HELP! Warning - School Boy Error Content

[M@r]{]

Really need some help. I left one of the switches in the down position and now I think I have a short somewhere:

I lowered one corner and left the switch in that position over night    When I come to the car this morning the hydraulics were dead.  I found a blown fuse, replaced it and all seemed well.  But then the rear hydraulics jammed open. The only way I could stop it was to disconnect the batteries.  When I try reconnected the bank that controls the rears it sparks it a big way - so something is shorting.

I havent got a clue where to start in trying to diagnose this.  Can anyone give me any pointers?  Or point me in the direction of someone who can?

I'm so angry with myself, what a completely stupid thing to do.  I was really looking forward to enjoying this car and now all i've done is given myself a load of problems      Not a good start to Lowrider ownership, hopefully it will get better  (or I can stop being cuh a prat!!!)

[StyleGrace&PumpinBass]

Welcome aboard Mark, congrats on buying the Datsun, a very well known car indeed, I've got a Street Machine magazine with an article on that car somewhere! I'm sure the problem will be something very simple and easily replaceable. How did you leave the switch in the same position overnight? Was the switch box leaning on something? Or did it just stick? I assume it was stuck in the "down" position and that the dumps (valves which allow the fluid to flow from the suspension rams to the tank reservoirs) were stuck open as a result. The problem is probably with the dump valves I would imagine, and they are quite easy to replace I think. Somebody else will probably know where you can get hold of some

[M@r]{]

Thanks for the reply.

For some reason the switches that just raise a corner at a time click into position, so you have to manually click them back.  The ones that raise both wheels together are spring loaded and go back to the off position automatically???

I left one corner in the postion where it lowers the car.  

When I first replaced the blown fuse it all worked ok - so the pumps seemed to be functioning correctly.  But then the pump that controls the rear just stayed on, the car went to max height at the rear but the pump just continued to work!!    I just legged it around the back and disconnected the batteries.  When I try to reconnect the bank that run the rears I get a massive spark - like there is a short.  The fronts work fine.

I'm no autoelectrician but it seems to me what ever tells the pump to pump  is jamming open - I believe thats the solenoid?  Fingers crossed this guys finds out easily enough tomorrow and it isnt too costly  

Welcome aboard Mark, congrats on buying the Datsun, a very well known car indeed, I've got a Street Machine magazine with an article on that car somewhere! I'm sure the problem will be something very simple and easily replaceable. How did you leave the switch in the same position overnight? Was the switch box leaning on something? Or did it just stick? I assume it was stuck in the "down" position and that the dumps (valves which allow the fluid to flow from the suspension rams to the tank reservoirs) were stuck open as a result. The problem is probably with the dump valves I would imagine, and they are quite easy to replace I think. Somebody else will probably know where you can get hold of some

[StyleGrace&PumpinBass]

Yes, I think you're probably right, if the pump continues spinning then the problem is most likely to be with a solenoid. Solenoids can stick due to low batteries, if you hear the pumps spinning with a lower noise then stop playing and get the batteries charged ASAP. It is an easy fix, and I'm sure a few people on the forum will know where you can get hold of a replacement solenoid.

It's weird that it has non centre-sprung switches.. that seems a bit dangerous!  

[M@r]{]

Yeah seems strange some are centre sprung and some not??   Would it be easy enough to swap them for centresprung ones?  Any ideas where to get them from?

It's weird that it has non centre-sprung switches.. that seems a bit dangerous!  

[fatdaddy]

you may be able to free the sol by tapping it with a spanner!

you should have two [or better, three] in a row to help avoid what you have had. replace them all anyway for sftey and get the correct switches to stop it happening again.
 

[M@r]{]

I took it to an auto electrician this morning.  A local hydraulics specialist recommended him as he has experience in that area.

The AE just called to say one of the solenoids is goosed - apparently its welded the connections together??  Also the pump has a problem but he has fixed that already.

One thing he did say.  The solenoids are 12v ones but the system is 24v??   He said they are designed to stay on permanently but as I'm pushing 24v through them they cant cope.  Any ideas why 12v solenoids have been used instead of 24v?  He has suggested replacing them with 24v ones.  What do you think?

[StyleGrace&PumpinBass]

I think 12v ones are generally used, but as Fatdaddy says, you use more than one (2 or 3) as a back up. Even in 36v systems, 12v solenoids are used, I think because the solenoids need to 'switch' over and transfer the electricity as fast as possible to reduce the spark created between the contacts (if there is a spark, then the contacts can arc themselves together, like you have described) - I assume that a higher voltage means faster switching for the solenoids (?). Lower battery power = lower speed of solenoid 'switching' = more chance of it sticking/arcing, so keep an eye on your batteries

I think if you used 24v solenoids on a 24v system, that just makes it more likely that the power from the batteries will be lower than 24v and therefore not be enough to 'switch' the solenoids, increasing the change of the same thing happening, so I guess I would stick with 12v ones, but have a couple of back up ones wired in  

[catboy]

as fd said there are usually two or three 12v ones in a row to help carry the load..  
this works by carrying the current over several and also provided one is not goosed it will switch the pump off..  I reckon (and i think most would agree) you're better off with 2x or 3x 12v sol's than you are with 1x 24v sol for exactly that reason..  

[catboy]

sorry, lil' russ beat me to it  

[M@r]{]

mmm, but worried.  He has just called to say it is done but the front corners are not working      They lift together but not individually?

He replaced one of the 12v solenoids with a 24v one.   There are x4 solenoids

[fatdaddy]

did they lift individually before?
that depends on the valving as well as the wiring.

tbh the way we wire lows is "wrong" and will make no sense to an AE, but experience shows that it works  

the same can be said of the hyd side of things............... if you tell a Hyd engineer what you can make a 2 ton yank car do with the input from a battery driven hyd power pack he'll say you are wrong and its impossible.

Low hyds are a very specific thing and they do what they do because we use VERY short bursts of inputs [electrical and hydraulic] and that allows them to survive............ it also explains why systems burn out VERY quickly and easily if an operator is not good on the switches/a sol sticks/ a switch sticks. there is NO safety margin to play with.

[M@r]{]

Update:  It is only one corner that is not working - the one I left in the on/down position         Its stuck at maximum lift.  You can here stuff clicking and what sounds like a pump when in the lift position but it wont drop.  When the AE fed a direct supply to the release valve it dropped.   So he seems to think there is a problem with the switch.

So, where can I get replacement switches?  Local Maplins dont have any of the centresprung ones

[catboy]

if you tell a Hyd engineer what you can make a 2 ton yank car do with the input from a battery driven hyd power pack he'll say you are wrong and its impossible.

he he..  depends which one you ask i guess  
this still sounds like a fucked sol or two to me and possibly a burnt out switch..
I would say for the cost of a couple of sol's replace them all and replace the dodgy switch too..  if you want to trouble shoot change the wiring over (so your left switch controls your right side or whatever) and that will prove out switch or sol's..

b

[M@r]{]

I tried a brand new switch and it made no difference      I really need to get someone who knows what they are doing to have a look at this