Injector testing

[David Mutch]

Hi all. My BMC has been feeling a little under par recently. Slightly rougher running than usual, especially at idle/low rpm. It has also been producing a lot more soot than usual, although this is evident only because it leaves a nasty black mark on anything I moor up next to and around the exhaust outlet. No nasty clouds of smoke when revving. No other symptoms really. From what I can gather, a bad injector seems a likely culprit. Just wondering what the best way to test the injectors might be, or whether anyone has any other suggestions as to possible causes. Cheers

[Dalslandia]

I bought a injector tester, you can come over with them and we test them.

How is the airfilter?

Edited January 16, 2018 by Dalslandia

[Tony Brooks]

Unless you have the right kit it is not possible to give pintaux injectors a proper test. You need to test fro Spray pattern, break (opening) pressure, Leak back, Dribble, and in the case of pintaux injectors the operation of the auxiliary spray hole at low speed. The last one really needs an extra bit of kit in addition to the more common pop tester.

I do not even bother to try to test my own injectors, I just take them out and take them to a specialist for overhaul.

3 minutes ago, Dalslandia said:

I bought a injector tester, you can come over with them and we test them.

How is the airfilter?

Do you have the extra kit for testing pintaux injectors? Agree about the air filter though as a first check.

Edited January 16, 2018 by Tony Brooks

[Dalslandia]

Had to look them up, https://www.scribd.com/doc/156417859/CAV-Pintaux-Injection-Nozzle-Rebuild

I do have a regular tester with hand pump, the force and stroke is manually operated but agree with Tony, best to leave them to a specialist, but check the airfilter first.

what I can see it would be possible with pintaux, have just tested the injectors on my both Scanias 6 + 4 cyl. so far, Think they are Bosch 

will test those two on the Volvo Penta MD II, it runs with potential to be better, vibrates and hard to start when cold 

Edited January 16, 2018 by Dalslandia

[David Mutch]

1 hour ago, Dalslandia said:

I bought a injector tester, you can come over with them and we test them.

How is the airfilter?

Thanks Dalslandia, but I think it might be prohibitively expensive to bring my injectors to Sweden!

The air filter has just been cleaned, so I don't think it's a breathing problem, unless it's something more serious in the valve train. Could valve clearances being out cause similar symptoms, perhaps? 

Edited January 16, 2018 by David Mutch

[David Mutch]

1 hour ago, Tony Brooks said:

Unless you have the right kit it is not possible to give pintaux injectors a proper test. You need to test fro Spray pattern, break (opening) pressure, Leak back, Dribble, and in the case of pintaux injectors the operation of the auxiliary spray hole at low speed. The last one really needs an extra bit of kit in addition to the more common pop tester.

I do not even bother to try to test my own injectors, I just take them out and take them to a specialist for overhaul.

Do you have the extra kit for testing pintaux injectors? Agree about the air filter though as a first check.

Thanks Tony. I suspected as much. I'd read some things about some simple tests to give an indication, such as measuring temperatures at each exhaust port. Not sure how much mileage there is in doing this test though, especially as I believe the two cylinders in the middle share a port. Just wanted to avoid the expense of professional testing if there was any way to rule out injectors. Do you think it's likely enough to be the problem to warrant having it done? Any recommendations as to where to take them? Anything to be gleaned from a simple visual inspection? 

Edited January 16, 2018 by David Mutch

[BEngo]

Before removing the injectors, give it an Italian tune up.  Find a quiet piece of canal, tie up securely in the middle (so you don't wash the bank away) and put it in ahead gear.Wind it up to about 2000rpm and wait for 30 minutes. Watch the temperature.    A good blast on a river will also do.  Getting the ends of the injectors hot and the  engine working hard can clear a surprising amount of cr@p out of the works.

N

[RLWP]

1 hour ago, David Mutch said:

The air filter has just been cleaned, 

That's interesting, what sort of filter do you have?

[Dalslandia]

Just got my Engine separated from the injectors, and took the latter home for testing, open at the same value and give 4 nice sprayes.

open pressure is 10 bar under, but so they was on all the Scania injectors as well, instument error I say.

[Dalslandia]

David, you haven't got fuel that wasn't up to standard, last time to fueled her up?

[David Mutch]

4 hours ago, BEngo said:

Before removing the injectors, give it an Italian tune up.  Find a quiet piece of canal, tie up securely in the middle (so you don't wash the bank away) and put it in ahead gear.Wind it up to about 2000rpm and wait for 30 minutes. Watch the temperature.    A good blast on a river will also do.  Getting the ends of the injectors hot and the  engine working hard can clear a surprising amount of cr@p out of the works.

N

Thanks. I had wondered about doing this. Just moved to the west end of the K&A, where you can't often get a head of steam up while cruising, so had considered it might just be gunking up due to not being made to do any real work. I'll give it a go

[David Mutch]

4 hours ago, RLWP said:

That's interesting, what sort of filter do you have?

Just the coil of wire mesh in a disk-shaped cartridge attached to the intake. I clean it out with diesel whenever I do an oil change. Why do you ask? 

1 hour ago, Dalslandia said:

David, you haven't got fuel that wasn't up to standard, last time to fueled her up?

