The Little Engine Who Couldn't Puff - 2.25l diesel woes.

[nickwilliams]

I'm posting this for my brother, Simon, who has recently taken delivery of a Series 88in Station Wagon re-build project from my son, Zak.

Simon has actually owned the vehicle since the 1970's and it's the vehicle I learned to drive in. However, it fell into disuse around 1985 or so and has spent the intervening years slowly dissolving away in a field. Then, a couple of years ago, Simon came to an arrangement with Zak for Zak to re-build it onto a galvanised chassis with view to getting it roadworthy again. 

To briefly summarise the (much longer) account below, the problem is that the engine runs for about 15 minutes and then stop abruptly. Simon has tried lots of tests and substitution of bits such as the injector pump but none of them have made any difference. We're now looking for ideas of what to check next.

Here is Simon's account of the problem.

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1.     Background

Land Rover Series 2A 2.25 litre 3 bearing crank diesel, vintage 1980 ish, rebored and new pistons.  Bottom end unchanged at rebuild.  Probably needs a new oil pump – oil pressure low (20 psi) with engine at running temperature.  Engine is fitted in vehicle (88in station wagon).  Reconditioned DPA pump fitted, timed using the recommended jig and the procedure as per the Rover instructions.  Injectors checked and re-fitted as serviceable initially, though events superseded this and they have since been replaced.  Coolant level in radiator is normal, oil level in sump marginally low (but needs replacing).

 

2.      Symptoms

Engine starts OK, not eager and needs heater plugs but then it always did. Copious blue smoke clears after 5 mins or so.  Runs at idle for about 10 mins then you can hear the idle speed slowing.  Over the next five minutes or thereabouts idle gets slower and some black smoke from the exhaust.  If you rev the engine with the throttle during this phase the engine revs rise very slowly despite snapping the throttle open (poor throttle response), when you let go again the idle speed is lower until it eventually peters out.  Engine stops abruptly as if it has seized (no compression bounce).  As quick as I can insert the crank handle and turn the engine with no evidence of seizure.  Cylinder head temperature is 70 to 80 deg C measured with non contact IR meter.

 During the latter stages of running the engine loosening the fuel feed banjo at the DPA pump shows a shower of fuel, there is no evidence of lack of fuel.  I have fitted transparent pipes to the fuel supply, no bubbles.

 Engine will restart though reluctantly – needs a lot of throttle to keep it running.

 Allow engine to cool back to ambient, then engine will restart exactly as per the above, idle for the same time, shut down in the same way.

Absolutely text book fuel starvation!  Except there is plenty of fuel at the DPA pump top banjo.  Driving the vehicle shows normal level of power for the first five mins or so after start, then rapidly diminishing until the vehicle won’t propel its own weight (low ratio on level ground!), then the engine dies as above.  

 

3.     Investigations/activities tried so far

-        Advanced injection timing.  Initial setting as per setting gauge sounded retarded, so DPA pump advanced till it sounded right.  Improved the initial start up, also reduced the quantity and length of time blue smoke emitted from exhaust.  May have contaminated the engine oil with diesel fuel running it with the original setting for the injection timing.  Injector 4 not contributing (much) to running – exhaust manifold at cylinder 4 cold for several minutes after start.

-        Checked fuel pick-up pipe in tank for leakage/blockage.  Nothing to see.  Fuel tank is open to atmosphere.

-        Changed fuel pipe from pick-up to lift pump for flexible hose.  No change.

-        Changed fuel filter.  No change.

-        Re-piped fuel lines looking for obstructions.  Checked connections are exactly as per published diagram in the work shop manual.  Fitted transparent piping looking for air bubbles.  Nothing.

-        Swapped engine mounted fuel lift pump for electric one. No change.

-        Reverted to mechanical pump.  Measure fuel delivery pressure at fuel filter outlet, steady at about 2 psi unchanged as the engine slows and stops.  Obviously this pressure collapses once the engine has          stopped.

