My handbook advises against bumpstarting your vehicle as it could damage your Cat. What are people's thoughts on this?

I would imagine if you got into a habbit of regularly doing it, rolling it downhill etc it would mess the cat up, but having done it once or twice myself, when necessary, to get me back on the road, I can't see it being a problem

When bump starting, unburnt fuel can be passed into the exhaust. If the catalyst is hot, that can ignite or explode the fuel, causing damage to the cat. If you are bump starting it because it is difficult to start, a lot of unburnt fuel is likely to be passed into the exhaust. If it starts easily, but the battery is flat, or starter is duff, the risk is small.

This is usually a petrol issue, as they have cats. A diesel without a cat presents no such risk. Manufacturer just has to warn, to avoid lawsuits.

The main issue though, is why is a bump start necessary?

Do it frequently with the school car. The learner stalls, I pop the clutch down, allowing the car to roll, clutch back up, engine restarted. Easier and quicker than trying to get the learner to turn the key back and forward again.

I agree. If the vehicle is bumpstartable it should start as soon as the clutch is engaged if it doesn't then unburnt fuel can be driven into the system which can then cause damage. The same goes for a tow start.
Mine is a motorhome and it is possible to flatten the battery when camping if I'm not careful.
Would it be possible to bumpstart or towstart if the battery were completely flat though. Does there have to be some power before it is possible?

Surely a motorhome should have an additional leisure battery to power the 'home part. It is then charged using an split charge control, to ensure both batteries are charged regardless of the state of the other.

As it is a diesel, starting from cold needs power to heat the glowplugs, otherwise it will need a long push and a lot of churning to start, and a lot of fuel will be pushed through unburnt.

A lot of motorhomes have the choice to power the habitation from the starter battery as well as the liesure batteries. Sometimes people (the missus ) can select the wrong battery by mistake. You only find out this mistake when you try to leave the site. ?

I would say that if the battery is completely drained and you are getting zero from the ignition, no electrics, no fuel pumping etc.....bump start isnt going to happen. On the couple of occasions ive done it, there was enough life in the battery, trying to start etc, that it was a viable option which thankfully worked. If completely dead, I think your only option if stuck would be to try jump starting off another vehicle with initial time taken to put some charge in but batteries don't hold up to complete discharge and do not normally recover, requiring change.

Mohojo said:

A lot of motorhomes have the choice to power the habitation from the starter battery as well as the liesure batteries. Sometimes people (the missus ) can select the wrong battery by mistake. You only find out this mistake when you try to leave the site. ?

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get said person to carry the untouched battery to the front of cab, and start the van's engine

Thanks for the advice. I will try to expain to her the errors of her ways.......my next post may be from a hospital bed......?

On a slightly different tack......has anyone tried the little lithium jumpstarter packs? I've just tried mine. It pumped up all the tyres on the car and started the engine 3 times and still had 75% charge!

Mohojo said:

On a slightly different tack......has anyone tried the little lithium jumpstarter packs? I've just tried mine. It pumped up all the tyres on the car and started the engine 3 times and still had 75% charge!

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Seems a bit of magic that actually works. Do the cables get hot? Which one did you get?

I got the Suaoki T 10. It is well built and compact. The leads weren't noticibly hot after starting the vehicle a few times.

I prefer the bigger heavy duty battery packs.....I use it for all sorts - starting cars, motorbikes,vans. Use the light for emergency repairs and or late night mechanical work if needed, charge phones, run portable dvd and much more, via the 12v power outlet. Pump up tyres in emergency, keep it tip top by charging via the van, it just stays in the cab and gets charged as I'm running.
I went inside it and ran off additional positive and negative wires, meaning I can easily run a heavy duty bulb, test bulbs, and other electical connections, motors etc.....swear by it, a must have! https://goo.gl/images/Gsejcd

Those little kits look clever tho, and defo handy for storage.....

ECM needs 9.5 volts to work

adlarplant said:

ECM needs 9.5 volts to work

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Can you explain this please?

I think ECM (Electronic Control Module) is another name for ECU (Electronic Control Unit) One of the things on a modern engine that needs electricity. Wheras the old diesel engines were all mechanical and would start and run with no electricity.
My Citroen Relay 2.2 usually starts first time as long as I remember to wait for the glow plug light to go out before trying to start it. But it is very reluctant to bump start - I have tried it when going downhill and you have to spin it over a long time to start. I wonder if its as case of ECU/ECM says no. Like when the ECU/ECM thinks the engine is labouring it will stop.

I can't see why it shouldn't start right away as long as it has enough power to energise the ignition and the glow plugs?

Mohojo said:

I can't see why it shouldn't start right away as long as it has enough power to energise the ignition and the glow plugs?

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Neither can I. But it takes a lot of turning over to bump start it when going downhill - even when there is enough battery power to start it first time on the key. I guessed it was a case of computer says 'No' but thats only a wild guess as I don't know anything about it.

NEVER bump start a puma powered Seval product .....................!!!!!!!!!!


The reason is that the oil tensioner in the timeing case will have no pressure and by bump starting , the sudden release of the clutch can cause the timeing chain to jump the sprockets , wrecking the head and camcarriers , also it can possibly rip the studs out of the head .!!!


These little niggles are well documented on the Ford Transit forums , as is the info regarding the tensioner being undersize ,not man enough for the job and needs periodic replacement to prevent the above failure as the vehicle ages .

Is the Puma engine the Ford 2.2?
Please can you explain why bump starting is different to starter motor starting?