JP3 won't start from cold (used to be just fine)

[sassan]

After 6 months of winter inactivity (winter mooring), I replaced the oil filter, oil and fuel filter of my JP3.

 

The thing then wouldn't start. I (and the various kind folks who offered a look at it) assumed I had let air into the fuel system when changing the filter, so our efforts mostly centered around bleeding it out. No luck.

 

Got a mechanic out and after making the same checks as us, he reckoned that the oil had sunk to the bottom of the cylinder bores and therefore wasn't giving a good seal around the pistons which meant too little compression. He sprayed a little easy-start in and it went immediately. He reckoned a good long run would let everything get relubricated and then we'd be fine. He said to seek further advice if it wouldn't start by itself under normal conditions.

 

Didn't start the next morning, gave it the tiniest spray of easy-start and it burst into life immediately.

 

If I turn it off and start it again while warm (tried up to half an hour later) it starts perfectly. It also runs absolutely fine.

 

I thought I could see a bit of exhaust coming out near the tops of the cylinders (around the changeover valves / fuel lines), but really hard to tell as there was also moisture rising off the exhaust cladding when warm. I double-checked the changeover valves and couldn't see any afterwards, but not 100% I saw it in the first place.

 

Keen not to keep using the easy-start, since A: apparently it's really bad for the engine long-term and B: I'd like to get to the bottom of the real problem.

 

Any advice gratefully received, thanks in advance.

 

 

Edit: Forgot to mention, have tried both with and without the overload pawl (although I've never needed it before). Always started within about the first rotation before. Batteries seem fine and the speed they turn it over seems in line with what it was before.

 

Another edit: I think it previously had "cheap" oil in it. I replaced it with Morris Golden Film SAE30 (only pumped out the oil from the tank, so there's a mix of oil (which I'm told is ok)).

Edited April 10, 2014 by sassan

[pete.i]

Hi I don't have a JP3 I have a BMC 1.5. But after changing my fuel filter I had the same problem. If you think about it when you change the fuel filter that will introduce a lot of air into the system. Also until the filter is absolutely saturated with fuel some air will still be there to circulate through the intake side of the fuel system.

 

What I found with mine was that for the first few times of starting I would have trouble. A quick bleed on the rotary fuel pump would clear it and then the engine would be fine until the next time. This situation continued for a while until, I assume, all the air bled through and now it starts fine every time. As I have stated a BMC is not a JP3 but they would both suffer from air in the fuel system. It doesn't need much air to stop it running properly and especially when the engine is cold which is when most diesels are hardest to start. I would also check that the heater plug connections haven't been disturbed (assuming a JP3 has heaters) as that will also cause starting problems when cold.

 

Pete

[sassan]

We went through clearing the air over and over again (pretty confident there's none now). We can hear a good injector creak from each of the three which indicates fuel getting through.

 

No such luxuries as heater plugs.

 

Thank you anyway, maybe I will do as you suggest and give it a few more runs before I worry.

 

People often say it's bad to use easy-start a lot, but noone is clear on how often is a lot. Will a 3rd, 4th, 5th time hurt? Or is this something that becomes a problem over months and years? I'm only using the tiniest little bit (see, I'm starting to sound like a drug addict already!).

[pete.i]

People often say it's bad to use easy-start a lot, but noone is clear on how often is a lot. Will a 3rd, 4th, 5th time hurt? Or is this something that becomes a problem over months and years? I'm only using the tiniest little bit (see, I'm starting to sound like a drug addict already!).

Yes I have heard it's not a good idea to use that stuff too often but, as you say, no-one says what too often is. I have never had to use it on my BMC but I did use it once on a Seagull outboard that I have. Anyway hope your engine problems get solved soon cos the cruising season is upon us.

 

Pete

[by'eck]

A few suggestions.

 

Ensure the compression change over valves are screwed in really hard.

 

You mention an oil tank so can I assume yours is a true marine version JP3M? If so you should have an overhead hand crank as well as electric start. If possible turn engine over by hand with throttle open and decompressed. You should hear individual creaks from each injector. This indicates fuel is spraying into the cylinders.

 

Operate the overfuel pawl on injection pump whilst pulling the throttle lever back to the overfuel position (I know you tried this already). Hold that position whilst cranking engine from cold.

 

Out of interest where is the oil filter on your engine since Lister didn't fit one? I believe they are retro-fitted on marine versions in the scavenge pump return pipe to the tank.

 

You really need to remove one or more crankcase covers and mop out sump as well as draining oil from same when doing a change. Just changing oil in tank is only doing half the job.

[GUMPY]

The high/low compression screws are screwed in arnt they?

 

beaten by a whisker

Edited April 10, 2014 by Loddon

[sassan]

A few suggestions.

 

Ensure the compression change over valves are screwed in really hard.