-        Swapped rebuilt DPA pump for another of indeterminate parentage (ebay purchase).  Set the injection pump timing (position) as per the pump taken off.  No change.

-        Check cylinder compression pressures cold and hot.  Results as follows:

                 Cold 1 = 23bar, 2 = 31 bar, 3 = 30 bar, 4 = 24 bar.

                 Hot 1 = 23 bar, 2 = 30 bar, 3 = 29 bar, 4 = 26 bar.  

         So effectively unchanged.  Cylinder head temperature (IR probe) measured 20 degC cold, 85 degC immediately after engine stop.  Pressure checked by removing all four heater plugs, and connecting the compression tester with an adaptor into each glow plug port in turn.

-        Removed exhaust and inlet manifolds check for obstructions (rag?)  Nothing to see. 

-        Ran engine with exhaust loose at exhaust manifold (is the exhaust blocked?) No change.

-        Checked injection pump actual timing.  I bought a Gunson piezo sensor based adaptor to trigger a timing light from the injection pulse.  This showed the engine running solidly at about 12 deg BDC injection start, not 15 deg as per workshop manual, measured at tick-over.  As the engine heated up and slowed the light flash got less reliable, though what flashes it did trigger showed the injection timing didn’t change as the engine slowed.  Not sure if this shows the sensor/trigger operation is not 100%, or is this evidence of a poor injection pulse (indicating no fuel?)

-        Changed all four injectors for reconditioned ones.  Testing of the originals elicited the comment that 3 was OK, 1 and 2 were “not the best”, and 4 was useless.  Fitting the replacements made the blue smoke emission immediately after start better (less of it) and for less time, but has made no difference to the engine shut down after about 10 to 15 minutes.

-        I have a minor leak on the injector pipes 2 and 4, but slackening any injector pipe causes the engine to run rough and slow.  Exactly as one would expect.  Haven’t tried this with the engine hot and slowing.

-        Removed thermostat capsule hoping to prevent engine heating up.  No change, though the measured cylinder head temperature was much the same at engine stop as with thermostat fitted.

-        Ran engine with radiator cap removed.  Plenty of coolant circulation, no evidence of bubbles at the radiator header tank.  Engine stops after 10 – 15 mins exactly as above.

 

4          Suggestions for Further Work

My understanding is that it is possible to measure the DPA pump transfer pump fuel discharge pressure by removing a blanking bolt on the side of the DPA pump.  If the DPA pump is being starved internally this could cause the symptoms seen.  But how come I have two the same?  Can anyone confirm how to do this and that the bolt opposite the body bleed screw is the right measurement port?  Would need to make a special banjo fitting – no problem.

-        Take cylinder head off, looking for evidence of scuffing in the bores pointing towards momentary seizing.   It’s an expensive experiment when I have no real evidence of seizure.

-        What are symptoms as of a cracked cylinder head?  Note no evidence of bubbles in the radiator whilst running or water contamination of the engine oil.

-        Engine breather generates considerable fumes once it reaches running temperature.  I can’t see why this should cause it to shut down, but any thoughts?

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I'm of the view that this problem need solving by measuring various parameters such as fuel delivery pressure, injection pressure, exhaust temperature etc until we understand exactly what's happening when it stalls. It's not going to be cured just by swapping bits until it works properly. So, suggestions of what to measure and why it would help would be welcomed.

We'd welcome any further ideas for things to check, or any other insight!

 

[steve b]

Hi Nick ,

Having read through the background , can I ask if the return line is working correctly with no leaks or restrictions ? 

Have you observed flow out of the return during this repeatable start - run - peter out to a stop ?

Smoke maybe not quite advanced enough FIP timing , the skew gear is the main culprit in apparently out of spec degrees of advance.

Steve 

[smallfry]

As you say, classic symptoms of fuel starvation. My initial thought was that the tank was creating a vacuum, but I see you have covered that one.

I assume that you have left the inlet manifold open, and not coupled it back up to the air filter and trunking ? Birds nest in the filter for example ?

