Engine Oil Drips From Block Plate Every 4-5 Seconds?

Pate · Sep 17, 2017

I have a 86 mustang gt 5.0 converteted to edelbrock carb with a 5 speed tranny. Noticed oil drip from block plate/inspection plate coming from block side. It would only drip while running and only every few seconds. So I removed tranny, clutch, flywheel, to see the rear main seal didn't appear to be leaking? so I changed it out with new one any way. I used felpro one piece. Also noticed lots of oil on oil pan near rear so I went ahead and got the 4 piece cork/ rubber set and installed it. Then I went ahead and changed valve cover gaskets. Then installed new flywheel and used black rtv on all bolts. New clutch kit and remounted tranny. Now I started car let it run till normal operating temp and not a single drop for the whole 30 mins it ran. Shut it down reinspected and everything was great not a drop of oil anywhere. Next day I let it run for a hr still no drops. Today I start it and ten minutes in it starts to drip again from front of block plate every 3-5 seconds? Now when I got the car it was leaking this away and also noticed that it has a pvc valve on passenger side valve cover that runs to carb and a chrome breather cap on driver side? Isn't it supposed to be one or other setup only? Would this cause me issues?

imp · Sep 17, 2017

Pate said:
I have a 86 mustang gt 5.0 converteted to edelbrock carb with a 5 speed tranny. Noticed oil drip from block plate/inspection plate coming from block side. It would only drip while running and only every few seconds. So I removed tranny, clutch, flywheel, to see the rear main seal didn't appear to be leaking? so I changed it out with new one any way. I used felpro one piece. Also noticed lots of oil on oil pan near rear so I went ahead and got the 4 piece cork/ rubber set and installed it. Then I went ahead and changed valve cover gaskets. Then installed new flywheel and used black rtv on all bolts. New clutch kit and remounted tranny. Now I started car let it run till normal operating temp and not a single drop for the whole 30 mins it ran. Shut it down reinspected and everything was great not a drop of oil anywhere. Next day I let it run for a hr still no drops. Today I start it and ten minutes in it starts to drip again from front of block plate every 3-5 seconds? Now when I got the car it was leaking this away and also noticed that it has a pvc valve on passenger side valve cover that runs to carb and a chrome breather cap on driver side? Isn't it supposed to be one or other setup only? Would this cause me issues?

The PCV should have a hose connected to it running to manifold vacuum pick-up. The breather cap on the other side filters and allows air to enter the engine's crankcase, and leave via the PCV. This gets rid of crankcase gases and burns them. Occasionally, a faulty PCV will "bleed" oil into the vacuum hose in small quantity, but none of this discussion should relate to your oil leak.

On the rear of the engine block there are two plugs driven into the holes running the entire length of the block which carry oil under pressure to the valve lifters. Often those plugs are a source of "mysterious" oil leaks. If you did not check them when the opportunity was there, well.........
imp

Pate · Sep 17, 2017

Now if ur referring to the two little screw in plugs behind the flywheel and above the rear main seal. I did notice them. I seen a little oil in that whole region but it was mainly a lot of built up oil. I wiped it all down really good and all around the plugs and never seen it build up around the threads. Should I have maybe unscrewed them and added some black rtv to them?

imp · Sep 18, 2017

Pate said:
Now if ur referring to the two little screw in plugs behind the flywheel and above the rear main seal. I did notice them. I seen a little oil in that whole region but it was mainly a lot of built up oil. I wiped it all down really good and all around the plugs and never seen it build up around the threads. Should I have maybe unscrewed them and added some black rtv to them?

It would not have hurt. I remember those plugs from way back being just like freeze plugs, driven into place. Screwed in plugs much less likely to leak. Have seen driven in plugs blown out, complete loss of oil pressure, but long ago. I'm guessing your plugs are OK, but guess is all it can be. Maybe main seal not right? imp

Pate · Sep 18, 2017

Just hate that it was all fine for about 2hrs now the leak is back. Is a drop every 4 seconds pretty bad? Would trying the bars main seal repair be worth a shot?

General karthief · Sep 18, 2017

Check the back of your intake, if it has the cork gasket it's guaranteed to leak. What intake are you using?
They make a one piece oil pan gasket that works better than the old cork stuff, rubber valve cover gaskets too.

