New Turbo on 2H causes several oil leaks?

[Freewheel]

This is kind of a take-off of my other active thread about a timing cover oil leak, which obviously does not have a provocative enough title

I've installed a turbo on a 2H with about 280,000 kilometers on it. Not tons of mileage as far as the 2H goes.

Since the install, (fuel turned up 1 turn, boost to 8 PSI) my formerly non- leaky engine has sprung leaks on both sides of the timing gear casing, and the rear main seal ( the clutch has started slipping and there is oil coming out of the weep hole in the bottom of the bell housing)

In my other thread, a couple of responses indicated that the turbo would cause increased blowby and increased pressure in the crankcase. I am trying to figure out how a vented crankcase, with pistons that run at about 400 PSI can possibly see increased blowby pressure with 8 PSI of turbo boost.

Am I missing something? I have done a lot of searching through oil leak threads and I haven't seen any that correspond to "install Turbo - get major oil leaks.

If any one has any experience with increasing oil leaks after a turbo install, and theories on why, please chime in!

 

[crushers]

where did you run the PCV line?

 

[amaurer]

x2 sounds like you have a problem with your crankcase vent. I believe the 2H's vent from the valve cover to the throttle body... soooo I've got money that says you either:

- Left that arrangement as-is and are now pressurizing your entire crankcase with 8psi...

or

- Removed the line and plugged it and are now pressurizing the crankcase with blowby...

Which is it?

Also, your logic is bad about the 8psi. Atmospheric pressure is 14.7psi at sea level, so if you add 8psi to that you're increasing the absolute cylinder pressure to 22.7psi... more than a 50% increase. If some way existed for you to do a compression test while the turbo was boosting (heehee) you'd measure more than 600 psi (a 50% increase over stock compression).

 

[Freewheel]

The crankcase vent is running into the air intake tube and the throttle body has been plugged off.

I took the oil cap off today and there was a bit of positive pressure out of the hole in the rocker cover at idle. As soon as I gave it a bit of throttle, there was actually a bit of negative pressure - I assume because the turbo air intake is actually sucking air out of the crankcase through the PCV line.

So good idea, but not the problem I am having.


Amaurer, I can't quite figure out your logic about relative pressures- not accusing you of being wrong, but failing to understand your math. How does atmospheric pressure affect compression pressure once the valves are closed and the fuel air mix is burning in the cylinder? As I understand it, blowby is the escape of gases during the piston power stroke, how does atmospheric or boost pressure affect this? And if 8 PSI of boost + sea level atmospheric pressure equals 600 PSI in the cylinder, how do people run 25 PSI of boost without turning their engines into inline pipe bombs?

I'm not trying to be antagonistic, just trying to understand...

 

[amaurer]

The crankcase vent is running into the air intake tube and the throttle body has been plugged off.

I took the oil cap off today and there was a bit of positive pressure out of the hole in the rocker cover at idle. As soon as I gave it a bit of throttle, there was actually a bit of negative pressure - I assume because the turbo air intake is actually sucking air out of the crankcase through the PCV line.

So good idea, but not the problem I am having.

Well you certainly aren't building any boost by just touching the throttle... so this is inconclusive, at best.

Where do you have the vent plumbed to relative to the turbo and the air filter?

Amaurer, I can't quite figure out your logic about relative pressures- not accusing you of being wrong, but failing to understand your math. How does atmospheric pressure affect compression pressure once the valves are closed and the fuel air mix is burning in the cylinder? As I understand it, blowby is the escape of gases during the piston power stroke, how does atmospheric or boost pressure affect this? And if 8 PSI of boost + sea level atmospheric pressure equals 600 PSI in the cylinder, how do people run 25 PSI of boost without turning their engines into inline pipe bombs?

I'm not trying to be antagonistic, just trying to understand...

Compression testing only measures the cylinder pressure before fuel is added - the cylinder pressures when you add fuel are much higher. For example an unboosted 2H is said to develop up to 177ft-lb of torque with a 91mm bore and 102mm stroke so the cylinder pressure is at least 1200psi during the combustion stroke. In truth its certainly higher than that - maybe double - when you account for the varying crankshaft position and the averaging of a dyno measurement between cylinders, etc etc etc.

So you may be thinking "ok, but then even the 200 extra psi is nothing compared to a 2400 psi cylinder pressure"... but keep in mind that with extra boost comes extra combustion, so as a first order approximation the max. cylinder pressure increases in proportion to the fuel-less pressure. So if you double the unfueled cylinder pressure (aka 15psi of boost) then you may also double the max. cylinder pressure... maybe nearly 5000psi.

 

[Freewheel]

Ok cool, thanks for that explanation of the pressures. Makes more sense now. I will not be casually turning up the boost !

Back to the details. The crankcase vent tube is plumbed into the crossover tube that connects the air filter to the air intake side of the turbo. So as the turbo spools, it should create an actual vacuum in the crankcase, no?

I guess I could try plumbing my boost gauge into the the crankcase to see if I have pressurization occurring there - I could "T" the boost gauge off from the crankcase vent tube....

 

[crushers]

if the PCV line is run to the feed side of the turbo then that isn't the issue, you can forget that as a cause.
your oil passeges are still being pressurized, take the oil cap off while it is running, add throttle and see if the fumes coming out the cap worsens.
if so them somewhere between the turbo and the cylinder pressurized air is entering the oil, could be a head gasket, could be a crack in the head (unlikely) but somehow this is occuring.

