A Diesel Mechanic I am NOT! [Catch-up Update #5] (April-May 2024)

Hello Everyone,

This update does not  have any Prowler related information in it.  I'm doing it to document how I probably should not have spent 5 weeks of my life this past spring!  Well, that might be a little strong, but it definitely feels like I tried to tear down a brick wall with the top of my head!

I won - in the end.  But, man the steep learning curve!

So, this is a single topic update with no Prowler stuff.  If you want to skip it - no problem, continue on.  If you're still interested, here the list:

     1.  New Coolant Pump;
     2.  First Injector Swap;
     3.  First Turbo Pull & Replace;
     4.  New Fuel Pump;
     5.  Second Injector Swap;
     6.  Second Turbo Pull & Replace;
     7.  Third Turbo Pull & Replace;

Last year, the oldest daughter just had to buy a 2011 Silverado 2500HD with a Duramax 6.6L LML diesel engine - with 170K+ miles on it.  I tried to warn her......but, whoop - there it is:

About 12-13 months later, it was slowly losing coolant and she noticed that it seemed under powered.  She took it to a local diesel place and they checked it out and ran an estimate.  Essentially, they diagnosed it as a leaky seal in the coolant pump and also that it had a stored code indicating that it needed a new turbo charger.  She was concerned about the injectors and asked them to include replacing the injectors in the estimate.

The estimate for the water pump, turbo and a new lower coolant hose was almost $10K and to include new injectors would add another $3K+ to the bill.  She paid $20K for the truck and still owes most of that to the bank.  So, she called dad.

You might imagine the discipline required to not lead off with, "I told you so!"  (I didn't.)  I knew that working on these things is a much different animal than your typical "gasser" autos and trucks.  I really did not want to get involved with it.  But, I offered to take a look and maybe I could replace the coolant pump when she was going to drive it down during a planned visit in April.  I suggested she get another estimate for other work.  When she came down, I made some room in the shop and we got it set up for doing the coolant pump work:

The next step was to cobble together some way to climb up and into a position to work on the truck.  The thing sits high, and with it jacked up to get the tires off, it's even higher.  Time to get started. 

1.  New Coolant Pump - Here's the new coolant pump order from RockAuto:

After removing the fan and fan clutch.  Apparently, that thing is buried somewhere down there!?!?:

After taking off a bunch more stuff - I found it.  Here is the new one in place:

As I approached the point where I could close this engine back up and finish this job, I made the fatal mistake of watching a couple of YouTube videos about how to change out fuel injectors in this truck and how to rebuild a turbocharger for it. 

I followed that with a major error in judgement and figured that "I can do that!"  Ugh!  Like a lot of things in my life, just because I can do something doesn't necessarily mean that I should do it!!  Before the pragmatic, realist side of my brain could catch up, I'd ordered a turbo rebuild kit and a set of "refurbished" injectors.

There was a little logic behind why I chose to order a turbo rebuild kit and "refurbished" injectors.  I told my daughter that I would do the work, but she had to pay for the parts.  I was trying to save her some $$$ even if it would cost me a little more time - I didn't mind.  In the end, it ended up costing me a lot more time and a her a bit more $$$.  But, I digress.

2.  First Injector Swap -  The refurbished injectors showed up first, so I started with them.  Getting these things out of and back into a Duramax LML is not so much hard as it is tedious.  It looks like there is a lot of room alongside these motors:

But, unless you want to spend a bazillion hours peeling off ALL the "stuff" that is near, around or over every injector - it is tight.  But, with some patience, persistence and flexible tools, you can get it done.  It's just......tedious.  Anyway, by the time I got the injectors all in and everything put back together, the turbo rebuild kit arrived.  Moving right along!

