Hi guys when I clean the valves I expected a lot of coal. Instead, with the drill, a rust color came out.
The residue I removed looked like sand-colored flour.
Could it be dirty fuel?
I didn't find any kind of crack in the valve guides.
it is likely that something has entered in the suction phase, some stone that has struck on the head .. I think
all this regardless of oil consumption and oil leaking from the exhaust.
I have to admit that the engine is in very good condition, I'm talking about the pistons, cylinder head and also the cylinders. I think he did not have too many hours.
What to say ....

That head has been worked on previously, look at the 3 punch marks on the valve, valves don't come out of the factory like that, so that means that engine has already done a lot of hours, from memory Cat felt you should get 10,000 hours out of a engine minimum if it was properly maintained, before you should need to recondition the engine.

Yes, there are plenty of stories of Cat engines doing 30,000, 40,000, even 50,000 hours, but probably more stories of engines only doing 3,000 or 4,000 hours because of poor or non servicing in dusty conditions, like no oil changes and air filters not being serviced.

The fact your valve guides are completely worn out, on a head that has been "reconditioned", or at least had a valve grind at some stage, might suggest your engine has upwards of 20,000 hours use, maybe more. You might have new pistons in it, but in the meantime, remove the rings from the pistons and check their end gap in the bottom of the cylinder, that will tell you if they are worn, there is a specification for both piston ring end gap, and side gap.

Your photo's of the cylinders are not very clear, but they should show cross hatching from the original honing from the factory, they must not be smooth and shiny, they can have a minor lip at the top, which must be removed before fitting new rings if you wish to save money, again, Caterpillar have a measurement for that wear tolerance of the cylinders.

If there is any noticeable lip at the top of the cylinders, the cost of new aftermarket sleeves is usually very cheap, often you can buy new pistons with rings and sleeves as a kit, now you have the pistons out, removing the sleeves is easy even with the crankshaft in place, just make sure you protect the crankshaft with lots of oily rags, this will allow you to clean the cooling system of the engine block thoroughly.

Hi Team,
the top piston ring shown looks well worn to me as there is the chrome showing on each side of the top compression ring--shiny lines running around edge of the ring, the chrome should cover the face as well and so appear shiny too--there is a Matt darker finish in the center of the ring face.
Also I feel sure that the oil ring is well worn too as the scraper ridges each side appear shallow to what I recall--stand to be corrected on this oil ring wear as piston ring end clearance checks will tell all.

Big end bearings look good--check clearances with the specific size Plastigauge or your equivalent or by measurements.

Cheers,
Eddie B.

As far as valve deposits go, you can expect the brown deposits on exhaust valves which get hot enough to burn off the carbon. It's the intake valves that accumulate the carbon and oily deposits from sucking oil past the valve guides and do not get hot enough to burn off these deposits.

remember to measure a bore for wear at the very top or very bottom as that is the part that doesnt get worn same with end gaping piston rings.
also check for ridges top and bottom of the bore any ridges need removal with a ridge reamer.

those are the big-end caps i assume, they are only lightly scored and look like they will be fine with just new slippers. have you checked them for play on the crank that will tell you if the rod journals need re grinding or not also check the main journals too. no point doing big-ends if you dont do the mains. a product called plasti-gauge is perfect for this task dont know if its available outside of Australia.

to use: you simply cut a piece of the plasti gauge place across the bearing surface to be checked and reinstall the cap tighten bolts to spec, remove the bearing cap again compare the now squashed bit of plastic against the chart on the packet and you have your measurement of wear or clearance(with new bearings) repeat for each main and rod journal. yes you use it with new bearings too to check they are correct a friend of the family returned 3 full sets of crank bearings becuase they were wrong clearance when he was building a engine for a car

 

I measured the cylinders. Diameter below the ridge 120.69mm I found a way to remove the plate below. The pistons, the connecting rods, the bushings are in very good condition. Chances are they remade the engine without changing the cylinders. Everything else is new. Just look at the cylinder head gasket which is like new. I have ordered the new parts. Valve guides, ring kit. Can I reuse the cylinder head gasket in your opinion?

Did you measure the end gap of the old piston rings at the bottom of the cylinders, I'd like to know how worn they were.

A new head gasket might only be $US50, or come as part of a inexpensive aftermarket "Valve Grind Gasket Set", if you did re-use that head gasket I'd be coating it with a suitable sealant, I use Permatex Aviation Gasket Sealant on my head gaskets, new and used, but have also used a spray on copper sealant successfully, that might have been made by Loctite I think, it was 10 years ago.

The proper Mechanics will chime in soon, theory is, new gaskets don't need sealants, but some of the older Cats really benefit from using them, like the D2 and D4.

Do you have a ball hone for honing those liners, you will need one.

What is that dark stain on the bearing shell in the last photo?

Looks like it had a half #$% overhaul, threw bearings rings and pistons in and pawned it off down the road. I'd check the crank, check rods, clean the pistons, get new sleeves, rings, bearings, have the head checked, new valves, guides, new gaskets, etc.

Another thing I noticed was that first piston has the ring ends all lined up, they should be staggered "apart from each other". I also have seen and had my own ordeal with the Cat dealer shop put rings on upside down on a D339, it used a quart a day after the rebuild and smoked erratically, they told us to just keep running it hard and hot to seat the rings, I thought BS! it just got worse so we requested two good mechanics come out to our shop and check it out, rings were upside down.

not only should they be staggered they should not be on the wiped side of the piston ie when looking at the crank pulley if the crank rotates to the right the right side is the wiped side. in other words the ring gaps should not be on the loaded side. all reciprocating engines have a loaded side and they wear that side more hence why bores wear oval.
Chrysler and Toyota famously tried to counteract this by building slant engines.

as for gaskets needing sealants or not some engines do and actually acl bearing co recommend the use of hylomar gasket dressing on their gaskets. unless you have had the mating faces ground a dressing is reconmended and unless the surfaces are out of true i wouldn't get them ground. there is several gasket dressings on the market be sure to select the correct one for the application as there is different products for different jobs.

as for a cyl hone ball type hones cut faster flat stone type cut slower but less likley to over cut. both types should be lubed with a mix of kerosene and oil or diesel fuel. keep the surface wet while honing a (spray bottle works best) then scrub the bores with hot soapy water or water based degreaser to remove all the grinding fines wipe dry and oil with wd spray or lanolin spray immediately to stop rust.

AND NEVER REUSE A GASKET that is asking for trouble. the only exception your in the bush hours away from home and have no other choice but then when home you replace it.. do it properly the first time and you dont have to touch it for years especially if you dont use it much. dont skimp on oil changes bad maintenance is what causes most failures.