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BMC 1.8 failure to start after tickover cut out


marksbrown

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Hello and first off I just want to say whilst I'm new to register, I've been gleaning useful information from your forums for years.

 

Background

I have a BMC 1.8 engine in a cruiser stern narrowboat that will not start. The engine has run without fault for two years with yearly switching out of filters and oil. The engine is started each time with checks on oil, coolant (blue antifreeze mix) and prop. In Autumn's heavy rain the rear of the engine was partially submerged for a day. I'm waiting on a welder this Summer to repair the rusted drains - until then I empty it out every time it rains. In the five years I've had the engine, it has always started.

 

Breakdown

On the 20th Dec I was running in tickover coming down the Hanwell flight. The engine cut out (no mechanical noises I recall but perhaps a clicking noise). I was a little distracted stopping myself crashing into a wall! On mooring up, the starter solenoid would 'machine gun' and no turning over would occur. Since then I have endeavoured to tick off everything I can find by searching through this forum. The starter battery is new. The connections to the starter solenoid have been checked for continuity and connections cleaned. The isolator switch has been replaced. The starter motor itself has been removed taken to a refurbisher who says it was filled with oil (definitely my fault when changing the screw-on filter). I've reattached this 'refurbished' starter (without the lower bolt). Attempting to start with both domestics and starter in parallel now produces the clunk of the solenoid engaging but no turning over.

 

I have removed all four heater plugs and cracked the injectors. I have sprayed a WD40 rust penetrant into each. The engine itself is poorly situated to say the least (to the point that I'm not entirely sure that the deck wasn't just welded over the top of it after installation) and so the crank nut is mere centimetres from the bulkhead. Regardless the crank nut can be turned with a reasonable force approximately half a revolution though slightly more in reverse. At this point I hit a force I cannot push past. I have tried to rock the crank back and forth slowly to free up the engine to no avail yet. I have removed the 'rear' of the engine next to the gearbox slightly (~ 5 mm) (as the gearbox and gubbins) prevent further movement. Nothing fell out and with a torch I could see nothing amiss (though I'm certainly no expert). An engineer has checked the fuel lines, fuel quality, filter sitting and battery connections but was unable to start the engine either.

 

To do next

I am going to listen to advice! My plan as it is would be : First, I shall be connecting my domestic battery again in parallel to the starter motor and measuring the voltage across the starter whilst engaging. The starter motor is engaged by a relay (which has been checked). If this fails I will remove the starter motor and endeavour to turn the flywheel a full rotation (which I should have done in any case). Beyond this, I could buy a new starter motor or endeavour to try something more drastic but I'm very much at the end of my ability to muddle through. Any advice or indeed engineers who would be willing to visit Hanwell would be greatly appreciated and of course remunerated.

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Far more knowledgeable members will be along shortly but if it were mine I would remove the rocker cover to see what is happening when you turn the engine over using the crank nut . The fact you can turn it half a revolution proves it isn't seized solid but something is stopping it turning over a full revolution . Depending on what you find with the rocker cover off the next step would be to remove the head and again depending what that reveals dictates what happens next . 

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When the engine was partially submerged, how high up the engine was the water? Could water have got into the sump through the dipstick hole or a breather or crankshaft seal?

Have you checked the oil since it was partially submerged? If you have normal, maybe black, oil you are probably OK on that score, but if you have a thick grayish mainonnaise-like substance then water has got into the oil. If the engine has been run like that all sorts could have been damaged.

For how long after it was submerged did the engine run before it cut out?

Edited by David Mack
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I have read this about six times trying to get a handle on what is going on.

 

Even with the old steel band around the brush apertures, I can't see a bit of oil spilt in a filter change filling the motor with oil, and with the modern type with a gasket and end cap I think it would be impossible. So the question is where did the oil come from. I think the rear main must be leaking and it has been thrown it by the flywheel. However, that should not stop it turning over.

 

Machine-gunning is caused by insufficient current to keep the solenoid in place and power the starter, or, rarely, a solenoid fault. If anything stops the engine turning then with old, partially discharged batteries the solenoid may well machine gun, but with new batteries it may not, so assuming the new motor has the correct pinion I would suspect something is stopping the engine turning. I note the photo shows the glow plugs out, so it is unlikely to be a hydraulic lock.

