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65 guy

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Looking for an answer to what might be happening. I’ll start off by saying it’s a 1968 289 motor and a c-4 trans. Car was a runner with a few drops of oil before car was parked and stripped down to be restored. The motor was completely overhauled at a machine shop and all that was added above stock was a very mild cam. Transmission was sent out and completely overhauled and a new torque converter was added. Running gear was installed into car and car has been completed. So after was run around the street a couple times it blows oil out the rear seal and leaks bad. Dropped oil pan and double checked seal and it was okay and changed it anyways. Put back together with new seal and gaskets and run till warm and as soon as you put it in gear and drive it it blows through again. Repeated again and same results. Took it to a shop and twice with the same results. I will help eliminate answers by saying that flexplate bolts were thread sealed, seal is in right way and it’s not from top of motor. Crank endplay was around 4 thousand and yes the breathers pcv valve are are working. Even changed back to stock valve covers to eliminate anything that was added. So then purchased another motor that was rebuilt and it never leaked before it was pulled and bairings endplay etc all were fine switch motors out and as soon as the car drove about 10 blocks it puked oil out in the same way. Talked to lots of experienced long term mechanics and we all are stump. Have to find someone who’s gone through this problem to help find what direction to go. If I don’t find the problem I’ll be cutting this car up and installing a Heidts front end and putting Chevy running gear in this thing to get away from this issue. Shame to do it but I don’t have time to play with this problem everyday and patience are wearing thin because everything was completely brand new on this car after restoration. Thanks in advance. Attached is a pic of streaks left after going back and forth twice. As you see it’s not a little leak.
 

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2Blue2

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symptoms
Engine Oil leaking from the the rear main seal, right?
oil seal looked ok on inspection
1968 block
Then switched engine out and second engine has same problem

The switched engine is throwing me off. Same leak with two motors? I assume you switched intake manifolds ( and other parts) on this swap?


A couple of ideas

1. On some old blocks there is a pin that used to hold the rope style rear main in place and if it is in with the 2 piece seal it will leak lots.
2. Back of block has oil galleys and a cam plug and one of these could be it.
3. Wrong flex plate imbalance
4. Don't use intake manifold end seals on ford small blocks, just use silicone on both ends
5. your sure its not trans fluid leaking. ( I know it sounds dumb but both motors leaking the same?)
6. maybe do a dye kit to see where it is leaking from. you said rear main leaks but also said it was good.

2009-10-17_193449_sbf.gif smallblock10.gif
Good luck post what you find out.
 
Last edited:

65 guy

Member
Apr 6, 2019
11
2
13
54
Alberta
Looking for an answer to what might be happening. I’ll start off by saying it’s a 1968 289 motor and a c-4 trans. Car was a runner with a few drops of oil before car was parked and stripped down to be restored. The motor was completely overhauled at a machine shop and all that was added above stock was a very mild cam. Transmission was sent out and completely overhauled and a new torque converter was added. Running gear was installed into car and car has been completed. So after was run around the street a couple times it blows oil out the rear seal and leaks bad. Dropped oil pan and double checked seal and it was okay and changed it anyways. Put back together with new seal and gaskets and run till warm and as soon as you put it in gear and drive it it blows through again. Repeated again and same results. Took it to a shop and twice with the same results. I will help eliminate answers by saying that flexplate bolts were thread sealed, seal is in right way and it’s not from top of motor. Crank endplay was around 4 thousand and yes the breathers pcv valve are are working. Even changed back to stock valve covers to eliminate anything that was added. So then purchased another motor that was rebuilt and it never leaked before it was pulled and bairings endplay etc all were fine switch motors out and as soon as the car drove about 10 blocks it puked oil out in the same way. Talked to lots of experienced long term mechanics and we all are stump. Have to find someone who’s gone through this problem to help find what direction to go. If I don’t find the problem I’ll be cutting this car up and installing a Heidts front end and putting Chevy running gear in this thing to get away from this issue. Shame to do it but I don’t have time to play with this problem everyday and patience are wearing thin because everything was completely brand new on this car after restoration. Thanks in advance. Attached is a pic of streaks left after going back and forth twice. As you see it’s not a little leak.
Also transmission was removed to check oil gallery plugs and cam plug and they were
symptoms
Engine Oil leaking from the the rear main seal, right?
oil seal looked ok on inspection
1968 block
Then switched engine out and second engine has same problem

The switched engine is throwing me off. Same leak with two motors? I assume you switched intake manifolds ( and other parts) on this swap?