3.  First Turbo Pull & Replace - Now, this part of the project is hard!  It is pretty much 6 hours (the first time you do it) of laying on your stomach on top of this engine with your arms reaching as far down as you can behind the engine to get the turbocharger out of there.  You literally cannot even see the thing before you get started: 

After about two hours of removing "stuff" you get down to this:

And, about 2 hours more cursing, yanking, bleeding and screaming.....you can yank the thing out and you're left with this under the hood:

And this sitting on your bench:

Here is the turbo rebuild kit that I picked:

It was a good aftermarket kit to rebuild the turbo at a reasonable cost.  The next day I started on the tear down of the turbo itself.  After stripping off all the easy stuff you get down to this:

Essentially, the whole compressor side of the turbocharger is removed.  Now, I had to get into the turbine side.  To do that, you remove the large band clamp you see on the left side here:

Then, with the help of a small chisel or old flat screwdriver, the two halves should separate (that's what the dude in the video did!).  Well, this one didn't.  I tapped, and tapped, and hit, and hit and beat, and whacked and beat until......thwack!:

Crap!  I heard the piece go flying and hit something far away in the shop.  This thing was not going to come apart.  I backed off on the intensity a little and continued to work on this thing (added heat) until it finally came "half in two."  But, I couldn't find the piece that chipped off.  I looked for hours!  I finally found it 15 feet away on my rack of steel stuff.  It had landed inside of a piece of uni-strut with it's flanges up.  Sheesh!  So, at least I had all the pieces:

Time for more practice brazing cast iron!  I had to chamfer all the pieces and make a little jig to hold the broken piece in place.  Then, I took it out to the welding table and got after it.  After brazing:

The band clamp would have held the two halves of the turbine area together without that piece in place without a problem.  The real problem would have been the hole that would allow exhaust gasses to leak out.  So, this braze repair did not have to be super strong, it really just had to plug the leak.  The repair turned out great:

With that taken care of, I could get back to the rebuild.  I cleaned all the pieces and this is what everything looked like before I started the reassembly and rebuild:

What was really wrong with the turbo to begin with is a locked unison ring.  In the turbine cavity, there are variable guide vanes that direct the exhaust gasses onto the turbine blades at variable angles (to control the amount of boost). 

In the pic above you can see all of the parts of the turbo that are on the exhaust side are rusty looking.  They are all cast iron so that they can withstand the heat of the exhaust.  The problem with cast iron is that it will oxidize and essentially "expand."  That's what caused the the unison ring to lock up and the two halves to seize together.  If the unison ring is frozen, then your boost is stuck at one setting, essentially.  This is a video that I made to share with the girls so that they could understand it:

In retrospect, I could have just fixed the unison ring problem, put all the old parts back into the turbo and reinstalled it.  It probably would have worked OK.  But, after investing this much time and effort to get the turbo out, why not just rebuild all whole turbo while it's all out anyway?  That was my logic, anyway.  Here is the turbocharger with the turbine, shaft and compressor wheel back in:

And, here it is ready to go back into the truck:

From here, it is pretty much the reverse of the process it took to get it out (pics above).  After I got the truck all back together - it would not start!

I spent a week trying to get this damn truck to start.  I spent hours reading forum threads with guys that had similar problems and what helped them.  I bled the fuel system, I bled the fuel filter, I charged batteries, I cranked it, and cranked it, and cranked it more.  Still, no luck.  But, in the process of reading all the forum, I found out about the high pressure fuel pump.

4.  New Fuel Pump -   This truck had a CP4 fuel pump.  No one likes it!  Everyone said that if you make it to 170-180K miles and your CP4 hasn't grenaded yet - you're living on borrowed time.  Her truck had 175K miles on it.  If the CP4 grenades - you have to replace most of your high pressure fuel system - including new injectors.  Well....OK.  So, since I was into this project this far and since I just installed "refurbished" injectors - seemed to be logical that I should replace the CP4 pump.  If I left the old one in and the thing did grenade, I would be changing injectors again, plus a lot more - not the least of which is pulling and rinsing the fuel tank.

