. The coach is in the storage
lot now, it wasn't leaking when I took it over there on Sunday. Like I said
earlier, I'm just going to have to pull the pan and get it over with, I'm
sure everybody is sick of my oil leak stoies by now!
BTW, I appreciate any and all input - you're gonna have to try a lot harder
if you want to insult me!
Seriously, I learn something new almost every time I read the GMCnet
messages, and I read them all - I probably need a life or something!

Peter
77 Eleganza II
Colorado

 

[peter brandt]

> Peter,
> Secondly, How bad is the leak? If it isn't creating a fire hazard or the
cost
> of oil running you broke it could be run for a while untill you decide to
> rebuild. Look at it as expensive undercoating?
> Dave
> 73 GoBus 230

Dave,

Mobil 1 undercoating - I like that!

It doesn't leak all the time, but when it leaks, it's BAD!
I noticed a slight oil smell that came and went, about 30 miles later the
smoke detector in the back of the coach started beeping! No fire, but lots
of smoke from oil getting on the mufflers. We're planning our first long
trip ( 3000 miles ) for the fall, so I really don't want to take a chance.
Like Tom W. says, "it's a lot cheaper to fix at home!"

Thanks,

Peter
77 Eleganza II
Colorado