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Quattrodave

BMC 2.2 Bleeding, Idle Stumble & White Smoke...

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Evening all,

 

I recieved my CAV DPA pump back from the refurbers last week, it was sent away as it was leaking diesel fron the front seal.  Decided while i was at it to get the injectors overhauled at the same time.  Spent yesterday refitting the parts making sure everything was clean, replacing all copper washers etc. All went fine until i came to bleeding, from the manual it says:

 

Slacken the two air bleed valves on the fuel injection pump.  One bleed valve is located on the govenor housing, while the other is incorporated in the hydraulic head locking screw situated immediatly above the pump name plate.  Operate the lift pump, and when fuel issuing from both valves if free from air bubbles, tighten the bleed valves.

 

2.2CAVPump.jpg.801147ca05f6cda878a620b20df05912.jpg

 

Sounds simple enough, opened both bleed valves and started pumping within a minute or so diesel was dribilling out of the lower valve... 30 minutes and a raw finger later still no fuel at the higher valve.  figured i'd carry on and try and start it turned it over with the injector unions looseuntil fuel appeared at all four, nipped them up and it started, very rough and lost of smoke but quickly settled down and it  ran ok for about 15 min then i shut it off.

 

Went back to it today to check all unions are nipped and no leaks, she started up pretty well but i noticed a bit of white smoke, definatly smoke not steam, had that unburnt diesel smell to it and the idle is little lumpy has a bit of a stumble to it.  Figured there might be a bit of air stuck in there so cracked of each injector union for a minute or so whilst running.  Once all nipped up again it hasn't made much difference, still a bit of white smoke and a bit of a stumble, rev it up and it improves, no white smoke and feels smoother...

 

Any ideas what i might have missed, do i need to go back and re bleed the pump??

 

Thanks

 

Dave

Edited by Quattrodave

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White smoke is unburnt fuel. Likely cause is low compression on one cylinder, check the tappets.

If you turn the preheaters on does it get better?   Does it get better with a warm engine?

 

You will get even running with white smoke is the timing is retarded, i.e. late.  Is the pump timed correctly?

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We've had problems with one of these this week, came in with oil leak, diesel leak from pump and uneven running, cutting out etc. 

Oil leak was obvious, injector pump leak not quite as obvious(was throttle arm loose and missing O ring). Sent it away , back within 24 hours with new rollers and seals.

Engine refuses to start, even with fuel where it should be and new battery, sounds like no compression, so tommorow will be checking injectors and tappets

 

 

20201004_210420.jpg

20201004_211016.jpg

Edited by matty40s

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Sent the pump back to BobBecks, not pumping with any pressure to give a spray pattern. 

Disappointed.

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We tested everything, pop tested injectors, all good. Bottom bleed valve on injector pump spurts spectacularly, top one dribbles, injectors loose just splash, definitely not been set up right.

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On 04/10/2020 at 20:58, Tracy D'arth said:

White smoke is unburnt fuel. Likely cause is low compression on one cylinder, check the tappets.

If you turn the preheaters on does it get better?   Does it get better with a warm engine?

 

You will get even running with white smoke is the timing is retarded, i.e. late.  Is the pump timed correctly?

No problem checking tappets, i take it i'm looking for a tight one (or more) ?

As far as i can tell the pump is timed correctly, the little arrow is pointing at the line. I can try turning the pump anti-clockwise to inject slightly earlier.

 

On 05/10/2020 at 13:44, matty40s said:

We tested everything, pop tested injectors, all good. Bottom bleed valve on injector pump spurts spectacularly, top one dribbles, injectors loose just splash, definitely not been set up right.

Any news on the pump, have they managed to sort it?

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39 minutes ago, matty40s said:

Works lovely now they have "done nothing ".

😀  When you bled the pump did you have diesel coming from both the bleed valves pictured at the top?

Edited by Quattrodave

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2 hours ago, Quattrodave said:

😀  When you bled the pump did you have diesel coming from both the bleed valves pictured at the top?

We had a fountain from the lower one, and a trickle from the top one and virtually nowt at the  injectors the first time.

When it came back the 2nd time, fountain from lower and upper one.

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5 minutes ago, Tracy D'arth said:

Stop spindle?

Sorry, what about the stop spindle, are you thinking it was in the stop position whilst bleeding?

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I cant find a digram of ALL the galleries in that pump so can't be sure but I thought the whole body of that pump was flooded with fuel at transfer pump pressure when running and lift pump pressure when bleeding. The regulating vale in the end cap moves to allow lift pump pressure into the pump body and once running transfer pump pressure pushes it the other way to pressurise the pump body from the transfer pump (I think - too long ago to be sure).

 

If the regulating valve is sticky I think it might give the symptoms described.

 

I would try that top bleed screw while running and I would take that bleed screw assembly out and make sure it in not blocked, the larger hexagon should just unscrew but nowadays I fear it might have been glued in to cover up thread damage.

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2 minutes ago, Quattrodave said:

Sorry, what about the stop spindle, are you thinking it was in the stop position whilst bleeding?

May be? But if it is in the wrong position you will get no pressure up to the injectors. I don't think it will bleed if its not in the run position.

I am not very familiar with the inline CAV pumps but a few time bleeding pumps I have found that the stop spindle has not been closing the dump port fully.

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We recently had one of these pumps that was playing up and it was one of the levers loose on the spindle so what Tracy said is well worth checking. Again I cant find any details of the stop mechanism and galleries.

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Spent some time on the boat the last few days and got some jobs done.  I've checked the valve clearances, set them at 12 thou 0.3mm as per the manual. TBH they were all pretty good, 1 was slightly tight 2 other a little loose.

 

I was going to use the rule of nine, but quickly realised the valve layout was  different E-I-I-E-E-I-I-E so wasnt convinced it would work so reverted to the cylinder rocking set the opposite which seemed to work just fine...

 

Re moved the pump top bleed valve cleaned it put it back and re bled, I now have fuel at both pump bleed valves!

 

Engine started easily from cold with 12 to 15 seconds of heat, slightly stumbly At first but after a few mins smoothed out and low sounds pretty good.  Still getting white gray smoke.  Had a look at the pump timing, the marks are aligned so turned the pump (as you look at the front of the engine) slightly anti clockwise to inject fuel slightly earlier... no difference...

 

20201011_123350.jpg.ab15e419bc43db1e2bbaa588ce5c249b.jpg

 

Same white / grey smoke I think the camera makes it look far bluer than it is, smells very diesely...

 

I'm beginning to wonder if one of the refurbished injectors isn't right... Anyone able to test them if I send them to you?

Edited by Quattrodave
typo

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I wonder if they fitted the wrong nozzles to the overhauled injectors. Its not unknown. I would also take them elsewhere for pop testing if you don't have a pop tester.

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BMC use Pintle injectors with the extra tiny side hole in the body end.  If they have fitted the wrong injectors it will run dirty and rough.  Often the unwary fit Perkins injectors because they look  similar but they are wrong and can push the heat shield top hat into the pre-combustion chamber, Not good.

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Thanks guys, the injectors 'looked' correct, I understand this doesn't really mean much... is there anyone on here able to test them, or any recommendations of who to send them to?

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