6CTA8.3 engine rebuild for Sur Móvil

Mos68x

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After getting and oil change and the truck washed at Blue Beacon Monday night for the upcoming ISO frame build I got a flat tire...

IMG_7840.jpg auaauaauaaua

which led me to try to drive it for an additional 12miles into town Tuesday, after the 40miles limping it home with the rear axle bound up with a chain binder since I had already used my last spare tire. I'll admit that the goal was actually to drive it much further, like the 90 miles to Prescott since I had to pick up the steel for the ISO container frame for the BHTRV project (link here). BUT the tire started shredding (or still shredding, I'm not sure since it was like 3am before I finally made it home and was beat, so I might not have felt it shredding then) and the tire was really shaking the rear of the truck real bad. When I got the flat I heard it right away since it was the front left tire and managed to pull over before I lost all air in the tire. When I went into town the next day I only made it to Seligman before I called it a wash and went to one of the shops to have them pull the tire off since I didn't have enough time to do it myself. Mind you, I had absolutely no warning or abnormal sounds up to this point. Unfortunately when I went to start the truck again I had a massive knock from the engine. auaauaaua I turned it off and restarted it, but it was still there. I wasn't sure where the problem was so I decided to limp it home and deal with it there. On the trip home the knock ended up going away but I also lost boost pressure. I ended up having to drop it into low gear in the TC to make it up the meager hills that I would've normally had no issues with before.

IMG_7853.jpgIMG_7854.jpgIMG_7851.jpgIMG_7849.jpgIMG_7856.jpgIMG_7857.jpgIMG_7859.jpgIMG_7858.jpgIMG_7855.jpg

Today I finally got part of the truck apart after getting a new generator and air compressor. The turbo definitely needs to be rebuilt, but it doesn't look like it needs to be replaced...yet. I've already been talking to 98G and have a rebuild kit on the way, I just hope that the engine doesn't have any oversized journals, or doesn't need anything to be oversized either. Of course the only way to know that for absolutely for sure is to tear it apart and measure everything. I'll take pictures as I go, for my own reference as well as for this thread in case there are others that need help doing their own rebuild. This won't be my first rebuild on any engine since I've been a gasser gearhead since before I was first driving (lawnmowers). However, this will be my first diesel rebuild so any specialty tips are appreciated. Engine basics are still the same, they just operate slightly different and use different fuel, other than that they are the same so I'm not at all intimidated by this rebuild. This is just another unfortunate step in my bad luck.:sad::sad: I may even build up the block/head some if I can. Of course the only things I can think of right now is valve springs, copper head gasket, head studs, and if Hamilton has it...a drop in cam and tappets. I would love to do a compound turbo setup since we have plenty of room so I can negate the turbo lag, but that will likely wait until after everything else is complete.

Anyways, enough rambling, if you have any ideas or suggestions feel free to post them.
 

74M35A2

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It looks like the compressor wheel retaining nut came off and was swallowed. You should find it embedded in the piston of one cylinder, the others should be ok. Pull the head off before you order parts, you may need less than you think. I think the worst you will need is one piston and maybe a valve only, hopefully not a replacement head.

Head studs are pricy for an 8.3L, but the head gasket is the weak part if increasing boost and timing. You may be able to O ring or fire ring the sealing surface for less than aftermarket head studs.

Bummer to to see bad luck hit the truck in more than one spot in the same week for you.
 

Mos68x

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Nut wasn’t injested thankfully, it was sitting in the inlet piping for the turbo...or at least I assumed it was for the center shaft since I didn’t actually try to thread it on to verify.

The engine rebuild was something that was planned, just not right now. I had planned to do the rebuild before I left for the road after I finished school.
 
Last edited:
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What was the reason that an overhaul was decidedly needed? Is there excessive blow by or fluids mixing?(oil and antifreeze) Low oil pressure or an internal clatter? Using oil or ran out of oil? The hours that these trucks usually see is no where near the need for an overhaul? I was a diesel mechanic for 6 years. Any issues other than above and its typically just a component failure or fuel issue that an over haul wont remedy. If theres no other issues throw a new turbo on and go. Just to be safe maybe pull the head and check for damage at most. If properly maintained a diesel engine should give 10 to 15,000 hours of life without an overhaul.

Sent from my SAMSUNG-SM-G890A using Tapatalk
 

Mos68x

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What was the reason that an overhaul was decidedly needed? Is there excessive blow by or fluids mixing?(oil and antifreeze) Low oil pressure or an internal clatter? Using oil or ran out of oil? The hours that these trucks usually see is no where near the need for an overhaul? I was a diesel mechanic for 6 years. Any issues other than above and its typically just a component failure or fuel issue that an over haul wont remedy. If theres no other issues throw a new turbo on and go. Just to be safe maybe pull the head and check for damage at most. If properly maintained a diesel engine should give 10 to 15,000 hours of life without an overhaul.

Sent from my SAMSUNG-SM-G890A using Tapatalk
Because of the engine knock, which I’ll admit could’ve been a fuel injector issue. The turbo is toast so a rebuild for it is absolutetly necessary. Considering how much trouble she has on a small incline at my property from a stop I reckon it’s possible that it could only be a turbo issue, but I doubt it since I was at least moving. I can try to just rebuild the turbo and see how that does.
 

