Glow Plug Slow vs Fast Quick Question

[Earwig225]

Is there an easy way to tell a fast glow plug from a slow from just looking at the plug?

Thanks!

[R.O.R-2.0]

the year of the car is an easier way to tell. what hear of car did the engine come out of?

83 or 84 they switched from slow plugs to fast plugs..

some say that plugs with brass nuts are fast, and silver/chrome nuts are slow.. something like that.

[8v-of-fury]

I do not believe they sell slow plugs anymore, all have switched to the fast. Or vice versa.

Either way, buy some Bosch Duraterms and don't worry about it! they will work with either Fast or Slow glow plug relay systems.

[R.O.R-2.0]

I do not believe they sell slow plugs anymore, all have switched to the fast. Or vice versa.

Either way, buy some Bosch Duraterms and don't worry about it! they will work with either Fast or Slow glow plug relay systems.

bought some 16 second plugs not that long ago.. they DEFINITELY still make both kinds, both 8, and 16 second plugs..

[maxfax]

I dunno if they still produce them, but there is a lot of old stock of slow glows out there..   Typically those are the dirty cheap ones you find on ebay..   Funny thing is, a lot of the no name cheapos heat up like slow glows...

I too have heard that the brass nuts are slow glows, but even that may not be a definitive way to tell..

[8v-of-fury]

Are you sure? You more than likely bought old stock. Most if not all (reputable) places only carry Duraterms now, as they replace ALL preceding p/n's and are far superior.  

Slows are silver.
Fast are brass.
Where the conductor touches.

Chances are they are already Bosch Duraterms. If they are not, spend the ~$11 a plug and replace them all with Bosch Duraterms. They can be manually controlled to be left on for 3 minutes after starting the engine to effectively reduce the amount of emissions, and "cold" running where combustion is just barely happening. I have actually had a manual controller fail in the on position and the plugs were left on for at least my 30 minutes of driving and then until the battery went dead when i shut it off.. They still start the car just as good to this day (this was in Jan 2010).

Bottom Line, No other plug but Bosch Duraterms should ever be substituted. The Glow system on an IDI diesel is just as important as oil.

[maxfax]

Throw the brass vs silver thing out the window..   I just compared a new set of duratherms vs a set of very old but brand new Bosch slow glows..   Both brass...

They'll have to come out to compare..  The P/N is stamped at the base of the threads it looks like..  Fast slows appear to have a pointier tip and all 3 sets I have here are made in France where the naked ladies dance..  err uhh anyhow the slows I have are German...

[8v-of-fury]

Didn't figure it was too believable. All I have seen are Brass..

Best way to tell if you are not sure is pull it out and heat it up i guess lol

[nathan_b]

according to the owners manual, slow glow plugs can stay on for up ro 90 seconds, fast glow systems dont stay on for more than 30s. Big difference, if you have ever sat out in your car in 10f waiting for 90s with the key turned in the preglow, you CAN tell the difference. haha

[8v-of-fury]

I think an old style plug staying on for more than 17-19 seconds max will burn out. I mean obviously in 10f its gonna take longer to glow yada yada.. but on a normal day (60f) a slow plug staying on for 90s will not be starting that car ever again.. let alone I think the tips explode off..

Duraterms are the only plug on the market to date, that have a self regulating voltage mechanism inside each plug. Many plugs have this feature, however Bosch has been known to be best. They can vary their own voltage draw based upon their temperature, which is why mine did not burn out after being left on for 30+ minutes.

[maxfax]

Duraterms are the only plug on the market to date, that have a self regulating voltage mechanism inside each plug.

Not quite true..  AC Delco, Beru, and NGK also have this feature on certain models they offer..   Although for a VW application Bosch seems to yield the best results..

[8v-of-fury]

I stand corrected, however I can't rely on them to be in my motor if I have never even heard they have this technology in their plugs...

[maxfax]

AC/ Delco has had them since the 6.2 years from what I've found out..  However, they don;t make them for anything but GM and Isuzu engines I believe..  NGK and Beru recently offered this technology within the last year or so..  I have a set of NGKs in a Mercedes..  So far they work as well as the Bosch..  Cost about the same too..  So far they seem better than the NGKs I tried in the VW a few years back..  They didn't blow apart or anything, but seemed to not get hot enough...