Need Advice with Tranni and Rear Engine Seals w Pics.

[oranngetang]

This is somewhat my first mechanical project, so these might seem like silly questions...

I have the engine and transmission out of my '70 Z. I had an annoying oil leak that would drip from the centre of the transmission onto the road, but couldn't figure out where exactly it was coming from. Upon removing the clutch linkage from the clutch cylinder I noticed the rubber boot was full of oil and this appeared to be where the oil was coming from.

The inside of the bell housing is oil-dirty but not exactly wet, and the flywheel on both sides is dirty, but dry. If the rear main seal on the engine was leaking I would think the flywheel would be damp or wet looking. It doesn't have the gear oil stink to it, so I'm wondering what you guys think the problem might be. The oil pan seal looks sketchy and wet, so thatmight be all it is. I took some iphone pics the best I was able to with a trouble light as a flash.

I don't know how many miles are on this car, the speedometer does not work, and it's been parked in a garage for the past 5 years or so.

I ordered an engine rebuild gasket set from MSA along with some other stuff, but didn't see any seals on their site. If anyone has a link or advice on where to get the seals I'll need to aquire, please PM them to me.

I've added some comment/questions to the pictures.

Rear Main Seal - looks like it might be worn, where the flash glare is.

Other Side

From the bottom

The dirty clutch cylinder boot / area. The cylinder seal itself seems dry, I doubt it's clutch fluid that is leaking.

Input shaft seal and fork. If it looks bad let me know, the rubbers on the fork look cracked and worn.

Another angle, looks like the oil is running down to the clutch cylinder boot from the front input shaft maybe.

Is this a crack or a stain, the way it goes two directions at the the bolt hole looks like a crack... Is it safe to reinstall this bell housing or should I be looking for another?

[spitz17]

I just did a very similar job to yours a few weeks ago.

My 2 cents is to replace ALL seals.

My rear main seal was leaking even though I didn't see a spot of oil on the flywheel or clutch. It was dripping down the back of the engine/tranny plate. My rubber boot was wet as well.

Once you replace the front transmission seal (remember to lubricate the inner lip of the seal), transmission front cover gasket, and rear main seal, reinstall everything. I say this, because you don't want to go back and replace the old seals a few months later if they decide to leak. If you still get leakage near the boot, it is most likely the clutch slave (or hose, if it's old enough). Keep in mind, from my experience, brake/clutch fluid sometimes drys up as it is not as heavy as oil. Again, if the clutch slave is leaking, replace it, but it is also recommended that you replace the clutch master cylinder at the same time, as you don't want a new slave or MC putting too much pressure on an old unit.

Also, there is another possibility of a rear main cap leak. There are four seals that slide into the block where the rear main seal's cap can be removed. I believe this must be done by removing the oil pan, which at the same time you can replace the oil pan gasket. Reference here: http://www.classiczcars.com/forums/showthread.php?37250-Rear-Main-cap-side-seals

Edited March 30, 2012 by spitz17

[oranngetang]

I don't mind changing everything, and it's probably a good idea like you said. Would you happen to have the part numbers or suppliers of the seals you ordered? I've been browsing rockauto, but there seems to be many different seals of different sizes and brands with the same part description. And I couldn't find any seals on MSA.

Just ordered Haynes manual and downloaded the Tom Monroe book to my Android tablet.

Edited March 30, 2012 by oranngetang

[Zed Head]

I had a similar problem, with oil running down the fork to the boot. I haven't confirmed it, because I have a different transmission in the car, but I think that it might have been leaking from the clutch fork pivot stud. On the FS5W71B, the hole for the stud threads all the way through the front cover to where the transmission fluid is. Looks like you have one of the 71A transmissions but it would be worth checking.

[oranngetang]

I ordered a rear main seal kit that should come with the side seals, a front input and rear output seal for the tranni, and a new clutch slave cylinder. I'll also take out that bolt, put some sealant on it and run it back in. Obviously new oilpan gasket is also enroute. Is there anything else I should do while I'm at it?

Another question, having the valve cover and oilpan off and on, I have been trying to keep any comtaminents out of the engine, but wouldn't mind giving it a 'flush' before sealing it all back up. Would diesel or something like it work to spray/drain out any dust before filling it with oil? I'll be doing an oil change after an initial run/flush anyway. I was expecting to be rebuilding this engine, but it looks like it's been recently done. The valvetrain and pistons look brand new, though the valves look a little out of adjustment.

[oranngetang]

The gasket set showed up a couple of days ago. Yesterday I set the valve lash and put the new main seal and side seals in, resting it further in to the block as to not ride in the old wear groove. I'm about to thread seal any internal bell housing bolts that penetrate the gear box, but Im hoping someone has advice for changing that input shaft seal. It looks like it'll just pull out with a pick and seal/push a new one in its place. Any thought? My books don't cover this.

Edited April 25, 2012 by oranngetang