Clutch contamination... rear main seal? (1 Viewer)

[Brimful of FJ]

Hi gang. Just want to say a quick apology to anyone that has answered on my previous posts. Life suddenly got in the way this year and kept me from the tank, but I'll be back in the game next month and will follow up on every post I started. I definitely appreciate all your help.

As I'm getting back into fixing up the car, I wanted to just do something simple this week before I go away for a few weeks, so I changed out the clutch fluid. It was black to start with. So I did the usual, but there was lots of air coming out the slave. I bench bled and there was then less air, but still a fair bit. However I did get the fluid perfectly clean. The main concern I have though, is after pumping the clutch a few times, I would try bleeding the slave only for murky, contaminated fluid to be present again. Where would this be coming from? Is there any obvious point of oil contact to the clutch fluid between the master and slave? There is no oil on the slave, including under the boot. But...

I have a clear oil leak present all over the bell housing pan, after which removing, can be seen on the release fork. (the fork doesn't have a boot, yet oil still hasn't travelled to the slave, in case you might be thinking that's the point of contamination queried above, it doesn't appear so on the surface). Does this seem to you like a rear main seal leak? And if so, is that what is getting into the clutch fluid? How?

Yes, there are screws missing from the pan, and there is no gasket. Previously neglected vehicle (not by me).

This car has not been driven for months, so none of the oil you see would be motion related, all passive seepage.

In review:
- Is this a rear main seal leak?
- If not, why so much oil?
- How is the oil (or whatever the contamination is) getting into the clutch fluid?
- Is there supposed to be a gasket around the pan? I have looked but can't find the answer. Name or part number?

Thanks in advance.

 

[charliemeyer007]

I have never seen black brake fluid - cloudy/dirty brown yea. I suspect the section of rubber hose and or the seals are breaking down. Could be due to age or someone added/used the wrong fluid, maybe they didn't the proper "red rubber grease" if they honed the cylinders. Any way if the rubber lining is going bad crap can leach out into your new fluid. I bought a new clutch master and slave with a braided stainless hose for like $160 off ebay. The hose is about 2' to long (fj45?) but for $50 more I could get a shorter hose. Clutch is now the best thing on my rig.

I have a rear main seal leak. I have the speedy sleeve to fix the issue, Next spring I'll install it. Plus I'll be doing the e-brake double seal fix then too.

 

[pb4ugo]

The clutch hydraulic system is independent, there's not going to be any cross contamination with oil. As mentioned, the hose or seals are probably breaking down. From your pics it looks relitively dry, you maybe getting gearlube seaping from the bearing retainer. Check the tranny, if it's over filled let it drain from the top plug and check the tcase gear oil level. We can't really see if the rear main is leaking.

 

[aging fleet]

A rear main leak really presents itself on the other side of the flywheel (not the clutch side). This is what my mine looked like, the seal is stuck to the flywheel and it's just coated with motor oil. If the leak is bad enough, the inside of your bell housing will be a slimy mess too.

Regarding motor oil and hydraulic fluid from the clutch, as @pb4ugo said, they don't cross paths. It looks like your oil leak is coming more from the transmission side.

 

[Brimful of FJ]

Thanks @aging fleet , good flywheel info. So you would suppose mine looks clean enough to not suspect a rear main leak in this case? That's a relief.
@charliemeyer007 It could be the hose, I'll attach a photo. Slightly aged in the outside, but I'd be surprised if it is that grotty on the inside. Thing is that the fluid coming out of the slave is only recontaminated if I have pumped the clutch, if I'm bleeding the slave without pumping the pedal, it stays perfectly clear. And the speed at which it gets murky again seems like more than a hose degrading. It looks like a fluid contamination when I'm bleeding it out. But, when I'm back in a month, I'll change that hose and see what the effect is. The master and slave do seem to look ok. Which seals were you suggesting could have issues?
@pb4ugo I opened the fill plug without it overflowing. Dipped my pinky, asked first of course, but didn't even reach the oil, so if anything, it's underfilled.

It may just be a bad gasket somewhere also as they are all RTV. Any prime suspects if that's the case?

I did mention there was no gasket on the clutch drain pan, is there supposed to be? Any part number? I can't find it.