Brother in law had very similar problem with a Disco 300 Tdi Auto. Turned out to be the IP was bunged up with the dreaded diesel microbes where it had been standing in a field for a couple of years ........ similar scenario ? His injectors came out Ok on testing though. He cobbled on a Bosch pump from a Peugeot 306 just to see if the engine would run, before investing in a proper replacement. And it did, albeit badly.

I cant see a cracked head would cause this. Smoke maybe, hard to start, pressurising cooling system etc

As for the breathing, its a possibility. Might have cracked piston or bore/ring problem, but again, more likely to cause misfire, hard starting and smoke. But who knows ? Surely would show up on hot/cold pressure test comparison ?

Could it be a valve problem ? Rust, sticking, weak spring etc ? Overall though, I feel it is a fuel or air problem. 

[Simon Williams]

Hi Steve, Simon (Nick's brother) here.  Thanks for taking the time to reply, and the answer to your question about the return line is that I haven't checked, 'cos it hadn't occurred to me that it might be a contributor to my problems.  But it's easy to do  and I'll report back.

To Smallfry, also thanks for your input.  I can confirm that the air cleaner is disconnected so the inlet manifold is open to the air. 

What are your thoughts on the disparate compression pressure measurements between cylinders?  What pressure should I expect?  

My thanks to you both

<Edit>Oh, and the fuel is clean and new in a new tank with all new pipework.

Edited July 25, 2022 by Simon Williams
Additional Info'

[steve b]

Hi Simon , 

The CR variance is a little excessive , probably worth checking the tappet clearances are correct . That said the lowest of your readings is within spec. 

Was any work done on the head/valves ? 

Steve

[nickwilliams]

Response from Simon (who is on moderated posts since he is a new member here):

Quote

I checked the tappet clearances carefully early on in this saga, adjusted a few of them (only minor changes) and have checked them again since.  They’re as near as I can get them.

I haven’t played with the spill back connections yet, more anon.

[elbekko]

Sounds to me like it could be losing compression somehow? But very strange that letting it sit for such a short time would bring the compression back to normal. And doesn't explain the hard to start/keep running afterwards...

I'm wondering how the engine reacts to ether/start pilot/... sprayed in the intake when it starts to bog down?

[smallfry]

23 hours ago, elbekko said:

Sounds to me like it could be losing compression somehow? But very strange that letting it sit for such a short time would bring the compression back to normal. And doesn't explain the hard to start/keep running afterwards...

I'm wondering how the engine reacts to ether/start pilot/... sprayed in the intake when it starts to bog down?

Now that would be an interesting experiment, but maybe ether needs less compression to ignite it, so might not reveal much ?

Also, the low compression figures are with pistons that might have both been down while the engine was stood. Rust in the bores perhaps ? Losing compression an possibly damaging the rings/pistons ?

Is cracked pistons a problem with the NA diesels ?

 

 

[Simon Williams]

Many thanks to all who contributed above, and here's an update.

I decided radical action was needed, so have taken the engine out of the vehicle and stripped it.  Finding abrasive dust (and lots of metal filings) in the sump.  The (new) pistons look like someone rubbed a broken brick up and down them, and while the bores were scratched it was (by comparison) minor.  But the big shock was the damage to the crank.  I suppose that the oil pump was pumping fresh abrasive slurry through the big ends and mains.  To the extent that the conn rod bearing shells for 1 and 4 were smashed flat to tin foil, and thus these two cylinders were not making a full stroke.  Which presumably accounts for the reduced compression pressures on these two cylinder (20 bar against 30 bar in 2 and 3).  How ever did it run without making a clatter to wake the dead?

For all the world the oil pump is undamaged (uh?) but the relief valve was jammed open by dirt in the piston bore.  It took a bit of getting out.  But the gears themselves are re-usable.