 

I think you need to make an effort to ensure you can turn the engine two full revolutions. If you can't then I fear it is likely to be expensive, but take the fan belt off in case the alternator has seized.

 

One last thing, a long shot, the clicking might have been a drive plate falling apart and that can jamb the flywheel.

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First off thanks for all of your prompt replies.

 

In terms of how water got in. My guess is there's a missing bolt on on the circular rear plate (sorry I don't know names) right at the bottom below the gearbox. I presume water ingress from the oil drip tray entered here. The water wasn't high but enough to overfill the tray into the bilge. Certainly not enough to submerge the engine. I presume the oil is what has been collecting in my drip tray that I should deal with. It really was less than a day, we just had a great deal of rain in London. This was back in October and I've run the engine a dozen times for hours since then. I also ran the engine three times during the cold snap during December and it started normally if a bit sluggish (most likely due to the age of my starter battery).

 

The oil is half filled on the dipstick and it still looks fine to my eye.

 

The fan belt is already off. I'll try turning the engine some more tomorrow. If I cannot do that then I'll remove the starter motor and check that the flywheel turns freely. In terms of expensive - well it is what it is. What cannot be changed must be endured.

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1 hour ago, David Mack said:

When the engine was partially submerged, how high up the engine was the water? Could water have got into the sump through the dipstick hole or a breather or crankshaft seal?

Have you checked the oil since it was partially submerged? If you have normal, maybe black, oil you are probably OK on that score, but if you have a thick grayish mainonnaise-like substance then water has got into the oil. If the engine has been run like that all sorts could have been damaged.

For how long after it was submerged did the engine run before it cut out?


From memory the dipstick tube on the BMC 1800 on our former boat came up as high as the cylinder head - the diptick was of the very long flexible variety.

I realise others may be different, but if like ours the entire engine would be more or less submerged, before anything could go down the dipstick tube.

All that said, it would be helpful to know just how high the water did go, and which parts ended up immersed.

 

EDIT: Cross posted with helpful extra info from OP.

The fact it has worked fine since October would make me think it fairly unlikely the the flooding contributed to the (recent) ssue the the OP still has.

Edited by alan_fincher
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1 hour ago, Troyboy said:

Far more knowledgeable members will be along shortly but if it were mine I would remove the rocker cover to see what is happening when you turn the engine over using the crank nut . The fact you can turn it half a revolution proves it isn't seized solid but something is stopping it turning over a full revolution . Depending on what you find with the rocker cover off the next step would be to remove the head and again depending what that reveals dictates what happens next . 

Before removing the head I would look to removing the gearbox and looking at the driveplate. 

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Before worrying about electrics, starter motor or fuel system you need to know that the engine will turn over. With the glow plugs out there will be no compression, and with the drive belt off a seized alternator or water pump won't be an issue (but check that both can be turned easily by hand). So nothing should stop the engine turning over even if you can't get much force on the crankshaft nut. If you can turn it over half a turn that means you don't have a seized piston or bearing. Which suggests probably something wrong with the drive plate or gearbox. Otherwise I would be thinking of something in a cylinder which stops a piston rising, or maybe a valve jammed shut so the push rod and rocker can't open it. All seems a bit unlikely but...

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Just now, David Mack said:

Before worrying about electrics, starter motor or fuel system you need to know that the engine will turn over. With the glow plugs out there will be no compression, and with the drive belt off a seized alternator or water pump won't be an issue (but check that both can be turned easily by hand). So nothing should stop the engine turning over even if you can't get much force on the crankshaft nut. If you can turn it over half a turn that means you don't have a seized piston or bearing. Which suggests probably something wrong with the drive plate or gearbox. Otherwise I would be thinking of something in a cylinder which stops a piston rising, or maybe a valve jammed shut so the push rod and rocker can't open it. All seems a bit unlikely but...

 

I agree, further investigation needed. I think Tracy suggested once that the 1.8 is more prone to suffering from the timing chain jumping teeth. If that has happened, a piston may well be hitting an open valve.

