Developed an oil leak. (rear main seal or pan gasket?) - FSB Forums
Register Home Forums Active Topics Photo Gallery All Albums Mark Forums Read Auto EscrowInsurance FSB Store
FullsizeBronco.com is the premier Ford Bronco Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools Display Modes
Old 03-25-2010, 04:24 AM   #1
Alaskan-78XLT
Registered User
 
Alaskan-78XLT's Avatar
 
Join Date: Jun 2008
Location: Two Rivers(just outside Fairbanks), Alaska
Posts: 210
iTrader: (2)
Bronco Info: 78XLT, 400-C6-205, D44 front and 8.8" rear at 4.10, 33" MTs on chromes w/ baby moons!
Post Developed an oil leak. (rear main seal or pan gasket?)

G'day Gents,

Developed an oil leak recently. Kinda expected some leaks since this week was the first time the truck has been highway driven for more than a mile or two at a time for about a decade; possible dried out seals/gaskets, suddenly under constant use again.


Anyway,
I think its either the oil pan gasket at the back or the rear main seal;
Its leaking from the seam that is the oil pan to the trans/bell housing plate, but only in the center side to side,(its clean of mud and wet with oil for about a 2" gap in the center) The rest of the pan is dry- sides, bottom and front. As is the rest of the trans. And yes it Is engine oil, Not tranny fluid.

Its running down that lower plate on the bell housing, some over, some behind that little flywheel access cover on the plate- straight down that cover and dripping to the ground.

If its the rear main seal, would it leak down inside the bell housing and run out the bottom(basically not seen till it comes out he bottom of the bell housing)?

Or come down from where the oil pan meets the tin cover on the bell housing(basically outside the bell housing like I have)?

Or could it do both/either if its the main seal?

Trying to get a feeler here for if it sounds like it is that seal, after all if I can be sure its the main seal, I won't bother doing just the pan gasket first... I'll just go after the main seal-- Its not like doing that seal is a new thing for me, done two other trucks before, although its been a while... but even so, its not something I want to do if I don't have to.


First thing tomorrow morning I'll tighten the rear pan bolts, since my Dad has had that happen before and cause a leak here; simple bolts worked loose... But until then, I figured I might as well get any thoughts y'all might have.

G.
__________________
*'78 Bronco XLT, Half-cab conversion , 400-C6-205,4.10s, 33"s 6MPG
*'76 F150 Trailer Special Ranger, 4x2, 460-C6, 3.25 Limited slip 7MPG
*'78 F250 Camper Special Ranger, 4x4, 400-C6-205,4.10s 15MPG(!?!)
*73 F250 Explorer 4x2-parts *79 Bronco Custom Ranger-Parts trucks
Half-Cabs@Supermotors
Alaskan-78XLT is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 03-25-2010, 09:23 AM   #2
Robs79BBbronco
Registered User
 
Robs79BBbronco's Avatar
 
Join Date: Sep 2007
Location: Walker, LA
Posts: 3,724
iTrader: (0)
Bronco Info: 79 Ranger XLT-460,NP435,NP205,stock axles/3.50's,2.5"RC lift,33"trxxs mt's,72 impala horn(best mod)
Quote:
Originally Posted by Alaskan-78XLT View Post
If its the rear main seal, would it leak down inside the bell housing and run out the bottom(basically not seen till it comes out he bottom of the bell housing)?

Or come down from where the oil pan meets the tin cover on the bell housing(basically outside the bell housing like I have)?
yep.....might as well do both since your dropping the pan anyway.
Robs79BBbronco is offline   Reply With Quote
Old 03-25-2010, 07:22 PM   #3
Alaskan-78XLT
Registered User
 
Alaskan-78XLT's Avatar
 
Join Date: Jun 2008
Location: Two Rivers(just outside Fairbanks), Alaska
Posts: 210
iTrader: (2)
Bronco Info: 78XLT, 400-C6-205, D44 front and 8.8" rear at 4.10, 33" MTs on chromes w/ baby moons!
Well, decided to see how bad it leaks when running to see if I can put this off a couple days till the weekend.. drove it a couple miles, let it warm up good, came home and crawled under it, and at idle it barely leaks at all... just a few drips. Shut it off though, and within half a minute I have a good 4" dia puddle under the thing... WTF? if its that main seal, it would only have oil pressure while its running, and should leak while running, not the other way around, right??

