Glow Plug Testing

[stg2500]

Is there anyway to determine if gkow plugs are still working? I have a 1984 Volvo 240 Wagon with the diesel that is getting hard to start in the mornings that are cool.



I thought that I have heard of a way to use a meter to tell if they are still good.

 

[Bob V]

Use an ohm meter and check terminal post to ground. Should be all about the same, if one or more is high or open, it's junk.

Bob V

 

[LSMITH]

Look for 5-15 ohms, over or under that and they don't work.

 

[LSMITH]

That Volvo likely needs a valve adjustment too. That can make a BIG difference in starting ease in cold weather.

 

[Skydiver]

Are they 12 volt?

Not sure about Volvo but, I had an old Mercedes 220D that the glow plugs were wired in series. About 3 volts each.

Took one out and hooked it to a battery. Yes it took my picture. Flash!!!

Tim

 

[illflem]

If your individual plugs check out but still don't work there is a fusible link on Volvos that I found fried a couple of times.

 

[JLEONARD]

I used to test the old VW glow plugs by clamping them to a metal engine part with vise grips, then touching a hot wire to the terminal end.

If they got red they were working. Simple.

Then let them cool a minute or so before touching!!

Jay

 

[stg2500]

Thanks for all the replies.



LSMITH,



Any info on the valve adjustment? How do you do it? The motor was rebuilt at appoximately 100,000 miles. It now has 143,000 miles. Is that a little too soon for the valve adjustment?

 

[78repowerwagon]

On Fords I use a big headlamp wired in series with the glowplug. Bright light - works good

weak light - weak plug

no light - bad plug



This only works on a 12 volt glow system.

 

[LSMITH]

I am not sure what the lash settings are for that engine, . 007" on the intakes and . 015" on the exhuast would be a decent starting point. They could be listed on a placard under the hood. Basically the work is just like any other, set them cold. 43K is a while, a LONG while if it had the head rebuilt when the engine was rebuilt. 15-20K is a good interval for the first 3 adjustments, then typically they will settle down a little and you can go 30-40K between adjustments.



I don't remember ever seeing hydraulic lifters on a Volvo diesel from that timeframe but it is possible. If it has hydraulic lifters the valve lash is not adjustable and nothing I have said applies.



I would guess that there is an import diesel website where more detailed information could be had if you don't have the service manual. My buddy that used to get me the info on the Audi and Volvo diesels when I needed it for a job retired last year. I have stopped doing the work on import diesels for the most part, I only have 2 cars that I am taking care of anymore and when they are gone I will stop completely. Just not enough hours in the week these days... ... .

 

[Uncle Joe]

The best way is to use a test lite,first disconnect the plug from the timer box to the plugs(6-8 pin plug),next connect the alligator clip to (+) touch the plug stud(where the wire connects) with the probe,if it lites up,plug is good , no lite=time for a new one as they only last couple of years tops under normal use.

Even if only 2 out of the 6 are bad it will have a hell of a time starting in cold weather... ... ... ... . Joe

BTW: when replacing glow plugs stick to Bosch... . I know that there are alternatives such as champion,IMO they are as bad as their spark plugs!