Swapped D950 Runs, Smokes Off Idle, Overheats, Fixable?

[el bob]

Hello. First post, new member. Bullet point summary up front. Detail and pics after.

* D950 Unknown Hours, Purchased in June
* Started easily, ran strong, exhaust puffed smoke intermittently
* Injector 1 failed - found it was leaking fuel
* New injectors installed for all cylinders
* Still starts easily, runs strong, smokes continuously off idle
* Running for 20-25 minutes at full pressure washing load, engine coolant reaches 220F on gauge
* Want to fix both issues, looking for suggestions on diagnosing problems

I bought a diesel powered, diesel fired hot water pressure washer as non-running, "needs new starter and ring gear." It has a Kubota D950 motor, that is not original to the machine. The pressure washer manufacturer says the machine came with a D722, but the records are old and the machine serial number sticker faded in the sun long ago. The engine the factory installed was smaller than the D950 on there now.

(intake side as received -- P.O. had pulled old 12V lift pump before selling. I don't know/have any history on missing overflow tank.)

Fixed the starter to ring gear meshing ...
I removed the aftermarket starter motor, re-fit the original starter motor, continuing where the original engine-swappers left off massaging the two parts to fit. They kept the original smaller motor's flywheel with ring gear, probably because it had the factory fit hub and double groove pulley bolted to it, to drive the pressure washer pump. They must have worked on sanding/grinding to bring the starter motor centerline (D950) closer to the ring gear centerline (D722 maybe), and I finished what they started. (I did not do the engine swap ... and did not know it was swapped when I bought it.)

Put on 12V lift pump ...
The previous owner had an electric fuel pump on it. Mechanical lift pump was still there, with open barbs, and the output barb had become plugged with debris. (looked like wood chips) Factory papers for the overall pressure washer machine show it came with an electric fuel pump. I bought and installed new electric fuel pump for diesel fuel, new 12V starting battery, and new engine oil and filter. I cleaned the engine air filter, drained the coolant, and installed a new coolant temperature sender and oil pressure sender. When I bought it, there was a disconnected CAT fuel pressure switch in the oil pressure port, and a 215F temperature switch in the coolant temperature port. Unrelated, but I drained and put in fresh non detergent oil in the pressure washer pump. (Still installing the pump in picture below, bolting it down after drilling mounting holes.)

Started the engine ...
With this work, and glow plugging 10 seconds, the engine fired up immediately. The pressure washer did not work immediately, and checking the valves revealed a chunk of debris holding a high pressure valve stuck open. Removed that, reassembled, and the pressure washer started working fine. Up to this point, the focus was just on seeing if everything could be made to run (engine and pressure washer pump). I did notice intermittent puffs of exhaust smoke, but nothing steady, and I had not yet run it long enough to see engine coolant get up to operating temp. The engine had oil pressure. Using a handheld tachometer and a piece of reflective tape on the pump input pulley, I set the max speed stop screw for the governor speed control lever with the pump input pulley showing 1500RPM.

 

[el bob]

The first time I used it for more than just a test, it ran for maybe fifteen or twenty minutes, starting smoking more than it used to (from intermittent puffs to almost steady), changed to a banging/clanking sound and I immediately shut off the engine. The next morning I fired it up to see if perhaps it would only repeat the behavior at operating temperature, but even cold it immediately starting making the louder noise. I cracked open each injection line tube nut one cylinder at a time to see if the noise went away. No difference on cylinders 3 and 2. Cracking the injection line on cylinder 1 made the noise disappear. I pulled the injectors and the holes for injectors 2 and 3 looked sooty, and the hole for injector 1 was clean. Same for the nozzles themselves. I ordered three new injectors from Oregon Fuel Injection and installed them. Noise was gone and motor was back running.

