Small oil leak from back seal, how long before seal go's?

[math1960]

Hello all, I've got a small oil leak from my blazer's back seal. What is ya'lls experience with this. Any idea how long before the back seal go's out? Guesstimate.

 

[JUNKYARDJOHN]

You're making it pretty hard not to come up with some smartxxx answer. John

 

[3dAngus]

Already gone. Replace.

 

[kevin-m1008]

If your talking about the rear main seal on the block?

I would wait until the leak gets to the point of you to being tired of the stains in the driveway. Or tired of keeping the engine oil level on the full mark.

mine leaks but by the time its due for a oil change its about 1 quart low. and who knows how much of that is being burned

YMMV

 

[math1960]

Thanks Kevin, that's the info I was looking for. I was told by a so called GM truck expert that on these old Blazers once the back seals start to leak any day there would be a sudden and catastrophic seal failure. I'm going to replace it but I can't right now. Thanks.

 

[DXTAC]

If it's leaking it's gone. It only gets worse as time goes on. I just couldn't stand kicking around the drip pan on the garage floor anymore so I did mine. Now the front pump seal is leaking on the tranny so it's time to do that too. That's a little more in depth than I wanna go though so I am going to have it rebuilt for $795 with a 3 year 36,000 mile warranty!!

 

[pctrans]

Look at it like this.....as long as it's leaking, you still got oil in it!

 

[SGT Estum]

I was under the assumption that ALL CUCV rear main seals leaked. I also assumed it's a lot of work to change it out.

I've got two M1009s and two oil soaked chunks of cardboard under them. They leak but it's pretty minimal.

 

[lavarok]

Thanks Kevin, that's the info I was looking for. I was told by a so called GM truck expert that on these old Blazers once the back seals start to leak any day there would be a sudden and catastrophic seal failure. I'm going to replace it but I can't right now. Thanks.

I would tend to agree with this "expert". A small leak is most likely NOT a rear main...a rear main will be a gusher. If it is the rear main and is small, it wont be for long. Remove the fly wheel cover and inspect. Oil pan leaks, valve cover leaks, and head leaks can easily explain a small leak dripping from the rear of the block.

I was under the assumption that ALL CUCV rear main seals leaked. I also assumed it's a lot of work to change it out.

I've got two M1009s and two oil soaked chunks of cardboard under them. They leak but it's pretty minimal.

If it is the rear main; it is not that hard to do... just very messy. I did a write up in the wiki for the job. Just commit a weekend and do it.

 

[DXTAC]

Seal is fairly easy to change out. Takes about 2-3 hours with basic tools on a creeper or on the ground. It's not necessarily fun but manageable. DEFINITELY messy as the drips from the open pan never stop. The longest part is waiting for the sealant to set. Mine had a newer style seal and NOT the old rope style. I'm going to assume it had been changed before after seeing the scoring. I think I'm going to buy a long block this spring or summer and swap it out anyway. But for now, no leak.

 

[Warthog]

While you have the pan off, you might as well replace the oil pump while you are in there. Cheap insurance.

 

[Barrman]

Are you sure it is the rear main seal? Use a light and look around the valley for evidence of fuel coming from the pump, draining out the little hole at the back and then running down to the crank and out the hole in the flywheel cover. Dirty diesel sure does look like dirty oil on the ground.

 

[10thMtn]

Troops, I too beleve that I made a major SCREW UP. I put some oil addative in last week. The Lucas, THICK stuff. Not alot , but what I felt would aid in lubrication. I beleve I have created a monster as now I too think I have lost a rear main seal. It is coming out the rear and the starter flywheel cover, and now even looks like its coming out the front on the timing cover ? Geezzz O man did I screw up ???? I would think you can still get this seal? What else should I tell my guy to replace while hes in there? Pan gasket im sure, OIL PUMP? ANYTHING ELSE ??? I would say right now im loosing 1/4 of a quart every 3 days or so.. I know its time @#$@#. I want to do the right thing here to preserve my unit, AKA Dubbed SAVOY 6 by my coworkers..hahah Geezz YOUR THOUGHTS ???

 

[lavarok]

I don't think the Lucas oil additive would have caused your problems. I use it all the time, but it is a lot warmer down here in Florida so thick goo tends to flow easier.

You should be able to buy the seal at the local auto parts store. As already mentioned above, change the oil pump as well while in there.

 

[Blue2actual]

Look at it like this.....as long as it's leaking, you still got oil in it!

That's brilliant. I never thought of it like that!

 

[top_prop]

have you cleaned or replaced you cdr valve?
http://www.steelsoldiers.com/cucv/48062-cdr-dummies.html
http://www.steelsoldiers.com/cucv/46068-cdr-valves-whos-got-em.html

 

[10thMtn]

CDR Valve was clogged with the SLUDGE mix of the Lucas and regular oil. I disconnected it for now. Let it drain out. UHH what a mess, so now I have a mix of , for the lack of a better term , "CRAP" draining on the block , I will give it a day or so and double check. I double checked the ATF and it was a little low but not black as if that seal had failed. I dont know I guess I will keep my eyes on it. Let me ask you all this , is there a breather other than the oil fil cap that it may be coming out of ? Like an overfil? Just reatching here. Lets say the CDR valve was the source of the problem? Building pressure I assume? Would that blow out the seal or ? What would it do ??

 

[10thMtn]

Lets say that CDR was the cause after reading the linked posts, DOES that cause DAMAGE to the REAR main seal? Meaning I clean and or replace the CDR am I still going to have an issue?
THANKS ALL , THANKS TOP PROP for the link.

I find it hard to surf through all this great info for exactly what I need , THANKS for the link

 

[jdeoliveira74]

I did mine it wasnt that bad. You have to drop the oil pan and oil pump but the replacement is a two piece slides right in after you get the old rope one out
I should have replaced my old oil pump while I had it appart just to be sure.

 

[top_prop]

why don't you give the cdr a good cleaning, pull the bell housing, whipe up the mess, and put it back together and see if you found the problem (clogged cdr)...

i'd then order a new cdr (sear cdr, cdr hummwv, etc at ebay.... one was listed for sale in one of the threads i linked....)

time will tell if you need a new rear main... in the interim just keep it full of oil