Slow leak from transmission

[Jhouser]

For the past several months I have had a slow drip coming right between the engine and transmission. I put dye in the engine oil and it is not coming from the engine. The drip is maybe 3 or 4 drops after driving and letting it sit over night. Never really see any drops in the parking lots and I have looked. The oil appears on the bottom of the brace that bolts from the tranny to the motor. The highest point I can find that is "wet" is just above "1cm" that brace on a little "shelf" on the tranny. This "shelf" is right behind the cover for the flywheel. After talking with Ben at daisy automotive over the phone he thinks it could be the seal from the engine to the tranny he has not seen it yet so thought I would ask around in case this has been seen before. I have periodically checked the tranny fluid level and it die not seem low. I have checked the clutch fluid as well and it has not gone down a bit. Is this something to watch or if the tranny seal time to spend the bucks on that?

Thanks in advance,

James

 

[Larry Bastanza]

A pic would be a significant help.

If it is the trans, you will need to pull it and relace the mainshaft seal. Typically I have seen this be an issue, and not very often BTW, if the mainshaft bearing has gone out.

HTH,
LarryB

 

[Jhouser]

Here is a picture with the area circled in red where I see the leak.

 

[OLDMNSX]

James,

I am not familiar with the dye that you are using. Do you use a "Black Light" to see the dye or is it visible with the naked eye?

Has the transmission fluid been over filled? Level the car and remove the transmission fill plug and see if fluid runs out. If so, let it set till it stops and then replace the plug. Is the engine oil overfilled?

Check the engine oil COLD each day before driving, sitting in the same level location and see if it is going down. After 10 days of driving you will know.

The area you are showing is the clutch housing. If you are having to add transmission oil then I agree with LarryB....transmission input shaft seal. If you have no other engine oil leaks and you are having to add small amounts of engine oil then you have a worn engine crankshaft rear main seal.



Remove the small flywheel/clutch cover plate and look up in the housing and see if you can tell if the oil is coming from between the flywheel and engine or from the transmission housing area.

I would have to ask the year and miles on your car, but would put money on the rear main seal being bad.

Same basic repair required.....remove the transmission and either replace the trans seal or remove the clutch/flywheel and replace the engine seal.

Either way the seal is only about $7. That is the good part........
Brad

 

[NSX209]

Possibly from the axle seal which connects the axle to the transmission case. Is your axle covered in oil?

 

[Jhouser]

Axle seals are good bone dry. I still think it is coming from the main drive shaft seal based on conversation with be @ daisy auto import. I will pull the dust cover to try to inspect more thoroughly.

Thanks,

James

 

[Larry Bastanza]

BTW, just to be clear, EVERY oil leak ends up where you are circled, so that location for the leak is not very revealing. Make sure you inspect VC Gaskets, spool valves, cam plugs again

 

[acuratech27]

BTW, just to be clear, EVERY oil leak ends up where you are circled, so that location for the leak is not very revealing. Make sure you inspect VC Gaskets, spool valves, cam plugs again

yes listen to larry leaks usually start high and work their way down. very rarely see a rear main and trans leak. good luck. keep us updated

 

[Jhouser]

I cleaned up under the car again and ran my hand around everywhere above the spot where I see the leak and looked at the spool valves, pulled the plastic shifter cable cover, etc and see no source of the leak. I pulled the dust cover and it did not appear it was coming from there. I also opened the fill bolt on the tranny and saw a small amount of fluid slowly seep out so I do not think it is over full. While cleaning up I removed the bolt in the transmission brace that goes to the engine and noticed that the threads were stripped/damaged and the aluminum was spiraled around the bolt. So it was overtightend at some point. I tried to loosely tighten and it will not take any torque (very loosely tried). I will need to get that repaired. Is there any chance that the bolt goes through and this could be the cause of the leak? Is this considered a major sturctural piece and should be fixed right away or still good for light driving? Only issue I see with the repair is that it sits right next to the header so would be difficult getting a thread repair piece in there. I put honda bond on the bolt and loosely tightened it for now and thought about driving around a bit to see if that is where the leak is coming from. If it is not coming from that bolt I have not clue where the source is. I will add dye to the tranny fluid next if that temp honda bond test does not work. Maybe the dye will be easier to see under the UV light to trace it.

James

 

[Brooklynzson]

I cleaned up under the car again and ran my hand around everywhere above the spot where I see the leak and looked at the spool valves, pulled the plastic shifter cable cover, etc and see no source of the leak. I pulled the dust cover and it did not appear it was coming from there. I also opened the fill bolt on the tranny and saw a small amount of fluid slowly seep out so I do not think it is over full. While cleaning up I removed the bolt in the transmission brace that goes to the engine and noticed that the threads were stripped/damaged and the aluminum was spiraled around the bolt. So it was overtightend at some point. I tried to loosely tighten and it will not take any torque (very loosely tried). I will need to get that repaired. Is there any chance that the bolt goes through and this could be the cause of the leak? Is this considered a major sturctural piece and should be fixed right away or still good for light driving? Only issue I see with the repair is that it sits right next to the header so would be difficult getting a thread repair piece in there. I put honda bond on the bolt and loosely tightened it for now and thought about driving around a bit to see if that is where the leak is coming from. If it is not coming from that bolt I have not clue where the source is. I will add dye to the tranny fluid next if that temp honda bond test does not work. Maybe the dye will be easier to see under the UV light to trace it.

James

Did you ever find out where the leak came from? I have the exact same leak.

 

[Jhouser]

No not yet, planning to pull the engine this summer so will find out then hopefully.

 

[99problems]

All these years and you never found out. My OCD would be on hyper drive.

I also have a similar leak. I'm replacing my TB/WP, cam seals, VC gasket, etc, and clutch very soon, so I'll update you with the possible culprit.

 

[Brooklynzson]

No not yet, planning to pull the engine this summer so will find out then hopefully.

Damn, you drove it for 4 years with that leak?

All these years and you never found out. My OCD would be on hyper drive.

I also have a similar leak. I'm replacing my TB/WP, cam seals, VC gasket, etc, and clutch very soon, so I'll update you with the possible culprit.

Thanks

 

[Jhouser]

So. I rebuilt the motor and took the tranny to a local shop and had them inspect and rebuilt it. Assembled and still have the leak. Initially saw it on the dyno. Did not seem bad as it seemed to leak a few drops as it cooled down. So I took it to the track this weekend and after 3 sessions it started coming out much faster and dripping while it idling. So what the hell is it. All seals have been changed. What did you guys figure out to be the problem. Btw not coming from high. Do not see it from insole the inspection either but hard to see in there.

 

[goldNSX]

Very annoying indeed. Did they separate the tranny from the engine?

If you think it's dripping faster when the engine is running it must be related to the oil pressure. Out of my head: did you check the oil pressure sensor? It's very hidden. You would see if there's a leak at the VTEC gaskets or the header cover gaskets.

 

[Mac Attack]

I have to say it... That's a really bad call taking a car to the track when you know it's leaking oil but you're unsure where it's coming from. Isn't that one of the inspection requirements before being allowed on the track?

Anyways...

If you are positive it's not coming from leaks up top, then it is either the engine rear main seal or from the transmission input shaft seal.

You say it wasn't coming from the engine previously due to the dye test. That means it was (probably still is) coming from the transmission.

What inspection/rebuild did the transmission shop do? You can't replace the transmission input shaft seal without opening up the transmission. Maybe they didn't replace that seal or damaged a new one installing it.