SO I am in the throes of rebuilding the engine having rebored it and having replaced the crank.  Early stages yet, and I've already got myself into trouble.  Anyone got an original set of big end bolts I can buy off you?  I have bought eight Britpart bolts to replace the ones I took out which were overtightened, but the Britpart bolts have significant problems.  The ground shank is 1 to 1-1/2 thou oversize, the head doesn't match the recess in the conn rod, and they are too short by 4 mm to use with self locking nuts as they do not have any threads protruding.  Are they intended to be  used with tab washers?  What sort of self locking nuts are the right thing to use anyway?  I don't fancy nyloks, though I can't really justify why not but I don't like the thought of the nylon getting hot.  The WSM just says use new self locking nuts, so I bought some Aerotight nuts but I'm now stuck for bolts.

I'm not sure of the forum etiquette of canvassing spares in this way, my apologies of it's out of order, please advise the accepted practice someone.

Best wishes all for a pleasant Easter Egg Holiday Sunday, I'm off to wrestle the rear main bearing oil seal into place.  I've fitted it once but trapped the side T seals and given myself excess clearance on the rear main bearing.  Happy days!

Best regards Simon

[steve b]

good decision to pull the engine I'd say 

Have you tried Turner Engines for new BE bolts? While it's apart check the skew gear for wear - end float , teeth and bearing fit too. Any out of tolerance in that assembly affects the FIP timing while running. 

 

Steve

[hurbie]

3 hours ago, Simon Williams said:

  Anyone got an original set of big end bolts I can buy off you?  I have bought eight Britpart bolts to replace the ones I took out which were overtightened, but the Britpart bolts have significant problems. 

do you know the part number for these ?

[Simon Williams]

Britpart p/no for conn rod bolts was ERC8751.  Original bolts are 80 mm overall length, the Britpart substitutes are 76 mm overall.  This length measurement includes the head (ie it's not just the reduced shank portion, it's the head as well).  I have asked the vendors to investigate if this is the only option but the phone has been quiet!

I have corrected the oversize dowel section, and out of curiosity tried grinding a bit off the side of the off-centre oval head on one of them.  This gets the head to fit into the recess in the con rod.  But I don't think the head sits flat in its recess so is going to put a skew load on the bolt.  Last thing I need now is for a bolt to let go!

Engine I'm rebuilding is a service exchange bought from LR in about 1979 to replace the original 1963 engine which was truly knackered!  It's the three bearing crank one.

<Edit>  I don't have a parts book for the Series 3 engine, so I haven't checked if the b/e bolts are common throughout this period, and across any minor variants of the 2.25L diesel.  It could be that the Britpart bolts fit something a bit later )or possibly the original 1963 engine)  But that doesn't help me to wriggle out  of the hole I've dug myself.

Thanks as ever Simon

Edited April 9, 2023 by Simon Williams
added comment about "is the series 3 engine different in this tiny detail?

[Simon Williams]

My apologies to Hurbie, I fancy I misinterpreted the question.

According to my parts list, the original LR part number for the big end bolts is 519440.  Self locking nuts are 277390

HTH Simon

[steve b]

Turner Engineering show stock of ERC8751 and the correct nut ETC5155. These are common to all 2.25 and 2.5 petrol and diesel including the 2.5TD.

Are you getting the rod BE checked for size and ovality?  Turner also have new rods.

Steve

[Simon Williams]

"Turners have new rods"

By 'eck that's a good answer.  So a set of four conn' rods are on order, and hopefully will arrive during the next few days.  They come with b/e bolts, nuts and small end bushes, and the shells I bought already should fit, result.

I hope.

Thanks to Steve for that little nugget, and also thanks to mod's for enabling my messages over the bank holiday.

I'll keep you posted how it goes.

Rgds Simon

 

[steve b]

Good choice - I thought they looked good value, complete and bolt in.

Do check that skew gear assy. while it's apart.

Look forward to the next instalment.

Steve

[nickwilliams]

Just make sure they pack them properly.....