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Okay so progress. I attached a piece of electrical tape to the crank and was able to turn a (near full revolution) in reverse from the 'block' and I was unable to pass it. I then came back clockwise and the same block was in place. Otherwise the crank turned nicely and I can hear air being pushed out of the heater plug holes. I presume that means my next step is to inspect the driveplate? I'm going to disconnect the plastic coupler, push the prop out of the way, somehow support the PRM gearbox from underneath (blocks of wood?) and inspect the driveplate. Hopefully find something. Still if the engine is able to near complete (> ~98%) that has to be a good sign right?

Edited by marksbrown
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3 minutes ago, marksbrown said:

Okay so progress. I attached a piece of electrical tape to the crank and was able to turn a (near full revolution) in reverse from the 'block' and I was unable to pass it. I then came back clockwise and the same block was in place. Otherwise the crank turned nicely and I can hear air being pushed out of the heater plug holes. I presume that means my next step is to inspect the driveplate? I'm going to disconnect the plastic coupler, push the prop out of the way, somehow support the PRM gearbox from underneath (blocks of wood?) and inspect the driveplate. Hopefully find something. Still if the engine is able to near complete (> ~98%) that has to be a good sign right?

 

That sounds like a lot of work, so I would want to eliminate a jumped timing chain first. Try fully loosening all the valve clearance adjusters and try again. If it still won't turn, then I fear it is gearbox off.  If it does then from how you describe the boat it may mean an engine lift/move back to gain access to the timing cover, or cut a large hole in the back bulkhead that you later seal with a plate and sealer-adhesive.

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With a bit of force I got the rocker cover off, loosened the lock nuts and unscrewed all 8 of the screws completely. The block still remains. I've disconnected the prop. I'm going to wedge blocks of wood underneath the gearbox. I'll need to disconnect something to do with oil connected to the exhaust (heat exchanger?) from the main body but I don't think it'll take long to do. Once I have the whole lot out, I'll take some pictures of the driveplate.

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Are all the valves moving when you rotate the engine? Check that one is not stuck open or dropped out of the collets.

Get one valve opening and rock the engine backwards and forwards. Does the valve respond instantly? If so its unlikely the timing chain or sprockets. If there is a big lag, it could well be the chain.

Is there any fuel coming out of the injection pipes when you turn the engine as far as you can backwards and forwards?

 

Take the dipstick/ filler plug out of the gearbox. Look inside with a good torch at the gears, do they move at all when you rock the engine? I know its an hydraulic clutches box but they usually will move without the engine running. I would drop the box off, you are almost there anyway, to check the drive plate.

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I tried balancing a mirror (I have to crawl under the stern deck to reach the crank nut). I can see *some* of the valves moving in time but not all. I'd need another pair of eyes to confirm they all did move. The bleed screw on the high pressure side of the injector is open and there is diesel present. There is no dip stick on the gearbox just the two pipes and the golden bolt (shown in the image above). There's no feasible way look at the gearbox and turn the engine from the front. I'm going to take off the box as you suggest and check the drive plate next.

Edited by marksbrown
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1 minute ago, marksbrown said:

I tried balancing a mirror (I have to crawl under the stern deck to reach the crank nut). I can see *some* of the valves moving in time but not all. I'd need another pair of eyes to confirm they all did move. The bleed screw on the high pressure side of the injector is open and there is diesel present. There is no dip stick on the gearbox just the two pipes and the golden bolt (shown in the image above). There's no feasible way look at the gearbox and turn the engine from the front. I'm going to take off the box as you suggest and check the drive plate next.

You won't see all the valves move until you can rotate the crankshaft by 2 complete revolutions, the camshaft runs at half the crank speed. If there is fuel coming out, the timing chain and injection pump must be working so the valves will open and close but is there no dead movement of the flywheel  backwards and forwards when the valves are moving? If there is it would suggest a very slack timing chain and broken tensioners.

My money is on the drive plate being smashed and part locking the flywheel. It is probably a spring cushioned flex plate like a car clutch plate and they do fall apart.

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1 minute ago, Tracy D'arth said:

You won't see all the valves move until you can rotate the crankshaft by 2 complete revolutions, the camshaft runs at half the crank speed. If there is fuel coming out, the timing chain and injection pump must be working so the valves will open and close but is there no dead movement of the flywheel  backwards and forwards when the valves are moving? If there is it would suggest a very slack timing chain and broken tensioners.

My money is on the drive plate being smashed and part locking the flywheel. It is probably a spring cushioned flex plate like a car clutch plate and they do fall apart.