G.
__________________
*'78 Bronco XLT, Half-cab conversion , 400-C6-205,4.10s, 33"s 6MPG
*'76 F150 Trailer Special Ranger, 4x2, 460-C6, 3.25 Limited slip 7MPG
*'78 F250 Camper Special Ranger, 4x4, 400-C6-205,4.10s 15MPG(!?!)
*73 F250 Explorer 4x2-parts *79 Bronco Custom Ranger-Parts trucks
Half-Cabs@Supermotors
Alaskan-78XLT is offline   Reply With Quote
Old 03-25-2010, 08:10 PM   #4
BigWheelz
Registered User
 
Join Date: Nov 2005
Location: Bedford, TX
Posts: 1,654
iTrader: (0)
Bronco Info: 1978 Bronco, 466 EFI
Quote:
Originally Posted by Alaskan-78XLT View Post
Well, decided to see how bad it leaks when running to see if I can put this off a couple days till the weekend.. drove it a couple miles, let it warm up good, came home and crawled under it, and at idle it barely leaks at all... just a few drips. Shut it off though, and within half a minute I have a good 4" dia puddle under the thing... WTF? if its that main seal, it would only have oil pressure while its running, and should leak while running, not the other way around, right??



G.
Sounds to me like it is leaking out of the back of the intake or valve covers and dripping down the block. Before you pull the pan be sure to check that out! Intake is a heck of a lot easier to do than an oil pan!
__________________
Opportunity is missed by most people because it is dressed in overalls and looks like work- Thomas A Edison
BigWheelz is offline   Reply With Quote
Old 03-26-2010, 07:37 AM   #5
Alaskan-78XLT
Registered User
 
Alaskan-78XLT's Avatar
 
Join Date: Jun 2008
Location: Two Rivers(just outside Fairbanks), Alaska
Posts: 210
iTrader: (2)
Bronco Info: 78XLT, 400-C6-205, D44 front and 8.8" rear at 4.10, 33" MTs on chromes w/ baby moons!
I honestly can't see an intake being easier... Be about the same PITA, I'd think but I'll take your word for it, I've yet to pull an intake off with an engine in the truck. Hmmm. Maybe if ya left the carb, etc on it and pulled it as one piece... (I have a eddlbrock performance intake that can go on if I have to pull this one! ) Hmm.

I Do have a slight valve cover leak that could have gotten worse at the back. I'll deffinetaly check them!

Its just so odd to me that it'd leak worse once the pressure is gone... its like its leaking along a course upward, so when pressure stops, it drains down and comes/drains out the leak faster. Could oil draining back from the heads do that at the intake gasket, or a head gasket?

I finally have time this afternoon to really get into this, gonna start where i said before and make sure the pan is tight, then look at the valve covers, head gasket area, back of the block and intake area the best i can... I'll go over it top to bottom and see.

Thanks for the ideas. :)

G.
__________________
*'78 Bronco XLT, Half-cab conversion , 400-C6-205,4.10s, 33"s 6MPG
*'76 F150 Trailer Special Ranger, 4x2, 460-C6, 3.25 Limited slip 7MPG
*'78 F250 Camper Special Ranger, 4x4, 400-C6-205,4.10s 15MPG(!?!)
*73 F250 Explorer 4x2-parts *79 Bronco Custom Ranger-Parts trucks
Half-Cabs@Supermotors
Alaskan-78XLT is offline   Reply With Quote
Old 03-26-2010, 08:39 AM   #6
91BRONC
Registered User
 
91BRONC's Avatar
 
Join Date: Aug 2007
Location: Trenton NJ
Posts: 108
iTrader: (0)
Bronco Info: 79 Bronco Ranger XLT 400 .30 over TMeyer flat top pistons C6
Just did my intake 2 weeks ago, oil was pooling on the back of the block by the oil pressure sender.
91BRONC is offline   Reply With Quote
Old 03-26-2010, 11:35 AM   #7
EastLA78Bronco
oscar espinoza
 
EastLA78Bronco's Avatar
 
Join Date: Jan 2009
Location: East los angeles
Posts: 1,539
iTrader: (2)
Bronco Info: 78 bronco, 460 mild built. D60 front 14 bolt rear. detroit lockeds. OBA. twin stick np205. built c6
Sounds to me like the rms...mine used to do the same thing as soon as I parked
__________________
[size="4"][font="Fixedsys"]78 bronco, 460 cid,true dual exhaust,c6 with a shift kit,NP205 twin stick,9"lift,shackle flip,14B/D60d, 410 gears, 40" boggers. croseovver stering r
EastLA78Bronco is offline   Reply With Quote
Old 03-27-2010, 02:20 AM   #8
Alaskan-78XLT
Registered User
 
