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Dear members,

Yesterday my dad just bought a Datsun 240z with a 280 motor swap. Today I figured I’d just check under the car for any oil leaks. And sure enough there was a substantial puddle of oil. Right underneath the u joint. Any one an idea what the cause could be of this leak?

Some observations we made: 

tranmission whines a bit (is this normal behavior?), the car jerked a bit yesterday while accelerating but later stopped jerking.  car has been restored (in 1998), recently new fluids: transmission, engine & diff. 

Also so the right floor pan is rather wet and greasy from underneath the car. 

I hope sincerely someone can help us out in finding what the cause could be of this oil leak. Thank you in advance!

Kind regards,

Winston

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Hi Winston, welcome to the forum.  That could be the rear output shaft seal on the transmission and/or someone pumped too much grease into that Ujoint and the grease is being flung off at high revs.  Get under the car with a rag and clean the area and Ujoint so when you next check it you will get a very clearly which one it is.  While you are under there open the fill hole on the transmission, if the fluid is at the right level it should start dripping out as soon as you remove the plug, if not fill the hole until it does.  Replace the plug and take the car for a drive but make sure you get the drive line up to temp, a spirited drive.  After the dive have another look.

If it was the Ujoint you may find there area still clean as you cleaned off the excess, if so you are done. If it is the transmission seal that is leaking the driveshaft will need to be removed and the seal replaced.

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8 hours ago, Winston456 said:

Yesterday my dad just bought a Datsun 240z with a 280 motor swap. Today I figured I’d just check under the car for any oil leaks. And sure enough there was a substantial puddle of oil.

You said puddle but didn't show one.  Unless that blank video has one in it.  Some video formats don't make it through, probably a phone thing.

Gear oil has a distinctive smell.  That rear seal is known to wear.

Did he buy the car for you or is it his?

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59 minutes ago, Zed Head said:

You said puddle but didn't show one.  Unless that blank video has one in it.  Some video formats don't make it through, probably a phone thing.

Gear oil has a distinctive smell.  That rear seal is known to wear.

Did he buy the car for you or is it his?

Oh im sorry for the puddle not showing, must indeed be a phone thing. I added a photo with the puddle. 

Smells like gear oil. It's his car. 

The car is getting fixed for free by the guy that sold it to us.  It's getting picked up tomorrow (transport truck not driven) 

Thank you Zed Head & grannyknot for responding!

Kind regards,

Winston 

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One other thing to be aware of is that when the seal wears really badly it can then wear a groove in the driveshaft slip yoke.  There's a metal spring inside the rubber seal that can wear through.  Metal on metal then.  Your leak looks like a bad one.

If the owner pulls the shaft and finds a groove you might want to wait on the repair.  The 240Z slip yokes are replaceable.

Good luck.

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No one mentions a bad bearing in the end of the gearbox?  What happens after the "repair" ..  putting in a new oilseal at the end of the trans..  this seal will wear very fast and you'll end up with the same problem..  check if there is any play in your driveshaft that is coming out of the gearbox.. just a mm is enough to break your new seal that the seller now is putting in..  You got a bad leak there and i'm not surprised if you have/had  to put half a litre of oil into your gearbox to fill it up.  Keeping it topped of is very important..

(after you got the car back from repair check the play by shaking the driveshaft just behind the gearbox.. there shoud be NO play.  do this also after a good run-in of the seal, say 100 miles..160 kms..?  i bet it will leak again by that time if the bearing is bad..)

Edited by dutchzcarguy

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3 hours ago, dutchzcarguy said:

No one mentions a bad bearing in the end of the gearbox?  What happens after the "repair" ..  putting in a new oilseal at the end of the trans..  this seal will wear very fast and you'll end up with the same problem..  check if there is any play in your driveshaft that is coming out of the gearbox.. just a mm is enough to break your new seal that the seller now is putting in..  You got a bad leak there and i'm not surprised if you have/had  to put half a litre of oil into your gearbox to fill it up.  Keeping it topped of is very important..

(after you got the car back from repair check the play by shaking the driveshaft just behind the gearbox.. there shoud be NO play.  do this also after a good run-in of the seal, say 100 miles..160 kms..?  i bet it will leak again by that time if the bearing is bad..)

Beste dutchzcarguy,

Dankjewel, we zullen er naar kijken!

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a few things to consider, is it gear oil or engine oil, already mentioned but you need to be sure.

IF gearbox oil, is it properly filled (not over filled), if its overfilled its likely to exit the vent on the top  and find its way down.

Is it the correct oil?

once that is for sure, then a through cleaning is in order, remove the shift boot and rubber cabin seal so you can see the top of the trans. Make sure all is cleaned up there. Remove the boot that fits on the transmission where the stick shift comes out (the smaller inner boot) See if there is excessive oil there. Clean out as best as you can.

replace the trans boot (the small rubber one not the larger rubber cabin seal boot).

With everything squeaky clean go drive it a few miles and then come back and carefully inspect.

Leaks from shifter linkage, vent, tail shaft seal, speedo drive are all suspect, so you want to catch it before the oil migrates and make it hard to find.

As others have mentioned, if the tail shaft bushing is worn too much, then the seal will have a tough time dealing with the excessive movement

 

 

 

 

 

 

 

 

 

 

 

 

 

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17 hours ago, Dave WM said:

As others have mentioned, if the tail shaft bushing is worn too much, then the seal will have a tough time dealing with the excessive movement

Oh well.. i've got new (seal) and used parts (shaft (parts)) for that…  

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