[Glue]

On 4/9/2023 at 1:45 PM, Simon Williams said:

<Edit>  I don't have a parts book for the Series 3 engine, so I haven't checked if the b/e bolts are common throughout this period, and across any minor variants of the 2.25L diesel.  It could be that the Britpart bolts fit something a bit later )or possibly the original 1963 engine)  But that doesn't help me to wriggle out  of the hole I've dug myself.

Thanks as ever Simon

I've got both the parts book and workshop manual for a series III. if you're still looking, drop me a line with an email address and I'll ping them over.

[Simon Williams]

OK, one step forward...

New conn rod's arrived today, not impressed with the packing job, but no damage so carry on.

New conn rods re supplied fully assembled with nuts/bolts fully tightened,  Yes the b/e bearing halves are fastened together with the bolts, but the nuts are fully tightened.  I shall need to hold the con rod in the vice to undo them.

Which I can do easily enough, but my WSM says quite specifically "use new nuts"  
I quote from page 69-A2 "Fit the connecting rod caps and new fixing nuts.  Tighten to 25lb ft."  Which doesn't seem a lot, but that's what the good book says.

Now part of the point of spending £160 in new conn rods was to be sure the nuts were the right thing and suitable for the service duty.  I haven't got as far as loosening off a pair of B/E bolts yet (they're bloody tight) so I haven't worked out what type of nuts they are, but I'm more than somewhat narked that they aren't new, by now they are used.

Do I just soldier on, 'cos I'm going round in a great big circle.  What's your opinion?

Thanks as always,

Simon

[hurbie]

28 minutes ago, Simon Williams said:

Do I just soldier on, 'cos I'm going round in a great big circle.  What's your opinion?

 

i would just put them in , don't think they put them on at  mox torque

could be the nuts are there to hold the halves together when machining.

[steve b]

set your torque wrench to 25lbft and see if they undo without a click. Put a suitable piece of wood in the vice and stick the BE over it.

If possible video it to argue for new nuts from Turners, but known new nuts tightened once would do for me I think.

Steve

[hurbie]

31 minutes ago, steve b said:

set your torque wrench to 25lbft and see if they undo without a click. Put a suitable piece of wood in the vice and stick the BE over it.

 

that will tell you nothing , you have to overcome the friction of the nut on the conn rod .

only way to tell what the real torque was  , make a small line on the nut and the conn rod, loosen the nut and set the torque wrench to 15 , see if the line drawn , line's up  , if not , undo the nut and set the wrench to 16 and do it again..... until your mark lines up , that setting was the previous torque setting.

[Simon Williams]

Good Afternoon, and thanks for all your help.  I've ordered some "fresh" big end nuts from Turners; for the sake of £10 or so it's not worth the worry.  But they look like nylocks!  I do hope someone's done their homework right.  I'm still tempted to go off piste with Aerotight nuts.  I've played with the question of how tight these nuts are as delivered, and as far as I can tell they are done up to the full recommended 25 ft.lbs.  

I had a very pleasant conversation with Richard Turner as of Turner Engineering this afternoon.  Who assures me that he's seen it all, and that these nuts will be safe as houses. 

Got another little riddle  where I'd appreciate the help of the forum 

I called into my local motor factors this morning, and I notice they no longer keep mineral engine oil on the shelf.  It's either fully or semi synthetic, in a variety of grades.

I've read somewhere that these old engines don't do well on fancy oils, and were never designed for them.  Is that an old wife's tale?  I could believe that the long life characteristics of modern oils are wasted on something designed in 1950, but are they actively counter-productive?

I've also heard it said that a special running-in oil (additive?) is worth having.  What's the collective opinion? If worth while what would you recommend?

[hurbie]

running-in oil is in my belief a thing off the past , when we rebuilt HGV engine's , they get the normal oil , and that is only changed at the normal interval ...(anywhere between 60000km and 140000km depending on use)

[steve b]

Try your local Ag supplier for mineral oil. 

As Hurbie says, correct oil and run it, I usually change oil and filter after 500-1000 miles or 3-6 months. 

Steve