variable vane turbo

Gentlemen, I have 0 knowledge of variable vane turbos. Farmer friend last fall had the actuator replaced on a 4WD Deere by Deere dealer mechanic. Now, during preseason inspection, a different Deere mechanic says vanes are "sticky". He determined that by working the actuator by hand. Says it may run 5 hrs, 500 or 5000 thousand. I understand that a bad actuator would hold you to low or zero boost, but what happens if it sticks full on? Will you now have a lean mixture like a gas engine, with corresponding high cylinder temps? He wants to change the whole turbo to the tune of 6 grand.

The "vanes" on a variable vane or variable geometry turbo can suffer from build up of soot causing them to not open or close completely and making the actuator work harder to open/close them. Generally when you replace a bad actuator you are fixing the symptom not the problem and the new actuator will most likely go bad quicker than the original. The turbo will more than likely need to be replaced. This is a big issue with Diesel trucks that use variable vane turbos as exhaust brakes most people leave them off when driving empty and turn them on when towing and the lack of use causes them to wear out quickly. Always turning on an exhaust brake will keep the vanes moving and help keep them from having soot build up.

How important is the tractor? If there is a spare, I'd run it until it fails. If it has to run when needed, I'd fix it.

Normal times I'd run to failure , but if parts are available now I'd own them.

As far as the lean thing, all diesels are lean burn unless full rack and rolling coal.

Each time you turn the key switch on the actuator will cycle completely. If it is sticking and does not make full travel it will set vgt out of calibration code.

Turbochargers do not need rocket scientists to work on them! I would never spend $6K just because of sticking vanes. Like others said, carbon buildup, or like I found on my Duramax, rust jacking preventing the unison ring from rotating. There is a stainless steel ring that rotates on a shoulder machined into the bearing housing face. Actuator rotates the ring. Ring has slots in it the vane pegs fit into. As the ring rotates, the vane pegs move in the ring slots causing them to open and shut. Watch a Youtube video how VG turbos work. I found the iron bearing housing had rust scale growing under the carbon. The machined surface had swelled because the rust growing under the carbon, stopping the ring from rotating on its shoulder. About 45 minutes with a sharp chisel pecking by hand on the iron surface removed the scale. Ring now rotated freely. I put anti-seize on the shoulder before final assembly of the ring. The turbine housing where the vanes pivoted didn't have any scale. I used grease to stick the vanes to the housing for assembly. Assembly of the bearing housing/compressor end was tedious under the windshield of the truck. Turbo has not given issue for the last 120K miles. It has 316K miles on it now. I believe the bearing housing was made of a poorer grade cast iron which rusted faster. Any turbo re-builder can do this. They will want to generate more profit margin though and complain or refuse. No warranties will be given for this kind of work. The worst part of working on turbos, the idiots assembling them don't use anti-seize when installing the bolts. They come out with difficulty. Just because the bolts may be stainless steel doesn't mean you'll have an easy job.

Stainless steel bolts tend to stick of their own accord. Surely the reason they are used is just the high heat part of it. Good on you for fixing that. "Man made it, man can fix it." Show those engineers who owns it.

I tried ordering a turbo actuator last week for my 6.7, on back order till April 1st.

Installation instructions state to check the movement of the actuator arm for sticking when replacing the actuator. Interesting that last fall it was ok to put an actuator on but now it needs a turbo rebuild.

Does the Deere turbo actuator have coolant that flows through it like the Cummins engine?

dieseldog5.9 said:

Does the Deere turbo actuator have coolant that flows through it like the Cummins engine?

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Yep

I find it interesting that in a preseason check, they are going to drain the coolant, pull the turbo actuator, inspect lever rotation, install turbo actuator, and refill and purge coolant.

The worst part of working on turbos, the idiots assembling them don't use anti-seize when installing the bolts. They come out with difficulty. Just because the bolts may be stainless steel doesn't mean you'll have an easy job.

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I’m of the firm belief that people who don’t put hot section bolts in with anti seize (hot section being manifold, turbo, exhaust, etc) should be shot for incompetence.

Most people dont give a crap about anti sieze. What are the odds of them working on the same part on the same machine in 5 or so years time? Working in house, I know it will be me again so i rarely put any bolt anywhere without copper grease, oil or studlock

"Shot" is a little harsh and only lasts until they die. Maybe twenty lashes with a cat-o-nine tails.

In the USA molybdenum disulfide seems to be in most anti-sieze products. I've even bought the purple antiseize with ground ceramic particles in the US. But in the UK they are crazy about copper grease.

I mean, the grease base (often lithium) burns away, so the antiseize material that remains in between the threads is either copper, MoS2, ceramic particles, or whatever. The melting point of MoS2 is higher than copper, and ceramic is even higher. But melting point isn't everything. The copper could act as a coating.

I know that the different anti-seize greases have different properties and are specified for slightly different uses, but in real life does anyone have experience using different types of anti-seize greases on the same high-temp threads and have noticed anything different?

Also, those stainless steel bolts are probably really difficult to get out because of the cast iron rust in the female threads. But if a steel bolt were used it might never come out. And as a note, be careful using stainless steel bolts with stainless steel nuts because the threads can self weld when tightened. This happens often with soft stainless steel nuts and bolts, like A2 304 hardware but also A4-70 316. A4-80 is a touch better, but still. I always use a wrap or two of teflon tape in low temperature applications, or antiseize when using stainless nuts and stainless bolts. Ideal for hot areas are two dissimilar non-corrosive metals: like stainless steel studs but nuts made of alloys, like brass.