Engine dying a painful death

[Josh]

Hello,

 

My engine is essentially at the end of its life(I think), the alternator is not much better, nor the exhaust so I need a replacement for the old Isuzu 3KC1 25hp unit that is current

 

This boat is my home and I need power, so... anyone have any ideas?, convert an old car engine?, grab an old mini-digger engine?

 

I just want to pick the brains of those with more experience at these things than myself before I spend my meagre savings on a lemon.

 

 

regards,

 

Josh

[Chalky]

Rebore & new pistons, Regrind crank and fit new bearing shells. Cheaper than a new engine. A boat engine is often converted to do the job. In a car or digger there is air flow round the exhaust to cool it. On a boat there's none so you often find a water tank built in to the exhaust casting to help cool it. You'll find a boat usually has a heavier flywheel, different engine mounts, different gearbox adaptor plate etc. Also there are specific safety requirements for pipework that don't apply to non marine engines. Often the conversion is expensive, especially if the parts are not standard and need to be fabricated. A re-build may be cheaper.

 

What makes you say that it's past it?

Edited July 10, 2011 by Chalky

[Guest]

Isuzu's reputably never die - they just grow old gracefully,

 

Revive it. as Chalky suggests...

[Guest]

I would have thought such an engine was rebuildable? What are its symptoms? Have you had a compression test on it?

 

Reason I ask is because there was a guy by us who had a BMC which he thought was knackered. It only needed glowplugs, but I couldn't convince him.

 

A cheapo frame generator would supply some electrical power while you sort it?

[Josh]

The re-bore is an idea, perhaps just a re-honing, rings and bearings if it is'nt too bad?

 

Just a point; the engine does not have a cooled manifold, its just a cast unit (probably why my alternator is dying, sucking air over it )

 

The reason I am thinking of a replacement engine is I can get one for almost nothing from a scrap yard/breakers and all Ian a can think of needing doing is the mounts, flywheel, oil extraction and a adaptor plate. like to be told what else would need doing though.

 

I have no charger and really cant afford to buy one or I would have and used the trusty genny I bought for the partial refit and rebuilt the engine when time/funds permit.

 

hmm... anybody have any plans for a DIY charger that can do 50A+?, all the switch mode plans I can find are only viable down to 40V (Electric car stuff). Transformer based systems are a tad tricky; finding cores big enough to wind onto is difficult (I haven't found one I feel confident is big enough yet) if anyone could point to a core big enough I would be grateful.

 

many thinks

 

Josh

 

Just going to add, I'm going to do another full service (only 50 hours since the last one) to see if it likes the added attention and add a few gallons to the tank.

 

I know it isn't an air bubble because both I and my father have bled the lines repeatedly.

 

I don't have access to a pressure tester that can handle diesel pressures, it will blow the dial off of the one I can borrow so...

[Nose Miner]

Hi, in my opinion you can't write off an engine without stripping it down and inspecting for any damage.

 

If you can give a more detailed description of the symptoms we can suggest the likely problems.

 

Getting another engine from a scrappy can be a way to go, but unless you strip that engine down, how can you be sure that it is any better than the one you hope to replace. If your engine turns out not to be economically viable it may be best to get another of the same sort and mix & match on parts to get a good un!

[RLWP]

To give you some idea of costs, I recently got a quote for a full recondition of an MGB engine from a local reconditioner - £800

 

The cost for your engine will be somewhere near that, and it will fit straight back into the space it came out of. That won't be true for a different kind of engine, so you will have to start solving the driveplate/gearbox/engine-mount/exhaust/cooling/controls problems afresh. That's tricky stuff

 

Richard

[Chalky]

It's worth investigating further and hiring equipment to test the engine before you condemn it. I've seen engines that were burning huge quantities of oil where the problem was a a faulty emissions valve (less that £20 to fix). Poor starters where the glow plugs were faulty. Apparent blown turbos that were due to inlet pipes where the cloth inners were collapsing and blocking the intake. Worn engines that had no power turned out to be carbon build up on the backs of valves. Poor idle control fixed by resetting the engine management. Lack of engine power due to faulty brake switch.

 

The engine in my MGB would use a pint of oil every 500 miles and had very low oil pressure. A new set of big end shells and rings restored the oil pressure and it went 6000 miles without using any oil.

 

Before you decide to replace it make sure that it is in need of replacement and doesn't just need some TLC.

[Proper Job]

For what it's worth, I've got to agree with previous posters.

