"8C wrote:

I know there has been a lot of talk of testing injection capsules by screwing them on the loose threads of the adapter. I have never tried it but I think it would make sense to use an old pre chamber to mount the capsule for an external test.

Thank you I think at this point it is best to let a shop inspect and check things out... Thank you

Hi Team,
the capsule screw on test is a rough bush method of checking if a capsule is capable of atomizing/spraying the injected fuel passed thru it--Number 6 injection capsule is stuck open and therefore faulty.

The video clearly shows No6 capsule is stuck open and is passing pump gallery fuel pressure flow out of its orifice.
This in turn, when mounted in the engine, will pass compression/combustion gas pressure back into the injection pump fuel gallery and so on to nearby injection pumps so preventing them from pumping fuel as the gallery fuel is now aerated.
We often found engine miss-fires/rough running caused by faulty stuck open capsule valves.
The capsule valve being stuck also appears to be severely restricting injected fuel flow as evidenced by the high pressure fuel leak at the unsealed joint with the adaptor.

George,
the seal you mention may be the dirt seal that goes under the injection line nut to keep dirt/water from entering the top of the pre-chamber, there is a second seal here to stop crud passing by the capsule retaining nut threads.

You seem to be getting closer with your bush tests.
New parts from Cat are rarely faulty but I would assume by now Cat are not likely making these older style capsules but are buying in After Market parts to their detriment.

Try a known set of correctly working capsules in there and see what you get, if no joy then manifolds off to check as advised earlier--blank off the turbo oil supply line or you will get oil soaked by engine oil at engine oil gallery pressure.

Jerk pumps are what other brand makers can call their injection pump plunger and barrel sets or style of injection pumps--country of comment or origin can call the same things something else also--makes things confusing for the unwary.

Regards,
Eddie B.

"8C wrote:

I know there has been a lot of talk of testing injection capsules by screwing them on the loose threads of the adapter. I have never tried it but I think it would make sense to use an old pre chamber to mount the capsule for an external test.

. I had that thought last night also. I bought aftermarket pre chambers for $27.00. Glad to hear ERBs explanation of why this is all happening. ( back blowing compression) George does have one pump for sure that is not supplying pressure, so I still recommend having the pumps tested.

Pliers tight is ok for testing. May still not entirely stop the leakage at the joint. Even with the leakage, I think we can say #4 & #5 nozzles are good and #6 is bad. Pumps seem to be building good pressure and volume, I wouldn't bother removing them again except to set lifter height unless it's already been done.

Old Beek, which pump do you think is bad?

Even a crude blow down test with a compressed air source and a blow gun wrapped in a rag or taped to fit tight and then stuck in the Precombustion chamber will be easier and tell much the same thing as removing the manifolds........without any broken bolts/studs to extract. Just listen for air blowing at intake, exhaust pipe and crankcase oil fill. There will be some noise at oil fill, rings just won't seal that well, but with engine set at TDC of compression stroke for the cylinder to be tested, both valves are closed and there should be no noise in intake or exhaust.

Could always build/borrow the correct test equipment as specified by CAT and get a real reading to compare to published specs to ascertain the cylinder condition. You may be able to hear a difference between cylinders in the amount of leakage by the rings, but it would still be nice to have a repeatable number to compare them to each other and to specs.

I would set each piston to TDC compression stroke and check valve clearance and injection pump lifter height and then do the blowdown check. That way you would only have to find the TDC position once for each cylinder.

Got a new engine at work doing exactly what your's is doing, same smoke and all. Brand new long motor, injectors, pump ect.

Cracked injectors and got fuel at all cylinders, cranks but won't fire.

Mechanics are leaning towards fuel pump timing. Find out tomorrow.

Testing of capsules and pumps is still advisable. If for no other reason convince Cat to replace their faulty units, and if your going to have the capsules tested, might as well have the pumps checked as well and at the same testing service.

Simple test for suspect capsule valve sticking. Disconnect line at holder, squirt a little oil into the body/holder and crank the engine. If it blows the oil out you've got a leaking or stuck injector valve.

Compression back flow would still have to get past the injection pump check valve to reach the fuel gallery. Theoretically this shouldn't happen but I suspect the check valve holds against hydraulic pressure but somehow is inadequate to prevent air back flow. Comments???

"ccjersey" wrote:

Pliers tight is ok for testing. May still not entirely stop the leakage at the joint. Even with the leakage, I think we can say #4 & #5 nozzles are good and #6 is bad. Pumps seem to be building good pressure and volume, I wouldn't bother removing them again except to set lifter height unless it's already been done.

Old Beek, which pump do you think is bad?

Even a crude blow down test with a compressed air source and a blow gun wrapped in a rag or taped to fit tight and then stuck in the Precombustion chamber will be easier and tell much the same thing as removing the manifolds........without any broken bolts/studs to extract. Just listen for air blowing at intake, exhaust pipe and crankcase oil fill. There will be some noise at oil fill, rings just won't seal that well, but with engine set at TDC of compression stroke for the cylinder to be tested, both valves are closed and there should be no noise in intake or exhaust.

Could always build/borrow the correct test equipment as specified by CAT and get a real reading to compare to published specs to ascertain the cylinder condition. You may be able to hear a difference between cylinders in the amount of leakage by the rings, but it would still be nice to have a repeatable number to compare them to each other and to specs.

I would set each piston to TDC compression stroke and check valve clearance and injection pump lifter height and then do the blowdown check. That way you would only have to find the TDC position once for each cylinder.

George and I talked on the phone when he first started to do the nozzle crack test. It is not in any video. He told me that #1 just dribbled out. No spray at all and not much dribble at that. Don't know why he didn't video that. I agree he needs to find TDC on each cylinder and ck lash, set plunger height and do that air pressure flow check.

"Misterskill" wrote:

Got a new engine at work doing exactly what your's is doing, same smoke and all. Brand new long motor, injectors, pump ect.

Cracked injectors and got fuel at all cylinders, cranks but won't fire.

Mechanics are leaning towards fuel pump timing. Find out tomorrow.

Yep, fuel pump timing was set incorrectly at assembly. Set it properly and off she goes.

Hi Team,
I totally agree that compression/combustion should not blow back into the fuel gallery past the injection pump check valve, BUT it does--have seen this several times over the years with a rough running engine that could not be traced to any one cylinder except that when the faulty nozzle line when loosened changed the rough running to smooth running--with a miss off course-- as the gasses blew back out the cracked injection line fitting with force.

Only ever saw one injection check valve cracked across its body and 1 or 2 springs broken up in all my years--low injection output at No1 cyl. could be caused by failed injection pump check valve and or spring as well as not timed correctly or having been seized and forced to rotate thereby losing its factory calibration setting adjustment position with regards the sector gear vs plunger helix--alters the fuel injected volume and so will be out of calibration to the other 5 pumps.

Scans show injection pump operation for this style pump.

Hope this helps.
Cheers,
Eddie B.

Thanks edb, I'd guess it's safe to say that the injection pump check valve would not be considered to be a "bubble tight' design. More common to have a resilient type seat for pneumatic applications.