Advice on turbo oil blow-by

[RisingSunLCS]

Hi,

This is my take on your oil in your charge pipe/oil consumption situation.

By the looks of you are running a 2H. How many kms are on it? Have you ever changed the Oil pressure relief valve in the timing case? Those are a common failure on 2H motors. Its located directly behind the power steering pump bracket about 2'' above the lip of the oil pan? If not, there is a good chance your motor is producing ridiculous amounts of oil pressure well above FSM specs. Seeing that, you never mentioned an oil pressure gauge along with your EGT, Boost and water temp gauges.

I think you are getting waaaaay to much oil pressure into your turbo housing. The kink in your drain line wasnt helping what so ever. I know its probably hard to tell if oil was also coming out the hot side of your turbo but, if you have any sign of oil into your exhaust system. I will almost bet you a $100 that your oil pressure relief valve is failing.

Hook up a mechanical oil pressure gauge and you will find out very quickly whats going on.

I literally just replaced my Oil pressure relief valve last week. When I hooked up my autometer mech oil pressure gauge. I found out that @ cold idle it was producing 120psi@ 750rpm. At 2000rpm I was @ 160psi w/the engine still cold. I have just recently installed a Garrett Turbo setup and the PSI rating for the oil seals is 60psi (as per a Garrett Turbo engineer @ DW Diesel in NY). I found out very quickly that i had to much oil pressure when it was puking oil out from both sides of the turbo.

New oversize oil pressure relief valve from Radd Cruisers and my problem is fixed. I would go that route before rebuilding your turbo. Oh, and go buy your self a oil pressure gauge the factory ones are very inaccurate.

just my .02

 

[DillonOnTheCoast]

Measure your crankcase pressure. Don't replace the turbo or it's seals. Turbo seals only ever need replaced when the turbo bearings wear out and that requires a rebuild.

I talked to the Turbo Glide folks and this was their guess as well. I know I can eyeball blow-by from the oil filler cap or measuring the oil captured in my catch can ... but is there a good way to measure crankcase pressure directly?

Did I miss your answer to the blowby tube? Is it still to atmosphere, or was it plumbed to the intake?

Plumbed to intake. I put a catch-can in the middle but haven't been driving it much since I put it on (so I haven't checked its contents yet).

either bad compression which really sucks or valves, in which are really easy. follow the book

I had Tor @ torfab.com check the compression. I'm not sure if these are hot or cold #s. I'll have to drop him a line and ask.

1. 400
2. 380
3. 380
4. 380
5. 370
6. 370

The spread between #1 & #5/6 is a hair out of spec per the FSM but I am told this is good compression for a 2H with 100k miles.

I haven't done the valve adjustment yet but it is on the list.

Have you ever changed the Oil pressure relief valve in the timing case? Those are a common failure on 2H motors.

I talked to the PO. He replaced the valve, reusing the old spring, when the motor was rebuilt 100k miles ago.

Oh, and go buy your self a oil pressure gauge the factory ones are very inaccurate.

I'd love to have an oil pressure gauge on the dash but it's kinda low on my project list right now. I may just swing by the local garage and have them hook it up and tell me what the oil pressure looks like.

 

[DillonOnTheCoast]

Had the oil pressure checked out and it is not excessive (70psi at cold high idle, 35psi when warm).

I guess this leaves me with the following possible explanations:

1. excessive crankcase pressure is blowing oil through the turbo, meaning the seals are in fact just fine
2. excessive crankcase pressure is preventing the oil return from draining, forcing oil past the seals (possibly damaging them)
3. inexplicable failure of the oil seals in the turbo

Other than looking at compression (and further a leakdown test if compression indicated poorly) I'm not sure how to gauge crankcase pressure. Given my compression numbers and the POs experience with the catch can, this seems unlikely.

So ... do I pull the turbo off and replace the seals? Would that leave me with good seals that are just going to fail again due to some underlying cause?

 

[Dougal]

Pull the dipstick, put a pressure line on that and go for a drive. Turbo oil seals aren't damaged by passing oil. Fix the problem and they'll sort themselves out.

Do you have a long enough line to reduce oil pressure at the turbo?

 

[DillonOnTheCoast]

Pull the dipstick, put a pressure line on that and go for a drive.

I don't know that I need to - I can see that the leak(s) is(are) getting worse. I now have oil coming out from the bottom of the turbo (at the oil return line fitting), where the dipstick attaches to the block and at an inspection plate on the LH side of the block.

This points pretty conclusively to excess crankcase pressure, yes?

Other than rings (I'm going to put that aside for the moment since compression tests ok), what are the possible causes? Valve adjustment? Is there a PCV valve on a 2H engine?

Do you have a long enough line to reduce oil pressure at the turbo?

I don't understand ... which line?

 

[Dougal]

The turbo oil feed line. It has to be long enough or have a restrictor in it to reduce feed oil pressure to a level the turbo can handle. Too much pressure will spit oil past the turbo seals.

Check you don't have a blocked or kinked breather.

There can be other causes too. I've recently changed oil brands in my Isuzu and it's started both smoking and burning oil. I'm only 35,000k from a rebuild, so it should just bad back in and settle out.

 

[DillonOnTheCoast]

I'm not sure about the oil feed - I'll have to take a look at it and maybe ask the previous owner about restrictors.

