1991 Golf GTD warm start problems

[rubadubdub]

Hello everyone
Just found this forum from link in tdiclub and looks to be a great site.  Ive searched the archives but had no luck so i'm hoping someone can help me with a problem with my car.

My Mk2 golf GTD has problems starting when warmed up. From cold glow plug lights come on for 10 seconds or so, then car starts on first turn.

But if i stop the engine once warmed up and leave it for anything longer than a couple of minutes, the glow plug light doesnt come on and it refuses to start without turning over between 5-15 times.

Stopping and immediately restarting the engine: the plug light is off but car starts striaght away, presumably as it's completely up to temp?

Anyone got any ideas?

Ive got a permanently flashing temp warning light which is believe is down to a dodgy sensor as rad fan kicks in and temp guage is ok, could this be affecting it somehow?

Cheers

PS. can anyone recommend a decent manual as there doesnt seem to be a haynes manual that covers 1991 gtds, or any diesels. Have seen Bentley manuals, how good are they for uk spec cars?

[burn_your_money]

Bad ground. Run a wire from under a starter bolt directly to the negative terminal on the battery, or just to underneath the bolt where the current ground connects to the engine. Clean up all the connections

[rubadubdub]

Cheers i'll give it a go.

I suspect there's a bad groud to the dash console as the lights and left indicator are playing up (that'll be in another post).

If this is the case could the bad earth you talk about be affected by anything in the dash? The glowplug circuit must run up there.

[Darkness_is_spreading]

Another quick check  is  if you have a leak in your system,  at low idle this  is not enough to purge the  air out of the system at idle.   When you run the motor on the highway at higher speeds the  air is bled out.   But then you shut the car down for the night,  and restart and  it starts fine because there is lots of fuel in the pump and the lines feeding the pump  but maybe there is air before   it which would cause  a crappy idle.  

Install some clear lines to and from the IP  and  make sure there is no bubbles  running into the pump.  If theres bubbles,  replace the fuel filter,  check for leaks  at the injectors,  hard lines, pump,  and  plastic  fuel lines.

To bleed just crack open all the lines on the injectors and crank till fuel comes out each port and then tighten down the nuts to the injectors. Should fire up  right away,  then  bring idle up  warm it up then  take it out and beat it till  your happy that the air is out.....  This could be melting tire  or  drag racing to help to get the air out.  :twisted:

[jtanguay]

my fuel system is kinda leaky too... it has a noticeable rough idle if let sit for a while... once i get driving it clears up pretty quick.

[rubadubdub]

Thanks for the advice. The idle is spot on all the time so my hunch is that there arent any air bubbles. Once ive exhausted the electrical avenues i'll check it out. I can definately mange the tyre melting part! I believe its called an 'Italian Tune Up' round here.. driving round the block at 60 in second gear. Dont know what the Italians have done to deserve this reputation as some of my friends drive like that normally!

Been searching and found this (last post only): http://www.golfgtiforum.co.uk/index.php?topic=2026.10

The suggested candidates for warm start probs are:
1. Cold start boost on the injection pump, operated by sensor (doesnt say where) and pulled by solenoid on pump by glow plug 1.

2. Leaky fuel injectors which are helped by glow plugs when cold but not when engine's warmed up.

Are either of these likely and if so, where is the sensor mentioned in 1. and for 2. is he right in that the glow plugs dont come on sometimes when car's up to temp?

Still after an engine manual suggestion.

[rubadubdub]

'burn your money'...
This is a rather daft question but just to be sure.

I just took a quick look at the starter, which bolt do you mean? The securing bolts holding starter to rest of engine or one of the others? The latter look to have red power cables on so dont want to short circuit it, but surely the starter securing bolts are earthed to car body anyhow...

If you could shed a little more light i'd be grateful.

[burn_your_money]

at work, quick answer, the securing bolts. High heat causes the cables to not carry enough current. More power needed
more later

[Doug]

My 87 Golf TD does the same thing as yours. I have read that this is typical for a TD but would suspect that your hypothesis on leaking injectors is the problem source. I just haven't got round to rebuilding the injectors yet.

[burn_your_money]

The suggested candidates for warm start probs are:
1. Cold start boost on the injection pump, operated by sensor (doesnt say where) and pulled by solenoid on pump by glow plug 1.

Does not apply to your car (unless UK is weird) Your cold start timing advance is controlled by the lever on the dash

My Rabbit used to do the exact same thing. I drove for 4 hours straight, stopped the car and it wouldn't start 10 minutes later. I had manually powered glow plugs and even after charging them for 10 seconds it didn't start. This is in the middle of summer as well BTW. I push started it and it started up ridiculously easy.
My ground wires were being heated up (from the tranny heat) and when they get hot they lose their ability to carry current (amps) as effeciently (which heats them up even more) By running the extra wire to below the securing bolt on the starter my car had the ability to pull all the amps it wanted and the car started no problem ever since... until I warped the head anways

[rubadubdub]

I tried your suggestion but had no luck.
Took some pictures to show what i'd done but card reader is playing up unfortunately.

Used thick copper cable rated at 20 Amp from top starter motor securing bolt  (sandwiched between starter and engine) to battery -ve terminal.

Battery connects and earth strap points on engine and car body cleaned with soapy water then rubbed lightly with wet & dry to get shiny surface back.

Once in place checked continuity with multimeter and there was a clear circuit from starter motor body to the end of my copper wire, which was then attached to battery -ve.

With engine warm and being restarted the glow plug light still didnt come on and starter motor turned over no problem, it just didnt like starting without the plugs.

Are there any sensors which tell the car how hot the engine is and control the glow plugs accordingly, as this would seem to be a likely candidate? Or am i barking up the wrong tree?

[rubadubdub]

Thinking about it, if the cause was too much heat in earth cables then logically it would be worst at starting soon after being stopped when in fact the opposite is true. Starting gets worse with cooling until the point where the glow plugs start coming on again.

[burn_your_money]

That's unfortunate that the ground issue wasn't the problem in this case, it's a good simple mod.

It is possible that you have low compression and the glow plugs are partially masking this.

The glow plug temp sensor is on the coolant flange on the front of the head. There are 2 there, one for the temp gauge and one for the glow plugs. Simply unhook one and then turn the key to "run" Either the glow plug light won't turn off or the temp sensor won't work.

[Wingaman]

The only thing I could see is the pump head is dead.

[rubadubdub]

I think i may have cracked it.

I tried removing the temp sender plugs when the car was having trouble starting and with (what i presume to be) the glow plug sender removed the glowplug light came on and the car started.

Plugging it back in the car struggled to start again.

I noticed that when unplugged the dash glowplug light came on for 15 seconds then switched off, rather than staying on permanently as i was expecting from burn your moneys advice. This is double the normal warm up time so can only assume its a built in default setting when the cars getting no info from the sender. I know from MK3 polos that removing senders makes the car assume defult settings so presume its the same.

I took some resistance readings from the sender when it was warmed up so i'll do the same when its cold and with the new one im ordering. If its any use i'll post them up here.

However knowing my luck the car has a few more suprises in store for me yet!