SandW

Hey. Got a question for your mechanical expertise. On my 300ZX, the main rear seal is reportedly leaking. It doesn't leak much in my driveway (a couple of drips a day, maybe), but apparently at high speeds, the wind blows it back on my underbody and onto my exhaust. The other day, after 40 miles on the highway I stopped at a red let and my car started smoking considerably bad. I thought it was on fire, as did a guy behind me. It bellowed up from the mid section (visibly from the exhaust pipes) as well as up from the rear of the engine when I opened the hood. It had done this slightly before, but never this bad. However this time, it was right after it sat for 3 weeks and possibly had a chance to pool more oil on whatever it leaks on. I'm guessing that's why it smoked so bad this particular time.

Nissan diagnosed it as the main rear seal, and quoted me $1100 to repair. I'm gonna take it one other place to confirm before doing any mechanical work however.

Question, do you know of any good oil additives that work to swell-up seals to stop leaks? I figured I could apply it to the crankcase, drive it to see if it seals-up, and then degrease the under-body (Nissan said the underside was coated with blow-back oil residue) to see it it corrects it for good.

I'm afraid by messing with the major repair (the main rear seal), they'll disturb other stuff, and possibly make other seals bad by replacing that one.

If I do get the rear seal replaced, do you recommend doing any other seals to prevent another from going bad after the main rear is tight?

thanks!
Chris

b300z

i dont think theres too much they can wreck changing the rear main seal.
is it an auto or manual?

theres a few seals you can change on the manual while its out. check out the rear end, and also change the exhaust gaskets.

MikeZ

A little word of advice:
NEVER EVER open the hood of your car when there's smoke. No matter where it's smoking. As you stated in your case, it wasn't a prob. However, I don't recommend doing it again, 'cause if there really was a fire(electrical, or fuel induced), all you would be doing is giving the fire more oxygen, which can Combust fuel or allow the fire to spread, burning you or however else is near the bonnet. So yeah, that's what I learned from hanging around stock car races.

CanyonCarver

You're getting raped if you pay the $1100. If you're getting the RMS replaced, spend the money for a new clutch kit and tranny mount while the tranny is out. If you're bold, you can also add in a new 1-piece driveshaft.

SandW

Ooops, the car is an automatic.

I went to a larger Nissan dealer further away from me, and they only quoted me $750 (that's $400 difference from the first Nissan dealer). All they ordered for parts thus far is the oil pan gasket, and the rear seal. Each was only about $20. I haven't had the work started yet, won't until next week unless I change my plans. I really don't have the space, tools or time to do it myself.

Should I remind them to replace any other seals with my automatic transmission 300? Someone told me to get these done also:
rear main seal retainer gasket,
half-moon gasket,
& apply liquid gasket below the rear main.

Also, since the exhaust will be down, I thought to replace the stock stuff from the CAT back with something with a little more rumble to it. I have NO CLUE as to what to buy, any suggestions? I don't want it extremely loud and obnoxious, nor do I want it stealth--just a medium rumble heard from close-by.

lowkeyz

i replaced my rear main to find oil was still leaking from the bell housing a week later.. went to a nissan garage and talked to a tech. which helped me out a lot...there is an alum. housing around the rear main that has a paper gasket and another rubber seal between the housing and oil pan. that gets ol n brittle and leaks.. 2nd time in i replaced the rear main again and the rear mains housing gaskets.. be careful as to not roll the ears on the rubber gasket on the housing and oil pan or else IT WILL leak again.. after i fixed that.. no leaks.. Thanks nissan tech... it helped he was a fellow z owner

napoleonzheking

20 dollars? YUCK, RMS's are like 11 from coz... just do it yourself... 200-300 for a tranny jack. there's a writeup on TT.net abuot chanding the rear main seal I believe. or at least taking the tranny out. Self explanatory from there... but at a shop. I would say like no more than 500... but I don't take my Z's to shops. no one knows how to work on them (not even the nissan dealership here. took it there for a t-belt job, they didn't even replace the tensioner (even though they said they did)) yah anyways /rant off.