(missing picture of new injectors installed)

The machine has since been used for some longer duration jobs, up to say 20-25 minutes continuous. With someone else doing the pressure washing, I can watch the machine and engine gauges. I bought and installed new fuel tank gauge caps, added 5 gallons of fresh diesel fuel, and put on a new high pressure gauge for the pressure washer pump output. It all looks good, and with the speed control lever reduced to idle, the engine does not smoke. If I increase the speed control lever position off (above) idle, the engine smokes out the exhaust steadily. I am not an expert in judging exhaust smoke. I am comfortable saying it is not smoking white. It is a black / gray and light (airy), not thick black. It will do this immediately after a cold start and stay that way when it warms up. If it is run hard (which is pretty much all it does when it is in use, after being allowed to warm up unloaded for a minute or two) for long enough, 20-25 minutes, the coolant temperature gauge will eventually rise to 220degF. (I didn't notice this fully in the moment but caught it in the corner of other photos reviewed afterwards.) Every time I have grabbed the upper radiator hose while it is running to see if it is hard, it has been soft and pliable. I have not tested the radiator cap, and the machine came missing a coolant expansion tank.

Last weekend I check the valve clearance. Besides cylinder 3 intake (spot on at 0.006"), the valve clearances as found ranged between 0.009" and 0.015". Adjusted the valves, turned the crank per WSM, checked again, and again. Valves are now all adjusted to 0.006". No change to the exhaust condition. Idle noises may be a bit smoother.

Which brings things back to the summary:

• D950 Unknown Hours, Purchased in June
• Started easily, ran strong, exhaust puffed smoke intermittently
• Injector 1 failed - found it was leaking fuel
• New injectors installed for all cylinders
• Still starts easily, runs strong, smokes continuously off idle
• Running for 20-25 minutes at full pressure washing load, engine coolant reaches 220degF on gauge

Want to fix the smoking issue and, if an IR temp gun confirms the coolant temp gauge reading, fix the overheating issue.

Could anyone please point me in the right direction for diagnosing / root-causing the smoking off idle? This is the first diesel engine smoking situation I have had to diagnose. Other than what I have learned from reviewing the DKD WSM for this engine, I do not have experience troubleshooting or working on diesel injection pump. Looking forward to learning though.

...

And an unrelated question. What is the fitting for in the photo below, located below the mechanical lift pump?

 

[85Hokie]

AS for the hot radiator - two things, first clean the outside of that radiator well, then do it all over again.
As for the inside, drain it, run some vinegar and distilled water through it - run it hot and then repeat, then flush with JUST water and drain and then come back with antifreeze and distilled - cleaning the outside is maybe more important than the inside. Air is better than water, water will compact the "chafe" .... air blown from inside back to outside.

Have you checked the temp of coolant at the BOTTOM of the radiator at the lower neck???? Use an infrared thermometer - and check while running top neck and bottom neck, should be OVER 60 degrees (F) difference, if more than that, great!

I cannot see you fan in any of the pictures - belt driven? IF so, check tension on that - a little slop in the belt will make a big difference in the cooling. Is the water pump doing it's job?


HAVE you check compression at all? IF so - what were those numbers?


and the last picture : this is a petcock to drain coolant from the block

 

[Lil Foot]

Can't help with your questions, but I gotta say "Nice write-up". Lots of facts, pics & history.

 

[el bob]

AS for the hot radiator - two things, first clean the outside of that radiator well, then do it all over again.
As for the inside, drain it, run some vinegar and distilled water through it - run it hot and then repeat, then flush with JUST water and drain and then come back with antifreeze and distilled - cleaning the outside is maybe more important than the inside. Air is better than water, water will compact the "chafe" .... air blown from inside back to outside.

Machine was filthy and caked in dirt as received, though not as much the radiator. Certainly washed the radiator and de-gunked the rest of the machine, but did not remove the wire mesh shroud protecting the radiator and clean/wash the radiator well, nor repeat. I did have an air blow gun out there when I was cleaning. Will do as instructed.

Have you checked the temp of coolant at the BOTTOM of the radiator at the lower neck????

No I have not, but I will at next opportunity.

I cannot see you fan in any of the pictures - belt driven? IF so, check tension on that - a little slop in the belt will make a big difference in the cooling. Is the water pump doing it's job?

Yes on belt driven fan. Belt had slop when purchased. Adjusted per WSM for 7-9mm deflection pushing with finger while adjusting alternator/generator mounting position to tension the shared belt. I do not know if the water pump is doing its job.

HAVE you check compression at all? IF so - what were those numbers?

No I have not. I only have 300psi max gas engine compression tester. I will buy the Harbor Freight 93644 kit, and if the adapter fits the D950 glow plug holes, do a compression test.

and the last picture : this is a petcock to drain coolant from the block

Great, good to know, thank you.