Small diesel diagnostics?

I posted this elsewhere, but I was told to try here to find more diesel people.

The first tidbit that I got there was...possibly a cracked head, which was possibly smeared over by a recent flattening and then returned???

What do you think?

The tractor is a Jinma 284 with the Yangdong Y385 engine.

It's been running hotter than normal for about two months now. A couple of weeks ago, it came to a head. I could barely get one lap around the field with the mower or baler without antifreeze boiling out of the radiator. I could hear a compression leak near the head gasket, so I took the head off. I sent the head to the engine shop for vacuum testing of the valves and flattening (they shaved just the tiniest amount off of it). I also found one of the copper seals on an injector was cracked. With that seal replaced, a new injector, the shaved head and all new gaskets...including head gasket, also a brand new thermostat, new coolant hoses, drain/flush/refill of coolant, it ran well again....but still too hot..and it's starting to sound like crap again.

So here is a list of what symptoms are and aren't showing:

Symptoms that are showing:
-Quickly overheating. Less than five minutes under load.
-Smoking (it stopped for a while after head gasket fix, but it's back...somewhat white)
-Knocking during revving, which also stopped after head fix and came back . (sounds a lot like a low octane knock in an old gas car)
-Oil pressure starts good and then drops quickly as it heats. (but it's done this for about two years now)
-A lot of "cake" in the coolant system. I replaced all three coolant lines. (upper, lower and pump bypass). The thermostat and water pump housings are aluminum...connected to an iron block...and all of the hoses are "cakey" at the end that connects to these aluminum housings)
-Looking into the top of the radiator, the engine heating process goes like this: coolant is stagnant, coolant is flowing, coolant then starts to froth and bubble violently.
-It DOES use coolant, but it's hard to tell if it's going into the engine somewhere or only losing it when it boils over.



Symptoms that ARE NOT showing:
-No leaks around water pump.
-No squealing or looseness of water pump bearing.
-No coolant in oil.
-Not using or leaking oil. I haven't needed to add any since my last oil change a few months ago.
-No squealing of engine bearings.
-Both upper and lower radiator hoses get hot (if one was still cold...I would suspect thermostat...even though it's new...or water pump)
-I DO see movement of coolant in the radiator after the engine gets warm. So I believe the thermostat is opening and the pump is pumping.


Any tips where I should look next from the gurus?

I'm thinking a compression test? I have the old injector that I replaced. I think that I could rig that up with an adapter to my compression tester.

What about these diagnostic fluids that you add to the radiator and then check for color change to see if compression is getting into the cooling system?

Fuel issue? Perhaps too much water in a sediment bowl or filter somewhere?

Coolant system blockage?...although I did just have the head off and had it all cleaned out at the shop

Not knowing that engine, will ask, wet sleeve, dry sleeve or parent block. Here is the first and easiest test I would make. Remove water pump belt, fill radiator to the very running over top. Start engine and rev it up and down while watching that coolant in radiator. If it moves, you have a combustion leak. Have to do this test in less than a minute as natural heating of the engine will of course move the coolant up and out of the full radiator.

If you get a raising of coolant or bubbles, next test to pin down problem is a leakage test. Compression test will tell very little if anything. I would take that old injection nozzle and make a fitting for an air hose. Remove all injection nozzles, get number one on exact top dead center. Apply air pressure with that test nozzle installed using regulated pressure so you can raise pressure gradually. Again watch in radiator for leakage. You will most likely have to mark front pulley or flywheel to get exact top dead on other cylinders as only the mate cylinder will match up with original tdc mark.

You will be able to compare any leakage past piston rings, valves etc . If a wet sleeve engine you may have a leak through a pin hole in sleeve. To pin that down you would need to back off valve adjustments so you leak test with piston at bottom of stroke.

I never like randomly taking a head off looking for leaks because once you get head off , you say, now what. I don't see anything. Trouble shooting is trouble some but on problem solving difficult situations, it is time well spent.

Hello lastcowboy32,


Four things you need to check that you did not mention. Fan and belt, water pump oitput volume, radiator
cap, and the radiator,

GUIDO.

(quoted from post at 11:52:19 07/05/16) Hello lastcowboy32,


Four things you need to check that you did not mention. Fan and belt, water pump oitput volume, radiator
cap, and the radiator,

GUIDO.

Click to expand...

Sorry.

No radiator leaks
The belt is in good shape and tensioned. The same belt drives the alternator, fan and water pump. No squealing and all are turning.
The cap only lets off steam/coolant when the temperature gets up to the red zone. Otherwise, it's fine.

This engine (in my opinion) always has problems with air flow. If you work it as hard as I do, the radiator fins must be kept blown out almost daily during the summer. It seems that the surface area is barely adequate when perfect. Only about 10-25% of the fins being blocked with chaff or hay dust will have a really serious effect on cooling.

I watch the radiator fins like a hawk and lift the hood to look at them every time I use the machine in the summer.

I can have the rocker arms off of this engine in about ten minutes.

If I disconnect the injectors...so no fuel...and take the rocker arms off....so no valves ever open...I should be able to then pressure test the cylinders in any position I want, right?

Have you flushed out the block & head coolant passages. Did the new headgasket have the same holes as the old one? i.e. have you inadvertently blocked off a coolant port?
Does the water pump still have its impeller? I know from experience that some Merc. engines suffered from the water pump vanes becoming loose on the shaft so if can happen to Merc. it's certainly a potential fault on a Chinese engine.

Head gasket is identical to the old one. I had my wife help me align and check it. She actually had a better eye for detail than myself.

