Leaking oil

[CajunCruiser]

Hi! I just bought my first bus so I’m new to this 💁🏻*♀️. Its leaking oil. It’s a 97 bluebird international DT 466 engine. He said they rebuilt the motor at 161,000 miles. It currently have 162,000. I have attached pics. It’s sounds good while running and oil level is good.
I have been so sad about this so I figured I would come here bc I been reading and y’all have lots of knowledge!! Thanks in advance

[Jolly Roger bus 223]

i wouldnt think at 1000 miles on a full rebuild it would be leaking?
but everyone has a different idea on what a rebuild consist of.
looks like the rear main seal.
and there are not to many diesels out there that dont leak somewhere.
please dont use the stop leak stuff?
just keep an eye on the fluid level and how fast or slow the leak is?
does it leak more while running or just little spots when parked?

[Clouse House]

Engine oil pan looks clean and dry outside. But that transmission is covered in oil. It's even soaking what I assume are the cooler lines.
Best trick I've found for tracking down leaks is to clean the surfaces as best as you can with a rubber safe degreaser. Then put baby powder on areas that you suspect could be leaking. It will show you a very obvious trail of liquid flow.

[CajunCruiser]

Originally Posted by Jolly Roger bus 223

i wouldnt think at 1000 miles on a full rebuild it would be leaking?
but everyone has a different idea on what a rebuild consist of.
looks like the rear main seal.
and there are not to many diesels out there that dont leak somewhere.
please dont use the stop leak stuff?
just keep an eye on the fluid level and how fast or slow the leak is?
does it leak more while running or just little spots when parked?

I doubt it would be leaking if that rebuild really happened.
Just the spots when parked. I will run it today and watch to see what happens!
Thank you so much for your reply. I’m clueless but been reading to learn more!

[cadillackid]

the blow-by tube.. if a DT or a T444E is even the least bit over-filled with oil and then is highway run at near its maximum RPM.. she's gonna blow oil out the draft tube all over the ground.. (that one looks normal fill) blow-by should be very minimal on a freshly in-framed DT466 as typically the in-frame kit sends you pistons that are matched with their liners... of course there are kits where everything is just in a box and the rebuilder needs to measure and match the best fit of rings and pistons and sleeves or a builder can bonehead the build and mix up a matched set then you;ll have excessive blow-by..



if the rear main is leaking you typically will find oil up inside the flywheel housing.. an in-frame rebuild usually doesnt replace the rear main seal as that needs done from the rear of the engine with the transmission and flywheel removed

[CajunCruiser]

Originally Posted by Clouse House

Engine oil pan looks clean and dry outside. But that transmission is covered in oil. It's even soaking what I assume are the cooler lines.
Best trick I've found for tracking down leaks is to clean the surfaces as best as you can with a rubber safe degreaser. Then put baby powder on areas that you suspect could be leaking. It will show you a very obvious trail of liquid flow.

I see where it’s dripping now!! Let me see if I can attach a pic

[Truthseeker4449]

I agree it seems to be a struggle to keep these old diesels from leaking everywhere.

However I agree with Clouse House, this doesn't look like an typical engine oil leak because the oil pan is dry. I agree with the assessment that the transmission cooler lines are leaking. You may be able to acquire new ones through International, but your best bet is to remove them and take them to a hydraulic shop like Colliflower or Tipco where they can make you a new set for a couple hundred dollars, for each hose. I also recommend a jumbo crossfoot set and large breaker bars, breaking them free can be a fight...

Is it a whole story and the only fix you need? Not likely. The bellhousing is curiously wet, either not cleaned off when the engine was rebuilt, or the rear main is leaking.

It should be noted that there tends to be two kinds of diesel engine rebuilding, in-frame, and out of frame. Out of frame is much more througho, but more expensive because now you have the labor of removing the engine and transmission from the bus. Why is the transmission coming out too? Because the bellhousing is so strong that the transmission is bolted to it alone and rarely gets a separate mount.

