BMC 1.8

[jimfin]

Hi All

We have a BMC 1.8 Diesel in our boat. Sometimes when motoring at about 2200 rpm it will jump to about 2500 for no good reason.

Any ideas on what might be the problem!!

[Proper Job]

Does it jump to 2500 and then return back to 2200?

 

Does the engine speed actually increase or is it just the Tacho reading? I am being serious as it's something I was asked to investigate. It turned out that the engine was staying at set revs. The fault was with the tacho.

[alan_fincher]

Bloomin 'eck!

 

I think if ours could go over 200 rpm for very long I'd expect the boat to start shaking to bits.....

 

2,500 rpm ??? Respect !!

[jimfin]

Does it jump to 2500 and then return back to 2200?

 

Does the engine speed actually increase or is it just the Tacho reading? I am being serious as it's something I was asked to investigate. It turned out that the engine was staying at set revs. The fault was with the tacho.

 

Goes up to 2500 and would stay there. It is the engine revs. Tacho is OK. There is a fairly new filter in it. Fitted about 30 hours ago

[STUBAG]

Goes up to 2500 and would stay there. It is the engine revs. Tacho is OK. There is a fairly new filter in it. Fitted about 30 hours ago

? alternator load decreasing as batteries are topping up?.....mine used to do this (aaah, the good old days)

[Speedwell]

As you imply it happens suddenly, is there some play in the throttle cable or its linkage to the throttle arm on the injection pump ?

Small amounts of air in the fuel system can have strange effects on running. This can be air getting in, air being expelled or air passing through the governer. My 1.8 has a slight leak in the injector pump and the air sometimes causes it to hunt at medium revs. A burst of high revs usually clears it.

Arthur

[RLWP]

Alternator drive belt slipping?

 

Richard

[jimfin]

Small amounts of air in the fuel system can have strange effects on running. This can be air getting in, air being expelled or air passing through the governer. My 1.8 has a slight leak in the injector pump and the air sometimes causes it to hunt at medium revs. A burst of high revs usually clears it.

Arthur

 

I think I might have this problem. I have felt around looking for a leak and noticed that the injector pump was a bit damp. Not dripping. Just damp with diesel.

Is it hard the take off the injector pump and get it sorted? I have also noticed that it is getting harder to start. When heated for a full minute, it's like it's tring to start on 3 cylinders. Might be some air getting in.

I have started winterizing it, so moght be a good time to do some work.

[RLWP]

I think I might have this problem. I have felt around looking for a leak and noticed that the injector pump was a bit damp. Not dripping. Just damp with diesel.

Is it hard the take off the injector pump and get it sorted? I have also noticed that it is getting harder to start. When heated for a full minute, it's like it's tring to start on 3 cylinders. Might be some air getting in.

I have started winterizing it, so moght be a good time to do some work.

 

If you suspect you have this problem, it is most likely to be in one of the joints in the pipework - even one that doesn't seem to be leaking fuel

 

Start off at the tank and check all of the joints with a pair of spanners

 

Richard

Edited November 7, 2012 by RLWP

[ditchcrawler]

I think I might have this problem. I have felt around looking for a leak and noticed that the injector pump was a bit damp. Not dripping. Just damp with diesel.

Is it hard the take off the injector pump and get it sorted? I have also noticed that it is getting harder to start. When heated for a full minute, it's like it's tring to start on 3 cylinders. Might be some air getting in.

I have started winterizing it, so moght be a good time to do some work.

I had an old Land Rover like that. I use to operate the lift pump by hand before attempting th start it and push the air out of the self bleed system before it got to the injector pump.

[Speedwell]

I think I might have this problem. I have felt around looking for a leak and noticed that the injector pump was a bit damp. Not dripping. Just damp with diesel.

Is it hard the take off the injector pump and get it sorted? I have also noticed that it is getting harder to start. When heated for a full minute, it's like it's tring to start on 3 cylinders. Might be some air getting in.

I have started winterizing it, so moght be a good time to do some work.

Mine is a leaking "O" ring in the throttle mechanism, which only started after I had the pump overhauled. (It's been back once which improved it but too much trouble to do it all again)

Arthur

[jimfin]

Mine is a leaking "O" ring in the throttle mechanism, which only started after I had the pump overhauled. (It's been back once which improved it but too much trouble to do it all again)

Arthur

 

Can you tell me how to remove the pump. Do I have to remove the timing chain?

[Speedwell]

Can you tell me how to remove the pump. Do I have to remove the timing chain?

It's fairly straightforward but messy. Just detach all pipes and cables, undo the 3 mounting nuts and remove it. The timing chain is not involved. Prepare for diesel spillage and protect pipes and pump from ingress of dirt. The pump has a master spline so it can only be fitted in one position, although there is timing adjustment, using the slotted mounting holes. An arrow and line give the supposedly correct timing setting (check how your is set)but if the timing chain has any wear the timing will need to be a bit advanced from that until no smoke is emitted when running.

