Sticking Linkage Fix
for
Sprinter 3500 I-5 Turbocharger

Several owners of Dodge Sprinter (Mercedes) based motorhomes with the inline 5-cylinder engines have had turbocharger "failures" which required expensive replacements.

When the linkage sticks, the engine loses boost and power then goes into Limp-Home Mode (LHM).  In my case, the problem followed two replacements of the faulty design Mercedes "turbo resonators", followed by replacement by an aftermarket "resonator eliminator".  At that point, air leaks could be eliminated and the code thrown by the ECU only said something like "loss of turbo boost" which covers a multitude of sins.  Also, in my case, the sticking linkage came unstuck by itself about three times before finally seizing-up solid.

A clue to the problem is that, under warranty, the turbocharger was replaced when the vehicle exhibited the same symptoms.

What I've found is that, in a the few instances where the diagnosis was discussed by the technician with the owner, the problem was not with anything internal to the turbocharger.

The problem was actually in the linkage between the actuator and the variable pitch vanes in the stator of the turbine.  What happened in these cases was that corrosion (rust) formed in the linkage which seized the parts and caused the turbocharger to fail to operate.

The first repair involves removing the pin from the top clevis of the link then disconnecting the electrical connector and removing the actuator.  This allows the actuator and link to be placed on the bench and the lower clevis pin carefully removed.  Once removed, both pins are cleaned and lubricated then reassembled and re-installed on the engine in reverse of the disassembly.  I do not advise trying to douse the lower link then force it to move.  This could destroy the actuator.  If the bottom link is stuck or stiff, it's best to remove the actuator and link and be gentle.

In the case shown, I didn't have to remove the actuator or link.  All I wanted to do was to re-lube the linkage as insurance against it sticking again.  The bottom of the link can be reached with the "greasy finger" from above but must be done by feel.

Note that you can click on the images to obtain high resolution versions.


Seen from the front passenger side, showing the aluminum heat shield in place.
There is one small bolt and two small nuts that have to be removed to be able to remove the heat shield.

Seen from the same location with the heat shield removed.
After removing the heat shield, you can see the turbocharger, located in about the center of the photo.  The rusty part of the turbocharger is the exhaust turbine which powers the aluminum-housed compressor.  The turbine housing is made of cast iron and, unless the turbocharger is new, will be rusty because it becomes hot when the engine is running.

Showing the top of the linkage, located between the rusty (normal) turbine and the aluminum compressor housing.
The arrow points to upper clevis (joint) of the linkage.  To remove the pin, carefully remove the snap ring.  I say carefully because I am the Voice of Experience From The Past.  Although I haven't had it happen on this particular chore, those snap rings have a habit of "escaping" as you pry them off.  They will propel themselves to somewhere in the next county, forcing you to resort to the junque pile or an auto parts store.

After removing the snap ring, push the pin out of the yoke so the link is free at the top.  If you are lucky, the bottom link isn't stuck and the link will move freely.  If more than even slight resistance to movement is felt, the actuator must be removed.  If the link moves, you can locate the bottom yoke by feel.  A small gob of your favorite hith-temperature wheel bearing grease applied to both of the clevis joints should do fine.  After applying the grease and before replacing the top pin, work the link back and forth to make sure the grease is going into the joint. 

Do NOT be tempted to oil or grease the lever where it goes into the turbine housing!  At best, the grease will simply melt and evaporate.  At worst, you might have a small fire.  Either way, there will be smoke.

I didn't photograph how to remove the actuator but it has to be removed from the bottom.  Follow the link down to the bottom.  That is the actuator.  There is an electrical plug that has to be removed and, as I recall, a couple of bolts mounting it.  It requires a little dexterity but isn't really difficult and the chassis doesn't need to be raised unless you are an unusually "large" individual.

Gob of grease being applied to the top joint of the linkage.
You can see the grease being applied.  I probably use a bit too much grease for some people's taste but, in my opinion, grease and oil are cheaper than new parts or work so, I use a sensibly large gob.

That's all there is to it.  Just put the heat shield back on and you're in business.  AND you could have saved a lot of money!

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