1985 6.9 IDI major oil leak, probably rear main seal?

[J_C_S]

Hi everybody, was recommended this forum by a friend for diesel repair help. Wondering if anyone has done the rear main seal on a 6.9/7.3 idi, pretty sure that's the source of my leak but seeing a ton of stuff online saying I need to pull the motor to fix it which seems insane, surely there is a better way to do that right? Would appreciate some advice if anyone has done that before on that gen. Thanks in advance

Truck has been sitting for about 15 years and I bought it last spring, while I'm in there anything else I should do?

 

[IDIBOBS]

Either motor or trans has to come out for sure. The motor could come out in an hour or so. If your doing all that I’d buy a reseal kit and do heads gaskets, studs, and all the other seals.

 

[IDIBRONCO]

Before you go hog wild and start pulling major components, make sure that your leak is actually oil and that it's not coming from the top side of the engine. You can have a fuel leak (oil leak too) on top of you engine and it will run down the back side of the block and onto the starter. That's by design. If your truck was sitting for 15 years, I'd be thinking fuel leak first. Welcome.

 

[asmith]

I agree with @IDIBRONCO. My valve covers were leaking a ton of oil, combined with a small fuel leak and it runs all down the back of the engine. I would clean real well back there and figure out for sure where it is coming from. If it is a rear main seal, either the motor needs to come out, or the transmission needs to.

 

[DirtyWood]

I've had two IDIs with leaky rear main seals but they were such small leaks it wasn't worth fixing. Maybe you have a nice clean concrete driveway and you want it to stay that way?

 

[Jesus Freak]

I've had two IDIs with leaky rear main seals but they were such small leaks it wasn't worth fixing. Maybe you have a nice clean concrete driveway and you want it to stay that way?

Do people that drive ancient diesel trucks have clean driveways? That might make a good thread "show us yer oil slick......" Lol

 

[Old Goat]

Welcome to the Forum.
Lots of good correct info here.
Lots of misinformation floating around out there.

I have a copy of this manual , 88 - 93 Engine Service Manual.
Has a lot of good detailed info. It is for the 7.3 Engine, but both
engines are pretty close to the same.
This is a paper manual,

1988 1992 1993 Ford 7.3 Diesel Engine Shop Service Repair Manual | eBay

Dealing with areas & problems specific to the 7.3 L Diesel Engine, sections include lube & maintenance, service brakes, clutch, cooling system, etc. The Diagnosis Charts in the Engine Section are designed to help locate & correct problems.

www.ebay.com

there is also the same manual but for the 83 - 87 6.9 IDI.
I have both and the 6.9 is lacking in a lot of info, but good to
have both.

Ford Truck 6.9 Diesel Supp 1983 - 1987 Shop Manual - Paper Book | eBay

Vehicle Model6.9 Diesel Supp. Contains Information OnDiesel Engine Only, Supp to 83-87 Ford Truck Manual. Year Range1983 - 1987. This is essentially the “How to Fix It” book. MakeFord Truck. PURCHASING POLICIES.

www.ebay.com

Some of the manuals are on CD, or you have to down load their PDF File.
I prefer the paper one.

Power wash the engine to get the crud off it to see what you have.
I have a Hotsy hot water pressure washer, really blasts the crud off.

Forget the using the Car Wash DIY spray wands. They are not
powerful enough. But better than nothing.

Goat

 

[DirtyWood]

Do people that drive ancient diesel trucks have clean driveways? That might make a good thread "show us yer oil slick......" Lol

I grew up doing concrete work with my dad so I got an education about the evils of leaky vehicles and people who think it's cool to write their initials in someone else's concrete.
Thank goodness I have a gravel driveway--it always looks clean!

 

[Jesus Freak]

I grew up doing concrete work with my dad so I got an education about the evils of leaky vehicles and people who think it's cool to write their initials in someone else's concrete.
Thank goodness I have a gravel driveway--it always looks clean!

Yeah, people do get fussy about an oil leak......I like it myself. It's a simple way to start diagnostics......"hey, what's that puddle?....." "Is it green? Brown?.......no, it's yellow.....oh, my dog just walked away from here, we're good, let's get going....."

