starting problem

Raesalmon

Guest
Hi - anyone had similar experience? or can suggest possible cause?
My 6 year old Toledo 1.9 TDI has developed a staring fault. It starts ok from cold (although like most diesels never really bursts into life) but she the engine is still warm / hot really struggles to start again, and often appears that it is not going to? Glow plugs have been renewed (although gp light refuses to go out) so what else could be causing this?

Any suggestions, experience or help much appreciated. Rae.
 

Dox1966

Active Member
Jul 13, 2007
243
1
Hi - anyone had similar experience? or can suggest possible cause?
My 6 year old Toledo 1.9 TDI has developed a staring fault. It starts ok from cold (although like most diesels never really bursts into life) but she the engine is still warm / hot really struggles to start again, and often appears that it is not going to? Glow plugs have been renewed (although gp light refuses to go out) so what else could be causing this?

Any suggestions, experience or help much appreciated. Rae.

It needs scanning for fault codes, on VAG diesels the flashing glowplug light indicates an engine fault.
 

Raesalmon

Guest
starting problem - possible cause

Thanks - this looks promising. Is the coolant temperature sensor and the coolant temperature sender the same thing? (just two different names for it?)
Looks fairly straight forward to fit too ?
Rae
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
There's one sensor component which fits into the pipework on the flywheel end of the cylinder head, but it contains two separate sensors, one which feeds the ECU and another which just feeds the dash gauge.

I think this is because the dash gauge is a remnant from older cars, meant to be usable in cars without an ECU, and is run off 12 Volts. The ECU is running off lower voltage, and also wants a more accurate reading.

If you have Climatronic then you can see what the ECU coolant temperature reading is from the diagnostic display: the Climatronic gets the coolant temperature reading from the ECU so it knows how much heat is available to put into the cabin air.
 
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Raesalmon

Guest
sensors

Thanks for that - presumably fitting a new sender component, that contains both sensors, will ensure that this will have been covered?
A little research shows that this is a likely cause of both the difficulty in starting when hot AND the reduced fuel consumption.
I have sourced the part at between £10 to £20 and am hoping that it is a straightforward job to fit myself?
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
Relatively straightforward. Take the engine cover off and locate the sensor: it's not easy to get at for all the other pipework and wiring in the way. There's a clip that holds it in and an o-ring providing the seal. If you don't have a new o-ring with your new sensor you'll have to make sure you don't lose the old one. Some people manage to change the sensor without losing too much coolant, but it may be better to drain some out first, especially if you have to recover the o-ring.
 

Seatmann

Rough around the edges
Sep 16, 2010
5,568
9
Scotlanda
Pull the old one out with the plug still attached, fit the new one then swap over the plug, that's about as quick as you can do it.
 

Raesalmon

Guest
replacing coolant temp. sender

Thanks guys - sounds fairly straightforward, will order the part and have a go at it.
Appreciate your help.
Rae
 

Jenks

Active Member
Jan 3, 2014
25
0
Staffs
Hi did you sort it ? Mine does the same and had it scanned with vag.com and I was told that it's to do with the starter motor (lazy) not enough rpm when hot comon problem.
 

TDI_luver

Newbie
Jul 11, 2006
115
0
Ireland
Hi did you sort it ? Mine does the same and had it scanned with vag.com and I was told that it's to do with the starter motor (lazy) not enough rpm when hot comon problem.

I have a '06 Toledo Mk III (Big arsed Altea) and it has exactly the same problem now since it was about 2 years old, I have learned to live with it as there are never any fault codes.

It would be interesting to find out what causes it though.

Like you, it starts instantly from cold without a hiccup, but stop the engine when its hot (full operating temp) and try to restart shortly afterwards and it wont start unless you keep cranking for 5-10 secs. However stop cranking and then try again and it fires up instantly !

I have put it down to a software glitch - as it able to start immediately on the second turn of the key, so its not a mechanical problem or a bad sensor.

Anyone have any ideas ? I assume it affects all makes/models with the 105hp 1.9tdi PD engine ?
 
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