Can never be sure, but it's from a reputable source, who I have dealt with for years, so I can only assume it's OK. Also just done the fuel filter, and no sign of contamination 

[Tony Brooks]

8 hours ago, David Mutch said:

Thanks Tony. I suspected as much. I'd read some things about some simple tests to give an indication, such as measuring temperatures at each exhaust port. Not sure how much mileage there is in doing this test though, especially as I believe the two cylinders in the middle share a port. Just wanted to avoid the expense of professional testing if there was any way to rule out injectors. Do you think it's likely enough to be the problem to warrant having it done? Any recommendations as to where to take them? Anything to be gleaned from a simple visual inspection? 

I would ask your local garage for a recommendation, all injection equipment specialists should have no problems dealing with BMC injectors. A visual inspection is not likely to tell you much unless a a pintle has broken off a nozzle.

You could try loosening each injector union (the large nuts) in turn an measure how much the revs drop each time. They should all be about the same but that gives indications of things like low compression etc. as well so is not specific to an injector. If one causes a loss of diesel knock it might indicate an injector is not atomising properly. If the injectors have been in use for many years I would suggest its time for an overhaul.

I can only talk about specialists in Reading.

5 hours ago, Dalslandia said:

Just got my Engine separated from the injectors, and took the latter home for testing, open at the same value and give 4 nice sprayes.

open pressure is 10 bar under, but so they was on all the Scania injectors as well, instument error I say.

I hope that was one nice open cone spray per injector, not four sprays from a multi-hole nozzle. How bad was the leak back and did you test for dribble?

[Dalslandia]

No dribble, it hold pressure, slowly dropping, but if that is the injector or pump i don't know, never go back to zero, (untill unscrew the pipe)

They are Bosch with 4 holes, not a tap injector. was serviced last Winter in  nov-16. so should be and is fine.

 

 

[RLWP]

8 hours ago, David Mutch said:

Just the coil of wire mesh in a disk-shaped cartridge attached to the intake. I clean it out with diesel whenever I do an oil change. Why do you ask? 

Because some filters are firstly not very good at filtering and secondly quite good at restricting air flow. Usually the wire mesh ones with a chrome plated top

Richard

[David Mutch]

5 hours ago, Tony Brooks said:

I would ask your local garage for a recommendation, all injection equipment specialists should have no problems dealing with BMC injectors. A visual inspection is not likely to tell you much unless a a pintle has broken off a nozzle.

You could try loosening each injector union (the large nuts) in turn an measure how much the revs drop each time. They should all be about the same but that gives indications of things like low compression etc. as well so is not specific to an injector. If one causes a loss of diesel knock it might indicate an injector is not atomising properly. If the injectors have been in use for many years I would suggest its time for an overhaul.

I can only talk about specialists in Reading.

I hope that was one nice open cone spray per injector, not four sprays from a multi-hole nozzle. How bad was the leak back and did you test for dribble?

Thanks Tony. Might give that a try. On the subject of low compression, whilst I don't suspect it in this case, I'd like to do a compression test, as I bought a diesel compression test kit on a whim a while back, and need to justify my purchase! Can this be done via the injector ports if I'm taking the injectors out anyway, or does it need to be done via glow plug holes on the BMC 1.5?

10 minutes ago, RLWP said:

Because some filters are firstly not very good at filtering and secondly quite good at restricting air flow. Usually the wire mesh ones with a chrome plated top

Richard

Thanks Richard. My filter is as you describe, and I suspect not the best at filtering. But for this reason I also suspect not very restrictive!

[Dalslandia]

David, can I borrow the comp tester for my MD II ?

 

 

Edited January 16, 2018 by Dalslandia

[David Mutch]

7 hours ago, Dalslandia said:

David, can I borrow the comp tester for my MD II ?

 

 

She looks far too well-loved to need it

[Dalslandia]

Thanks David

[Tony Brooks]

9 hours ago, David Mutch said:

Thanks Tony. Might give that a try. On the subject of low compression, whilst I don't suspect it in this case, I'd like to do a compression test, as I bought a diesel compression test kit on a whim a while back, and need to justify my purchase! Can this be done via the injector ports if I'm taking the injectors out anyway, or does it need to be done via glow plug holes on the BMC 1.5?

You can test in either hole so it will depend upon what adaptors the compression test kit has.

[David Mutch]

14 hours ago, Tony Brooks said:

You can test in either hole so it will depend upon what adaptors the compression test kit has.

Thanks very much Tony. Hope I've got one to fit the injector holes then! I'm sure it's in the manual, but just in case, do you happen to know what sort of numbers I should be hoping to see compression-wise?

[Dalslandia]

475 PSI 33,5 kg/cm2 or something from the net, but sounds high.

Edited January 17, 2018 by Dalslandia

[Tony Brooks]

9 hours ago, David Mutch said:

Thanks very much Tony. Hope I've got one to fit the injector holes then! I'm sure it's in the manual, but just in case, do you happen to know what sort of numbers I should be hoping to see compression-wise?

I am afraid not and I think it's not in the manual. I would be looking for around 400 psi but more to the point that all compressions are within 10% or so of each other.

[Dalslandia]

The value 475 was found on a boat forum the OP had a 1.5 L BMC Diesel, his highest Reading was 425 the 3 other was a lot less, 

[David Mutch]

5 hours ago, Tony Brooks said:

I am afraid not and I think it's not in the manual. I would be looking for around 400 psi but more to the point that all compressions are within 10% or so of each other.

Thanks. No, it's not in the manual. Guess it varies a fair bit depending on cranking speed and such like. 400 sounds reasonable, given the compression ratio. 475 sounds optimistic, but then I don't know what effect the heat of compression would have. I guess if it's firing and they are all similar then whatever absolute numbers I get are fine, as there's no sign of excessive blow-by. I'll do the test and report back