Rebuilt engine won't start

[notaminga]

Hi all, I'm new to the forum and am hoping I can pick your brains and get some help.

 

I have a Land Rover 2.5 engine in my boat, which I have just rebuilt after the crankshaft died. It's been a complete rebuild with rebore, new pistons, new valves. Every part that went back into the engine checked out as perfect.

 

However, since getting it all back together it will not run for more than a few seconds. It coughs and splutters, giving out much white smoke, before grinding to a halt.

 

I've double checked the timing - spot on. Changed the injectors - both sets produce the same effect. The fuel injection pump is new. Air supply is good, fuel is being squirted out by injectors.

 

Compression test showed all four cylinders at 240 psi. This seems a little low to me but I'm told that a cold engine will read low.

 

All the indications are that the head gasket is tight and not leaking. There is no water loss and no pressurisation of the header tank.

 

I've been trying for a week to get this going and have run out of ideas.

 

Can anyone suggest anything new which might help?

[RLWP]

You have a poor fuel supply?

 

Richard

[notaminga]

I thought it might be that too, so have put in a temporary supply from a container of clean diesel, which bypasses the filter - still no joy.

[RLWP]

What kind of heater plugs does it have?

 

If you have white smoke, you have diesel

 

If it runs for a few seconds, it runs

 

In this weather it may need quite a lot of heater plug to make it start, and full speed too

 

Richard

[notaminga]

I changed the heater plugs for new ones - what type? Land Rover ones! Wired in parallel.

 

It takes about 30 seconds of heat to fire up and it seems to me that the engine dies again as soon as the plugs cool down.

[pete23]

what lr engine is it?? a 19j??

[Kieron G]

Hi, We have the 2.5 NA in our old ex MOD landrover ( i guess it's the same engine ) and it relies on a good ten seconds of glow plug preheat to fire up in this weather.

[nb Innisfree]

You could try a little heat from a blowlamp via the air inlet to keep it going and let it settle in.

 

ETA: Remove the air filter first!

Edited December 11, 2012 by nb Innisfree

[notaminga]

what lr engine is it?? a 19j??

It's a 12 j , as far as I can tell.

[Timleech]

Hi, We have the 2.5 NA in our old ex MOD landrover ( i guess it's the same engine ) and it relies on a good ten seconds of glow plug preheat to fire up in this weather.

 

I don't know the engine, but for a diesel 240 psi is low. I would suspect bumping clearance is high (gasket too thick, possibly).

 

Tim

[nb Innisfree]

I don't know the engine, but for a diesel 240 psi is low. I would suspect bumping clearance is high (gasket too thick, possibly).

 

Tim

 

Some indirect run at that I think? Maybe a combination of cold cyl walls and rings not bedded in yet?

[simon&jan]

Valves too tight ?? Take the injectors/glowplugs out and squirt a bit of oil down the bores , spin it over and check compressions again

[bizzard]

I think i'd double check the valve and injection timing again. All the turning over your doing I would have thought would have warmed it up enough to start probably without the heaters.

Also have you cracked all the injector pipes open and turned it over on the starter to check and ensure good strong air free spurts of fuel from them.

Edited December 12, 2012 by bizzard

[wonderdust]

Fuel stop solenoid maybe? Is there a continuous 12v supply?

 

Fuel lift pump, was this removed? Needs to be put back in correct position when replaced.

Edited December 12, 2012 by wonderdust

[RobinJ]

I have a Land Rover 2.5 engine in my boat, which I have just rebuilt after the crankshaft died. It's been a complete rebuild with rebore, new pistons, new valves. Every part that went back into the engine checked out as perfect.

 

However, since getting it all back together it will not run for more than a few seconds. It coughs and splutters, giving out much white smoke, before grinding to a halt.

 

I've double checked the timing - spot on. Changed the injectors - both sets produce the same effect. The fuel injection pump is new. Air supply is good, fuel is being squirted out by injectors.

I still think its the timing!

We put a new chain on a 1.8 and were convinced the timing was right, but eventually ruled everything else out (turned out the marks were in the wrong place!)

It coughed and ran very badly for a few seconds, giving out clouds of white smoke, reset the timing ran fantastic!

[Timleech]

I still think its the timing!

We put a new chain on a 1.8 and were convinced the timing was right, but eventually ruled everything else out (turned out the marks were in the wrong place!)

It coughed and ran very badly for a few seconds, giving out clouds of white smoke, reset the timing ran fantastic!