If you haven't already got a workshop manual, you should get one. They are available on line - there has been a recent post about where to get one. I could email a Calcutt one if you like.

Arthur

[jimfin]

 

If you haven't already got a workshop manual, you should get one. They are available on line - there has been a recent post about where to get one. I could email a Calcutt one if you like.

Arthur

 

That would be great Please mail me at jimfinoc1@gmail.com

The timing is OK as I have no smoke.

I just found a workshop Manual on http://www.thenorfolkbroads.org/BMC%201.8%20Workshop%20Manual.pdf

Is this the same one you have?

Edited November 8, 2012 by jimfin

[Albion]

That would be great Please mail me at jimfinoc1@gmail.com

The timing is OK as I have no smoke.

I just found a workshop Manual on http://www.thenorfolkbroads.org/BMC%201.8%20Workshop%20Manual.pdf

Is this the same one you have?

When you remove and refit the pump watch out for the spring loading device (to stop spline chatter I think) which looks a bit like a metal mushroom where the head of the mushroom is a duplicate of the spline and master spline pattern on the drive spigot but is offset radially slightly and makes it more difficult to refit the spline. You need to get the head of the mushroom AND the spline inserted more or less at the same time.

Roger

Edited to add that you can see the part that I am talking about which is item 89 on page 12-15 of the manual that you have found.

Edited November 8, 2012 by Albion

[jimfin]

Thanks. I found that and printed it off. Is there a seal kit I can get for this pump or should I leave it in to be checked over ect.

[Speedwell]

Overhauling these pumps is a complicated job requiring special equipment. It's not really a DIY job, although I did replace the "O" ring to reduce the leak from the throttle area. The ring came from the overhaulers and they lent me a spanner to fit the odd sized nuts(bolts?), which held the sub-assembly in place.

I've emailed a copy of a workshop manual although I'm fairly sure it's technically the same as the one in your link.

Arthur

[jimfin]

Received all that. Thank you, Thank you all for your input. I am wiser over the last 2 days.

Now not to make a mess of it.

I'll try and keep you posted.

[jimfin]

When you remove and refit the pump watch out for the spring loading device (to stop spline chatter I think) which looks a bit like a metal mushroom where the head of the mushroom is a duplicate of the spline and master spline pattern on the drive spigot but is offset radially slightly and makes it more difficult to refit the spline. You need to get the head of the mushroom AND the spline inserted more or less at the same time.

Roger

Edited to add that you can see the part that I am talking about which is item 89 on page 12-15 of the manual that you have found.

 

Can this also cause a problem when taking the pump out. I have all nuts ect disconected, but the pump will not come all the way out. It has only come out about 1/4 inch. I have jiggled it around and tried a small bit of leverage with a screw driver, but it will not come out.

Any other advice before I take off ther timing chain cover!!??

[RLWP]

How did you mark the timing?

 

Richard

[jimfin]

How did you mark the timing?

 

Richard

 

I marked it with a center punch. But I think you are asking if I put the crank in a certain position before I started. If this is the question. I did not.

[RLWP]

I marked it with a center punch. But I think you are asking if I put the crank in a certain position before I started. If this is the question. I did not.

 

No, I wanted to be sure you had done something like your centre punch marks.

 

Richard

[Albion]

Can this also cause a problem when taking the pump out. I have all nuts ect disconected, but the pump will not come all the way out. It has only come out about 1/4 inch. I have jiggled it around and tried a small bit of leverage with a screw driver, but it will not come out.

Any other advice before I take off ther timing chain cover!!??

Not to my knowledge. The end of the mushroom stem just slides into part 45 (I think) on the pump drive and that then just slightly radially misaligns the head of the mushroom with its splines from the input drive shaft. The stem of the mushroom then acts as a torsion spring thus stopping drive spline chatter I believe. The only thing that I remember being difficult about the job was access to the third securing nut between the pump and the block which IIRC I modified a spanner to reach behind and give some movement to as it is all rather tight for access behind there. I don't think that you should have to remove the timing chain cover at all to be honest.

Roger

[RLWP]

A quarter of an inch sounds like the clearance at the back of the drive gear. Perhaps you could try being a little more forceful - gently though

 

Richard

[Speedwell]

Not to my knowledge. The end of the mushroom stem just slides into part 45 (I think) on the pump drive and that then just slightly radially misaligns the head of the mushroom with its splines from the input drive shaft. The stem of the mushroom then acts as a torsion spring thus stopping drive spline chatter I believe. The only thing that I remember being difficult about the job was access to the third securing nut between the pump and the block which IIRC I modified a spanner to reach behind and give some movement to as it is all rather tight for access behind there. I don't think that you should have to remove the timing chain cover at all to be honest.

Roger

Just wanted to agree that there is no need to remove the timing chain cover.

When I took my pump off, I wasn't aware of the mushroom device. Whether it hadn't been fitted or stayed in the pump, I don't know.

Arthur

 

I see Monkey 1 has just posted the perfect guide to fixing the leak at the throttle spindle.

Arthur