Problems with BMC 2.52 expert opinion sought re Injector Pump

[Despeculator]

Background

Engine professionally rebuilt late 2017

On refitting starting problem noticed

Engineer stated it was due to needing to be run in

appears to have been incorrect

Since then

New starter motor

all injectors repeatedly serviced

glow plugs done

cylinder off, redone and refitted - by professional

compression tested 400 each cylinder

lift pump replaced

all filters changed again last week, including oil

tappets checked

fuel line changed to eliminate leaks

key switch changed 

Rotating pump makes little difference although retarding it fully sometimes can allow a start after several minutes cranking

 

The engine has large amounts of white smoke

It refuses to start unless warm

it was running temperature wise ok

oil pressure is slightly low but levels are right

plenty of water out of exhaust

 

Last weekend I took off the injector pump

I changed it for another unit

I also inserted a 6mm dowel and checked pump drive position which is spot on 86 degrees

the replacement pump made things much worse

more smoke, won’t start and now cuts out, temperature much higher

prior it would run fine, just smoking badly and not starting

 

So questions:

I think this is a timing issue

i have another pump on the way which is the model designated for my  Thornycroft 154 and it’s been rebuilt

I intend to fit this to get a comparison

 

Is it feasible that the timing marks have been set as per smaller BMC’s, ie marks aligned for crank and cam, would it run? The 2.52 has them aligned to links on the chain. Reason for asking is when I inserted the 6mm dowel for TDC, whilst the pump is aligned, the mark I made for TDC when the head was off appears to be about 120-180 degrees different (I’m guessing hence not being precise).

 

Any other thoughts of what the problem might be appreciated or if anybody is near Cardiff and thinks they might be able to fix it, please yell 😊

Edited December 8, 2021 by Despeculator

[Tracy D'arth]

White smoke on cranking is fuel injected but not burnt, usually to retarded timing but also when too cold to fire up. Can you feed it hot air from a heat gun or blowlamp whilst cranking?

Is the fuel good?

 

[Despeculator]

Fuels good - note I’ve been trying to sort this since 2017 - we took her around UK in 2018 with a dodgy engine 😊

 

I may be able to get power on board for a hair dryer or similar but I haven’t tried that to date. She will start immediately if you put a whiff of easy start into her but I don’t like using it.
 

If the timing marks were aligned as per a smaller BMC, ie with marks together and not to the chain, would it run and if it did would it appear badly retarded?

 

thanks for coming back on this

[Tony Brooks]

15 minutes ago, Despeculator said:

Background

Engine professionally rebuilt late 2017

On refitting starting problem noticed

Engineer stated it was due to needing to be run in

appears to have been incorrect

Since then

New starter motor

all injectors repeatedly serviced

glow plugs done

cylinder off, redone and refitted - by professional

compression tested 400 each cylinder

lift pump replaced

all filters changed again last week, including oil

tappets checked

fuel line changed to eliminate leaks

key switch changed 

Rotating pump makes little difference although retarding it fully sometimes can allow a start after several minutes cranking

 

The engine has large amounts of white smoke

It refuses to start unless warm

it was running temperature wise ok

oil pressure is slightly low but levels are right

plenty of water out of exhaust

 

Last weekend I took off the injector pump

I changed it for another unit

I also inserted a 6mm dowel and checked pump drive position which is spot on 86 degrees

the replacement pump made things much worse

more smoke, won’t start and now cuts out, temperature much higher

prior it would run fine, just smoking badly and not starting

 

So questions:

I think this is a timing issue

i have another pump on the way which is the model designated for my  Thornycroft 154 and it’s been rebuilt

I intend to fit this to get a comparison

 

Is it feasible that the timing marks have been set as per smaller BMC’s, ie marks aligned for crank and cam, would it run? The 2.52 has them aligned to links on the chain. Reason for asking is when I inserted the 6mm dowel for TDC, whilst the pump is aligned, the mark I made for TDC when the head was off appears to be about 120-180 degrees different (I’m guessing hence not being precise).

 

Any other thoughts of what the problem might be appreciated or if anybody is near Cardiff and thinks they might be able to fix it, please yell 😊

 

After all that work plus the 400 psi compression test all i can think of confirms your thoughts about valve timing. I suspect one tooth out, so certainly worth having the timing cover off and redoing it. I am not going to comment on you own mark etc. but the ineffective crank angle around TDC  is only a few degrees, nothing like what you seem to have found. If the timing was that far out I can't see how it would even run.

Edited December 8, 2021 by Tony Brooks

[Despeculator]

Ok, so I guess if the chain tensioner was not tight that also might have a similar effect - I’ll try the third pump first as I’m trying to not take the cover off unless I have to but it’s looking more and more like it’s necessary - thanks for coming back on this

[Bee]

'The replacement pump made it much worse' That's odd, if it had not made any difference that would have been sort of expected. These engines (From what I know) are usually good starters and with good compression I would have expected it to start OK. White smoke is indeed unburnt fuel and it does sound like a timing issue, All I can think of is a stretched or slack timing chain. After that I'm stumped I'm afraid.

[Tony Brooks]

1 minute ago, Despeculator said:

Ok, so I guess if the chain tensioner was not tight that also might have a similar effect - I’ll try the third pump first as I’m trying to not take the cover off unless I have to but it’s looking more and more like it’s necessary - thanks for coming back on this

 

If the 2.5 tensioner is the same as a 2.2, and I think it is, then it is a ratchet device that needs two little pins squeezing to release in once the chain is on. If this was not done the chain would be slack but I would expect you to hear it thrashing about, I would also expect internal  cover damage.

[Despeculator]

Yes that’s why I changed it, I was expecting little or no change, when it got worse it made me think about timing again.

 

I’ll fit the third pump as it’s a known good entity in theory but if it’s the same I’m resigned to taking the timing chain cover off, not an easy job 😊

3 minutes ago, Tony Brooks said:

 

If the 2.5 tensioner is the same as a 2.2, and I think it is, then it is a ratchet device that needs two little pins squeezing to release in once the chain is on. If this was not done the chain would be slack but I would expect you to hear it thrashing about, I would also expect internal  cover damage.

Ok there’s no real chain noise at all, only what you’d expect. I think you’re correct, it is same as 2.2 BMC, only the capacity is different 

[john.k]

Sounds like fuel timing major discrepancy .

Edited December 8, 2021 by john.k

[Tony Brooks]

3 minutes ago, john.k said:

Sounds like fuel timing major discrepancy .....the engine is actually firing on residual fuel in the cylinders.......your estimate of 180 deg is probably correct .........in other words ,fuel injection is at btdc on the wrong stroke of the engine

 

As It is not possible to fit the injector pump 180 degrees out given the correct timing when the chain was fitted then that just brings us back to valve/pump sprocket timing with the pump sprocket incorrectly timed.

[Despeculator]

3 minutes ago, Tony Brooks said:

 

As It is not possible to fit the injector pump 180 degrees out given the correct timing when the chain was fitted then that just brings us back to valve/pump sprocket timing with the pump sprocket incorrectly timed.

Ok many thanks - I’ll aim to have a go at it over next month or so and let you know how I get on - really appreciate the advice and feedback - thank you to all 👍

[john.k]

I jumped the gun a bit,OP says the motor has been in use for 3 years or so.....Although ,I will admit I got caught with the first Perkins Phaser I worked on .....the fuel timing is quite unusual to reduce pollution.