Time to tear the whole top off this engine again.  Most of the stuff you have to take off to get to the turbo, you also have to remove to get to the fuel pump....only more!  Yay!  Well, it ain't getting done looking at it - so:

You even have to remove the AC compressor and lay it off to the passenger side.  Now, only a bunch more to remove.  The fuel pump is buried under all those steel fuel lines:

More cussing, more bleeding and more sweating and finally - there it is:

The good news, it did not appear as though this pump had grenaded.  Here's the new one (not cheap!):

After more, well.....you get the idea......it is snugly back in place:

And, timed correctly to the timing gear/pulley:

One more time! Put everything back together and put all the coolant back in.......only to find a coolant leak.   Fun!  I finally figured out where it had to be coming from.  Tear more stuff back apart so that I could get to it, pulled it out, and, yup!:

Rolled the O-ring while I was installing the tube.  New O-ring, put everything back together....again...and it was time to try to start this truck again.

Fingers crossed, I tried it.  IT WOULD STILL NOT START!

I am skipping a lot of detail here.  I spent hours bleeding fuel filter housings, pulling codes, reading forum posts, charging the batteries, etc., etc. that I did in an attempt to get it to start.  I spent hours and days - still no start!

At this point, I threw in the towel and called a tow truck to haul the damn thing down to a local shop.  They had it for a over a week and could not figure it out either.  I was bugging them every day (I had to have this truck running ASAP).  Turns out they made the same bad assumption that I did.  That the "refurbished" injectors that I put into it were good.  After about 4 hours together one Friday afternoon, their diesel mechanic and I went through the GM "no start flow chart" one more time - then, we found it!  Those $%#(!@|? "refurbished" injectors were garbage!  Out of the 8 of them, 5 leaked like sieves!  The fuel rail cannot build pressure if you have 5 gaping, freaking holes in it!!!

5.  Second Injector Swap - By this time, the shop wanted rid of me (and this truck)!  Hell, I wanted rid of it even more!  The manager told me that they did not have a mechanic to spare to work on an injector job.  So, they helped me get a good set of rebuilt injectors overnight (on a Fri night) and allowed me to work on it in their parking lot on a Saturday morning.  The next morning I got up early, loaded up a bunch of tools and headed down to their shop:

I started working on it about 830am, the injectors showed up at 10am.  I had the injectors swapped out in about 3 more hours.  Then, finally, that afternoon - Eureka!! 

I finally got the damn truck started and running!

The joy of this success was quickly steamrolled by the next issue.  When I took it for a test drive, this thing laid down an unbelievable stream of smoke out the tailpipe!  JEEZ - what now?  I slept on it overnight and in the morning decided that my turbo rebuild must have been bad.  I was going to have to pull it - again!  However, I didn't want to do that in their parking lot.  I took a calculated risk that if it was dumping oil into the exhaust, there was enough oil in the pan to make it back to my shop.  So, that's what I did, and you might have thought that the county was on fire by the time I got the thing back my place!  I watched the oil pressure warning closely and everything went fine - aside from the huge smoke plume.

6.  Second Turbo Pull & Replace - You know the drill from the first turbo pull described above.  After tearing the turbo apart again, I found it!  Somehow, I do not know how, but I'd forgotten the oil seal on the turbine end of the turbine shaft:

The red arrow points to the seal that was NOT there when I pulled it apart.  UGH!!  I put it all back together - again, but correctly this time!  This time, the truck started and ran pretty well.  It ran good enough that I was able to use it to pull a trailer out to the coast to help the middle daughter move out of her apartment there.

However, on the drive to the coast and back, I still noticed some (a little) smoke from the tailpipe at certain times (mostly accelerating off of a full stop).  I researched this for a few days.  I read forum threads online and went to visit a couple of the local diesel shops.  The owner of one shop told it to me straight:  "We don't rebuild turbos for that exact reason; what you are experiencing right now.  Eight or nine times out of ten, the rebuild goes fine.  But, the 1 or 2 times it doesn't, we end up having to do the job a second time, for free.  That is costly!"  And, with that said, I pulled out the card and ordered a new, re-manufactured turbo that is an OEM replacement.