Mos68x

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I just had a thought...

I live at an altitude of 5800ft, and considering the turbo is called an “altitude compensator” has anyone been forced to run their diesel without the turbo at any elevated elevation and experienced major power loss?
 

red

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The 8.3 relies heavily on the turbo to make it's power. Without the turbo working the power to weight ratio is horrible, like a little Toyota pickup with the 22re 4cyl and 5k pounds of trailer behind it will be a hotrod in comparison.

Probably not a engine rebuild needed. Knocking noises from bearings and other big engine damage don't tend to go away on their own. Could be the noise was from the compressor wheel bouncing off the housing and got quiet once it made enough room for itself.
 

Mos68x

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The 8.3 relies heavily on the turbo to make it's power. Without the turbo working the power to weight ratio is horrible, like a little Toyota pickup with the 22re 4cyl and 5k pounds of trailer behind it will be a hotrod in comparison.

Probably not a engine rebuild needed. Knocking noises from bearings and other big engine damage don't tend to go away on their own. Could be the noise was from the compressor wheel bouncing off the housing and got quiet once it made enough room for itself.
I know rod knocks don’t go away on their own, but would a fuel injector issue? Saw a couple YT videos of other Cummins diesels fuel injector issue knocks that sounded a lot like mine that day when I watched them later that evening. Makes me think the issue really lies in the turbo, but the injector was causing the knock.
 

Mos68x

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To test that theory would be really easy since I can buy a rebuild kit for the turbo that doesn’t include the turbines for about $25. If that does fix the issue, then I’ll order a new turbo cartridge if I want to replace the two turbines.
 

Mos68x

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Compressor wheel is already chewed up, I wouldn't use it anymore.

A fuel injector issue can go away on it's own sometimes.
Yes, it is chewed up, but it’ll work to see if the turbo was the problem. If it’ll build boost and restore most of the power then I’ll replace the entire cartridge, not just the turbines. Replacing turbines, including the cost of the “rebuild kit”, was $250. For that kind of cost I might as well buy the cartridge instead and get a new housing as well.

Cartridge
https://m.de.aliexpress.com/s/item/32766325068.html

vs

Rebuild kit
https://m.bonanza.com/listings/turb...MI_6H01aj51gIVBrXACh1nSAlIEAQYBSABEgLV0_D_BwE
Compressor
http://baeturbosystems.com/oereplacementturbocompressorwheelbybaeholseth1e3599642.aspx
Turbine
https://picclick.com/Turbo-charger-H1E-HX40W-Turbine-Wheel-Shaft-262249446295.html

I just was looking for a link to show you what I mean and I found one for considerably cheaper than piecing everything together, think I’ll try that instead since it’ll be cheap enough to do before the 1st when I get my retirement.

Finding links that weren’t eBay was kinda tough, but you should be able to see what I’m referring to.
 

Tinstar

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Running that turbo wheel as is and you risk bearing failure or worse, the wheel will/could disintegrate at speed causing a lot of damage.
It’s like a grenade going off.
Your guaranteed an engine rebuild then with all the metal it will injest.

We had chinook that was ready to lift and the number 1 engine had a turbine wheel explode. We thought it was a mortar round exploding at first.
Did extensive damage to aircraft.
Different mass of components I know but you get the point I hope
 

Mos68x

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Already ordered a new cartridge. Found one for $138, over $100 cheaper than piecing it together. Should be here by the 23rd hopefully.
 

74M35A2

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Chinese clone at that price level? If so, I would have rather went with a used genuine Holset one, but the hot rodders are having decent luck with Chinese turbos on their budget builds. Will be interesting to watch.
 

Mos68x

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Right now I don’t care if it’s a Chinese clone lol I just need the truck running again. I do want to do a compound turbo setup, but I need to find a small turbo that’ll make boost when I want it to. I’ll probbly call Garret for that info later on after I do some of the other stuff like valve springs, studs, and the head gasket. At that point if I don’t keep the H1E(HX40W) I’ll be using some other turbo that’ll be built to last and that’ll make the boost I want.
 

Jericho

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Tin Star is absolutely correct on the turbo. I rebuilt / overhauled hundreds , You couldn't even blend that and get any where near a balance on it , They are just like a grenade , shrapnel and all Don't change just the inducer,the exducer will need to go as well, Would wonder how mush was ingested ?
 

Mos68x

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Well I got the new turbo cartridge in on Saturday, but didn’t get it on the truck till today. I had already pulled the old one out and had the two oil lines disconnected. Just wanted try to start the motor and see if I thought just the turbo might fix it. It definitely didn’t want to start so I sprayed a tad bit of ether to get it to start. Knocked as soon as it started so I killed it immediately. Looks like I will continue with the rebuild kit that I just received from 98G yesterday, thanks John! I should’ve taken some video of the attempted engine start, might do that tomorrow. I have another car that I’m trying to fix so that I don’t miss too many days from school.
 

74M35A2

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Starting fluid has a very low octane equivalence number, so it knocks loudly when combusting in a gas or diesel engine. Did you run the engine for at least 5 seconds or so, to make sure the knock was not the ether?
 
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