Leyland 401 starting problems

[BRISTOLLH]

Hi there, hope you can help.
I have a 1979 Bristol LH with a Leyland 401 engine.
It was in passenger carrying use and then a driver training bus until around 2005 and since then it's been used as a mobile home and is now being recomissioned.
While it was lived in the engine was run evey few days to charge the batteries though the bus wasn't moved.
According to the then owner it started first time every time, and each time I started it on several visits this was proved correct and it fired into life after 3 or 4 turns of the engine.
It drove 350 miles back to my place at up to 55mph with no issues whatsoever, the engine never missed a beat and it was duly parked up.
Since then it has proved extremely difficult to start - having to crank away for ages and the only way it will start is with the throttle pushed right to the floor and keeping the starter turning as the engine starts to fire (reluctantly) until I can risk releasing the starter button.
As it ran so well previously and started each time while static I can only assume something has changed after the journey home. It had enough oil and I filled the tank to the top with diesel as I didn't know if I could rely on the gauge.
Any ideas as to what might be wrong?
On a seperate note I see it has two alternators, though only one has a drive belt - the other has it's lead disconnected. What would be the thinkign behind this and can it run on just one ? - batteries appear to be charging fine and charge light goes out when engine is running.
I look forward to your responses

[G-CPTN]

I suggest that you might have a cracked fuel-feed pipe that could allow the fuel to drain back.

WRT the alternators, the second alternator might be to cope with the use as a mobile home (with batteries for lighting and other uses). Is there a sign of such a system?

Some coaches probably had an extra alternator to cope with on-board electrics such as a sound system for the tour guide or maybe a video player.

You might find that one alternator is 12 volt (and the other 24 volt).

[BRISTOLLH]

Thanks for the quick reply - that's worth investigation as when it arrived it was raining and I did notice one of the puddles had a rainbow effect that you get when diesel spills in water......at the time i put it down to oil dripping off a hot engine.
Re the alternator - looks standard fitment but is just sitting there disconnected. I'll examine it to see if its 12 or 24 v

Thanks again

[dmackay]

I think it may be the non return valve up at the fuel pump on the return pipe, maybe someone has lost lhe little ball when mistaking it for a bleeder ( it happens)

[robertdavey6]

My bus mechanic suggests that the engine stop might be worth a check. Is it working correctly.
Also, is it an alternator or a dynamo for the electrics?

[bristol1318]

Hi,
New to forum and spotted your problem with your LH. They are not always the easiest vehicles to start and could be a pain especially in cold weather. The main fuel pipe from the lift pump if still original will be steel, these do corrode and go porous allowing the fuel to run back when stopped. Best thing is to get a new length of rubber pipe and re pipe. These vehicles do have a cold start excess fuel device fitted which does help. If you lift the floor trap over the engine and look at the throttle linkage spindle on the fuel pump you will see what looks like a button. To use it pull the engine stop right out and back in again and push the button down, it should stay in by itself. Now attempt to start with full throttle applied, once the throttle is released the button will pop up again. On the subject of the alternators most of these vehicles were fittted with two alternators but they do generally end up running on one and I have had my LH for 13 years running on one and not had any problems with it. Hope all this helps if you are not already sorted.

[Willem]

I've restored and maintained several Leylands and if problems like you've describe occur it has to do with fuel issues. Today's diesel is much more aggressive than diesel from decades ago. No sulfur and all kinds of additives that may harm the fuel filters along the fuel's travel to the pump and from there to the injectors. The lack of sulfur may cause problems with the pumps, either the DPA or the line pump. Lack of lubrication may cause early failure of the pumps. Another problem are the fuel filters, both inside the tank and those smaller ones built in the fuel line. The older filters are made of fine copper wire and today's diesel will attack the copper in a way that it, in due course, entirely dissolves the copper. The copper particles can clogg the next filter in the fuel line, but at the same time, the diesel will dissolve that filter too. The copper particles will enter the pump with all kinds of disasterous effects to the pump.

So, make sure the fuel tank and fuel lines are absolutely clean, replace the fuel filters with ones that are able to handle modern fuel without braking up fuel filters like the old copper ones. Furthermore, it might be wise to add sulfur replacements from time to time. Just to protect the pump, specially the DPA rotation pumps will undoubtedly be very happy with some extra TLC.

The Leyland engines are very reliable indeed, we have one that has done more than 1.5 million miles........ Older vehicles must be checked regurlarly, specially those that are hardly ever used. And last but not least, it might be better not to start the engine if you don't intent to drive the vehicle at all. Instead, remove the injectors and put some engine preservative oil into the cylinders. Starting an engine without driving it warm will cause severe clogging of the valve and valve seats with soot in due coarse. Starting the engine without driving it warm will also cause deterioation of the seals, causing engine coolant entering the engine oil. Therefore, always check the oil for water prior to even look at the starter button......

[coastie]

Originally Posted by Willem

I've restored and maintained several Leylands and if problems like you've describe occur it has to do with fuel issues. Today's diesel is much more aggressive than diesel from decades ago. No sulfur and all kinds of additives that may harm the fuel filters along the fuel's travel to the pump and from there to the injectors. The lack of sulfur may cause problems with the pumps, either the DPA or the line pump. Lack of lubrication may cause early failure of the pumps. Another problem are the fuel filters, both inside the tank and those smaller ones built in the fuel line. The older filters are made of fine copper wire and today's diesel will attack the copper in a way that it, in due course, entirely dissolves the copper. The copper particles can clogg the next filter in the fuel line, but at the same time, the diesel will dissolve that filter too. The copper particles will enter the pump with all kinds of disasterous effects to the pump.

So, make sure the fuel tank and fuel lines are absolutely clean, replace the fuel filters with ones that are able to handle modern fuel without braking up fuel filters like the old copper ones. Furthermore, it might be wise to add sulfur replacements from time to time. Just to protect the pump, specially the DPA rotation pumps will undoubtedly be very happy with some extra TLC.

The Leyland engines are very reliable indeed, we have one that has done more than 1.5 million miles........ Older vehicles must be checked regurlarly, specially those that are hardly ever used. And last but not least, it might be better not to start the engine if you don't intent to drive the vehicle at all. Instead, remove the injectors and put some engine preservative oil into the cylinders. Starting an engine without driving it warm will cause severe clogging of the valve and valve seats with soot in due coarse. Starting the engine without driving it warm will also cause deterioation of the seals, causing engine coolant entering the engine oil. Therefore, always check the oil for water prior to even look at the starter button......

Blimey! So much I didn't know about diesel engines! Many thanks Willem.

[coastie]

Oh! And by the way, a very warm welcome from the Isle of Anglesey, Willem!

[G-CPTN]

Welcome to Truck and Bus, Willem.

Your knowledge and experience will be much appreciated here.

I look forward to reading more of your comments and, hopefully, seeing some of your photographs.