Alaskan-78XLT's Avatar
 
Join Date: Jun 2008
Location: Two Rivers(just outside Fairbanks), Alaska
Posts: 210
iTrader: (2)
Bronco Info: 78XLT, 400-C6-205, D44 front and 8.8" rear at 4.10, 33" MTs on chromes w/ baby moons!
Well, its not the valve cover or the manifold... man it takes some doing to see all of the back of the manifold and top of the bell housing-- every time i need at the back area on the top of that engine i wonder why i have such a high truck Need a better front bumper to stand on.

Anyway, the bell housing, manifold, blockm et-all are all dry. Got a head a little wet from a valve cover, but its dry for a looong ways below that spot, so its not that doing this. The pan bolts are all tight too.(damn!)

I'm betting it is the rear seal at this point... I did pull the access cover to the flywheel and its bone dry, no residue like I'd expect if it was leaking and spraying it in to the bell housing. Could still be just the pan gasket, but pulling/putting the pan back is the hardest part of doing the rear seal, so I'm gonna do the seal whether it looks like it was the pan gasket or not when i get it off.

Went and got a pan gasket and gasket maker--since they only had the 4 piece gasket. rear seal, oil, oil filter, drain pan... $70 about floored me, but I need the oil change anyway, so the $25 for gaskets and seal ain't too bad, I guess.

So, first thing tomorrow, I'll be getting into this.

Thanks again for the thoughts and advice guys, I'll let ya know how it goes.. :)

G.
__________________
*'78 Bronco XLT, Half-cab conversion , 400-C6-205,4.10s, 33"s 6MPG
*'76 F150 Trailer Special Ranger, 4x2, 460-C6, 3.25 Limited slip 7MPG
*'78 F250 Camper Special Ranger, 4x4, 400-C6-205,4.10s 15MPG(!?!)
*73 F250 Explorer 4x2-parts *79 Bronco Custom Ranger-Parts trucks
Half-Cabs@Supermotors
Alaskan-78XLT is offline   Reply With Quote
Old 03-28-2010, 09:44 AM   #9
Alaskan-78XLT
Registered User
 
Alaskan-78XLT's Avatar
 
Join Date: Jun 2008
Location: Two Rivers(just outside Fairbanks), Alaska
Posts: 210
iTrader: (2)
Bronco Info: 78XLT, 400-C6-205, D44 front and 8.8" rear at 4.10, 33" MTs on chromes w/ baby moons!
It quite leaking.

I figured if I had to drive it to get it into the garage to do the work, that I'd have to wait a few hours for it to cool and the oil to drain--so as to not drip on me constantly while doing the work. So, why not a last little drive to the mail box and back before the possibility of it being apart for a couple days(if I found something else wrong)?

its about a 1/2 mile drive. stop. leave truck idling. get mail. look under truck; no leak. Hmm.
drive home, park in garage, turn it off; No leak. Well, OK, two or three little drips. Hmm.

not anywhere near the 4" circle i was getting before. WTF??

figured maybe the seal and oil were not up to temp, oil not thin enough yet to leak like it did... So went and drove it the same distance as the trip to my buddies was a few days ago when it did it real bad... ran it hard too...

Nothing more than a couple little drips. eh?
The same out come after coming home.

All I can think of is the day before when I checked to see if it was simply the pan bolts loose, I 'snuged' them, found them tight, 'snuged'/tightened them lightly to double check and left it at that... there was maybe 1 degree rotation of the bolts, if that.... Its not like they were loose... All I can think of is that that pressed the gasket a little, moved it just enough, and it stopped leaking...

It could start again I know, after all there is something wrong with the gasket that it started leaking to begin with, so I'm not going to put off doing the gasket and rear main for too long. But if it stays this good for a couple days, I'm gonna leave it until I have to be under there and the exhaust/starter out anyway for the trans removal for rebuild that I'm planning on doing mid April.

at the verry least, I have the oil, seal, gasket etc on hand now.