 

Replacing the engine for a different unit should be your absolute last option. There are some very expensive elephant traps in boat engine replacement.

 

Even if you can get a Isuzu short block (or full recon), you'll still have your work cut out in replacing all of the marinising bits.

 

Get a definitive diagnosis as to what is actually wrong with it and then look at getting it rebuilt (DIY or by A N Other)

[bag 'o' bones]

For a diesel engine to stop working completly it would have to be seriously shagged. Even engines that are totally worn out will still run - eventually.

 

So along with the previous posts i'd say try the cheap checks first. Start with a good service first and then work from there. You might find the engine is just bunged up with rubbish and just needs a good clean out.

 

If you don't know much about engines it might be worth buying the generic Haynes diesel engine service manual.

[Guest]

Afterthoguht to my other post: I know of a Peugeot diesel that had little compression and would not run. Apparently the tappets had gone tight due to the valves pocketing. Was cured in a couple of hours they tell me.

Now tell me I am wrong, but I don't believe all boat engines have the tappets checked as often as they might?

[bag 'o' bones]

Afterthoguht to my other post: I know of a Peugeot diesel that had little compression and would not run. Apparently the tappets had gone tight due to the valves pocketing. Was cured in a couple of hours they tell me.

Now tell me I am wrong, but I don't believe all boat engines have the tappets checked as often as they might?

 

I'd go with that. Looking at the Beta marine operators hand book there is no mention of when the tappets should be adjusted let alone how. Or maybe there self adjusting these days? I don't think so though they look fairly old school to me.

 

Having said that modern valve seats are that hard these days that valve seat recession shouldn't be a problem.

[Tim]

I'd go with that. Looking at the Beta marine operators hand book there is no mention of when the tappets should be adjusted let alone how. Or maybe there self adjusting these days? I don't think so though they look fairly old school to me.

 

Having said that modern valve seats are that hard these days that valve seat recession shouldn't be a problem.

 

Kubota workshop manual says adjust at 800 hours.

[Josh]

I have just done a full service and my wrists haven't half had a workout pumping the oil and air out (used asda 15-40 and unipart 10-40).

 

Just for reference; how do you adjust the valves on these engines, they are OHV; can I adjust it with a spanner or do I need shims?

 

GOOD NEWS! she started! bad news was it was lumpy to say the least, a good blast in gear while tied to the moorings seems to have sorted it (at least for now).

 

she would start and then stall run with no power, or simply refuse to start without lots of heat from the plugs when last winter I could start the engine without heat while frozen in. (won me a beer )

 

Only a couple months ago I did the Cheshire ring without incident and it was running fine until a few weeks ago when it started struggling it seemed to perk up after the last service and then deteriorated badly until this service, now it seems to be running OK.

 

This whole thing is a little confusing and has busted my budget for this month with the filters/oil (very, very tight budget.).

 

 

Thank you for all your replies I really appreciate it,

 

Josh

[RLWP]

If it were my engine I would be checking out the fuel side

 

Richard

Edited July 11, 2011 by RLWP

[Nose Miner]

 

she would start and then stall run with no power, or simply refuse to start without lots of heat from the plugs when last winter I could start the engine without heat while frozen in. (won me a beer )

 

 

Sounds to me like you have a fuel supply problem, rather than anything explicitly mechanical to do with the engine.

 

Just for clarification: is it burning copious quantities of oil? Is it drinking lots of water? Is it overheating? Is it making loud clacking or banging noises as it runs? Is it producing smoke and if so what colour? Is it excessively vibrating?

[Chalky]

Have you changed the fuel filters and drained the water trap? Any signs of brown sludge or jelly in the fuel filters - Diesel bug? My isuzu picked it up and it ran badly then wouldn't re-start. Liberal dosings with bactericide fixed it.

[Josh]

Sounds to me like you have a fuel supply problem, rather than anything explicitly mechanical to do with the engine.

 

Just for clarification: is it burning copious quantities of oil? Is it drinking lots of water? Is it overheating? Is it making loud clacking or banging noises as it runs? Is it producing smoke and if so what colour? Is it excessively vibrating?

 

 

 

Well, I changed the fuel filter last service and then again today and there wasn't /that/ much junk in it when I emptied it to check; just the usual black stuff that was in the last few (not sludge) and I don't have a water trap. Its the Liverpool boats set-up from '93 I think (degraded fuel lines?).

 

No overheating or excessive smoke (just normal diesel smoke) or drinking anything except a little oil maybe a cup every 20 hours or so, if that. Certainly nothing excessive.

