Oil Leak after Motor Build

[crazybear]

Did a complete rebuild on the motor and have put about 150 miles on it so far. Car is a 92 300zx TT 5spd. a puddle forms up on the garage floor overnight. its about 4-5" in diameter.

It is oil and not to be confused with trans oil. leak is exactly where trans and motor meet up. it pools up in that area. i can even see oil in the bellhousing and its seeping out a little where clutch fork is.

did a dye test this weekend and we could see a leak developing on the bottom lip of the rear section of the oil pan.

I assume it is the rear main seal, but that was replaced during the build. valve cover gaskets and cam seals have been replaced.

any suggestions on determining if it truly is the rms? i dont want to tear into it and find out it was a simple fix or oil pan leaking.

I even read that clogged PCV valves could cause a leak, I will check those tonight.

similar problem to me, but my RMS is new: slight-oil-leak-t284994.html

[crazybear]

so far clutch feels good and no slipping.

btw, i did not replace the RMS. a friend did it when he rebuilt the bottom end, but he has done many motors. is it possible he messed up when installing it?

[J30tChumpCar]

There is a possibility it was damaged on installation, it would have leaked immediately.

[crazybear]

There is a possibility it was damaged on installation, it would have leaked immediately.

Yea, the car has been leaking since day 1.

[J30tChumpCar]

I clean everything with non chlorinated brake parts cleaner (caution flammable) if possible compressed air then run for just long enough and reinspect, it may take several sessions and cans of cleaner to decide.

[t.mcginley.jr]

Is there any oil on the back or sides of the engine? or just on the trans/bellhousing area?

[crazybear]

Is there any oil on the back or sides of the engine? or just on the trans/bellhousing area?

nothing on the sides of the engine. its just in trans area. there is oil on the bottom lip of the rear part of the oil pan.

[t.mcginley.jr]

Is there any oil on the back or sides of the engine? or just on the trans/bellhousing area?

nothing on the sides of the engine. its just in trans area. there is oil on the bottom lip of the rear part of the oil pan.

Well basically since you know its not coming from up on the engine somewhere (i.e. valve cover gaskets, etc.) then it's probably your RMS. There's nothing else back there that would cause an oil leak. Like you suggested, it could have been installed in the retainer wrong. There's also the possibility that the crank had a deep enough groove worn in it from the previous RMS's that it isn't sealing properly with the new one. They sell thin sleeves the go over the end of the crank for this problem, but it's kinda late now.

How much oil leaks out? is it like a daily puddle or just some drops?

[crazybear]

there is a puddle everytime i drive it. its very thin, and about 10-12" in diameter

I was thinking it might be from pcv valves being clogged (i will check those before i tear into RMS) or too much pressure buildup in the crankcase. My camaro used to do same thing because the pcv was installed wrong and pressure was forcing oil out. wishful thinking that this could be the same thing. but its possible.

[t.mcginley.jr]

Yepp, definitely a possibility. These engines are fairly sensitive when it comes to their pcv valves (unless you bypass them, but that's another story). When's the last time they were changed?

[crazybear]

Yepp, definitely a possibility. These engines are fairly sensitive when it comes to their pcv valves (unless you bypass them, but that's another story). When's the last time they were changed?

well i bought the car from a friend with a blown motor (blew the piston rings). he told me he replaced them less than 5k miles before it happened.

[ThisIsSparTTa]

Most likely RMS it sounds like. If you google, you'll find LOTS of people that had to do them 2-3 times to get them right. A lot of people will recommend using a little RTV on the outside. I think I may have a slightly leaking RMS after my rebuild, but I need to finish up other leaks first to make sure.

Also, do a double check from up top. Find the HIGHEST point you can find oil coming from. 2 of my really bad ones were surprisingly the VTC solenoids. Not sure how I borked that (I previously did Valve Cover gaskets with no problems), but they were both leaking a good amount down the back of the engine and onto the transmission.

[t.mcginley.jr]

Most likely RMS it sounds like. If you google, you'll find LOTS of people that had to do them 2-3 times to get them right. A lot of people will recommend using a little RTV on the outside. I think I may have a slightly leaking RMS after my rebuild, but I need to finish up other leaks first to make sure.

Also, do a double check from up top. Find the HIGHEST point you can find oil coming from. 2 of my really bad ones were surprisingly the VTC solenoids. Not sure how I borked that (I previously did Valve Cover gaskets with no problems), but they were both leaking a good amount down the back of the engine and onto the transmission.

Same, my VTC solenoids and intake valve covers were leaking oil after my rebuild. I didn't tighten down the covers enough, which made it leak from there AND around the solenoids because the RTF didn't seal good enough.

Anyway, as long as he replaced the pcv valves with OEM ones they should be fine. In that case, it would really just be the RMS and not excess pressure.