AMC Eagle Den Forum

The Mighty 258 => The Engine => Topic started by: lapoltba on January 19, 2013, 04:38:27 PM

Title: Does it look like I need a rear main seal?
Post by: lapoltba on January 19, 2013, 04:38:27 PM
I'm mechanically inclined, but have limited experience with cars, and zero with the 258.

Here are a few pictures of my bell housing as it was when I removed it this morning.  My question is:  Does it look like the oil is from the rear main seal or is that just normal clutch dust mixed with water/grease/oil and to be expected?  

The head had been rebuilt and installed professionally with a new (non-plastic) valve cover.  Looking at the head, there is no oil leaking from up there.   I haven't taken the flywheel off and won't unless I have to, since the flywheel was obviously resurfaced recently.

For some reason they aren't embedding properly.  LINK TO THE GALLERY INSTEAD: http://min.us/mZghaEmKETxSX (http://min.us/mZghaEmKETxSX)


(http://i.minus.com/ibhjxEfepqBXrF.JPG)
(http://i.minus.com/iIy9WcH6mKZQl.JPG)
(http://i.minus.com/iTy5PONOHI6lD.JPG)
(http://i.minus.com/ibhVgaCFxvDtUP.JPG)
Title: Re: Does it look like I need a rear main seal?
Post by: vangremlin on January 19, 2013, 05:28:37 PM
How much oil are you going through?
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 19, 2013, 05:32:26 PM
Well, the car is being resurrected from sitting 10-15 years and has not been on the road.  I let it idle for 15-20 minutes in the driveway last weekend since It had been sitting outside in the yard at the shop for a few months.  

So to answer your question.  I don't know.

I would hate to get everything back together just to find out that the seal is leaking and I need to pull it apart again.
Title: Re: Does it look like I need a rear main seal?
Post by: eagle87 on January 19, 2013, 06:14:36 PM
i believe the answer is when in doubt replace!
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 19, 2013, 06:18:03 PM
I know that's always the right answer, but it's not the one I wanted to hear.  I haven't put the clutch back on yet and I need to get the exhaust downpipe off tomorrow. I'm going to see if I can poke around a bit more and figure out it it is actually leaking I guess.   It's hard to see with the flywheel there.
Title: Re: Does it look like I need a rear main seal?
Post by: mudkicker715 on January 19, 2013, 06:39:18 PM
Pulling the flywheel doesn't take much. however i do not thonk it will give a better answer.
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 19, 2013, 06:43:47 PM
It takes alot more when I don't have a compressor to run the impact gun...  :banghead:

Anyway, I asked the question knowing I didn't have enough info to get a really good answer.  I just wasn't sure if anyone could really tell by what was inside the bell housing.
Title: Re: Does it look like I need a rear main seal?
Post by: vangremlin on January 19, 2013, 07:57:50 PM
As I understand it, there are two ways to two options for changing the rear main seal.  Either pull the engine, which means disconnecting the bell housing and transmission, or dropping the front drive train to get the clearance necessary to remove the oil pan, which as I understand it, doesn't require separating the engine from the transmission.  Depending on exactly where you're at in putting things back together, replacing the rear main now may save you some work, but then again, it may not.

How's that for helpful advice??   ;D
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 19, 2013, 08:02:26 PM
Heh.  I've been doing some searching and reading on my own and came up with the same info.  At the moment, the entire trans and bell housing are removed already and the engine is supported from underneath.   

I would feel much more comfortable tackling this if I had one of those ever so helpful guides.  Something like "Rear main seal change for dummies" would be perfect.   Even better yet would be a fellow Eagle owner somewhere nearby that would be willing to lend a hand for a day. 

Like I said, i'm mechanical inclined, and can tackle most anything with proper instruction/guides/info.  Wrenching on engines and transmissions is not something I am too terribly comfortable with though.
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 19, 2013, 08:14:36 PM
I was just thinking...  The back of the oil pan and everything else outside the bell housing looks fairly good. 

Again, not knowing much about the 258 and t4 in my car....   Would an input shaft seal on the trans leak and spew oil/ATF like this?  If a rebuild would be good, now is the time to do it since the trans is sitting on the floor under the car.
Title: Re: Does it look like I need a rear main seal?
Post by: Bird-o-Prey on January 20, 2013, 11:25:37 PM
IF...you decide to replace the rear main seal.  I would recommend pulling the engine out to do it.  I have replaced the main seal by bracing the engine and lowering the front cross member.  I had a number of the welded in nuts inside the frame rail become 'un-welded' during removal, thus necessitating further drilling and welding when I put it back together.  I am not a licensed mechanic, but I have been wrenching on cars since I was about 10.  In my experience, I would never do it that way again.  At least with the engine out, you can really gain access to clean the engine bay as well as have unrestricted access to the bottom of the engine to change the seal as well as the oil pan gasket as well as seriously degreasing the engine!  It is also an opportunity to change the cam shaft and gears and chain (if you are so inclined) as the radiator and AC condenser are not in your way.

I plan to do that myself this spring.  Pull the engine and swap to a 4.0 head as well as change the lifters and pushrods and camshaft and gears and chains.  I will replace the main seal and oilpan gasket and clean & paint the engine as well.  The point is, you will be much better off with the engine out instead of lying on the ground getting dirt and oil in your face.

My 2 cents.
Title: Re: Does it look like I need a rear main seal?
Post by: eaglefreek on January 21, 2013, 06:34:07 AM
I would inspect the engine side of the flywheel. If it is relatively free of oil residue I would suspect the input seal of the transmission.
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 21, 2013, 06:58:15 AM
The engine side is bone dry.  Very dusty & dirty, but dry.  Looking at the splines on the input shaft, the are not greased as you would expect, they are wet with oil/fluid.  I suspect it is the input shaft seal on the trans as well.  I will pick a seal up tonight on my way home from the dentist.  Won't have time to do much with it though.  It's a cheap part and relatively easy to do since the trans is already out so i'll start there.

Thanks for the tip.
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 24, 2013, 06:47:45 PM
Pulled the input shaft cover/housing off tonight.  The seal was dry and had a few small cracks in it.  I don't know if it is the original one, but whoever put it in used red loctite on it and it was a *itch to get out.  There was also black RTV on the bolt flange so I cleaned everything up with a razor blade and a brass brush.

Popped the new seal in with a very light coating of Permetex Black on the outside only.  Also put a light coat on the mating flange and it's curing for an hour or two, then i'll tighten it down.  Can anyone direct me to a torque spec I can reference?  I thought there was one in the eaglepedia but I couldn't find it.
Title: Re: Does it look like I need a rear main seal?
Post by: BenM on January 25, 2013, 04:10:03 PM
I can only find for an SR-4:
"Be sure to align groove in cap and cutout in gasket with oil hole in case. Coat bearing cap bolts wit nonhardening sealer and install bolts."

Tighten bolts to 13 foot-pounds - 18 Nm.
Title: Re: Does it look like I need a rear main seal?
Post by: lapoltba on January 25, 2013, 04:34:57 PM
Hmm, there was no gasket and I didn't see an oil hole....  Working on downloading and installing the mitchell on demand manuals, or the alldata manuals, hopefully I can use that.


Ahh, nevermind.  I found the t4 t5 suppliment.  No such gasket or alignment called for.