Glow Plugs Staying On

[austen smith]

Hi all.

We have a T25 with retro fitted 1Y - 1.9 circa 1985. Engine installed by VW specialist (I'm told) and glow plugs wired up correctly (we think).

Battery went flat over night. Really flat. Pretty sure glow plugs staying on due to the relay be burnt.

Replaced relay problem solved. Battery now stays charged no probs.

But by checking circuits and voltage supply we have found that the glow plugs appear to be on all the time even when the engine is hot! Me thinks that this is why the relay burnt out and glow plugs were using battery power with ignition key off all night. If this makes sense.

Following a run I put a voltmeter on No 4 glow plug and found live 12 volts with the hot running engine.

I have spent all evening reading the wiki and variuos other threads and got a better understanding of the glow plug operation.

I have to check but I feel that the glow plug temperature sensor must be at fault and allowing the glow plugs to stay on when the engine has reached operating temperature???????????????????????

What do you guys think?????????????????????????

Any help greatly appreciated and many thanks.

[colinthefox]

If your glow plug relay is working properly, then with the temp sender disconnected the plugs should stay on for about 30 seconds from engine start. With the temp sender wire shorted to earth the relay should not come on at all.

So if your relay stays on more than a minute, even with a duff sensor, then that would appear not to be the problem.

Having said that I don't know what your problem actually is, unless the wires to the relay are on the wrong terminals.

Correct wiring is:-
L white/red to indicator light
T Blue/white to temp sender
50 Red black to starter trigger
85 Brown to earth
87 Big fat red to glow plugs
30 Big fat red from fuse
86 Black from ignition

Hope this helps

[austen smith]

Cheers

Going to check it this morning (Sunday)

Thanks for the assistance