Beru Glow Plugs - What's the difference...

[Rhothgar]

Evenin' all!

Can anyone tell me the difference between a Beru 909MJ and a Beru GN909?

The reason I ask is because I fitted a new set of NGK plugs to the Xant a while ago and I have the following issue:-

On cold start, it has become smoky again and frequently stalls with the recent decrease in temperature. Battery has been replaced with a Bosch S4 004 the other week for the avoidance of doubt over winter.

Been on both Citroen and NGK cross-referencing website and it is telling me for the 5962.3J Citroen P/N that 3473 Y-924J are the exact replacement which are the ones I have fitted.

Now! I've read numerous posts on here extoling the virtues of Beru GN909 glow plugs but was curious to see if this cross-referencing information can be relied upon or has anyone else had similar troubles with non-Beru Plugs that are supposedly an identical match to the Beru marque.

Many thanks, Rhothgar

[CitroJim]

As far as I can tell, just a different part number Roger..

Both the GN909 and 909MJ appear to be usable in a 1.9TD according to all the cross-references I've looked at on the 'net. What the difference is I don't know but there must be one...

The GN909 is the normal one and until tonight I'd not heard of the 909MJ...

If you have a handful of 909MJs then they'll be OK...

[Rhothgar]

Hi Jim

I had an inkling that it may just be a revised part number for some reason.

BTW, can you review the post as I edited it with some more info, 7 minutes after you posted!!! Cheers!

[Peter.N.]

Check how much voltage you actually have on the glow plugs, should be about 11v or a little less. I have had a couple of vehicles recently with low voltage due to poor connections on the glow plug relay (you will be able to see if they have been getting hot) and even high resistance plug interconnecting wires, so check the voltage on each plug.

Peter

[Rhothgar]

That's interesting!

I was reading about the prs of using the GN909 which states that they can take 13.5 Volts and up to 15.5 Volts (with alternator recharging the battery) because they self-regulate and adjust themselves so as not to burn out.

From what you are suggesting though, it sounds as though you are referring to a different system maybe an earlier one. I have to ask is this test valid for a S1 1.9TD Xantia.

I am expecting higher voltages at the glow plugs. Also, would the voltage not be the same at each one because they are wired in series? Or am I looking for a different voltage because one may have shorted?

Many thanks for the input thus far.

[Xantidote]

Voltage to all the glowplugs should be the same, as they all wired in parallel - this assumes the feed bus-bar along with it's crimped connectors are in good condition. The 1.9Td's glowplugs have a resistance of less than 1 ohm, and will increase in resistance as they fail, or go infinite resistance. The effect of this is a slight increase in voltage to the other glowplugs. I've not had experience of a glowplug actually shorting out.

[CitroJim]

Roger, also check you're post-heating properly...

After the engine starts the glowplugs will re-ignite and remain so whilst the engine is idling and the coolant is below 60 degrees. The post-heating will cease if the engine is revved beyond 1/3rd throttle and/or the coolant is above 60 degrees.

Post-heating can last anything up to three or four minutes and is primarily to help cold running and smoke emission when cold..

[Peter.N.]

The two cases I refer to involved my XM estate and my sons P100 pick up. The XM suddenly lost all glow plugs when I was working on it, I removed the relay and found one lead had broken off, I crimped on a new tag but couldn't get the nut undone as it had been 'cooking' for quite a while. I eventually got the nuts off and fitted new tags but having cleaned the mating surfaces I reassembled them without the shakeproof washer as it seems that's where the high resistance was.

My sons truck had been getting progressively more difficult to start, I checked the voltage on the glow plugs and found they varied by as much as one volt, I made up new link leads from heavier wire than the original and equalised the voltage but it was still low. I renewed the battery and relay connections and ws rewarded with an extra volt or so, which is a lot at about 60 amps, the total load. A drop of one volt at cold start voltage represents about a 10% loss, as this also reduces the current flow by 10% you have now lost a fifth of total power.

You will always get a voltage drop because of the high current drawn but if you can get 11 volts on the plugs you are doing well, much less and you are loosing efficiency, much more and not all your plugs are working!

Peter