 

Bad valve timing would certainly affect the compression pressure. OP said they have double checked the timing, maybe that was the injection timing & not the valve timing?

 

Tim

[notaminga]

The head gasket was standard for the engine and the head has been skimmed - you would think this would lead to higher compression. The hotspots were also replaced.

 

The manual says the compression ratio is 21:1. By my reckoning multiplying this by air pressure at sea level (14.7 psi) suggests that compression should be over 300psi, but I have been hoping that the figure will be higher once the engine is running, hot and rings bedded in.

 

The fuel pump is electric and maintains a good constant flow of fuel. The fuel system beyond the pump maintains positive pressure with no leaks. The stop solenoid checks out.

 

My initial feeling was that it must be timing, so I have checked it right back to basics by making sure that crankshaft at TDC aligns with both the camshaft and the injector pump, through observation rather than relying on the timing marks. As it happens all the evidence points to the timing marks being correct and lining up properly. As RLWP said, the engine runs - albeit briefly.

 

I'm back to the boat today armed with some new, clean, white diesel, a can of easy start, a blow torch and fingers crossed. Don't worry, the easy start and the blow torch won't be used in conjunction

 

Thanks for all your suggestions - I'll report back later.

 

Mari

Edited December 12, 2012 by notaminga

[Timleech]

240 psi is very much on the low side for getting combustion. The fact that all cylinders are the same suggests a basic error rather than poor seating of valves or rings.

If today's tests don't work, do check valve timing again. A bit of oil introduced to each cylinder will help rings to seal and bump up the compression ratio for starting, too much can cause damage though.

 

Tim

[notaminga]

I must admit I can't see any reason for the compression being low through error - the block was rebored to fit the new pistons, and they do in fact fit. There is no sign of any head gasket leakage. Indeed there is no sign of valve leakage or leakage around the injectors/glow plugs. Needless to say there was no sign of any cracks or damage in the head or block. I suppose a leakdown test would tell me more, but difficult to arrange in a boat moored in the middle of nowhere, and we don't have the equipment to do it.

 

I even considered whether or not I had fitted the wrong crankshaft, but have confirmed that it is indeed the right one - at least the piston crowns do rise flush with top of the block.

[RLWP]

New pistons - are they the correct ones?

 

I don't know if it is possible to fit lower compression ones mind

 

Richard

[ditchcrawler]

I must admit I can't see any reason for the compression being low through error - the block was rebored to fit the new pistons, and they do in fact fit. There is no sign of any head gasket leakage. Indeed there is no sign of valve leakage or leakage around the injectors/glow plugs. Needless to say there was no sign of any cracks or damage in the head or block. I suppose a leakdown test would tell me more, but difficult to arrange in a boat moored in the middle of nowhere, and we don't have the equipment to do it.

 

I even considered whether or not I had fitted the wrong crankshaft, but have confirmed that it is indeed the right one - at least the piston crowns do rise flush with top of the block.

I take it you rebuilt the engine and its you who has checked everything. Any chance of getting a fresh pair of eyes on it and getting someone else just to check. I often found when fault finding for any length of time someone else would spot something that was obvious to them but we had been looking past for hours.

[Paul C]

 

The manual says the compression ratio is 21:1. By my reckoning multiplying this by air pressure at sea level (14.7 psi) suggests that compression should be over 300psi, but I have been hoping that the figure will be higher once the engine is running, hot and rings bedded in.

 

 

 

That's a bad reckoning to use - the compression is adiabatic, not isothermal.

[RLWP]

That's a bad reckoning to use - the compression is adiabatic, not isothermal.

 

Excellent stuff - have a greenie

 

Richard

[Yamanx]

Sorry I haven't read all the replies, but sounds like timing. Even though you have checked this, the timing needs to be exact as it will get worse at every revolution. Don't rely on the timing marks, particularly if you've rebuilt the engine and changed the crank etc., just try adjusting the pump timing "out" a little in each direction so to speak and see if that makes a difference. It might still "run" as you have suggested rev up high with diesel in the cylinders then die as the injection timing is not correct.

 

That's a bad reckoning to use - the compression is adiabatic, not isothermal.

 

Type 2 adiabatic, or type 1?

 

 

 

Sorry

[RLWP]

Sorry I haven't read all the replies, but sounds like timing. Even though you have checked this, the timing needs to be exact as it will get worse at every revolution.

 

<snip>

 

Eh, how????

 

Richard