Technical 70 HP diesel turbo adjustment

[DaveMcT]

Is there a specific setting or special tools for adjusting the turbo waste gate actuator? I’ve replaced the turbo core and got it “close” but engine has an obvious turbo lag.
I think it needs adjusting but I cannot get to the adjuster nuts.
Any ideas?

 

[koalar]

Add a pressure trsnducer sensor

In 3rd wide open throttle until 3K revs then back off

Max pressure should be between 1596 - 1748 mmHg

 

[DaveMcT]

Thanks that's very useful and on my list.

My issue is setting the turbo waste gate itself. The compressor end has no marks to align it to the core and it's position affects the waste gate actuator. The actuator itself is adjustable but I've no idea what the starting length should be.

Is there any advice from Fiat on how to adjust the actuator. Its tucked behind the turbo and I can't even get a spanner on the lock nut.

 

[koalar]

The rod is preset at the factory

There's no adjusting when fitting a new one

The above procedure is from fiat's elearn diagnotic test for turbo pressure

To me it dose not sound like a wastegate problem. There should be some preload and initally held shut. Unless it's flapping around it can't cause lag

 

[DaveMcT]

It's quite possible that I don't have enough tension on the actuator rod. The issue is that one of the snail shell bolts is impossible to turn (not enough space to swing the spanner) and the waste-gate rod has the same problem.

The turbo core is new but I kept the original ends (snail shells) and actuator. The compressor end has an O ring seal and four M6 bolts with thick washers to retain it to the core. The actuator is held by two of those bolts. However, there are no marks to ensure exact alignment. Any relative rotation will affect the actuator pushrod length. I should have scratched the old core to the compressor shell, because my Sharpie pen marks had rubbed off. Hind-sight yet again.

Where do you connect a boost pressure gauge? Is it simply a T joint on the turbo waste gate actuator hose?

 

[koalar]

 

[DaveMcT]

Thanks

 

[DaveMcT]

The exhaust is not yet fitted so I've removed the rad fan and pulled the turbo, along with catalyst. It's a tight fit.

The waste-gate was being held shut but I've tightened the actuator rod a little and screwed it all back. The actuator moves nicely with (careful) use of a spanner on the arm. I also noticed a handy divot in the intake shell at the oil supply banjo so I've made sure this is centralised. It was out by a few mm though probably made no difference.

I don't have Examiner so will have to fit a T joint to the waste-gate actuator pipe and measure boost blow-off pressure from there. Goodness help me if it needs adjusting as there is virtually no way to reach the push rod adjuster with turbo in the car.

 

[koalar]

The waste-gate was being held shut but I've tightened the actuator rod a little and screwed it all back.

Not sure how this helps with your problem of low end lag

Randomly increasing the crack pressure just adds another variable to the mix. Let's hope it does not over boost now

The car was probably running okay before the chain broke

As well as the top end rebuild

There's the wrong size injector washers
Replaced fuel pump
Replaced injector
Rebuilt turbo
Adjusted waste gate

To add into the mix

touching one thing at a time makes diagnosing any subsequent problems easier

There no obvious starting place

Check cylinder pressure

Checking the air-fuel ratios at idle

Checking the MAF is reading correct

Checking the turbo pressure

 

[DaveMcT]

The turbo settings are wrong because I replaced the turbo core. Bearings were worn and there was oil in the air tubes. Getting that set correctly will be a pain in the **. I had marked the push rod settings with sharpie pen then cleaned it. D'Oh. I will have to connect a pressure gauge and see where it blows off. I've seen the pattern of an excessive boost "corrected" by the ECU. That could easily be what I've got going on.

The injector washers will technically make a difference but I can't imagine there's a serious change to be made. I have not been able to find a procedure for finding the washer thickness so have set them all the same.

The engine must have been running like a dog before the chain broke. Inlet manifold was all but clogged with soot and at least one rocker needle bearing had fallen apart. Broken rockers can't deposit needle rollers into the sump because the engine stops. Then there's the wobbly turbo shaft.

Fuel pump was leaking, so who knows what the common rail pressure used to be. Poor spray patterns would add to combustion issues. It refused to start on the first attempts. Diesel fuel dripping off the gearbox gave a clue. New pump fitted and it fired up no problem.

I had expected to see the engine light from all the changes since the last time it ran. So far, it's stayed off. I will be getting MES connected to look at the values as I'm sure there is stuff to find.

The engine cylinders and bearings are in really good condition. I think it had regular oil and filter changes. I removed the pistons as it was already most of the way there. I'm very glad I did - soot-clogged oil control rings won't stop much.