As for the breather, I recently added a catch can. I suppose it is possible that the catch can is blocking things up but that seems unlikely since it is so simple.

 

[Dougal]

How big are the connections on the catch can? A lot of ones on the market are too small for diesels. Diesels produce a lot more blowby than petrol because they always run positive cylinder pressure.

 

[DillonOnTheCoast]

You may have been right on the catch can. The connections were about half the size of stock. I removed it, cleaned the leaked oil from the engine so I can see if it comes back and emptied the can. It had collected about 4oz/120ml of oil in under 200 miles.

My guess is that the can was collecting oil indicating excessive blow-by. Meanwhile the restriction it introduced caused some of the new leaks to occur (around dipstick, at the oil return line from the turbo, etc). At the same time, the turbo seals are leaking which is why I have oil seeping around the intake manifold despite the catch can.

Does that sound right? Am I correct then in looking at excess crankcase pressure as the cause of both the oil blow-by and the leaking turbo seals? What other diagnostics would you recommend?

Do you have a long enough line to reduce oil pressure at the turbo?

It's a braided stainless hose. It looks like it is about 3'/90cm. I'm not sure about a restrictor but I bet this is the stock part from the Turbo-Glide kit.

 

[Dougal]

The catch can probably is the culprit. Fine on a 1.6-2 litre petrol but not enough for a 4 litre turbo diesel.

Your turbo line sounds fine.

 

[DillonOnTheCoast]

I'm still trying to figure out the original problem (the leak started before I put the can on). I've got the name of a local Diesel shop nearby where I'll have them check the crankcase pressure & other diagnostics.

Anything else you guys recommend I check or have them check?

 

[DillonOnTheCoast]

From removing the oil filler cap and eyeballing the opening, it sure doesn't look like like an issue with crankcase pressure. In any event, I dropped it off at a local shop so they can take a stab at diagnosis.

 

[DillonOnTheCoast]

They recommended running the breather down to the pavement (draft hose). They speculated that perhaps there was enough vacuum upstream of the turbo to pull additional oil vapor through the breather when it was plumbed that way originally. I'm just going to keep an eye on oil consumption.

It doesn't appear that I'm losing any oil through the turbo so far but I haven't put many miles on it yet.

In short, I just gotta keep topping it off. Tomorrow I leave for Mexico, so we'll see how that works out.

Catch ya'll on the flipside.

 

[dousty]

Don't get caught out by a blocked air cleaner either, that will cause your turbo to pull oil in from the bearing housing.

 

[DillonOnTheCoast]

Been on the road for a few days now. So far I've used almost 2 quarts in ~1100 miles. There's no oil seeping out around the intake manifold so I am no longer thinking about the turbo. Either way, oil consumption hasn't gone down since routing the breather down to the ground as opposed to the upstream turbo plumbing.

Yesterday a concerned trucker waved me over and told me that he thought I had a smoking wheel-bearing. My very long breather hose exits back there.

I checked it out and while I couldn't see much smoke coming from the breather hose while idling (I'm sure that's what he was seeing), I could see some oily sludge deposited back there.

There's a couple photos attached.

1. That sludge used to be routed into the intake
2. This breather hose is really long. I'm probably going to cut it off as I'm worried about it blocking up with said oily sludge.
3. 2qt in 1100 miles? This doesn't sound good but it doesn't jive with the compression test either.

My plan right now is to just keep driving and buy lotsa oil. I guess rings/cylinder hone is in my future?

 

[Jan-78FJ40]

Hi Dillon,
that's a lot of oil/sludge. Could you post a pic of the current routing? Did you just block off the place where the breather was routed into the intake?

General question to all: If the rings were shot, wouldn't the compression be bad?

cheers,
jan

 

[DillonOnTheCoast]

Hi Dillon,
that's a lot of oil/sludge. Could you post a pic of the current routing? Did you just block off the place where the breather was routed into the intake?

Yep. It is blocked off on the plumbing upstream of the turbo. The breather now comes out of the valve cover, down to the RH frame rail and back to the rear of the vehicle exiting near the spare tire.

General question to all: If the rings were shot, wouldn't the compression be bad?

That's what I thought but then I read this recent thread about a 3B with good compression, turbo and excess blow-by.

My new barely informed theory is glazing on cylinder walls or compression rings, just bad enough to let some oil through.

 

[ErikHJ]

Also here issues with oil in the turbo. Got a HJ61 12HT engine.

Engine is overhauled, new pistons, all done.

But on start up load of smoke for a mile. So Turbo was suspected, and with good reasons:

Nice amount of oil were you don't want it. And it wasn't coming from airintake. But after turbo revision smoke issue wasn't solved.

So oil pressure test (also considerring the fact that the oildrain on the turbo is not the original full metal, but with "coolant" tube). Engine running, oil cap open, and oil drain of turbo free flowing in a bucket. Still the same issue, slowly oil is appearing.

So today I had a look at the oil pressure relief valve. (nice messy oily job )

But that actually looks pretty OK as well.

So either the turbo is still an issue or I'm missing other causes.

Cheers,
Erik

 

[ErikHJ]

Also removed the second oli pressure relief valve (near the oilpump). Also looks OK. Thicker spring tough.

 

[ErikHJ]

So here is the other pressure relief valve positioned.....

Here both pressure relief valves: