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BMC 1.5 - Which Oil


David Schweizer

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6 hours ago, Boater Sam said:

The design of these BMC engines is ancient. They all smoke to some degree, pause, waiting for the rush of owners who swear that theirs' never smokes. They were designed before the second world war when no one gave a damn about an engine smoking a bit.

Really?

The BMC "B" series dates from the early 1950s, surely?

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2 hours ago, alan_fincher said:

Really?

The BMC "B" series dates from the early 1950s, surely?

No, I think it's a pre-war design, the British Motor industry was still in a poor state after WW2, using clapped out pre-war machine tools.

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Apart from the length of stroke there are a great many similarities between the BMC B series petrol engine and the pre-war Austin OHV valve engine. I suspect Harry Bathgate was an Austin engine designer. The A & B series BMC OHV valve engines were I am sure post was builds if not designs and may rank as the longest lasting designs ever.

However whether one can say claim a diesel engine with a totally different head is the same design as a pre-existing petrol engine I would suggest is open to question.

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Well I know I'm no expert, and mauybe Wikipedia is not the most reliable of sources, but whilst this article acknowledges similarities to an OHV engine used in the Austin A40 Devon, it still dates even that OHV engine as post war.

Any other references are to a side valve engine I think.

https://en.wikipedia.org/wiki/BMC_B-Series_engine

For what it's worth it states that the design of the B series started around January 1952.

So how similar was any engine produced in or before the war?  Not very, I'm thinking, and at the moment I still feel the B series diesels as used in canal boats are a post not pre war design.

I also think the poster that made this claim has been pretty tough on them.  Yes, because of their age, there are many knackered ones about, but one in good order really isn't that much smokier than something designed many decades later.  Ours was certainly not in the fresh flush of youth, but it didn't smoke much unless abused.

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Hi Tony

I didn't see an extra hole next to the pintle (it was one of these from ASAP: https://www.asap-supplies.com/brands/bmc-leyland/injector-nozzle-only-bmc-1-5-diesel).

All

I've ordered a complete set of washers from Calcut. I'll take the injectors out when I get them and take a look again. My prediction is that I will find top hats in all four chambers but plan copper washers over three of them and nothing over the 4th. I'll extract the top hats to check that the plane washers are present behind them and fit them if they are absent, replace the top hats and fit the atomisation washers, refit the injectors with a full complement of spill rail washers and see where I am. If I find the top hats are missing, I'll need to order them separately.

I will keep you posted.

Thanks for all your help.

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Hi Tony

I just took them apart and replaced the nozzles - removing and replacing whatever parts I found already there. As I said, I annealed the washers I found on the assumption that since they were there when I took the old nozzles out, they should be there when I put the new ones in. Thanks to everyone here for explaining how the old assembly is wrong. I will ensure I have: plain washer, heat shield, atomisation washer, injector in that order.

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3 minutes ago, davehindle said:

Hi Tony

I just took them apart and replaced the nozzles - removing and replacing whatever parts I found already there.

Then take the injectors out and get them calibrated. They will all be operating at different pressures now

Richard

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Unfortunately, you can't just replace the nozzles, you need to replace them and recalibrate them. I get this done professionally for the engines we rebuild, I don't have the equipment, clean space or experience to do this regularly

Richard

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1 hour ago, davehindle said:

Hi Tony

I didn't see an extra hole next to the pintle (it was one of these from ASAP: https://www.asap-supplies.com/brands/bmc-leyland/injector-nozzle-only-bmc-1-5-diesel).

 

Your link does not show an image of the pintle end of the nozzle and even if it did it might be a generic photo.

Pintle nozzles have a perfectly flat bottom face with just the pintle sticking out.

Pintaux nozzles have a sort of small raised dome in the centre with the pintle sticking out of it. If you did not know what to look for and probably also be in possession of a good magnifying glass it is no surprise that you did not see the auxiliary spray hole. You may see a black dot on the side of the domed bit.

If you had the kit to set the injector up properly and pumped the tester very slowly you might have seen the auxiliary spray but a  s you do not have the kit you would not.

As you have new nozzles I have assumed that the leak-back, dribble, and spray pattern will be within limits but there is no absolute guarantee they will be. It gets me how many people think they can just fit [parts to injectors to cause problems whilst professionals like Richard, myself and others always send them to a specialist for overhaul.

You can not properly test or set up injectors with out a "pop tester" that will allow you to check back leakage, spray pattern, dribble and reset the break pressure. To properly test a Pintaux nozzle you need an additional bit of kit but for field testing you can get away with an ordinary pop tester.

Did the nozzle have a little dome around the pintle?

 

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If the end of the injector is completely flat and just pintle  not pintaux, they could be Perkins, wrong ones.

The design of the "B" series petrol is prewar but construction started postwar, the diesel engines are later but share much of the basic design. The thick wall 1.8D was the last update.

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3 hours ago, Boater Sam said:

If the end of the injector is completely flat and just pintle  not pintaux, they could be Perkins, wrong ones.

The design of the "B" series petrol is prewar but construction started postwar, the diesel engines are later but share much of the basic design. The thick wall 1.8D was the last update.

and some have been known to push the end out of the top hat.

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Hi All

I haven't looked inside yet so I don't know what is missing / present but before I start replacing what I think is missing, can you have a look at this please? I've taken this from the workshop manual - blown up the injector part of the diagram, removed the irrelevant engine parts and added the text for each of the numbers on the original.

Two things jump out at me:

1. There seem to be three washers in the injector chamber, not two - one 'joint washer' under the heat shield, the atomiser washer and a joint washer between the injector and the heat shield. Does the 'joint washer for injector' sit on the brim of the top hat or is it not needed?

2. There is only one 'washer for banjo bolt' marked, not two. Comments in this thread and the contents of the washer kit suggest that there is a copper fuel washer above and below the spill rail.

bmc1500-injector-assembly.png

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That is correct, two copper washers and one crimped steel atomisation washer down the hole as y7ou describe. The sizes are such that I think its impossible to get them wrong.

There should be soft washers both above and below the fuel rail banjo. I have no idea why you do not have a leak if there is only one.

I have never gone out of my way to remove the top hats (heat shields) unless they were broken, I had to to get the old atomisation washers out or they came out on the injector. If they do not come out it might not be so easy to get them out on a well carboned engine so if they are in there and there is no signs of blowing past the injector I would not remove them so that washer is not required (its the one with the thinnest "wall" and largest hole).

Edited by Tony Brooks
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Hi Tony

Great tips again but I think you misunderstood my post. The comments I made (1 and 2) relate to the manual rather than my actual observations of my engine. The manual tells us we need 1 washer under the banjo bolt but none under the spill rail. It also tells us we need a total of three in the injector chamber - thanks for confirming this. 

I have now extracted my injectors and I see that I do have heat shields (they look a bit rough - the holes in a couple of them look a bit misshapen). What I did find was that none of the heat shields had atomiser washers. 

Thanks for advising that I don't need to take the heat shields out - I tried but they wouldn't budge. 

I will install new atomiser washers and reassemble the injectors with their existing heat shields and joint washers. 

Thanks again

Dave

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I had an old motor cycle spoke with one end bent a right angles, sharpened to a point and hardened. I could often work the point between the atomisation washer and the heat shield. If that did not work sometimes by putting a smallish screwdriver across one side of the wahser and hammering it the washer would distort so it could be hooked out.

You might find that if you get a long tap (as in tap and die) that is the same size as the hole in the atomisation washer but smaller then the hole in the heat shield you could screw it down a turn or so and the use pliers to pull it and the washer out.

If all that fails the I am afraid its heat shield out. You MIGHT be able to hook it out but you may well not. In that case is either head off and try to get something up the pre-combustion chamber throat to drift it out or bodge a tap suitable for the hole in the heat shield onto an impact slide hammer and try to extract it in situ that way. I think we had one we made with the tap brazed to a length of steel pipe, and old coupling as the weight and a length of steel bar welded to the top of the pipe.

However looking at your photo I am not so sure there is a washer down there. Where the carbon has chipped away it looks like flat steel to me with no signs of the squashed crimp that should be in a washer. You really should get rid of the carbon and then spin the engine on the starter (eye protection) to blow any out of the cylinder. If it turns out there is no washer then I would replace the heat shield. If the hole is much oversize then you will have reduced compression. 

 

Edited by Tony Brooks
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That heat shield looks eroded. If it has been used without a fire washer it will be.

Bite the bullet, pull out all 4 and replace with new parts,  and all new washers, they are not expensive.

If there is a washer down there and you put another one on top, you will break the end off the heat shield.

I cannot understand not having a copper washer above and below the spill rail union, they would never seal properly.

 

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