Oil Leak on 93 240sx... Oil Seal... which one?

[sickamaya]

Hello all,

I've been the proud owner of a 93 240sx hatchback now for 7 and a half months now. During this last 7 and a half months I've acquired a new habitual obsession of reading through these forums... but nonetheless... I have done plenty and plenty of search filtering as well as just browsing through these forums for information and help.

Now... with that aside.

I've found lots of helpful information that has given me an idea of the problems i might be specifically having that happen to be common amongst 24o owners.

I'm not a mechanic... but am pretty much obsessing about being one... now anyways.

I'm going to lay this all down to get the best advice from you all as possible.

Ever since I've purchased the car, I've had an oil leak. I've made sure to keep oil in it at all times, so as far as I've been told.... that's all that it needs to not ruin the engine. At any rate, under the hood is getting more and more filthy as this time goes on. I took the car to my mechanic, and they tried a typical diagnoses, and concluded oil leak... probably front main or rear main seal. (are these 2 terms correct?) The problem is... I am getting different answers from different people. The mechanic specifically stated that wherever the oil leak is... it's about 7 hours of labor to get to where it's located, and they quoted me about 700 bucks to do the job.

I read on the forums that 240's commonly break oil seals when they are overfilled with oil. Which I have never done, since the damn thing was leaking when I bought it. It's not too severe, but I'd like to know how accurate what my mechanic told me was. What's the procedure for getting to this oil seal to replace it, meaning what all parts will need to be removed?

Again, these forums are my refuge, I've already had tremendous help from this community and my appreciation is infinite.

Another reason I ask this question in this manner is because I also happen to still have the rattling timing chain guides inside my engine, and have just been planning to use the genius guides that have been written up for the nissan lovers. If I'm going to be taking the valve cover and distributor off, would this be the right time to go ahead with the oil seal repair as well? Or do I just have no clue what the hell I'm talking about?

This is why I normally just read.

One final thing I have not really been able to pinpoint is with the vibration noises seemingly being caused by the PAIR Valve or something involving the intake pathway under the hood. This rattling sounds a bit like a fan does when you stick some cardboard through the blade cover, or like used to tie to the fork of our bicycles to rub against our spokes and sound like we were bad ***... you guys know what I'm talking about?

anyways this noise happens during the first 5 to 10 minutes of driving primarly during the brief decelertion that occurs with standard gear shifting (push clutch, off gas) really only from 1st to 2nd and 2nd to 3rd, and only around 2500 to 3000rpm. After the first 5 to 10 minutes... the problem goes away during the driving period, only to return every time i start to drive after the car has been parked and not running for some time.

I have used the FSM as my primary source of information regarding the 240sx... so I am associated with the terminology used in that book, especially when it comes to the parts. So I read, and thought it sounded like the PAIR VALVE or A.K.A. the Pulsed Secondary Air Injection Valve.

I've found the same trouble description on the forums but no one is really calling it the PAIR Valve, rather the AIV, which I assume is AIR INTAKE VALVE. Is the same part?

I just have to say that I am in a situation of budget planning, and I need to narrow these things down according to priority and exact cause of trouble.

I think that pretty much covers it.

So just to summarize my rambling ***:

Oil Seal? Which One according to description of problem? Guide to accessing the leak for seal repairs?

Should the oil seal be done along with timing chain guide removal in terms of convenience? (I ask this because timing chain guide removal seems critical and urgent and is my 1st priority at this point)

Lastly, according to description of rattling around intake area, what is the part giving me grief, and best solution to problem?

Thank You very much for being patient enough to read through my scattered *** brain's stream of consciousness.

Take Care!

[180fan]

The front main seal is very easy. Takes me about half an hour to get the car up, change the seal and back down. I will avoid the obvious steps of "raise the car"

Front seal:1. take belts off2. with a 27mm socket, pop the crank pulley bolt, either put the car in 5th or use an impact wrench3. with a 6" pulley puller and the bolt loosened out almost completely, tighten the bolt on the puller while keeping the crank bolt stationary. 4. When the crank pulley is about an inch or two away from the front cover, you should be able to wiggle the crank pulley off.5. Around the crank, you'll see a rubber seal, that's your front main seal. With a small flat head screw driver, pry it out of its groove but be careful not to score the mating surface on the front cover or the crank.6. position the new seal in its place. With a rubber mallet, you can tap the new seal in place.7. put the crank pulley back on, torque to 100 ft-lbs (verify this number, I'm pulling it from the top of my head and could be wrong).8. put your belts back on

Rear seal:1. pull the driveshaft2. if you haven't drained the fluid from the transmission, you can start cussing from the fluid draining out the back. Otherwise proceed to start removing the transmission.3. You'll see a pressure plate/clutch disc/flywheel (MT) or a flexplate/torque converter (AT) assembly staring you in the face. Remove these parts and now you'll see a big O. That's the main seal for the back.4. again with the small screw driver, pry the seal out but be careful not to score the mating surfaces. 5. Tap in with a rubber mallet or suitable tool. 6. Put back on the flywheel/clutch/pressure plate assembly or flexplate/torque converter assembly.7. sucker a bunch of friends to hold up the transmission while you tell em which way to move it around to get the transmission on.8. offer beers to keep them from killing you and put the driveshaft on.9. fill up fluids for the transmission

[180fan]

The rear one sucks big time to do. The front one is a cakewalk.

[AZhitman]

Bump for Article Status.

[rogoman]

Before you condemn either the front or rear crank seals, first pin-point the origin of the oil leak; you may just have a bad valve cover gasket leak. If there's a constant drip during operation, you'll need to jack up the front of the car and while it's idling, get under the car to find the source of the leak.

The chain rattling may due to a loose top chain guide or upper chain side guide; both of these guides can be permanently removed as per a Nissan TSB.

[rps-13]

i did mine today, it sopped leaking but then the leak came form the insides of the seal not form the sides or arounds, oil is coming form the crankshaft like from the area where it turns the oil pump why is this?

[rps-13]

i did mine but then the leak started to come from the insides of the crankshaft why is this? from the area that turns the oil pump, why is this ?