Pate · Sep 18, 2017

It does have cork on intake. I did look there first and wiped it all down real good behind intake and there is no stream or leaks coming from it. I'm not sure what intake I'd have to look. It was already done when I got car. I did the 4 piece oil pan so I didn't have to lift motor at all. Now I have not drove the car at all. Only let it run in my driveway. And like I said did fine for 2 hrs of idiling all together and then all the sudden back to the drip every 3-4 seconds? I've double checked and even triple checked the valve covers and the rear of intake for leaks with no signs. Also it only drips while running once it's off it stops.

Pate · Sep 18, 2017

Now I did notice that the first couple days my oil pressure was running near the A in normal on gauge then yesterday when the drip came again my oil pressure stayed more to the O of normal on gauge? Don't know if this is related or not or just a possible dirty tube or weak oil pump.

General karthief · Sep 18, 2017

I would suspect the rear main seal, what happens is the surface of the crank where the seal rides has worn down enough for it not to seal good, they make a sleeve that installs over the crank end to take up the worn space so the new seal can do its job, also what happens is the new seal was not lubricated when installed and wore the rubber prematurely or the spring poped off. Unfortunately you will have to pull the trans and related stuff to get to it so make sure the drip is not coming from someplace else but I bet'n on the rear main seal by you description.

Pate · Sep 18, 2017

That's what I figured too. I did put oil on inside of seal where it meets crank and I put black rtv on block side like a couple other people have suggested to do on here. So I will need a sleeve and a new seal? Will the same felpro seal work like I bought last time? Or do I need a special seal to work with the sleeve?

General karthief · Sep 18, 2017

You may be able to slip the sleeve past your existing seal but they are cheap and I wouldn't chance it, I think they sell them together as a 'kit'.

Pate · Sep 18, 2017

Oh ya I didn't mean for it to sound as if I was gonna use old one again. Sorry. I wasn't sure if I buy same one with sleeve or if it came in kit like u just stated. Man nothing like doing it twice lol. Hopefully this one will go better. So should I buy the sleeve anyway or should I assume I didn't put it in correct? Wasn't sure if there's a way to tell if it's worn?

General karthief · Sep 18, 2017

Don't assume anything, get the sleeve and a new seal.
I've got maybe 10k on a new seal, it seeps maybe a drip or two after driving it, I can live with it though, I do have the annoying leak at the back of my manifold, drives me nuts but I'm swapping heads soon an will fix it. I don't mind my crap to look like crap but a leak will drive me nuts.

Pate · Sep 18, 2017

Right on. I'll do the sleeve and new seal this go around.

Pate · Sep 18, 2017

is there a way to test the seal before u get tranny and all back in place? Or is it trail and error

Pate · Sep 18, 2017

They got a Mahle sleeve at Autozone 17.99 or they have a duralast sleeve for 64.99? Any recommendations on which one to use and which RMS to use with the sleeve?

imp · Sep 18, 2017

If a choice is possible between 2-piece rear main seals, or 1 piece complete, real metal-channel oil seal, always go with the latter. No heavy duty engine is to be found using a 2-piece. I was surprised when I got my '78 Fiesta with 1.6L Kent (English) engine, it had a "real" rear crank oil seal, pressed into a bolted-on retainer. I recall vividly the old "rope" seals I struggled with on all my FE engines, Shop Manual recommending air-pressure check of side-seals! How many teens have an air compressor? imp

Pate · Sep 18, 2017

Ya it's a one piece

imp · Sep 18, 2017

@karthief is right on the money. Seals can only function well and acceptably given adequate control over operating conditions. Shaft surface condition (and size) is one of those. Another, not mentioned, is shaft radial run-out. A seal element can only "follow" just so much "wobble" in the shaft it is trying to seal. Given how much work has prevailed here, I would begin to suspect possible excessive main bearing clearances as contributing to the trouble.

FWIW, I worked in the oil seal industry, Victor Gasket and Seal Divisions, of Dana Corporation, for many years. imp

Pate · Sep 18, 2017

Ptfe felpro seal or rubber felpro seal?

Engine Oil Drips From Block Plate Every 4-5 Seconds?

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