 

[peesalot]

It looks to me like your rear main may be a bit seeping, the oil on fork is from trans, comes out the weep hole at bottom of bearing retainer, I have had same issue with my LS & sm420 for awhile, I periodically remove inspection cover to confirm what you see in your pic, a dry clutch, clean things up and see how fast it recurrs. I know when mine does it, long freeway runs it increases ( the trans drip), not ideal but the 420 doesnt need a rebuild yet and it has never gotten slung around in the clutch. Not saying leave it, or its proper just feedback.

 

[mattressking]

Spray it out with brake clean, wipe it out, watch it. The trans dripping looks to be the input shaft seal/gasket, can't service without removing the trans anyway, so it would behoove you to do RMS and clutch simultaneously.

 

[Brimful of FJ]

Late response, but back from my trip and getting back into the project from tomorrow.
Thanks for the input, I think I will get the essentials done and register it so I can drive, and will then do the seals on the transmission and RMS in one go when driving season ends. So I take it the general thought the main leak is coming from the input (maybe also output) seal along the transmission. I will replace them along with pretty much every seal I can find under the rig in a few months.

But I definitely want to get the clutch issue sorted asap. @charliemeyer007 I have taken note of that $160 replacement, but what did you think of the hose pic? And here is a photo of the clutch master, seems ok from the outside, as well as the slave. Do you suspect an issue with the seals in the master or the slave? Which is more likely to cause dark fluid coming out of the slave when bleeding? If you would like me to go into full detail explaining what I'm seeing when I'm bleeding it, I will go and get some pics for you. Thanks for the help.

 

[charliemeyer007]

Your pic above is the steel line that goes into the master. On mine about a foot down the steel line it coupled into a rubber line that went into the slave. My new kit is a one piece braded stainless hose that goes from the master to slave. The 10/18 pic looks like the rubber line - mine was all checked up on the outside (OEM 72) I didn't try to look or swab the inside.

Your cap and reservoir look clean. Use you finger and swab the under side of the cap - does it leave a black smear?

There are kits for both master and slave like about $20 each. You could hone the bores, install the kits in an hour or two.

 

[Brimful of FJ]

Your pic above is the steel line that goes into the master. On mine about a foot down the steel line it coupled into a rubber line that went into the slave. My new kit is a one piece braded stainless hose that goes from the master to slave. The 10/18 pic looks like the rubber line - mine was all checked up on the outside (OEM 72) I didn't try to look or swab the inside.

Your cap and reservoir look clean. Use you finger and swab the under side of the cap - does it leave a black smear?

There are kits for both master and slave like about $20 each. You could hone the bores, install the kits in an hour or two

Sorry for late response, I didn't actually get a notification about this post for some reason. I saw it last night. I took your hunch and double checked the hose, I think it is probably the issue, as you may concur with from the photos below. Its quite decrepit around the end. I should really have notice that area before.
The cap in the photo is new as the old one was cracking. A bit of dirt under the old one, but nothing scary. The reservoir is good because I cleaned it out while doing the first fluid change, it was like a shot of sambuka though. I'll post a pic of the fluid I just took out again now, which is the colour new fluid turns to after I pump the clutch a few times. I can only assume the hose must be rotting as you suggested. You also said seals could be breaking down. Which seals are those? In the internal mechanisms or the master and slave?

I would prefer to take your advice and get the braided steel, but I won't find it easily here and I'd be paying a fair bit for shipping, so I'll have to go with rubber. I will post when I've changed it over and tested. Next week I hope.

What would a dirty underside of the cap have suggested?

Clutch flexible hose part number: 90947-02358

 

[charliemeyer007]

Yea the internal parts can "rot" too. The rebuild kits have all the rubber parts. So the other day while is was working on wiring I noticed that there is now some blackness in the new master brake cylinder reservoirs from the caps. Been a few months and its not like what your pic has. I guess they are not putting in all the anti-oxidants in the rubber any more to save two cents.

 

[Paul_A]

Gear oil will smell far different than engine oil or brake fluid. If it isn't gear oil then check the rear of the valve cover for leaks. The fan blows it back and it collections at the low points like the clutch housing. Is your clutch master fluid going down? These are easy things to check. Clean and dry everything and keep inspecting. Eventually you should find the source.