Oh, there was another thing that I noticed during the drive - the noise.  I hadn't actually realized it at the time, but this aftermarket kit that I purchased was not an OEM kit.  It was a performance kit that make the truck accelerate really nicely.  But, the turbine is a nine fin design instead of the OEM version.  So, it makes a turbine whine, and it was pretty loud.  This wasn't going to work for my daughter.

Guess what!?!?

7.  Third Turbo Pull & Replace - By now, you might imagine, I was getting pretty good at ripping the turbocharger out of this truck.  I was hoping that the third time would be the charm.  When I got it out, the turbine side looked dry and about what you'd expect on that side of the turbocharger:

But, when I spun the compressor wheel off, I found this:

It doesn't show up well on the pic, but you could see where the oil had been spinning off of the back of the compressor wheel.  There were radial streaks.  I suspect that the oil seal on the compressor side was leaking a small amount of oil (yes - it was in there correctly).  When the truck is slowed and idling (like at a corner, or a stop sign) the oil would build up on the back side of the compressor wheel.  Then, when you would accelerate, as the exhaust pressure built up, the wheel spun faster until it would fling all that oil into the intake plumbing.  Then, it would get burned in the cylinders and come out of the tailpipe - which is what I was seeing.

Here is the new, re-manufactured turbo that I purchased ($2K):

Here it is, back in the truck, before all the topside stuff got put back on for the umpteenth time:

The day after I got it all back together, I had a trip to make to the Bay area.  I decided to drive this truck to make sure it was going to be good.  Glad I did!  Cuz, on the drive down and back, I had the "Coolant Level Low" light go on several times.  I went through 2 gals of pre-mixed coolant.

Back to the drawing board - AGAIN!!!  This truck hated me.  We were supposed to leave the next day to take the trailer with all of the apartment contents up to Seattle.  So, I got up early, jumped on it again and finally found the culprit.  The fitting you see at the bottom of the tube:

Problem is, getting to that area is about 2/3 of the work it takes to just pull the turbo!  Unbelievable!  Two hours later, I had it out, again:

And, here you see the culprit O-ring.  Once again, this got rolled over when I put it in and it was the cause of the coolant leak. 

Fortunately, the local GM dealership had a new one in stock.  I got it, we put it in, put everything back together (for about the 6th time), and held held my breath as I filled the coolant reservoir.   We drove away at 3pm that day with the trailer in tow.  I got the "Coolant Level Low" again 2 times as the system "burped" over the first hour of the drive.  After that, the coolant level maintained itself and it appeared as though this horrific experience was over.

By the next day, we had logged 450+ miles on the way to Seattle and the coolant level was still staying topped off.  The next day, I returned the truck to my daughter in the Portland area:

So, I finally won!  In the big scheme, she now has a truck with an engine that should run fine for here for another 150K+ miles.  So, that's a good thing.  If you change the oil and take care of these diesel engines, they will go 250-300K miles.

I got my truck back, loaded a trailer onto a trailer and headed for home:

Lessons learned:
1.  Pay the money and buy good, "re-manufactured" parts the first time.  The labor involved with fixing these vehicles is problem enough.  Having to do it 2X or 3X because you put in garbage parts only makes the whole situation worse!
2.  Only fix one thing at a time.  When you overhaul 4 or 5 parts or systems at one time, and the thing doesn't start when you get it all back together - it can be difficult to determine which part or system is the "unhappy" one.
3.  Don't answer the phone when your kids call about help with their vehicles!

I'm glad that I could help my kid with this and save her a fair amount of labor costs.  But, it certainly came at a cost of time.  In the end, I learned a lot and can now say that I finally won.  Still not entirely sure it worth it though!?!?

Thanks for checking out the blog.  See you, again, soon!