Van now running! - a couple of teething problems

[fix]

Well my rebuilt 2.1 engine is now in the van and running, im well happy

Firstly a BIG thanks for the help everyone, you know who you all are and im sure I was annoying but I really appreciate all your help!!


Anyway im not out of the woods but almost, there are a few little problems:


1. Battery light is staying on - I tried not to tighten the fan belt too much so i didnt damage the water pump bearings, would the battery light not be intermittent if the alternator wasnt turning enough? (ive just replaced the 45amp with a 90amp alternator) - Not sure what setting to put a multimeter on but will find out and make sure the alternator is working.

2. Bled the coolant system when the van was warming up, header tank is full but i definately havent put 18 litres of water/coolant in the system. Also the coolant light is flashing and hasnt turned off (I have had the van running about 15 minutes upto operating temperature then turned it off).

3. The isolator valve to cut petrol off when switched to lpg doesnt seem to be working, the valve is totally closed when switched on petrol. I had to bypass the valve to get the van running (I think a pm to Steve at Gasure is a good idea about this).


Any advice on the above is appreciated, hopefully the van will be driving in a couple of days!

Thanks

[tetleysid]

1. Here is what you do, simple car alternator test ;
Make sure all the accessories on your car are turned off (lights, radio etc.) and then rev up the cars engine to a fast idle (say 2000-2500 rpm).
Set the volt meter or multimeter to the DC scale and measure the voltage across the battery terminals - red lead of the voltmeter on the positive terminal, black on the negative. You will need someone to rev the engine whilst you connect the meter to the battery.
With the engine at a fast idle, the voltage on the meter should read around 14 volts (13.5 to 14.4). The alternator needs to generate a larger voltage than the battery's rated voltage to overcome the internal resistance of the battery.

2. You need to be very patient with bleeding the cooling system of a T25. Get the front end up in the air this will help expel air in the system, if nescessary open the bleed valve at the radiator and leave it overnight. If the warning light is flashing then the coolant level is low in the expansion tank, I know you just topped it up right, but it will use up whats in the tank real fast if its still hungry for liquid, good luck.

3. Sorry I don't feel qualified to reply to that one.

Hope this helps fix yer van Fix

[Cruz]

Is lifting the van necessary when bleeding?

This is from someone who has bled plenty of vans

http://www.brick-yard.co.uk/forum/bleed ... 29710.html" onclick="window.open(this.href);return false;

[fix]

Thanks for explaining how to check the alternator, seems easy enough. The help to rev the engine while I connect the multimeter will be my foot!

The coolant level indicator stayed on when the level was brimmed, but as the system isnt fully bled im not too worried about that just yet. Im thinking when I go back to the van tomorrow it will have dropped a fair bit.

Ive seen that guide before Cruz and wished I had it to hand I just didnt have time once the van started up.

Will try follow Baxters procedure tomorrow and see how I get on, that air will get pushed out!

[tetleysid]

Of course its not crucial to raise the front but it can help, as for the science air will always rise through water and if the fronts higher than the back theory has it that with the bleed valve open to atmospheric pressure it will find its way to the header tank? I have found this method works for me but then again hey ho waterever floats your boat

I do concur that the advise given on here is good

[Oldiebut goodie]

1. Battery light is staying on

Have you checked that you have power to the alternator for the excitation? (the alternator not you!)

[fix]

The system seems to be bled properly now, all good

Lol I dont know what alternator excitation means, I will do what tetleysid said about the alternator tomorrow and see what the multimeter says.

The battery was nearly flat after I brough it back from the MOT centre today, though that could be as its been ran for probably an hour and a half on a 3/4 full battery and has been started quite alot of times (I hope!).

[fix]

Abit of an update.


Speedo comes and goes, works sometimes. I can be driving along with no speedo then suddenly it starts working.


Checked my battery and theres a reading of 10.5 amps at most, checked at the alternator and same reading. The battery light comes and goes, stays off most of the time. It might be when the battery is getting towards flat it comes on. Does that sound like a duff alternator?

I think I will try fix it myself if so, the alternator is 90amp which I bought off ebay for £35, I would rather fix it than waste £35! I will put my olf 45amp alternator back on tomorrow to see if it works.


The stereo is sorted, wire had come loose. Shame I cant use it as my battery isnt charging!

