396 oil leak - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 7 (permalink) Old Sep 29th, 03, 08:17 PM Thread Starter
Senior Tech
 
Join Date: Jul 2003
Location: Rancho Santa Margarita, CA
Posts: 521
Post

It's actually a 1970 402 engine, but anyway.

The "396" engine currently in my 68 (originally an SS350) runs strong, but has this nasty oil leak coming from the back of the block inside the bell housing somewhere. It only leaks while the engine is running, pressurized. I inspected the best I could around the rear main seal from under the car with the tranny, clutch etc. all in place and it does not seem to be coming from there. Where else could it be comming from back there? The oil tends to get onto the flywheel and then gets slung all over the inside bell housing. I was wondering about the rear cam plug. How hard are these to repair? Can they be repaired reliably without disassembling my top end?
I want to make this engine last until I save up enough for a 454 or 502, and aside from this leak, it's up to the task.

Thanks!
Tim

Meanchicken
68 SS
ZZ502; TKO-600; 3:73 Moser 12-bolt w/Detroit TruTrak; SSBC Force 10 4 wheel power disks;QA1 Coil Overs; Global West Tubulars;GNX Quick Ratio 12:1 PS; Hotchkis Front Sway Bar
87 Buick Grand National (does 10's)
Meanchicken is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old Sep 30th, 03, 02:38 AM
Senior Tech
Eric
 
Join Date: Dec 2000
Location: Kentwood, MI
Posts: 8,097
Post

I'm not as familiar with eth BBC but on the small blocks I have never seen a rear cam plug leak. Usually its either the rear oil pan gasket or the rear main.

A valve cover or intake gasket can leak and run down in that spot too. On a SBC there are a couple 1/4" threaded holes on top of the bell housing that if left open could allow oil from the intake etc to drip into the bell housing. Kind of a long shot though.

There are a couple oil galley plugs that I suppose could leak too but that is also a long shot.

E85 racer and E85 carb builder
www.horsepowerinnovations.com

68 Camaro, E85 powered 427" small block. 9.96 @ 133 MPH, 1.319 sixty foot on motor. 5.92 eighth @ 116 with a 1.42 sixty breaking beams with back tire on the bottle
Eric68 is offline  
post #3 of 7 (permalink) Old Sep 30th, 03, 07:43 PM Thread Starter
Senior Tech
 
Join Date: Jul 2003
Location: Rancho Santa Margarita, CA
Posts: 521
Post

Yup. I checked all the usual suspects like the back of the valve covers, intake, head gaskets, but those are all outside the bell housing and the back of the block outside the housing is dry, so this leak is definitely under the bell housing.

Around the rear main and pan appears too dry also. Leaks from either of these spots would typically result in a lot of drip off the bottom pan, but the pan is not that wet either.
This leak seems like it is originating up higher than the rear main which is why I suspect the cam plug or maybe some other oil galley opening that might be present.

I'm like you in that all my experience is with small blocks. I bought the car with the 396 already in it so I haven't seen the backside of the engine above the rear main yet.

With the way the oil is scattered around the inside of the bell housing, it almost seems like it leaks forceably when the system is pressurized as opposed to a drip. I'm also wondering if maybe this is gear lube from my 4 speed leaking from the transmission input shaft seal as the tranny is pretty wet. I relly gotta crawl under there and lokk at this closer.

Still curious about the difficulty of replacing/repairing the rear cam plug without pulling the top end off the motor.
Tim

Meanchicken
68 SS
ZZ502; TKO-600; 3:73 Moser 12-bolt w/Detroit TruTrak; SSBC Force 10 4 wheel power disks;QA1 Coil Overs; Global West Tubulars;GNX Quick Ratio 12:1 PS; Hotchkis Front Sway Bar
87 Buick Grand National (does 10's)
Meanchicken is offline  
post #4 of 7 (permalink) Old Oct 1st, 03, 05:31 AM
Senior Tech
 
Join Date: Feb 2002
Location: Central Illinois
Posts: 1,063
Post

If it is gear lube, it will smell like gear lube.
I know that may sound extremely simple, but you can tell the difference between motor oil and gear lube with a simple sniff test.

68 Camaro, 555 big block, Doug Nash 5-speed, 3.54 gear.
smits67 is offline  
post #5 of 7 (permalink) Old Oct 2nd, 03, 04:48 AM
Senior Tech
 
Join Date: Apr 2000
Location: holliston, mass
Posts: 622
Post

There are oil gallery plugs back there as well as the cam plug.

It's either the rear main or a plug..

John

John...
68ragtop is offline  
post #6 of 7 (permalink) Old Oct 2nd, 03, 08:43 AM
Team Member
John
 
Join Date: Sep 2000
Location: Washington, Michigan USA
Posts: 7,727
Post

There's no seal of any kind on the 4-speed input shaft; any lube that gets through the front bearing runs down the inside of the bearing retainer and drains back into the case through a drainback hole. [img]graemlins/thumbsup.gif[/img]

JohnZ
CRG
'69 Z/28 Fathom Green
JohnZ is offline  
post #7 of 7 (permalink) Old Oct 2nd, 03, 07:37 PM Thread Starter
Senior Tech
 
Join Date: Jul 2003
Location: Rancho Santa Margarita, CA
Posts: 521
Post

Thanks for all the feedback, guys. The news that the 4 speed input shaft has no seal helps to narrow it down further.
I suspect it must be one of the oil galley plugs or the rear cam plug...won't know until I get the engine out or drop the trans and flywheel out of the way.
Tim

Meanchicken
68 SS
ZZ502; TKO-600; 3:73 Moser 12-bolt w/Detroit TruTrak; SSBC Force 10 4 wheel power disks;QA1 Coil Overs; Global West Tubulars;GNX Quick Ratio 12:1 PS; Hotchkis Front Sway Bar
87 Buick Grand National (does 10's)
Meanchicken is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome