Datsun Roadster Forum-311s.org

At a loss - Just can’t seem to find the source of a small annoying leak (6-8 drops total after each ride). It’s clear and has no real smell so must be engine oil.

Location: Appears to be coming from the vicinity of the clutch fork boot. Drops seem to slowly run down the passenger side of the bell housing (from somewhere around the rubber boot area) and then reach the lowest point of the bell housing (at the weep hole) before dripping down. **But, it’s not from the front trans seal nor the rear main seal. To confirm this I put a rag around the clutch fork boot to absorb any “mystery oil” and after 12 hours there is absolutely nothing from the weep hole and bottom of the bell housing is dry (1st pic). I ran a pipe cleaner in the weep hole to make sure it wasn’t plugged and still nothing. Normally I would see the first drop in about 20-30 mins after shutting it off. Also, it’s not coming from anywhere on the top of the engine (2nd pic) - Everything up there is dry.

What I’ve eliminated by observation so far: It is NOT the -
Hydraulic clutch slave (no leaks, reservoir never goes down),
Oil pan or trans pan (no leaks, leak originates somewhere higher on the car),
Tach cable connections (both dry),
Fuel pump and oil filter housing (both dry),
Trans pressure relief valve (working properly, no pressure leaks, area dry),
Front trans seal or rear main (as previously mentioned).

Like I said - I’m at a loss. Appreciate throwing some ideas my way and I’ll check each of them - Thanks.

I had a very similar instance, however it was on my CA18. This scenario was nearly identical though, and I chased this weird drip for a long time. It turns out it was leaking from between the oil pan and block where there was a slight Bend in it. It was right where one of the crankshaft counterweights were so it was forcing the oil through at high RPMs. The bend was minor and I used goop to seal the pan. There was also a bracket there, making it a good pry spot, but also obscured a proper view and helped to guide the oil down the back, making it look like a rear main leak.

D P wrote: Thu Oct 21, 2021 7:32 pm I had a very similar instance, however it was on my CA18. This scenario was nearly identical though, and I chased this weird drip for a long time. It turns out it was leaking from between the oil pan and block where there was a slight Bend in it. It was right where one of the crankshaft counterweights were so it was forcing the oil through at high RPMs. The bend was minor and I used goop to seal the pan. There was also a bracket there, making it a good pry spot, but also obscured a proper view and helped to guide the oil down the back, making it look like a rear main leak.

I originally thought it was blowback on to the bell housing & clutch fork boot from a oil pan leak as well. But I’ve confirmed there is no leak at all from the pan and the same drip happens in the same fashion whether or not the car is driven (idling for awhile produces the same resultant drip - eventually). Oil pan & trans pan are always dry.

Been chasing this Gremlin for a while now. Very annoying!

On a 1600 ? Rope seal
Ive seen cars come in no leaks , change oil and its like you didn't get the oil filter on right but the change of oil causes the rope seal to gush
Or a tiny crack / gap in the pan
You might dye it and look with a black lite

redroadster wrote: Thu Oct 21, 2021 10:54 pm On a 1600 ? Rope seal
Ive seen cars come in no leaks , change oil and its like you didn't get the oil filter on right but the change of oil causes the rope seal to gush
Or a tiny crack / gap in the pan
You might dye it and look with a black lite

1600 - Correct. Had that thought as well. But since I’ve confirmed there is no oil at all leaking from the inside of the bell housing or present on the trans faceplate (flywheel cover), that eliminates the possibility that it’s the engine’s rear main seal (or front trans seal for that matter) - That’s a good thing! A big plus for peace of mind.

I’ll keep the dye idea in my back pocket for use if I actually reach the point of unconditional surrender - Thanks.

Although brake fluid has a distinct smell...suggest you check the fittings on the brake proportioning valve. They may be weeping a little and gets worse after a drive with brake pressure...fluid running down a brake line perhaps? A quick touch with your finger will tell.

jrusso07 wrote: Fri Oct 22, 2021 9:08 am Although brake fluid has a distinct smell...suggest you check the fittings on the brake proportioning valve. They may be weeping a little and gets worse after a drive with brake pressure...fluid running down a brake line perhaps? A quick touch with your finger will tell.

That’s something I hadn’t considered, and plausible since the lines run right near the area where the oil is seen and if leaking, could have mixed with old oil (residual splash back) on the bell housing before dripping down.
Alas, just checked the valve, reservoirs and lines - No leaks.
However, everything I rule out should get me closer to finding the issue - Thanks.

Give it the taste test
Brake kleen it off and recheck
Oil leaks in the frt.migrates to the back of the engine , with the suction the car creates

redroadster wrote: Fri Oct 22, 2021 3:12 pm Oil leaks in the frt.migrates to the back of the engine , with the suction the car creates

Yup. Taking a systematic approach and checking everything with a gasket one by one … This will take a while