Diesel rebuild pictures

[Nikolas]

Hello to everyone!

Here are some pics from a diesel engine I am rebuilding. The story is that I bought an old forklift with a Nissan DS25 engine. Its a 4 cylinder diesel, indirect injection. The engine was overheating very soon after being started, there was exhaust in the water. We pulled the head and it is beyond repair, so a new head is going in.

At the same time we pulled the pistons so that we can replace the rings and rod bearings. Crank is in excellent shape. So its not really a complete rebuild but rather a refresh. The question is, by looking at the cylinders, are we just throwing money away? Of course it would be best to change the liners too, but then the engine needs to be taken out and the cost rises. Other than these scratches the liners measure ok.

We will resurface the liners of course, nothing fancy just an electric drill type thing so that the carbon goes away and we get some type of crosshatch. Again, the liners measure ok in overall shape. Take a look at the pics and let me know what you think. I can upload more pictures (pistons etc) if needed.

 

[Johnny]

If a drill hone will smooth most of that out, you should be okay. However, image 4 and 6 show a couple of pretty deep cuts. Not sure those will come out and might take a new liner. If you have to pull the engine, might as well replace all four and do it right.

 

[RF Overlord]

I'm not a diesel expert, but those pix look like that engine was run hard, not properly warmed up, and didn't get the oil changed often enough. Maybe it's just the lighting, but those scratches look pretty deep. Will you be able to resurface the liners properly without making them oversize? If not, I bet it burns oil.

 

[Nikolas]

Well, my fingernail doesn't get caught in the scratches. I know this isn't very scientific! Maybe the lighting is not very good but it's more of a discoloration rather than a scratch, it is really imperceptible, you can't even feel it.

 

[Pablo]

Look pretty rough. Tell us more about the usage and stuff,

Firefox and No Script will allow you to view the picts without allowing ALL those places access...........

 

[Nikolas]

I don't know much, I got this machine used. It had a bad head and it was overheating. I bought at right about the scrap price so I figured it can't be that bad.

 

[Ken42]

Image Shack is notorious.....
I am with Johnny if the hone will not remove the scratches you will need to go oversize or replace the liner.

Ken

 

[440Magnum]

Originally Posted By: Ken42

I am with Johnny if the hone will not remove the scratches you will need to go oversize or replace the liner.

Ken


Me too- that wear looks pretty bad. I can't see any sign of the original honing marks, just the vertical scratching. It'll be a real oil burner without cleaning that up or replacing the liners.

 

[xxch4osxx]

I think I would just replace the liners and know its been done right. To not do it and have to pull the engine apart again to redo it properly will cost alot more than doing it now when its already apart. But thats just how I would do it.

 

[Eddie]

I would first get a good cyl honing and then see what it looks like. I suspect you can have a good running engine with a good hone job and a new set of rings. I would measure the roundness of each cyl to see if it is within specs.

 

[Shannow]

Originally Posted By: Nikolas
Well, my fingernail doesn't get caught in the scratches. I know this isn't very scientific!


That was going to be my question.

If you can't feel the scratch running your nail across it should be OK. Especially on a beater that you paid scrap value for.

 

[slammds15]

If the honing will remove the discoloration and leave a nice finish I would most likely re-use them. You mentioned the engine overheated? If so, seeing as how you have it torn down this far I would replace the liner o rings and check liner protrusion. Its little work and little cost but well worth it! I've had to repair many less intelligent and lazy mechanics repairs because of this. The engine over heats due to head gasket or other related head failure and it bakes the liner o rings. A few engine hours later there is coolant in the pan or the head gasket fails again. I'm not familiar with your engine, I can't really give you any technical advice other than the basics. But again I cant stress the liner o rings enough.

If you pull the liners you will also be able to inspect for pitting and rust. 1/16" of rust is comparable to 1" of cast iron when it comes to cooling. That may be responsible, besides the over heating for the visible scuff marks.

 

[onion]

I don't have any experience with that particular engine, but plenty with Cummins, Deere, Detroit, and Mercedes diesels. Without having the engine in front of me to look it over, feel the scratches, and measure a few things, this will only be a guess.

That wear looks to me like you have either a failed air cleaner or a break in the air cleaner piping, and have been sucking dirt into the intake. If that's the case, then the piston rings will be ground down, and the edges will be sharp... they may even be visibly thinner than the new ones. This is a common failure mode with industrial engines. Don't know what sort of conditions this machine was used in, but even highway trucks see enough dirt to ruin an engine... and it's a huge issue with agricultural and construction equipment- so much so that they often have both an 'inner' and an 'outer' air filter. Seeings how you're overhauling the engine, you'll definitely want new air filter(s).

As for the scratches- obviously the best thing to do would be to replace the liners. By all rights these SHOULD be replaced. Why does the engine have to come out to replace them? Like I said, I've never had a Nissan diesel apart- but in any modern diesel with wet liners that I've worked on, the liners are removed out the top using a puller... no need for engine removal. This is also true of some engines with dry liners (older detroits and Macks), though I'm told that removing the liners from an old Mack is quite a job. Personally I would investigate this further.

As for reusing the old liners- you MIGHT get away with it if you're careful and lucky. If, after honing the liners, they still measure in spec AND you can't really feel the scratches (better yet if you can't SEE them, but that might not be realistic), then they might be alright. Of course, you're taking a chance that you'll have a hard-starting oil-burner... awful hard to make an educated guess at that without being there in person.

 

[onion]

BTW- Do you plan to also replace the main bearings? If you have good access to the underside of the engine, then with most engines they can be replaced with the engine in-chassis... though this is something that takes some experience. Not sure I'd recommend it if you haven't done this before- just pointing out that it can be done. What do the rod bearings look like? If they're in good condition, then you probably don't need to replace the mains. But if they're worn, you'll want to replace the main bearings.

Also, doing an in-chassis overhaul is a dirty business- there's no getting around it. I'd suggest that once you get everything apart and get the gasket surfaces clean, take a solvent sprayer and wash out the cylinder bores and the oil drain-back holes; spray out the crankcase from the bottom on both sides, and let it drip dry overnight. It'll make a mess, but you can mop that up. Then of course be sure blow out the head bolt holes with compressed air and carefully wipe off the rod journals before installing the pistons & rods.

So what happened to the head? What caused the overheat? Those cooling jackets sure look crusty... makes me wonder what the radiator looks like inside.

 

[Errtt]

I would first hone til it look good, then take measurements. Telescopic gauge set, then mic it. If it's within specs, might live with that, otherwise new liners. Rings set in squared and ring end gap must meet specs also.

 

[XS650]

Originally Posted By: Shannow
Originally Posted By: Nikolas
Well, my fingernail doesn't get caught in the scratches. I know this isn't very scientific!


That was going to be my question.

If you can't feel the scratch running your nail across it should be OK. Especially on a beater that you paid scrap value for.


Nikolas, what Shannow said about not feeling the scratches is good advice. What you said about your nail not getting caught in the scratches may be something a lot worse.

 

[RH+G]

IS this an old Nissan Forklift or Komatsu?

 

[Chris142]

The thing got really hot. The pistons expanded and caused the damage you see. Hone it and install new pistons and rings and it should run another 20 years.

 

[Jim 5]

Please post a picture after you hone the bores!

 

[Scienceman]

+1 this is interesting.