A couple of ideas

1. On some old blocks there is a pin that used to hold the rope style rear main in place and if it is in with the 2 piece seal it will leak lots.
2. Back of block has oil galleys and a cam plug and one of these could be it.
3. Wrong flex plate imbalance
4. Don't use intake manifold end seals on ford small blocks, just use silicone on both ends
5. your sure its not trans fluid leaking. ( I know it sounds dumb but both motors leaking the same?)
6. maybe do a dye kit to see where it is leaking from. you said rear main leaks but also said it was good.

2009-10-17_193449_sbf.gif smallblock10.gif
Good luck post what you find out.
was not originally a
 

65 guy

Member
Apr 6, 2019
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2
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Alberta
Checked oil gallery plugs and cam plug after removing flex plate. They were dry. Rear seal was a neoprene seal originally on both engines not a rope seal so no pin. Never use original rubber underneath intake for the valleys, just right stuff sealant. Yes it’s engine oil running out. The flex plate was originally off new motor and was transferred to second motor. But both engines leaked the same. No upper end leaks at all
 

horse sence

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If those plastic seals are put in dry they will burn up instantly ,they have to be greased or oiled ,if you have two motors doing the same thing the builder may have over looked this
 
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65 guy

Member
Apr 6, 2019
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Alberta
Different engine builders. All replacement seals were put in wet also. That’s what makes this weird that both engine have done this.
 

2Blue2

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only other thing back theres the oil pan gasket or a pin hole in oil pan. But the leak in pictures looks big so there must be oil on everything.

oil filter has seal damage? Crank oil seal surface damaged?
I'm out of ideas for the limited information I have.
Time for a dye kit to pin point where it is occurring from.
 

65 guy

Member
Apr 6, 2019
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2
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54
Alberta
Changed everything again from top to bottom including seal and try again. Will have torch and zip cup ready if it fails again. Will update
 

65 guy

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Apr 6, 2019
11
2
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54
Alberta
So here is an update. Leaked again after new seal etc again. Last resort I’m thinking the arp bolts are causing the issue. Never had the original bolts with new engine so we purchased arp bolts to install. Sounds to easy, called arp and they said it’s not an issue. but it is something that was installed on original motor and carried to second motor. Thinking shoulders or something is different to cause it. Will pull tranny tonight and put original bolts in that I have rounded up from a guy. Sounds to easy because you’d think that much oil couldn’t pass through. Arp bolts fit nice and torqued proper but it’s the only thing left. Will post tomorrow on the results and if this is what the issue was I hope it helps someone in the future as this has been a nightmare.
 

2Blue2

will be trying this sex one when I can find it
Mar 5, 2019
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so we purchased arp bolts

It wouldn't be the bolt shoulders as much as the tread sealer needed for flex plate bolts.
Im guessing you never thread sealed the flex plate bolts? I think they do penetrate the oil crankcase of block.
 

65 guy

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Apr 6, 2019
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Alberta
No all where thread sealed when put in. Maybe arp bolts were packaged wrong who knows but they are getting tossed into garbage if this was the cause of this. Will know tomorrow after I change them back to original bolts.
 

65 guy

Member
Apr 6, 2019
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2
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54
Alberta
So here is an update. Pulled tranny back and changed bolts. After pulling the first bolt out this is what I found. Pic at end. So I’m thinking the bolt from arp isn’t long enough to close off oil flow in crank???? Let me also say that while the first motor kept leaking I had phoned arp and asked them if the bolt might have been an issue and they flat out said not a chance, so we looked elsewhere to find the problem. Not having the original flex plate bolts to compare the new arp ones to we were assuming they are right. Checked with parts store and they said right part number but maybe a possibility of a miss package on arp fault who knows. So started it up tonight and leak has gone away. Who would has guessed. All the bs for 6 friggin bolts!!!! Well I’m closing I know I can change a rear seal and pan gasket in 25 mins laying under car and re and re tranny in 45 min lol. Practice make you faster. Thanks for all input guys and hope this helps someone out that runs into this issue.
 

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2Blue2

will be trying this sex one when I can find it
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65 guy

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Apr 6, 2019
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54
Alberta
It’s the wife’s summer car
 

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