G.
__________________
*'78 Bronco XLT, Half-cab conversion , 400-C6-205,4.10s, 33"s 6MPG
*'76 F150 Trailer Special Ranger, 4x2, 460-C6, 3.25 Limited slip 7MPG
*'78 F250 Camper Special Ranger, 4x4, 400-C6-205,4.10s 15MPG(!?!)
*73 F250 Explorer 4x2-parts *79 Bronco Custom Ranger-Parts trucks
Half-Cabs@Supermotors
Alaskan-78XLT is offline   Reply With Quote
Old 03-28-2010, 11:31 AM   #10
LarryP
Thanks 351w500
 
LarryP's Avatar
 
Join Date: Mar 2005
Location: Northcentral,CA.Twain Harte, up here in the mountains
Posts: 5,449
iTrader: (52)
Bronco Info: 88 Centerion 460 Dana 60/10.25 78 Bronk Cromo shafts,Detoit 4.56's lift 7" Deavers 38's 9"rear disk
On my 78 i had the exact same thing going on and i figured it was the rear main,cause when i bought it the dumb ass had 12 qt of oil in it. anyways It wasn't my pan gasket or the rear main seal It was my oil pressure sending unit behind the carb. It went bad and oil was coming out the top were the wire push's on.
Check this on yours,it might be doing the same thing.
__________________

I take Prayer Requests. God Bless
LarryP is offline   Reply With Quote
Old 03-28-2010, 12:17 PM   #11
TheUnforgiven
Dr. Brian & Mr. Unfer
 
TheUnforgiven's Avatar
 
Join Date: Aug 2004
Location: Oswego, Illinois
Posts: 18,337
iTrader: (10)
Bronco Info: 2006 Kia Spectra
sometimes seals will start to seal again after they start being used again. my 1990 f150 would leak from the steering box and the pinion if it sat a few weeks.

drive it a day or two, leaks gone.
__________________
2006 Kia Spectra 4 banger/5 speed that tows a 14ft boat while getting better gas mileage than any of your broncos could ever dream of getting.

Quote:
Originally Posted by "Bronco" John Galt View Post
New nuts are in the plan.
"Kids, they see the good in everything and through their eyes, they open ours." - Hank Davis
TheUnforgiven is offline   Reply With Quote
Old 03-29-2010, 09:12 AM   #12
johndeere
Registered User
 
johndeere's Avatar
 
Join Date: Feb 2009
Location: Firth, ID
Posts: 62
iTrader: (0)
Bronco Info: 96 F250 XL
Quote:
Originally Posted by BigWheelz View Post
Sounds to me like it is leaking out of the back of the intake or valve covers and dripping down the block. Before you pull the pan be sure to check that out! Intake is a heck of a lot easier to do than an oil pan!
x2. Seen a couple times I thought it was the rear main and it was the valve covers dumping out the back.
__________________
1996 Red F250 XL 351W ZF5 4.10's
johndeere is offline   Reply With Quote
Old 05-04-2010, 12:22 AM   #13
Alaskan-78XLT
Registered User
 
Alaskan-78XLT's Avatar
 
Join Date: Jun 2008
Location: Two Rivers(just outside Fairbanks), Alaska
Posts: 210
iTrader: (2)
Bronco Info: 78XLT, 400-C6-205, D44 front and 8.8" rear at 4.10, 33" MTs on chromes w/ baby moons!
Just thought I'd pop in and update this, since i got it apart.

It was the oil pan I'm sure, or at least 95% of it was. the last guy that put this together put a 1/2" x 3/4" pead of silicone gasket maker around the oil pan at the front and back. It squeezed out into the pan, had chunks of it in my oil... and on the oil pump screen. Blech. Thankfully not through the oil pump screen. But at the back the curved seal/gasket under all this crap had squeezed out on one end, and rolled over the edge of the pan.. looks like it would have sealed for a while, but once it got old and hard, it'd just blow out further. Was soaking wet with oil on both top and bottom of that seal piece so it was deffinetally leaking there.

The rear main seal was also replaced with a two piece rubber one before. But the idiot put it in with the ends meeting flush with the block to cap seam... and no evidence of the sealer required between block and cap. Its amazing that this Ever held oil pressure there at all IMO. Should have leaked from the get go. The seal came out a little rough on the bottom piece, but intact. The top piece came out with only about 1/4" of length of the little lip on it still attached... the rest had sepperated.

So both were leaking.

I'm hung up now at getting the oil pan gasket off the block, its one of those rubber coated felt jobs thats baked on reeeeeaaal good. its been there a while, as the last guy left it there and over did the gasket silicone stuff over it. Thankfully the silicone peals right off. Just found out that permatex makes a spray gasket remover that soposedly dissolves this kinda rubber/felt gasket to a gell and you can scrape it right off. Gotta go try to find a can locally tomorrow.

