[jct69z]

Ok guys. I promise I have done more than enough homework, reading previous post on this subject and trying to troubleshoot this problem before I resorted to asking for help (in typical male fashion).
Here goes...I had about 700 miles on a newly rebuilt 69 DZ302 when I notice a substantial oil leak dripping from the bell housing. After replacing the valve cover seals twice, putting dye in with the oil and detecting a small leak in to intake manifold and removing and resealing that, I now find myself with a very clean engine that still drips oil from the bell housing. Like other post, it only leaks while running at over 3000 or so. Does not leak when at idle or off. Bead of oil seems to form on underside of rear of oil pan but rear main around crank remains dry. Should I first remove and reseal the oil pan or pull the transmission and inspect the rear main and oil plugs in the rear of the block. Not wanting to take any real short cuts here but I would prefer to pull the engine as a last resort. Thanks in advance for all of your great help!

 

[Everett#2390]

Not wanting to take any real short cuts here but I would prefer to pull the engine as a last resort. Thanks in advance for all of your great help!

I think you said it all right there.

One thing you might do before pulling the engine is put some dye in the oil and look with a black light to "see" where the oil is leaking. You'll to drive the car for about 50-60 miles to dilute the oil and distribute it for the leak.

 

[dawg]

pull the pan first and reseal

 

[douvy]

I think you may be looking at one of the plugs in the back of the engine or possibly the rear cam plug. In either case it is a real pain in the neck to either pull the engine forward enough to get the flex plate or flywheel off or drop the trans. I had this happen once and pulled the engine forward. I chased the pipe threads on the problem plug and used teflon sealant, which took care of the problem. The problem is (as usual) the leak won't get better on it own. good luck.

 

[speedfreek]

I think you may be looking at one of the plugs in the back of the engine or possibly the rear cam plug. In either case it is a real pain in the neck to either pull the engine forward enough to get the flex plate or flywheel off or drop the trans. I had this happen once and pulled the engine forward. I chased the pipe threads on the problem plug and used teflon sealant, which took care of the problem. The problem is (as usual) the leak won't get better on it own. good luck.

This is where I thought it might be coming from.^^

 

[30lbtest]

bellhousing is lowest point, dont assume leak has anything to do with anything where you see the oil....I had oil drips in the same place and it ended up being oil pressure sender on top. the compression fitting on the tubing was junk. I also was using rubber valve cover gaskets, right side always leaked and oil was out of there too, went to cork and now a have a leak free motor. before you jack the motor to do the pan or seperate the tranny do all the easy stuff first.

 

[jct69z]

Thanks for all the advice. I have spent a lot of time looking for leaks (and dye) all on top of the bell housing. I feel pretty certain it is not leaking there any more. I am now wondering how much oil could have been in the bell housing from before and since I have the leak possibly stopped, if what I am seeing is residual oil that is leaking out. It is noticable less than when I first noticed the leak. Still doesn't explain why it only show oil at higher rpm's (1,500 - 2,500) though.

 

[JimM]

the bellhousing will hold a lot of oil. I'd bet it only "leaks" at higher rpm's due to the breeze from the fan.

 

[duntov3030]

jct69z.....Sounds like you're living the "recently rebuilt oil leak blues" like so many of us have. As you're finding out, oil leaks can surface in multiple places after a rebuild. Sounds like you've cured most of the easy stuff, on top of the engine. Since you're still seeing some leaking, presumably around the oil pan, I'd pull it, re-seal it and go from there. Since the engine has relatively few miles since the rebuild, you're probably getting a significant amount of blow-by around the piston rings, creating pressure in the crankcase that can force oil out, around an imperfect seal. The lower crankcase pressures at idle and lower rpm are not significant enough to cause a leak around a "pretty good, but less than perfect" oil pan seal. Let us know what you find.

 

[jct69z]

Thanks duntov3030, I'll take your advice and replace the oil pan seal!