The more cost-effective in-framing leaves the engine in the bus, but doesn't always remove the transmission so the crankshaft can be serviced. This is usually enough to breathe new life into the engine it usually refers to just replacing the cylinder liners (a nice feature of the DT466, most other skoolie engines require serious machine work) which may or may not come with new pistons and rods. Either way you have new cylinder bores, new piston rings, new rod bearings, but not always new main bearings or a rear main seal. Just depends on how in depth they decided to go.

Even still we can give them the benefit of the doubt and say the rear main was replaced, but wasn't set correctly. I'm not familiar with the DT466 rear main, but on the Cummins L9s they want you to set these things up extremely precisely with dial indicators and what not. The instructions are honestly quite confusing. On the L9 the rear main also requires removing the bell housing, which also has the engine mounts attached to it. This only adds to the difficulty because you need to support the very heavy engine.

TLDR: Replace the transmission cooler lines, degrease the engine and transmission, monitor closely to identify the source of the leak. Do NOT use any sort of stop leak product.

[CajunCruiser]

I’m not saying it originated there

[Truthseeker4449]

Sorry I spent a while typing that and in that time several posts happened.

As for your picture, to be quite honest I can't identity that part because I'm not familiar with that model of transmission.

I will say oil leaks usually follow gravity and flow rearwards due to the engine and transmission being inclined a few degrees. Your picture implies a source higher up, tho the drop on that part is highly suspect as a source.

[CajunCruiser]

Originally Posted by Truthseeker4449

I agree it seems to be a struggle to keep these old diesels from leaking everywhere.

However I agree with Clouse House, this doesn't look like an typical engine oil leak because the oil pan is dry. I agree with the assessment that the transmission cooler lines are leaking. You may be able to acquire new ones through International, but your best bet is to remove them and take them to a hydraulic shop like Colliflower or Tipco where they can make you a new set for a couple hundred dollars, for each hose. I also recommend a jumbo crossfoot set and large breaker bars, breaking them free can be a fight...

Is it a whole story and the only fix you need? Not likely. The bellhousing is curiously wet, either not cleaned off when the engine was rebuilt, or the rear main is leaking.

It should be noted that there tends to be two kinds of diesel engine rebuilding, in-frame, and out of frame. Out of frame is much more througho, but more expensive because now you have the labor of removing the engine and transmission from the bus. Why is the transmission coming out too? Because the bellhousing is so strong that the transmission is bolted to it alone and rarely gets a separate mount.

The more cost-effective in-framing leaves the engine in the bus, but doesn't always remove the transmission so the crankshaft can be serviced. This is usually enough to breathe new life into the engine it usually refers to just replacing the cylinder liners (a nice feature of the DT466, most other skoolie engines require serious machine work) which may or may not come with new pistons and rods. Either way you have new cylinder bores, new piston rings, new rod bearings, but not always new main bearings or a rear main seal. Just depends on how in depth they decided to go.

Even still we can give them the benefit of the doubt and say the rear main was replaced, but wasn't set correctly. I'm not familiar with the DT466 rear main, but on the Cummins L9s they want you to set these things up extremely precisely with dial indicators and what not. The instructions are honestly quite confusing. On the L9 the rear main also requires removing the bell housing, which also has the engine mounts attached to it. This only adds to the difficulty because you need to support the very heavy engine.

TLDR: Replace the transmission cooler lines, degrease the engine and transmission, monitor closely to identify the source of the leak. Do NOT use any sort of stop leak product.

Thank you so much!! I truly appreciate your reply and all the knowledge! I have zero knowledge which is why I came here! I read this forum a lot and there’s a wealth of knowledgeable people! I had it 2 weeks drove it from Missouri to my home in Louisiana and once after that a few miles. No leak until now. I will find a known diesel mechanic around here since I have no idea how to do those things. And get him to check the things you said!!

[CajunCruiser]

Originally Posted by Truthseeker4449

Sorry I spent a while typing that and in that time several posts happened.

As for your picture, to be quite honest I can't identity that part because I'm not familiar with that model of transmission.

I will say oil leaks usually follow gravity and flow rearwards due to the engine and transmission being inclined a few degrees. Your picture implies a source higher up, tho the drop on that part is highly suspect as a source.