Will have another check on Saturday. I see other threads in this forum recommending A: opening them for a while when hot and then closing and running for a while before stopping to clear soot and reseal; B: a little oil (on the threads, I presume? Or take them out and oil?); and C. tapping them with a rubber mallet while turning to get them good and tight.

 

 

You mention an oil tank so can I assume yours is a true marine version JP3M? If so you should have an overhead hand crank as well as electric start. If possible turn engine over by hand with throttle open and decompressed. You should hear individual creaks from each injector. This indicates fuel is spraying into the cylinders.

 

Did this.

 

 

Operate the overfuel pawl on injection pump whilst pulling the throttle lever back to the overfuel position (I know you tried this already). Hold that position whilst cranking engine from cold.

Did this.

 

 

Out of interest where is the oil filter on your engine since Lister didn't fit one? I believe they are retro-fitted on marine versions in the scavenge pump return pipe to the tank.

Correct, it's on the return pipe to the tank. Oil pressure is normal (after it's going, obviously). Can see oil flowing from engine back to tank.

 

 

You really need to remove one or more crankcase covers and mop out sump as well as draining oil from same when doing a change. Just changing oil in tank is only doing half the job.

Is that something I ought to do now? Or advice for next time?

 

I also didn't use the full 25L, just got it to a good level such that plenty was there to be taken into the engine from the bottom of the tank (a bit over half). Maybe the fact I didn't empty the sump is the reason I didn't need it all. I'll certainly do it properly next time (or before, if recommended).

[by'eck]

Will have another check on Saturday. I see other threads in this forum recommending A: opening them for a while when hot and then closing and running for a while before stopping to clear soot and reseal; B: a little oil (on the threads, I presume? Or take them out and oil?); and C. tapping them with a rubber mallet while turning to get them good and tight.

 

 

 

Did this.

 

 

Did this.

 

 

Correct, it's on the return pipe to the tank. Oil pressure is normal (after it's going, obviously). Can see oil flowing from engine back to tank.

 

 

Is that something I ought to do now? Or advice for next time?

 

I also didn't use the full 25L, just got it to a good level such that plenty was there to be taken into the engine from the bottom of the tank (a bit over half). Maybe the fact I didn't empty the sump is the reason I didn't need it all. I'll certainly do it properly next time (or before, if recommended).

 

I would certainly mop out sump at next oil change (every 450 hours) but the choice is yours.

 

Not much left to check. If you can feel good and equal compression on each cylinder it should start easily.

 

Shots in the dark now, but check tappets when cold (8 thou) and spill timing of injection pump.

[mattlad]

I would recommend re-rechecking the fuel system. It stands a good chance that you have managed to introduce a very small air leak into the system.

 

Most diesel engine faults are caused by fuel supply issues, it could be that you have disturbed a pipe somewhere or have fitted the fuel filter incorrectly (or even fitted a faulty filter!) Trust me I've seen it once or twice during a 27 year stretch in the motor trade.

 

Okay then, dozens of times!

 

Have you tried rigging up an alternative fuel supply?

 

Check the most obvious, most likely faults first and make sure they are properly eliminated before chasing other faults!

Edited April 10, 2014 by mattlad

[Timleech]

Could be stuck piston rings?

Maybe try to introduce some RedEx into the bores & leave it for a few days, too see whether that helps?

The main trouble with Easy Start is that it can produce very high cylinder pressures when it ignites, and than can, for instance, damage piston rings especially if they are already worn. It's not so much how often you use it, but how much you use. If there's not something seriously wrong, then just a whiff should be enough to get things going.

 

Tim

[sassan]

I would recommend re-rechecking the fuel system. It stands a good chance that you have managed to introduce a very small air leak into the system.

 

Most diesel engine faults are caused by fuel supply issues, it could be that you have disturbed a pipe somewhere or have fitted the fuel filter incorrectly (or even fitted a faulty filter!) Trust me I've seen it once or twice during a 27 year stretch in the motor trade.

 

Okay then, dozens of times!

 

Have you tried rigging up an alternative fuel supply?

 

Check the most obvious, most likely faults first and make sure they are properly eliminated before chasing other faults!

The fuel filter in this case is one of the big sock-like ones that you clean rather than replace. There are also two, with a changeover lever. This has allowed me to switch back to the one I haven't messed with and rule out problems with that (except of course air introduced while changing). It's odd that it would work fine once started (with the easy-start) but not from cold. Perhaps there's a small leak that's allowing fuel to leave the pipes and be replaced by air overnight? I'll give it another check over and perhaps try starting it, immediately stopping it and then trying to start it again (which I think might help to rule out this possibility?).

 

Could be stuck piston rings?

Maybe try to introduce some RedEx into the bores & leave it for a few days, too see whether that helps?

The main trouble with Easy Start is that it can produce very high cylinder pressures when it ignites, and than can, for instance, damage piston rings especially if they are already worn. It's not so much how often you use it, but how much you use. If there's not something seriously wrong, then just a whiff should be enough to get things going.

