I own a 1997R Polo 1.9D. Now 87k miles.
Last winter, as the weather became cold, starting became problematic, had to churn for ages etc. Diesel owning friend reckoned probably glow plugs. Looked at the job and decided I didn't have time myself, so let the VW dealer look. They said 3 of 4 plugs were u/s, so they fitted a new set and all was OK, until this winter.
Starting from cold is a bit slow and noisy (more than normal for a diesel) and runs a bit rough when it starts. This seems to be helped if I turn the key off when the glow-plug light goes off, then back on again and put some more heat into the plugs before starting.
The problem is far worse if the car has been left for a couple of hours, i.e. not time to get properly cold. Then the start-up is horrendously uneven and noisy, unless I do the extra glow-plug heat routine.
I read HJ's coment on a recent post that he thinks VW diesel injectors should be changed at 80k miles and this got me thinking. This seems quite an expensive job, but if that's the problem I'll do it, because I intend to run the car another few years yet.
Thanks for reading my long and involved post - I look forward to any wisdom you might be able to offer.
Andy
|
I too have a Polo Deisel. (The best diesel engined supermin of that era) I had the same symptoms as you described and changed the glow plugs myself which was an easyish job but did require the purchase of a ratchet spanner as access was restricted.
There are different types of Diesel engines for Polo's as a 97 car you may have the old indirect engine that also powers Scoda Favorits/Felicia's in which case the injector should be OK (swirl chmabers/indirect) or it may be a later SDi engine which case you may be right.
Check which engine you have.
|
|
|
Mine is the older, non-SDI engine. Sorry, should've said.
My first thought was glow plugs again, but it is only 12 months and 20-25,000 miles on the new set, shouldn't they last longer than that?
I can't think how to explain it, but it just doesn't seem the same as last winter when the plugs were faulty. Also, when I heat them for longer, starting is much better, wouldn't failed plugs be equally useless no matter how long I sent power to them?
Thanks
Andy
|
|
|
Andy,
Don't know if this is the cause, but sounds similiar to a problem I had on my vectra diesel (not the current cold start problem, the last one). Mine exhibited the exact same symptoms, with a few minutes of rough running (accompanied by smoke) after startup, which was due to air ingress in the fuel supply.
Replacing the whole filter head assembly on mine cured it, but I'm sure some of the other backroomers will provide useful diagnostic tips for air in the fuel.
-David L
|
|
|
Don't know about the Polo but some diesels do require two glow-plug heats in cold weather. Your handbook should mention this if it applies to the Polo.
Another thing worth looking at is the electrical continuity from battery to glow plugs, especially the bus bar contacts. This circuit relies on good electrical contacts to keep the voltage up but the contact areas are prone to corrosion on some cars. This may not be the cause of the problem in your instance but it is an easy and cost-free place to start.
|
|
|
|
this does sound like air in the pipes, has the fuel system got a small section of clear piping between the filter and injector pump? if so, check for air bubbles in the return line when some one else starts the car
|
|
|
IMHO it should be possible to check the glowplugs in situ with a resistance meter.
When I checked a set that came out the good ones had a small resistance, about 10 ohms if I remember correctly, The duff ones were infinity.
Someone else probably has the exact parameters.
|
|
|
Thanks for the advice - I'll have a look for air bubbles (there is a clear bit of pipe somewhere) and see what I can test around the glow plugs. I'll probably be back for more advice after the weekend. As you can probably tell, I dont't know much about diesel's!
Cheers
Andy
|
|
|
Ten ohms sounds reasonable or maybe a bit high to an electrical engineer (me) since Volts divided by resistance gives the current in amps, in this case 12/10=1.2 amps. Volts times Amps = Watts, or 12x1.2=14.4W, not that much.
It is clear that if the resistance is much higher you don't get much heating at all.
Hope this is of help to someone.
|
|
|