G.
__________________
*'78 Bronco XLT, Half-cab conversion , 400-C6-205,4.10s, 33"s 6MPG
*'76 F150 Trailer Special Ranger, 4x2, 460-C6, 3.25 Limited slip 7MPG
*'78 F250 Camper Special Ranger, 4x4, 400-C6-205,4.10s 15MPG(!?!)
*73 F250 Explorer 4x2-parts *79 Bronco Custom Ranger-Parts trucks
Half-Cabs@Supermotors
Alaskan-78XLT is offline   Reply With Quote
Old 05-23-2012, 03:06 PM   #14
montygazu
Registered User
 
Join Date: May 2012
Location: Oklahoma
Posts: 2
iTrader: (0)
Bronco Info: 1979 XLT Ranger
Mystery Oil Leak

Hello all this is my first post and I am very excited to find this forum. I have a 1979 Bronco that I have been working on for two years. It has a 351M and I have replaced the cam, lifters, springs, timing gear/chain. The heads have been rebuilt and I topped it off with an edelbrock intake and holley carb. I have an oil leak that after the engine has been running spews enough oil onto the passenger header to create an large amount of smoke. This is not a continuous flow of oil. I have checked and rechecked the head and replaced the valve cover gaskets (just went with rubber). It leaks over the starter and onto the header so I assume it is not the rear main. Any advise would be great.


Last edited by montygazu; 05-23-2012 at 03:47 PM. Reason: added photo
montygazu is offline   Reply With Quote
Old 05-23-2012, 03:42 PM   #15
jermil01
Charlie doesn't surf!!
 
jermil01's Avatar
 
Join Date: Apr 2003
Location: JAX, FLA
Posts: 11,728
iTrader: (31)
Bronco Info: 1992 xlt, 351EFI, .040, E40D, D44 SAS w/Trutrac, Detroit locked 8.8, MAF conv, Tweecer tuned..
certainly..welcome to the site..great job searching by the way, you deserve a for that. I'd head over to the noobie section and start your own thread. You'll get more attention that way.
__________________

Vote 4 Top 4x4 Site!!!
jermil01 is offline   Reply With Quote
Old 05-23-2012, 07:34 PM   #16
vmirmow
Registered User
 
vmirmow's Avatar
 
Join Date: Dec 2009
Location: Clemson, SC
Posts: 83
iTrader: (0)
Bronco Info: 1979 Ranger XLT 351M 4BBL C6 part-time NP203 on 35's
Good looking motor montygazu. I don't know what your leak could be other than valve cover gaskets or possibly (but less likely) the oil pan gasket. I don't trust the rubber ones; I've had them squeeze out and leak even when properly torqued. I much prefer cork for the valve covers. Can you see where it looks like the oil is coming from?
vmirmow is offline   Reply With Quote
Old 05-24-2012, 08:58 AM   #17
Julio00oo
Registered User
 
Julio00oo's Avatar
 
Join Date: Oct 2011
Location: OKC
Posts: 17
iTrader: (0)
Bronco Info: 1979
Welcome to the Party!

Monty

Where in Oklahoma are you? I'm in OKC about to move back to Stillwater in a couple weeks to finish up some classes though. We should swap some knowledge. I've got a 79 too. There's not too many of us out here.

Nice looking 351, I've found some little leaks on mine at the gaskets in all locations over time. I'm thinking of doubling the gaskets next time I've got the intake off.
Julio00oo is offline   Reply With Quote
Old 05-24-2012, 09:32 AM   #18
Robs79BBbronco
Registered User
 
Robs79BBbronco's Avatar
 
Join Date: Sep 2007
Location: Walker, LA
Posts: 3,724
iTrader: (0)
Bronco Info: 79 Ranger XLT-460,NP435,NP205,stock axles/3.50's,2.5"RC lift,33"trxxs mt's,72 impala horn(best mod)
Quote:
Originally Posted by vmirmow View Post
Good looking motor montygazu. I don't know what your leak could be other than valve cover gaskets or possibly (but less likely) the oil pan gasket. I don't trust the rubber ones; I've had them squeeze out and leak even when properly torqued. I much prefer cork for the valve covers.
^this. do you have an open breather on that valve cover? or is it a pcv valve?(cause i noticed you did not have one on the drivers side)
Robs79BBbronco is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  FSB Forums > Bronco Discussions > 1978-'79 Bronco Tech


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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
Forum Jump


All times are GMT -4. The time now is 07:35 AM.


2003-2009 FullSizeBronco.com. All rights reserved