 

As loosening the valve clearances did not seem to have any effect, I agree with you.

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I think the issue is the gearbox. I've removed the box to see the driveplate. A can get a thin screwdriver all the way about between the flywheel and the edge. There's no obstruction and the driveplate looks okay. After the gearbox is removed the engine spins quite nicely and easily in full rotations.

 

Trying to turn the gearbox from the inside I find that it sticks solid at one point but I can turn back and again it sticks. I'm going to out on a wild limb here and assume I should have been changing the oil (somehow) on the gearbox as well in the last 5 years. I'd mistakenly assumed it was part of the engine/oil system.

 

Thank you for all your help. I assume the gearbox either needs a specialist to take a look at it or a direct replacement at this point.

out.jpg

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19 minutes ago, marksbrown said:

 

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The gearbox dipstick is integral with the filler plug, the brass nut seen in the lower left corner of the gearbox in the photo above. When you remove the plug there should be a 150mm long steel rod about 4mm diameter attached to the nut with marks on the lower end for the oil range.

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1 hour ago, Tony Brooks said:

 

As loosening the valve clearances did not seem to have any effect, I agree with you.

 

 

But from the OP's photo, it looks to me as though he's backed off the locknuts on each of the tappets but not the tappets themselves. They also also need totally unscrewing so valve springs are not being compressed. Or just take the rocker shaft right off to prevent any valves being compressed. 

 

 

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Just now, MtB said:

 

 

But from the OP's photo, it looks to me as though he's backed off the locknuts on each of the tappets but not the tappets themselves. They also also need totally unscrewing so valve springs are not being compressed. Or just take the rocker shaft right off to prevent any valves being compressed. 

 

 

Unnecessary, the valves are all retained, none dropped, and they are moving. His problem turns out to be a jamming gearbox, probably due to lack  oil change.

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6 hours ago, marksbrown said:

 I'll need to disconnect something to do with oil connected to the exhaust (heat exchanger?) from the main body but I don't think it'll take long to do.

Gearbox oil cooler, probably looks something like this. The two small connections on the side carry oil to/from the gearbox and the larger connections on the end carry cooling water. To avoid losing your coolant and antifreeze from the engine circuit, better to disconnect the oil pipes (here or at the gearbox end) as you need to drain the gearbox of oil anyway.

 

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About a pint of (dirty) oil came out of the gearbox along with a spring and a nut. The gearbox is still jammed. I wasn't able to remove the plate from the gearbox so it's currently sat in my bilge.

 

The next step is probably to open it up and assess tomorrow. If needs be I can presumably set it for emergency operation but I suppose the hope is the placement of aforementioned spring/nut will be obvious. If not I will either need to find a replacement (a few hundred on ebay) or get this serviced.

 

At any rate I will need to set the valve clearances back to the manual specification, reattach the rocker cover and remount the alternator & fan belt - which will keep me busy regardless.

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  • 3 weeks later...

Okay so using a spare (broken) prm delta 20 gearbox and the useful manual I was able to dissemble the gearbox, remove two broken bolts from the input shaft clutch pack, damaged piston rings and replace both. I've reassembled (after a great deal of cleaning) however I'm in two minds about whether to use it or not. There was no other damage visible however now it's back together the gearbox experiences an uneven torque when I turn the input shaft by hand. Like there's a slight misalignment between the input and lay shafts. It does turn by hand and I'm sure it'll work but I'm a little worried frankly due to my inexperience whether this will be an issue.

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One more update. once the gearbox was reassembled it was fine. I've put everything back together and I've replaced the heater plugs on the engine for good measure (because why not). The engine and gearbox are now back together. I've bled the engine through and I've been able to get it to start! However there is an issue. Once it starts it remains at full throttle and won't come back down to tickover. I've managed twice to start it this way and in both cases, the stop lever causes the engine to stop.

 

The linkage from the control lever to the injection pump looks sound (the turning bit with a spring attached) and responds to the control lever. I've checked the tightness on the injector union nuts and I've just finished further tightening the heater plugs (they're slightly longer than my older ones). Before I try running it again, I wanted to run the problem by wiser heads. Is there anything else I can & should check prior to cranking again? Again thanks for all your advice.

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