[fix]

Well another update, about the alternator.

I was going to put my old 45amp unit back on, removed the 90amp and the pulley, shims etc to realise i didnt have the correct nut to tighten everything back onto the 45amp unit.

So I then put the pulley and shims back on, but somehow was left with a shim extra. I left it off and decided to clean up the voltage regulator and tested the alternator, which then managed 11.5 amps.

I then swapped over the voltage regulator on the 45amp unit which definately worked before, and still got 11.5 amps.

The brushes looked the same on both voltage regulators, so im now taking the assumption the brushes and voltage regulator are working.

Which has made me question the gap between the alternator and the "star" thing thats spins round, flywheel? Im not sure of the name. I removed a shim and there is still about a good 5mm gap between the unit and the flywheel, which to me seems too much. There is a shim between the flywheel and the unit, if I remove that and tighten everything up there isnt enough gap and it all jams up.

Basically I got an extra amp from the alternator somehow, and im thinking it could be the gap to the flywheel.

Does anyone know what sort of gap there should be ?

Thanks

[Oldiebut goodie]

Do you mean volts as opposed to amps?

In which case you are not getting any output from the alternator. Check that the alternator is receiving the excitation voltage from the battery. The alternator needs that otherwise it will not work.

[fix]

Sorry yes I mean volts

I'm not sure what you mean about excitation, there is one small blue wire and what looks like two red wires one bigger than the other attached to the alternator.

Should I be testing one or both of the red wires for voltage when the alternator isn't running?

Thanks

[Oldiebut goodie]

copied from wikipedia:

The field windings are initially supplied via the ignition switch and charge warning light, which is why the light glows when the ignition is on but the engine is not running. Once the engine is running and the alternator is generating, a diode feeds the field current from the alternator main output, thus equalizing the voltage across the warning light which goes out. The wire supplying the field current is often referred to as the "exciter" wire. The drawback of this arrangement is that if the warning light fails or the "exciter" wire is disconnected, no excitation current reaches the alternator field windings and so the alternator, due to low residual magnetism in the rotor, will not generate any power. However, some alternators will self-excite when the engine is revved to a certain speed. Also, some warning light circuits are equipped with a resistor in parallel with the warning light that will permit excitation current to flow even if the warning light fails. The driver should check that the warning light is glowing when the engine is stopped; otherwise, there might not be any indication of a failure of the alternator drive belt which normally also drives the cooling water pump.

there is a pic of a 90A alternator here http://wiki.club8090.co.uk/index.php/VW ... Amp_Wiring

[fix]

Thanks for the info, I understand abit better now

So basically a wire from the ignition supplies the initial power to the alternator, once the alternator starts spinning it supplies power back which turns the battery light off.

So if there are two red wires to my alternator one will be from the ignition and one will be to the battery? Surely the ignition is powered by the battery anyway so there would only need to be one wire.

The battery light does come on before the engine starts and then goes out when running, so I'm guessing the excitation wire is doing its job.

[Oldiebut goodie]

The excitation should come from the blue wire.
I am wondering if all your earth leads are making good contact. You should be getting higher voltage output than that. (especially as you get no change in voltage with change of brushes and regulator).
Have you tried to charge the battery up to a good charge (13.5v +) - it may be that the voltage is too low to excite it ( not sure what voltage they need to excite). 10.5v is low. I am surprised that the van will start.
Also some alternators will not begin to charge until they reach a certain rpm - maybe 1500 rpm or so. Did you give the engine some welly as opposed to just leaving it to tick over. Mine will not charge until I have blipped the throttle to pick up the revs., if it is just left to tickover the charge light remains on. (several people have this on their vans)

[fix]

Ah excitation is from the blue wire, so that goes to the ignition negative? Surely I should be able to test the wire with my multimeter.

Batteries been charged twice to almost full, 12 hours or so.

I think its strange after leaving a pulley shim out and checking both voltage regulators its the voltage has gone from 10.5 to 11.5.

I've revved the van to fast idle, as its just been rebuilt I don't want to push it too much. To be honest I don't think the voltage changed at idle or when it was revved.

About bad earths, when I put the engine back in the van my haynes mentioned an earth strap, I never saw one just a few wires earthed to the engine bay and one earth on the engine by the left head. That was just the same when the old engine was removed.