 

[J_C_S]

I've had two IDIs with leaky rear main seals but they were such small leaks it wasn't worth fixing. Maybe you have a nice clean concrete driveway and you want it to stay that way?

Main issue is that the leak just isn't that small- it's seriously just ******* all over seems like, way worse than any vehicle I've owned before

 

[J_C_S]

Welcome to the Forum.
Lots of good correct info here.
Lots of misinformation floating around out there.

I have a copy of this manual , 88 - 93 Engine Service Manual.
Has a lot of good detailed info. It is for the 7.3 Engine, but both
engines are pretty close to the same.
This is a paper manual,

1988 1992 1993 Ford 7.3 Diesel Engine Shop Service Repair Manual | eBay

Dealing with areas & problems specific to the 7.3 L Diesel Engine, sections include lube & maintenance, service brakes, clutch, cooling system, etc. The Diagnosis Charts in the Engine Section are designed to help locate & correct problems.

www.ebay.com

there is also the same manual but for the 83 - 87 6.9 IDI.
I have both and the 6.9 is lacking in a lot of info, but good to
have both.

Ford Truck 6.9 Diesel Supp 1983 - 1987 Shop Manual - Paper Book | eBay

Vehicle Model6.9 Diesel Supp. Contains Information OnDiesel Engine Only, Supp to 83-87 Ford Truck Manual. Year Range1983 - 1987. This is essentially the “How to Fix It” book. MakeFord Truck. PURCHASING POLICIES.

www.ebay.com

Some of the manuals are on CD, or you have to down load their PDF File.
I prefer the paper one.

Power wash the engine to get the crud off it to see what you have.
I have a Hotsy hot water pressure washer, really blasts the crud off.

Forget the using the Car Wash DIY spray wands. They are not
powerful enough. But better than nothing.

Goat

Thank you for this, great info! Will check out the listings

 

[J_C_S]

I agree with @IDIBRONCO. My valve covers were leaking a ton of oil, combined with a small fuel leak and it runs all down the back of the engine. I would clean real well back there and figure out for sure where it is coming from. If it is a rear main seal, either the motor needs to come out, or the transmission needs to.

I figured I could do it just taking out the trans, just haven't ever actually seen it recommended for that gen. Information seems so few and far between for them which is just crazy to me, the OBS trucks theres millions of forum posts and videos showing you how to do every little thing. I guess these are just slightly too old

Thanks for the info, much appreciated

 

[IDIBRONCO]

I figured I could do it just taking out the trans, just haven't ever actually seen it recommended for that gen.

There's no reason why it isn't recommended. It's basically the same process for any generation of our trucks. If your truck is 4X2, then it's probably easier to drop the transmission. If it's 4X4, then that's your call because there's more to do to drop a 4X4 transmission. People have replaced clutches by dropping the transmission. If you go that far, you should have the flywheel resurfaced. Once that's removed, you're at the rear main seal. Either way you go, just be aware that oil will leak out once you remove the flywheel/flexplate. The bolt holes go through the crankshaft. Just plan on an oil change at the same time.

 

[DirtyWood]

And when you do the rear main seal it seems a lot of people need the seal kit that comes with a repair sleeve since the rotating seal wears the metal surface a tiny bit and a new seal often leaks if installed without the sleeve.

 

[Old Goat]

I did the Rear main on my 86 probably year N half back.
I have the T-19 and that thing weighs 150 LBS.
If you drop the trans, just make sure you have a trans jack to safely remove it.
I have this one, picked it up off CL for a killer price. Guy used it once, then put it on CL. Think I paid $85.
Just make sure it is safely secured on the plate. The chain that is supplied is to secure the trans is a joke. Lube up the 2 screw adjusters good.

https://www.harborfreight.com/800-lb-low-lift-transmission-jack-70192.html

Haven`t worked on a auto tans, probably close to the same.

You say you have a fuel leak down the back of the engine.
Could be the IP leaking, or one of the hard lines screwed onto the pump leaking. If the Vibration dampners are not on the hard lines, vibration can cause them to crack, any fluid drips onto the valley pan then to a drain at the back of the pan.

Note: scroll the bottom of the page up, and there are 3 related rear main Seal Threads.


Goat