 

yeah, it rattles like a bag of spanners in a tumble dryer but that could be anything from the gearbox to the big end the thing is too damn loud to diagnose.

 

The excessive vibration I would suspect to be normal for a 3 cylinder engine, right?

 

Not a clue how many hours are on the engine, the counter says 3.3k but that has obviously been changed at some point.

 

 

 

Regards,

 

Josh

[Chalky]

A 3 cylinder engine should be smoother than a 4 since the firing strokes are 120 deg out of phase (ok 240 if your pedantic) vs 180 (360 for pedants). This is why high end car makers tend fit 6 & 12 cylinder engines (or use V8s / balancer shafts to achieve the same effect).

 

If you've got a rod/screwdriver you can use it to detect the source of the noise. Hold one end against your ear (use a non sharp end etc (obvious health warning)) and hold the other against what you want to listen to. The sound will transfer through the rod into your ear louder than the air born noise and will let you listen to the part its resting against. Can be useful for diagnosing where noise is coming from.

[RLWP]

A 3 cylinder engine should be smoother than a 4 since the firing strokes are 120 deg out of phase (ok 240 if your pedantic) vs 180 (360 for pedants). This is why high end car makers tend fit 6 & 12 cylinder engines (or use V8s / balancer shafts to achieve the same effect).

 

<snip>

 

Sixes are inherently smooth, threes are not. This is because you can set a six up to take out the out-of-balance couples in a three

 

Richard

[Josh]

A 3 cylinder engine should be smoother than a 4 since the firing strokes are 120 deg out of phase (ok 240 if your pedantic) vs 180 (360 for pedants). This is why high end car makers tend fit 6 & 12 cylinder engines (or use V8s / balancer shafts to achieve the same effect).

 

If you've got a rod/screwdriver you can use it to detect the source of the noise. Hold one end against your ear (use a non sharp end etc (obvious health warning)) and hold the other against what you want to listen to. The sound will transfer through the rod into your ear louder than the air born noise and will let you listen to the part its resting against. Can be useful for diagnosing where noise is coming from.

 

Thanks, I will try using a rod/screwdriver trick tomorrow and see if I can find the rattle.

 

Don't V8 and V6 engines bounce all over the place without balance rods? straight 6 engines and v12s are pretty smooth. I wonder if it is possible to squeeze a straight 6 under the back deck, and how would a NB handle on the plane?

 

I'm not too sure about 3s being smoother than 4s to be honest, why else would there so many small 4 cylinder cars when its cheaper to build a 3 cylinder engine?

 

 

regards,

 

Josh

[JDR]

A 3 cylinder engine should be smoother than a 4 since the firing strokes are 120 deg out of phase (ok 240 if your pedantic) vs 180 (360 for pedants). This is why high end car makers tend fit 6 & 12 cylinder engines (or use V8s / balancer shafts to achieve the same effect).

 

Certainly not true on bike engines. I've had a few BMW K75s - 120 degree flat triples and they required balance shafts.

Although a 120 triple will be smoother than a 180 triple (this is what the Slater Brothers did with the Laverda 180 3C engines to create the Jota.)

[Nose Miner]

Unless you have an unusual engine, being a 3 pot won't make that much difference to vibration. Canal boat engines have larger, more massive flywheels to iron out the bumps.

 

If the engine is vibrating excessively look at the tightness and functioning of the engine mounts, they could have worked loose or broken altogether. This is a common problem. Is the vibration problem better/worse/the same in gear and out of gear? If it's worse in gear it could still be engine mounts, but may also be a bent or misaligned shaft, or a damaged coupling.

 

Check also any pulleys on the front of the engine - they should run smoothly without wobble.

 

The condition of the filters and/or the fuel in them is not necessarily a good indicator. The thing to check is fuel flow through the system. If you can disconnect the tank return line and run it into a suitable container, with the engine running, check for a good consistent flow. If you can run it through a bit of clear hose, you can check for air bubbles (there shouldn't be any). If the flow is poor or non-existent, you are looking at a blockage somewhere in the line.

[nb Innisfree]

Certainly not true on bike engines. I've had a few BMW K75s - 120 degree flat triples and they required balance shafts.

Although a 120 triple will be smoother than a 180 triple (this is what the Slater Brothers did with the Laverda 180 3C engines to create the Jota.)

 

I owned a Yamaha XS 750 triple, 120 deg spacing and no balance shaft, had a pleasant and

low frequency vibration but have to say 4 cyl bikes I rode were much smoother (and blander)