Air compressor, safty cut out?

[Jonny Boaterboy]

I have had a few problems with my compessor! I have just made one good one from a P38 air compressor and whats left of mine. While hoseing off the underside I must have given the air intake a good drink by mistake....... :doh: water has been drawn into the compressor and caused the bearing to give up! Having made one good one I pluged it in started the engine to find it working very well....... like a little child I covered up the outlet to see what sort of presure it had....... and it cut out! I left it for 30 sec or so, raised and lowered the surspesion to depleate some of the air hopeing it would cause the compessor to kick in but nothing. As it is cold and wet out side I decided to come in and ask you all if there is a cut out of some sort that will have reset it's self by the morning

Any Ideas?

Thanks

Jonny

[Range Rover Blues]

It has a thermal cut-out inside the motor and also it will only runs for a certain length of time regardless to prevent battery drain and motor damage.

The P38 pump is essentially the same unit, but drilled in a different place and the motor is longer, just for the sake of it

[Jonny Boaterboy]

Thanks RRB, I did manage to work that out in the end as the pump would kick in about every 3 mins...... the length of time it isolates the pump if it is unpluged or the thermal cut out kicks in. Can you just confirm my line of thought is correct:

I have put on the rebuilt compressor from the P38 but the suspension will not rise after starting the engine. I have waited 3 mins put it into drive raised and lowered the suspension, put it flat on the ground as apposed to leaning over at 45 degrees, and all I'm getting is the compressor kicking in every few mins running for a few seconds then cutting out again. My first thought was a valve had stuck shut in the valve block so I took that off striped it all down to find every thing OK. I put it back on to find the same problem. I then plugged my old compressor in to see if that worked, which it did.

This brings me to the conclusion that the P38 pump has a fault. From my understanding the compressor cuts out for three reasons

1) the correct pressure is reached in the tank and the pressure switch cuts in
2) the thermal cut out kicks in for 3 mins.
3) or as you have said it cuts out to prevent battery drain and motor damage.

I think that there is a fault on the thermal cut out side of the pump as when I first put it on I covered the outlet and it cut out. Now it is on, it keeps cutting out every time it pumps now there is a little bit of pressure to work against which is telling me that the thermal cut out is too sensitive and will cut it out even with a tiny amount of heat which is generated when is works against a small amount of back pressure.

Does that sound about right? I hope so, as I have ordered a new crank, barrel and piston and plan to rebuild my original pump that was working fine electrical but due to water getting in there has a wreaked bearing!

Currently waiting for delivery from the states so I have time to ponder on things!

Thanks

Jonny 

[Range Rover Blues]

Yes it sounds like the thermal cutout is way to sensitive, possibly a sign that it's been overheated way too badly in the past.

Does any air come out of the P38 pump when it's running?

You can swap the piston and barrel out of a P38 pump into your old one for now, you release the crank/balance weight with a small allen or torx key (probably the latter on the P38) after taking a samll grubscrew out of the crank housing.

Have you noticed the heads are different though? don't mix them up ;)

[Jonny Boaterboy]

Yes the P38 pump is pumping air quite well, the barrel and piston were in good condition, the only indication of wear was on the Teflon seal which had worn a little more on one side but it still created a good seal.

I did notice the different heads but it was only because my local L.R. garage told me that the classic and P38 were the same pump apart from the heads and the mounts that I realised they were interchangeable, I didn't realise the length was different but it doesn't seem to have made any difference! I wish the valve block and compressor were set up like the P38 in the engine bay it would make life alot easyer!


Glad you mentioned that the balance weight comes off with the crank as the weight on my compressor is all tarnished due to the water getting in, do you know if there is a seal the other side of the crank and balance weight? I'm hoping there is as the only damage to the compressor is the crank bearing.

The air dryer was very wet as well, I took the contents out and dryed them in the oven but have some new dryer contents coming from Rover renovation so will put that in when it arrives,

Thanks mate

Jonny
   

[Range Rover Blues]

Rover Renovations are really helpful aren't they.

The dryer contents are silica gell IIRC, so you can dry them out in the overn with no real problems.

The motor sits on 2 sealed ball bearings, so if the seals stayed ok then the water shouldn't have got into the motor.  Be careful if you try to strip it down as the brushes are at the other end of the motor and are radial brushes, ie if you pull the end plate off you might not get it back together again.

If you ordered a seal and barrel kit then you get a new balance weight anyway, if yo uonly ordered the seal then it's a good idea to take the balance weight out to fit the new seal but you can do it in-place.

[Jonny Boaterboy]

Rover Renovations are really good, I ordered the classic EAS overhaul kit and rang him up to confirm a few things and after explaining it was the crank that had gone he said he would throw a secondhand crank in for free! I,ve been watching the tracking of the parcell and it should be here tomorrow taking only 5 days from the states! it on royal mail were as good!

The crank is off my compressor now.... (took a bit to get off due to the water getting in there) and on arrival of the new crank will put it all back together and see if it works!

Let you know if it does!   [-o<

[Range Rover Blues]

Great.  I fancied the uprated pump they stock, but it's over $250 IIRC and you have to butcher the enclosure to get it in, but with my Arnott GIII springs I need a faster supply of air.