Air Start System: BMP Series

[Coltman15]

Hello all, 

First post and I’m in need of some guidance. I’ve got a Czech made BMP and I recently burn up the electric starter so I’m left with the air system starter. Problem is my air bottle is empty and in the USA it cannot be filled legally with compressed air, as it’s an oxygen bottle. So my question is, can I use nitrogen safety to start the bmp? 

Edited May 16 by Coltman15

[robin33ba07]

Can you not jump start it from the batteries ,that will allow you to use the "lube primer " the jump lead points are beside the batteries if you have Soviet jump leads or remover the battery covers and directly onto the batteries 

 

[Mk3iain]

If you look on youtube for "Mr Hewes"  they have been starting a T72 using inert welding gas as a stopgap. I would thing nitrogen would be ok.

[Coltman15]

5 hours ago, robin33ba07 said:

Can you not jump start it from the batteries ,that will allow you to use the "lube primer " the jump lead points are beside the batteries if you have Soviet jump leads or remover the battery covers and directly onto the batteries 

 

Electrical systems work fine in the bmp, batteries are good. The starter itself is shot.

So I’m just trying to air start, but my in vehicle air tank is empty, this trying to fill it with something commonly available as a stop gap measure. 

[Coltman15]

4 hours ago, Mk3iain said:

If you look on youtube for "Mr Hewes"  they have been starting a T72 using inert welding gas as a stopgap. I would thing nitrogen would be ok.

Yes! I saw his video, I asked him what exactly was in his welding gas tank but he never responded. 

Edited May 17 by Coltman15

[David Herbert]

I don't understand the problem with recharging the vehicle's air tank with air. This is just like a truck air system but presumably at a higher pressure. It never did have oxygen in it and to put oxygen in it would be very bad for the engine because it would cause major uncontrolled explosions rather than progressive burning of the fuel. If you can recharge it with nitrogen you have presumably sorted out transfer pipes and pipe fittings so why not connect it to a compressor and pump it up as high as the compressor will go and see if it starts. If it does the vehicle's own compressor will take it the rest of the way for next time. I expect that Mr Hewes is using CO2 because that is cheap and easy to get but the limited oxygen content of air would obviously be available for initial combustion where as using any inert gas will only spin over the motor, hopefully fast enough to let its momentum suck in the air that it needs to fire once you stop injecting the inert gas.

One other comment is that you MUST prime the oil system with the electric pump before every start or it drains down and is initially unlubricated.

Best of luck, they are great fun to drive but watch out for drones!

David

[Coltman15]

26 minutes ago, David Herbert said:

I don't understand the problem with recharging the vehicle's air tank with air. This is just like a truck air system but presumably at a higher pressure. It never did have oxygen in it and to put oxygen in it would be very bad for the engine because it would cause major uncontrolled explosions rather than progressive burning of the fuel. If you can recharge it with nitrogen you have presumably sorted out transfer pipes and pipe fittings so why not connect it to a compressor and pump it up as high as the compressor will go and see if it starts. If it does the vehicle's own compressor will take it the rest of the way for next time. I expect that Mr Hewes is using CO2 because that is cheap and easy to get but the limited oxygen content of air would obviously be available for initial combustion where as using any inert gas will only spin over the motor, hopefully fast enough to let its momentum suck in the air that it needs to fire once you stop injecting the inert gas.

One other comment is that you MUST prime the oil system with the electric pump before every start or it drains down and is initially unlubricated.

Best of luck, they are great fun to drive but watch out for drones!

David

The problem is more the pressure of the air in the vehicles system. It starts with 70 kg/cm2, or about 1000 PSI. A regular truck air compressor can only get to a couple hundred PSI. The tank in the BMP is an oxygen tank, with oxygen fittings, so legally a commercial gas supplier cannot fill the tank with compressed air. So it’s either buy a Nitrogen tank, with an O2 adapter to fit the vehicles plumbing or buy and O2 tank and high pressure air compressor (around $3-5k). 
 

I was hoping to do what Mr Hewes did with the T-72 but with a new built nitrogen tank, just having the new tank filled periodically if the vehicle sits for a while. At least until my starter motor arrives 

Also, has anyone ever done business with Axel Heyse?

[Mk3iain]

Is there not a compressor driven from the engine to recharge the system once running ?

If so you would only need an intial start. 

Edited May 17 by Mk3iain

[Coltman15]

13 minutes ago, Mk3iain said:

Is there not a compressor driven from the engine to recharge the system once running ?

If so you would only need an intial start. 

There is, but it takes a while for it to build pressure. High rpm driving for a solid 45min to an hour. I don’t always take it for a full ride after she’s started.

[attleej]

A couple of suggestions.

 

1. Fix the starter.  You will have to so at some point because you will get so much less for the vehicle without it working.  OR Re-engineer a modern starter to fit your engine.  It might not be as difficult as you think.

2. Can you get the high pressure compressor off the engine and drive it with a small petrol engine or suitable electric motor?  If you could get access to it, it would not be a very difficult job.  You might also be able to buy a small high pressure compressor from somewhere.  

 

John