 

[BreckenridgeCruiser]

As crushers said, check your fluids for contamination (coolant in oil, oil in coolant, combustion gasses in coolant) as a head gasket or head issue could be an issue.

If it is, I am planning on running some of the fluid fix stuff in mine to see if that works and will let you know!

 

[Freewheel]

I'm not seeing any of the classic signs of a head gasket problem. Oil's nice and black. Coolant's not contaminated.

When I rev the engine with the oil cap off, no blowby comes out - if anything, there is a very mild vacuum when running the engine in neutral at 2000 rpm.

Maybe, though I only have 280000 km on the truck, just the sheer age of the seals is starting to show. That rear mainseal is a 25 year old piece of rubber, maybe it's just time - and the fact that it started right after the turbo went on is just a coincidence? Anyone know what age/ mileage the rear mainseals tend to fail at?

 

[amaurer]

Revving the engine does not build any boost. You keep saying you feel a vacuum but unless you've got your hand over the oil cap when you're driving up a hill at 40mph and pushing 10psi then your tests aren't doing any good.

Head gasket/head crack/even block crack wouldn't cause rear main leaks. The rear main isn't attached to any other system, really... so either all your seals went bad by coincidence when you fitted the turbo or you are, indeed, pressurizing the crankcase somehow. Toyota's rear mains are nice one-piece seals, they last a long time;my money is still on the latter.

Did you keep the same size hose for the crankcase vent? I nearly blew every seal in my 3B when I downsized the vent diameter.... and that was before a turbo.

Post a pic of your system.

 

[Freewheel]

The vent tube is the same as stock. The Turbo is an entire AXT kit, watercooled, oil fed and came with exhaust and intake manifolds and all the attachment bits - this isn't a homebrew jobby.

Im going to T the vent tube into the boost gauge and see what I see at 100kph up the side of a mountain...

 

[LCDiesel60]

Freewheel--hope all works out OK.
Have the same turbo and am amazed with the quality and performance. 86HJ-2H. Haven't had any seals leaking on our rig but find an oil residue on the intake side of the turbo boot to intake pipe fitting--looks to be minor increase in blow-by with the oil traveling from the valve cover into the turbo intake system.

Normal for turbo diesel and what I used to see when I drove diesel semi trucks ages ago.
Installed the AXT system ourselves.

Hope you find the solution--at least you are paying attention and working through the options.
Take care,
LCDiesel60
Oregon

 

[RufusTheDufus]

Disconnect the crankcase vent hose from the turbo intake. Add a section of hose to it and route it somewhere that you can watch as you are driving. If you have excessive blowby it will puff like a small exhaust pipe. You could also attach it to a homemade manometer to measure the actual pressure in your crankcase.


Get yourself some of this Auto-RX stuff. I've run it in my H diesel. It works and will clean up your rings. It's possible that the addition of boost pressure could be messing with carbon buildup on your ring packs.

 

[RufusTheDufus]

Im going to T the vent tube into the boost gauge and see what I see at 100kph up the side of a mountain...

Are you going to disconnect the boost gauge from the turbo when you do this?

 

[Freewheel]

Hi Rufus, yes, I was going to plug the T on the boost controller hose(where the boost gauge is plumbed right now), and attach the boost gauge to the crankcase vent instead.

Although I like your idea of a vent hose poking up where I can see it - simpler with what I have lying around in the garage.

LC Diesel. Thanks for the encouragement. And the info about the oil residue inside the intake - I've noticed that as well, but figured (hoped) it was fairly normal.

With that oil though, make sure your hose clamps are tight! I was blasting across town to a mountain rescue callout yesterday and the elbow between the turbo and the throttle body blew off. In the center lane in traffic going uphill - the amount of black smoke was amazing - It looked like someone had torpedoed the Exxon Valdez in the middle of the road.

The elbows went on (and come off) much easier with that coating of oil than they did when newly installing them!

 

[Freewheel]

And 3 years later I find this post and realize that I needed to finish it off! The oil leaks were caused by a pinched hose between the crankcase ventilation outlet and the turbo air intake. (as Crushers first question pointed to) The hose that came in the AXT kit was the wrong length and it was folded over and pinched in a way that was not very obvious. Anyway, that internal crankcase air pressure caused the mainseal to leak and the clutch to slip, it also blew holes in the gaskets on the timing gear covers (both inner and outer gaskets) Replacing the pinched hose cleared up the mainseal leak immediately, but I've been living with the leaking timing valve covers for the last 3 years - and they leak a lot!
Anyway - hope this resolution helps anyone who may stumble upon this thread. And thanks to those posters above who pointed me in the right direction, though I didn't realize it because the problem was so hard to see... note to self, always look harder!
Thanks guys.

 

[crushers]

cool. thanks for the update

 

[TG74]

Picking up an old thread. I too am having this issue, though I can’t be sure if it’s the turbo or not. Attaching a video here showing the vent system and various lines. Oil pressure is up a bit too on the gauge.

 

[TG74]

Picking up an old thread. I too am having this issue, though I can’t be sure if it’s the turbo or not. Attaching a video here showing the vent system and various lines. Oil pressure is up a bit too on the gauge.

View attachment 3676418

View attachment 3676419

View attachment 3676420

View attachment 3676421

Couldn’t get a vid up here so photos instead

 

[duncanrm]

Picking up an old thread. I too am having this issue, though I can’t be sure if it’s the turbo or not. Attaching a video here showing the vent system and various lines. Oil pressure is up a bit too on the gauge.

How high is it on the gauge? Have you had a test gauge on it? What leaks have you got?