Turbo Exhaust leak ?

[mallred]

Is it possible for exhaust on a 3b turbo to enter past the oil seal on the turbo into the return to the pan ? It appears as though the blowby is more soot than oil. where it builds up it does not wipe of like oil but gritty and stuck to the paint.

I have the crankcase breather pipe to the inlet to very close the turbo and about 18 inches from the air filter and in the mornings when cool the gases roll out of the airfilter for about 2 mins until it warms up.

I tried to do a comp test and got 475 on the first 2 cyl and the fabracated backyard tester I put together went to s*** and showed 275 on the next 2 cyl and 275 when I redid the first cyl, so I think they are equal and my new $nap on guage I got of ebay will be here maybe tommorow, But it think it might be the turbo instead. I have been loosing boost, it was never very high 6lb but now I can only get about 4 lbs and seem to be loosing top end.

I am going to look around for a hose and put it on the oil return and see what happens.

Any thoughts?

Myrle

 

[fjbj40]

if this is happening in the morning at idle then I would say it is not the turbo ! I have had quite a few turbos in the past and have never heard of turbine side exhaust gases doing that , but it might very well be possible . It sounds more like excessive blow by because there is not that much pressure / velocity at idle to do that on your turbine side at idle.
Have you checked your ex. sytem for blockage...sounds like it may be possible if you are slowly loosing boost...do you have an EGT gauge ? are your temps slowly rising as boost is falling ?
Most turbos faill at the compressor side as a rule of thumb.

This post is probably going to open up a pretty good discussion with lots of theorys....my bet is blow by or blocked exhaust.


Lets see what others have to say ...HTH'S , Daryl

 

[mallred]

Found it.

After the failed comp test I have been trying to figure this out, I had my wife start the truck up while cool with no Glow plugs and found a bad exhaust leak where the manifold connects to the u adaptor for the turbo. This answers the lack of boost. It must have been there for quite a while the black area in the pic was there when I bought it and it is red under that black. I my boost tops out a 6 psi now and it runns better than it has since I got it. It also cools down on the egt much quicker now it was holding onto the heat for quite a while after a load before. I also changed out the injectors that I had rebuilt out of the bj42 and although they did look fairly new but the #4 and #2 had almost a tempered look to them. I put the ones out the bj40 into the bj42 and it runs very well.


The 40 still has blowby issues but not nearly as basd as I tought it was.

Do these pics of the injectors I pulled indicate anything with the tips being discolored ?

Thanks, Myrle

 

[Greg_B]

Good you found it. That was a strange one...

Take a look at the bottom flat section. Are they cupped? If so, they need replacing. As I understand it, as the crack pressure goes lower with age the tip does not mist as well, larger droplets formed, more fuel closer to the tips, heating the tips more, weakening the springs more, less misting, more heat to the tips, yada yada yada. End result is weakened springs and cupped tips.

If you are close to an injection shop they should be able to bench test while you watch so you can at least know the crack open pressures.

hth's

gb