I do wonder about the impellers on the water pump, but water pump problems wouldn't cause the knocking and smoke.


Maybe I can check the water pump by removing the thermostat and disconnecting the top radiator hose, disconnect fuel from injectors...then turn the engine over with the battery. The water pump should pump coolant out of that upper radiator hose, if the thermostat is removed from the loop, right?

I would take another look at the head gasket. I had two kubota engines come in a couple years ago. Just had head work done. But were over heating in a
short time. Head gaskets looked the same but found two holes covered over on the new gaskets.

Did they magna-flux the head? Are you sure the head is not cracked?

The "cake" could be from mixing of different types of antifreeze, especially where aluminum is involved. You could have a lot of it in the block insulating the coolant from the cylinder wall castings.

Time to REALLY Clean the cooling system AND send the radiator to a shop to be Roded...

I'd even pull a couple "Freeze Plugs" and Hi-Pressure wash the inside of the water jacket..

You WILL get a huge amount of crap out...

Ron..

You probably have a cracked cylinder liner.

Pete23 has the all the steps to take. With the return of the white smoke, and knocking, my first hunch is that you are 'burning coolant' in one cylinder. So also pay attention to the coloring of the injector tips, for signs of coolant. But follow Pete23's steps to locate your problem. What others have said about cleaning your coolant passages may come into play, too, Mark

I can offer a few possible suggestions.
Water pump - I have seen the impellers corroded off to the point of nothing left but a flat plate.
Cracks anywhere/everywhere. Heads are notorious for cracking on most engines. They will usually crack a long time before a block will crack.
Buildup of gunk in the block, head, radiator, and other cooling system passages. I do remember in one instance, an overheating engine was found to be still half full of the original casting sand. Cleaning out coolant passages would be vital to proper function of the cooling system.

(quoted from post at 06:53:51 07/06/16) I can offer a few possible suggestions.
Water pump - I have seen the impellers corroded off to the point of nothing left but a flat plate.
Cracks anywhere/everywhere. Heads are notorious for cracking on most engines. They will usually crack a long time before a block will crack.
Buildup of gunk in the block, head, radiator, and other cooling system passages. I do remember in one instance, an overheating engine was found to be still half full of the original casting sand. Cleaning out coolant passages would be vital to proper function of the cooling system.

Click to expand...

Thanks all.

It seems that my first step will be to get the head back off. My shop said that they can check it for cracks...but not before I check the new gasket to make sure that it lines up with each and every hole...again...but I've missed things before. This engine also has a history of mismatched parts. When I replaced the water pump about five years ago, the gasket that came with it needed to be cut, because it partially covered a passage....I don't know if there are different "revisions" of this same engine???

With the head off, maybe I can pull some freeze plugs and get a wand down into some of the cooling passages and blast them out.

Thanks all. I'll post back in a couple of days.

(quoted from post at 18:51:40 07/06/16)

(quoted from post at 06:53:51 07/06/16) I can offer a few possible suggestions.
Water pump - I have seen the impellers corroded off to the point of nothing left but a flat plate.
Cracks anywhere/everywhere. Heads are notorious for cracking on most engines. They will usually crack a long time before a block will crack.
Buildup of gunk in the block, head, radiator, and other cooling system passages. I do remember in one instance, an overheating engine was found to be still half full of the original casting sand. Cleaning out coolant passages would be vital to proper function of the cooling system.

Click to expand...

Thanks all.

It seems that my first step will be to get the head back off. My shop said that they can check it for cracks...but not before I check the new gasket to make sure that it lines up with each and every hole...again...but I've missed things before. This engine also has a history of mismatched parts. When I replaced the water pump about five years ago, the gasket that came with it needed to be cut, because it partially covered a passage....I don't know if there are different "revisions" of this same engine???

With the head off, maybe I can pull some freeze plugs and get a wand down into some of the cooling passages and blast them out.

Thanks all. I'll post back in a couple of days.

Click to expand...

I have gotten literally pounds of crud out of blocks. Of course if you get it hot tanked they take care of it for you, but "in frame" you can' get that done. One time I made a little spoon out of sheet steel and spooned a lot out of the back through a large passage opening in the deck.

.[/quote]


Head is off and at the shop for pressure testing.

Sadly, this is the third time that I've removed the head in two weeks...so I can do it in an hour or so. Nothing like repetition.

I checked the head gasket vs the passages and all passages were accounted for and in the correct position. I also didn't see any spots on the head gasket where coolant or oil was hitting the gasket from a blocked passage.

I'm thinking that I'll just drop the water pump anyway. What's another pound to an elephant?

Then figure out how to get the gunk out of the block, if there is any.

Some of the passages look cruddy when I look down through the holes in the top of the block with the head removed.

It'll be fun....I'm sure.

I don't see coolant in the oil. So, I'm doubting a crack in a sleeve or cylinder.

Is there any way that the lower half of the engine (rod bearings, main bearings...etc) could be so poor that, even though the engine runs, there's just so much friction that it's heating up way, way faster than normal...as in boiling out of the radiator in five minutes of operation?

With the head off, is there another way to check for cracked sleeves/cylinders? Something to spray on the walls to highlight a crack maybe?

Any other cowboy engineered methods?

(quoted from post at 07:45:45 07/08/16)
With the head off, is there another way to check for cracked sleeves/cylinders? Something to spray on the walls to highlight a crack maybe?

Any other cowboy engineered methods?

Click to expand...

My shop called me. The head pressure test showed no cracks.

Head gasket was verified.

Moving on to other possible causes.