Uneven engine operation.

[Jason]

Well if it's not the pump it would have to be a mechanical problem with the engine, however the miss sounds to be intermittent. If there was a cylinder down on compression due to a ring issue or valve not sealing, the low compression would cause poor running consistently which typically will diminish as rpm increases as there is less time for the engine to loose compression. Have you done a leak down test? Another possible way to help with diagnosis would be to pull the injectors and inspect the tips of the nozzles. If there is a cylinder that is struggling to fire correctly the nozzle will be either moist with fuel or carbon'd up more than the other nozzles. Something to look at anyway. If you still can't narrow it down to a particular cylinder via injector inspection or a leak down test, I would suspect the pump and try swapping with another one.

Jason

[samvear]

Thanks for helping!!! Thanks to your advice, it is easier for me to endure the war. You give advice. I check them. It takes away from the war.
v8volvo - this applies to you too.

Originally Posted by Jason

Have you done a leak down test?

Yes. I did a test. The difference between the cylinders is 0.5 kgf / cm2
IMG_20220616_182709.jpgIMG_20220616_182735.jpg (Instrument readings are not correct)

Another possible way to help with diagnosis would be to pull the injectors and inspect the tips of the nozzles

That's the difficulty, that soot on nozzles and washers is the same. Even after a long trip.

If you still can't narrow it down to a particular cylinder via injector inspection or a leak down test, I would suspect the pump and try swapping with another one.

It may be necessary to do so


I have a question:
what if the engine has a different degree of compression in the cylinders? If anyone cylinder protrudes from the block less than the others. A leak test won't show this.
Can I try to reduce the thickness of the washers under the injectors?

[Jason]

There is no adjustment for injector height, just the heat shield. But you would be able to detect difference in compression via a compression test.

Jason

[samvear]

Compression test:

Cold........Hot

1) 25,5....27
2) 25 ......25
3) 25 ......26
4) 25,5 ...26,5
5) 25,5....25,5
6) 25 ......26,5

The readings of the device may differ from the actual ones.
The device shows values less than another. Add 1.5 to the data.

[Jason]

I'm used to psi here but I'm assuming those values are bar? Looks pretty consistent across the board. Not much left to do other than swap to another pump.. I'm fresh out of suggestions.

Jason

[v8volvo]

Yeah, I agree, it sounds like the only option left may be to try a different known good pump.

Or another option that could be easier if another known good pump is not easily found: If you have a Bosch fuel system rebuilder shop that is operating near you, then you might also be able to bring them the injection pump and have them run it on their test bench. If there is any issue with the pump they would be able to see it when they run their tests, and then probably would be able to rebuild the pump and fix whatever might be wrong. These old VE pumps are still used in many pieces of equipment and vehicles all over the world so any good diesel injection shop with the Bosch sign out front should be experienced and certified to work on them.

One other test that could be worth a try: if you are able to get an infrared thermometer, you could check the temperature of the exhaust manifold at the port for each cylinder. If it has a weak/skipping cylinder (due to any issue -- fuel pump or injector, or something in the base engine) then you might be able to see that the problem cylinder is running cooler than the others.

The compression readings look nice and the engine sounds good in the video other than the driveability problem.... so it hopefully should be a very nice runner once this issue is figured out.

[samvear]

Originally Posted by Jason

I'm used to psi here but I'm assuming those values are bar?

Yes.

v8volvo and Jason!
Thank you for your advice. When the opportunity arises, I will try.

[Jimarilo]

My recent 940s 1995 purchase runs like this ......lumpy on warm tick over. Cold and hot start works perfectly

I changed the fuel filter and clogged air filter but still lumpy

Will investigate further after I change the cam belt

Is the crank bolt 27mm and the torque setting 300 lbs ??

I don't have the tool for locking the crank pulley, but will figure something out. Also need to find a bigger torque wrench lol

[ngoma]

Originally Posted by Jimarilo

My recent 940s 1995 purchase runs like this ......lumpy on warm tick over. Cold and hot start works perfectly

Too little info to make a diagnosis, if that's what you are looking for. What is the history? Did it come on immediately one day? Have you checked the IP timing? Valve clearances? What is the power? Smoke? How many mileage?

Originally Posted by Jimarilo

Is the crank bolt 27mm and the torque setting 300 lbs ??

I don't have the tool for locking the crank pulley, but will figure something out. Also need to find a bigger torque wrench lol

More like 350 lb-ft. You may be a mechanical genius but most "figure something out" with a monster torque wrench solutions don't work out successfully in the end.

Forum members have made satisfactory facsimilies of the Volvo special tools, you can search here and find them. Involves welding and fabbing skills.

[Jimarilo]

Originally Posted by ngoma

Too little info to make a diagnosis, if that's what you are looking for. What is the history? Did it come on immediately one day? Have you checked the IP timing? Valve clearances? What is the power? Smoke? How many mileage?


More like 350 lb-ft. You may be a mechanical genius but most "figure something out" with a monster torque wrench solutions don't work out successfully in the end.

Forum members have made satisfactory facsimilies of the Volvo special tools, you can search here and find them. Involves welding and fabbing skills.

Indeed, I am starting to think this engine is more trouble than it's worth. A nice merc 300 straight 6 would be a lot less trouble. Just changing the rocker cover gasket is a bleeding nightmare to change, especially if the nuts on the injector side are rusty and seized. It is probably just a matter of time before it starts leaking again on the exhaust side

I took the cambelt cover off to have a look at the belt as I am still in contemplation mode regarding the belt change, as I need so many specialist tools before attempting the replacement. So with the slack on the adjusting pulley side, I slackened the adjuster bolt and let the adjuster take up any slack, which it did. What a difference that made, no stuttering when pulling away or when changing up the box and a little less lumpy on tick over.

The air intake pipe that goes over the rocker cover has evidence of oil in it so suggests the engine is breathing heavy and at 165K I am thinking it is in need of a rebuild ......but is it worth it ??