 

Tim

It has indeed required only the barest whiff. I'll add piston rings to my list of things to check.

[koukouvagia]

I had an identical problem with my Kelvin. After a few weeks idleness and when the weather had turned colder, it was impossible to start. Up till then all was well - or so I thought. After fiddling around trying to eliminate non existent fuel problems, it was time to examine the rings. To my amazement the ring gaps were nearly half an inch instead of about 20 thou! Also one ring had about two inches missing altogether. Once the engine was rebuilt with new rings the difference in compression was obvious. I used to be able to put my foot on the flywheel and push the engine over against compression. There's no way I can do this now.

Just a thought.

Edited April 10, 2014 by koukouvagia

[Old Son]

I had a starting issue with my Beta. It would start but no power and then peter out. A quick bleed and it would start and run fine for the rest of the dat. A few weeks later it would do this again. The problem was traced to a lose copper feed pipe in a fitting. The fitting was tight but the olive must have not gripped the pipe properly when it was fitted. I must have had a very small air leak. I agree, check out the fuel system very carefully.

[by'eck]

What put me off the scent of the air in fuel line issue was your reference to having tested for creak from each of the injectors. Could it be that you did this once to satisfy yourself there was no air in the system, but haven't done it since, particularly before failed attempts to try starting from cold?

 

If so it could be as suggested that there is a sufficient leak for air to get into the system overnight or over a longer period. Tell tale signs will be fuel weeping slowly from unions or filters. The fuel line from filter to injection pump looked fine on my installation and passed close visual scrutiny until it was taken off and a banjo union almost fell off the copper pipe. It was only soft soldered anyway so needed a silver soldered replacement to conform, but that did fix a similar issue for me.

[Proper Job]

I had a similar problem on Ocelots JP and it was air getting in to the system.

 

Left for a few days and it would be difficult to start/need bleeding. Overnight, it would start after a bit of winding. Once started, it could be started with ease any time during that day.

 

When you checked the injectors for creaking, was that when the engine was running or during your attampts to start it?

 

My money is still on air getting in to the fuel lines.

[sassan]

Hmmm, I must admit that I have not checked the fuel lines since my initial attempts to start it. I shall test it again while cold tonight or tomorrow.

 

I'll exhaust the other possibilities and do a great deal of reading before I start messing with the tappets and spill timing. Wouldn't problems with either be apparent when running though?

 

Edit: ordered a set of feeler guages, just in case I do need them (at a fiver, might as well have them in the toolbox).

Edited April 11, 2014 by sassan

[Proper Job]

 

Edit: ordered a set of feeler guages, just in case I do need them (at a fiver, might as well have them in the toolbox).

 

Are they imperial?

[David Mack]

I have a Petter PH1 on a dumper truck which is a reluctant cold starter - especially in winter. I suspect the rings/bores are worn but haven't looked inside.

 

What works for me is with the decompressor on give it at least 50 turns on the starting handle before attempting to start it. This seems to get the oil moving, and ensures that the moving parts are lubricated. And the 25 squirts of diesel in the cylinder increase the compression ratio which also helps starting, even if it does mean the engione is a bit smoky when it does fire up.

[sassan]

 

Are they imperial?

They are indeed. They're in thousandths of an inch, with mm marked on them as well. Assumed imperial was best, since both the manual and you good folks seem to be that way.

[MtB]

 

Are they imperial?

 

And would it matter?!

 

Back in the days of decimalisation I used to work in a petrol station. (Back then petrol stations dispensed the petrol for you!) One smart Alec came in and asked for a fiver's worth of four star, but said could he have it in gallons not litres please. Very droll.

 

 

MtB

[martyn 1]

PM sent

[Proper Job]

 

And would it matter?!

 

Back in the days of decimalisation I used to work in a petrol station. (Back then petrol stations dispensed the petrol for you!) One smart Alec came in and asked for a fiver's worth of four star, but said could he have it in gallons not litres please. Very droll.

 

 

MtB

 

Of course it matters..........

 

All of my adjustables are Imperial

[The Bagdad Boatman (waits)]

squirt oil into the air intake inlet valve works as well as easy start but not as aggressive.

[junior]

Any update? Updates are not only good for the curious amongst us, but others who have a similar fault in the future will no doubt do a search and stumble across this thread.

[George94]

I'd certainly give the decompression wheels a good oil and screw them in and out several times as tightly as possible,

 

Checking the tappets is a very easy job. Just whip off the cylinder head covers, and turn the engine until each rocker in turn lifts off the valve. Bung in the feeler, check the clearance and adjust if necessary at the other end. Loosen the lock nut, turn the screw, tighten the lock nut.

 

Replace cover. Start the engine.

 

I like to start my engine every month when it's not being used. Keeps it oiled.