I figured it flows rearward … I’m under here now looking

[CajunCruiser]

Originally Posted by cadillackid

the blow-by tube.. if a DT or a T444E is even the least bit over-filled with oil and then is highway run at near its maximum RPM.. she's gonna blow oil out the draft tube all over the ground.. (that one looks normal fill) blow-by should be very minimal on a freshly in-framed DT466 as typically the in-frame kit sends you pistons that are matched with their liners... of course there are kits where everything is just in a box and the rebuilder needs to measure and match the best fit of rings and pistons and sleeves or a builder can bonehead the build and mix up a matched set then you;ll have excessive blow-by..



if the rear main is leaking you typically will find oil up inside the flywheel housing.. an in-frame rebuild usually doesnt replace the rear main seal as that needs done from the rear of the engine with the transmission and flywheel removed

Thanks!! I appreciate this! My knowledge is zero but I’m trying to get educated on this! I’m thinking I should just have it checked.

[Clouse House]

I was going to say;
"Can you get a white cloth or paper towel and try to get some on it? Preferably a drip that is hanging but not yet fallen? Anything on the outside of the trans will be too dirty to tell what color it original was.
Golden (like honey) to brown to black is engine oil, looks for hints of yellow and orange in dirty fluid. Red (like cherry cough syrup) to brown is transmission fluid, look for hints of red.
That would definitely narrow it down from rear main (engine oil) leaking from the engine onto the trans and coating everything as it moves down and to the rear or the trans. VS a port or seal on the trans leaking down."

But after looking at your pictures more while typing, I think you might have an engine and a transmission leak.
The photo you took in post #6 does look heavy in transmission fluid but from the photos in post #1 it looks like it's coming from higher up. Actually in one photo in particular you can see a very wet engine oil pan bolt. So potentially they pinched or misaligned the oil pan gasket. Or maybe something even higher up.


Looking closer at the marks on the ground it looks like you might have two different leaks. The front where you have several drops is darker like engine oil, probably from higher up as a slight breeze can change where a tiny drop will land. While the rear larger mark is lighter and I swear it looks reddish to me.



I really feel like the only way you're going to find out is to clean all of that gunk off. It's a crappy job but it'll give you a definitive answer.

[CajunCruiser]

Originally Posted by Clouse House

I was going to say;
"Can you get a white cloth or paper towel and try to get some on it? Preferably a drip that is hanging but not yet fallen? Anything on the outside of the trans will be too dirty to tell what color it original was.
Golden (like honey) to brown to black is engine oil, looks for hints of yellow and orange in dirty fluid. Red (like cherry cough syrup) to brown is transmission fluid, look for hints of red.
That would definitely narrow it down from rear main (engine oil) leaking from the engine onto the trans and coating everything as it moves down and to the rear or the trans. VS a port or seal on the trans leaking down."

But after looking at your pictures more while typing, I think you might have an engine and a transmission leak.
The photo you took in post #6 does look heavy in transmission fluid but from the photos in post #1 it looks like it's coming from higher up. Actually in one photo in particular you can see a very wet engine oil pan bolt. So potentially they pinched or misaligned the oil pan gasket. Or maybe something even higher up.


Looking closer at the marks on the ground it looks like you might have two different leaks. The front where you have several drops is darker like engine oil, probably from higher up as a slight breeze can change where a tiny drop will land. While the rear larger mark is lighter and I swear it looks reddish to me.



I really feel like the only way you're going to find out is to clean all of that gunk off. It's a crappy job but it'll give you a definitive answer.

The bigger spot by itself when I wiped it is reddish! The pic attached is when I dabbed the drops sitting on the bolt of the oil pan. I’m going to clean it this evening or tomorrow morning. What kind of degreaser should I get? Thanks so much!

[Clouse House]

I prefer "Purple Power." It is a concentrated cleaner that you can water down inside of a spray bottle. You just want to make sure you wipe it off before it dries, cause it leaves a residue. Definitely not a paint prep cleaner, but great for oil.