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BMC 1.5D Starting issues


colinnorth
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3 minutes ago, Mikexx said:

 

To be honest I thought these pumps were very sensitive to air such if any air got in them they would never start and require bleeding .

 

The 1.5 pump is a complete pig to bleed

 

Richard

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4 minutes ago, RLWP said:

The 1.5 pump is a complete pig to bleed

 

Richard

For all you other out there (not Richard because I am sure he knows).  If having diligently followed the bleeding procedure two or three times including keep bleeding the injector pump body for at least 30 seconds after you think you have removed the air remove the return pipe form injector pump to filter and put the end in a jar. Loosen the injector unions and spin the engine on the starter. That will usually shift and reluctant air in the pump. If you don't loosen the injector unions there is  a fair chance it will start during this procedure.

 

 

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2 minutes ago, Tony Brooks said:

For all you other out there (not Richard because I am sure he knows).  If having diligently followed the bleeding procedure two or three times including keep bleeding the injector pump body for at least 30 seconds after you think you have removed the air remove the return pipe form injector pump to filter and put the end in a jar. Loosen the injector unions and spin the engine on the starter. That will usually shift and reluctant air in the pump. If you don't loosen the injector unions there is  a fair chance it will start during this procedure.

 

 

There's another trick which you told me about, to do with having to pump the lift pump while cranking

 

The 1.8 on the other hand seems pretty easy to bleed

 

Richard

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1 hour ago, Mikexx said:

 

I was thinking about this. It takes a little time for unburnt diesel to exit the exhaust and so wondering how long this takes the OP to see smoke and then how long to start?

 

I would be tempted to operate the lift pump until it feels hard and unresponsive after the engine is stopped. To make sure you have a complete lift pump quantity of fuel at pressure to overcome any leak. And try again when cold to see how pumps are required to get in the same state in the morning and compare. Or indeed any other time after stopping and starting a while later.

 

If the fuel stop tap works this would also ensure fuel doesn't drain back into the tank, as well the return valve in the lift pump. I have known a return valve to fail in a lift pump.

 

To be honest I thought these pumps were very sensitive to air such if any air got in them they would never start and require bleeding .

 

 

From memory, it is impossible to hold any pressure in the system if the filter is the type with the banjo bolt with a restrictor orifice as any pressure leaks back to the fuel tank?

 

https://ads-crete.com/shop/product/filter-calib-union-ref-7111-135a/

 

IIRC, this is the type banjo bolt fitted to CAV filters, a problem if blocked with a VERY small air leak elsewhere. If this orifice is blocked any air in the system cannot leak off back to the tank and results in a fair bit of cranking to drive it out via the injectors.

 

Edit: When we had a shared ownership boat in the early 90s it was standard practice to operate the lift pump prior to a first start after the boat had been left standing for any time.

 

 

Edited by OptedOut
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The fact the OP says the engine sounds lovely and smooth when it's running concerns me. A properly timed indirect engine of that era should have a good diesel "knock".

 

So assuming decent compression then the pump timing could be retarded, quite possibly as the result of a worn timing chain.

 

1.5's are also quite marginal on cranking speed, so make the sure the starter's not lazy.

 

Both of those observations are irrelevant if the time taken for smoke to appear out of the exhaust is excessive though.

 

Finally, most BMC's are on at least their 2nd rebuild by now, and the pumps are seldom reconditioned. If it's lucky it might have had a £300 overhaul (which will be not much more than a seal kit, trust me) at some point and the first thing that suffers on CAV rotary pumps when they're tired is the injection pressure at cranking speed. The downside is we're seeing pumps so tired now that just the parts needed have been over £1000.

Edited by Rose Narrowboats
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  • 2 months later...

Back on the boat for the first time since lock down kicked in, with a diesel compression tester.

Test 1: remove glowplug 1, stop fuel, crank and measure. Step an repeat 1-4. All with engine cold and not having run since mid March.

Cylinders:

1 390, 2 410, 3 410, 4 410

Start engine and run until warm repeat test:

1 410, 2 430, 3 430, 4 420

This does not seem too bad to me.

After the tests the engine started immediately ok.

This is beginning to sound like a colder weather issue to me.

I will try again tomorrow and see what , if any starting issues there are.

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Are the heater plugs wired through a relay or just the ignition switch? I have found that the plugs don't get full current if there is not a perfect connection all the way back to the battery. Check the voltage on the plugs as they are heating but not cranking the engine. Ignition switches do develop poor contacts eventually hence it is better to use the switch to power a decent high current relay feeding the heaters. You are letting the plugs heat for 15 to 30 seconds before you crank the engine aren't you?  If not, the voltage on the heaters will be lower when cranking, hence improper heating.

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19 minutes ago, colinnorth said:

Back on the boat for the first time since lock down kicked in, with a diesel compression tester.

Test 1: remove glowplug 1, stop fuel, crank and measure. Step an repeat 1-4. All with engine cold and not having run since mid March.

Cylinders:

1 390, 2 410, 3 410, 4 410

Start engine and run until warm repeat test:

1 410, 2 430, 3 430, 4 420

This does not seem too bad to me.

After the tests the engine started immediately ok.

This is beginning to sound like a colder weather issue to me.

I will try again tomorrow and see what , if any starting issues there are.

It's great to be back on our boats, let's hope we can all use them fully fairly soon.

In my experience when the air temperature is like today at 20c +, you will be able to start any diesel engine fairly easily, even without wiring up your glow plugs heater wire.

Basically the act of compression to the air in the cylinder gets hot enough to fire the engine up in seconds in warm weather.

When the air is colder in winter at say between 0c and 10c the air can, (no will take longer to heat up in your cylinders.

If it doesn't start in this weather without any hesitance, then it is not your glow plugs and you need to look elsewhere.

By the way your compression figures are pretty good for an old engine. It's far from clapped out or other description for that matter.

 

I can only say again, check your glow plugs housing 1 by 1 , remove them completely and use a LONG 4mm drill bit to tap into the carbon beyond the length of the glow plug. TAP THE  DRILL BIT INTO THE GLOW PLUG CHAMBER WITH A SMALL HAMMER TO CLEAR THE CARBON.Then replace your glow plugs. It's an easy job to do and takes about an hour. 

 

BMC diesels are renowned for carbon build up with lots of smaller journeys being the culprit.

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Thank you for your input.

I can confirm that the glow plugs have all individually tested across 12 v and ‘glow’ witnessed. The glow plug holes are regularly reamed with the appropriate drill (I have the Morse Taper version of the drill which makes reaming a doddle).

The glow plugs are switched from the ignition switch and 11.8-12.2v arrives at the glow plug during the warming cycle. The glow plugs are not powered during the starter motor part of the cycle. I hold the glow plugs powered for about 30 seconds.

The head was removed a year ago (for an unconnected issue) and the starting issue is the same before and after.

This does seem to be a cold weather issue so I will probably leave things as they are for now.

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