Technical Glow Plug Help - US Ducato (Promaster)

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Technical Glow Plug Help - US Ducato (Promaster)

PM Montana

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Greetings from the other side of the pond! Many of us US diesel owners (3-liter with M40 6-spd "Comformatic") are having serious issues with glow plugs. Typical situation is this: 1. Error code. 2. Bring to Ram dealer. 3. Dealer snaps off glow plug trying to remove it. 4. Ram dealer tells customer it needs a new head (>10,000 US dollars if warranty expired). 5. Wait a month or two. Or three. Or more.

There must be a better way! Some background first. In the US the van is sold by Ram and called a Promaster (PM) starting in 2014. Most are sold with gas engines but some of us opted for the diesel with the Comformatic (as you in UK call it?). However the diesel was discontinued in 2016 for a variety of reasons. Most of us on the Promaster Forum blame Ram (and their dealers!) for their lack of training mechanics and the mechanics general lack interest in this "different" powertrain.

Many owners of these great (in my opinion) vans are scared or running away or both. Those of us without the glow plug problems are crossing our fingers we don't have the problem, and those with issues are paying way too much for a repair (extracting a glow plug) that the Ram Dealer should be able to handle.

So my question for my Ducato mates on this forum include:
1. Are we diagnosing this correctly (reading your threads it seems electrical issues tend to be a bigger problem than actual glow plug failure)??
2. How common is snapping off a glow plug on these 3 liter diesels? I see few complaints on your forum about this!
3. If we need to extract the glow plugs and they snap due to corrosion (or poor American technique) where do I find an extraction tool? We need some here!

I do know there are differences between the Ram and Fiat models but I suspect - and without any evidence - that the glow plugs are identical. Not sure about the glow plug electronics. Probably not.

Thanks mates for all your help and reading through this long-winded message.
 
The usual procedure for glow plug removal is to get the engine as hot as possible before removing them then spray a lot of penetrating spray into the area then very gently work the plug back and forth as soon as you feel some resistance tighten them back up a little way before undoing again
 
Hi PM Montana

The glow plug control unit has built in monitoring which checks the current drawn by each glow plug (typically about 10 amps). If any of them are out of spec, it will report an error. If the current is too low, it means either the glow plug has failed and gone open circuit, or that there is a fault in the wiring and connections. Given that the connections are in an exposed position on the front of the engine, connector corrosion is a distinct possibility. The glow plugs themselves can be tested for resistance in-situ, though they are rather buried and limited dismantling of the front of the vehicle is needed for access. Fault indications that come and go will point to bad connections, whereas indications that don't go away are more likely to be a genuine failure.


In the UK, there are many tales of problems with glow plugs being snapped off during removal by inexperienced technicians, as the torque needed to remove them when corroded in exceeds their mechanical strength. With skill, patience, experience and proper technique they will come out. If they do snap, there is a whole industry of specialist removal firms here with dedicated tools to extract the remnants.
 
@PM Montana
Even if the glow plug has snapped off this does not mean a new cylinder head is required. The head has to come off but you are just looking at removing a steel thread thread from an allow part. Any good machine shop should be able to do this even if they have never heard of a diesel glow plug. An engine overhaul shop dealing with older engines would have no trouble either. Even if the thread in the alloy head is destroyed a threaded insert or helicoil repair can be made.
There are specialist tool to do the job too see.

https://www.machinemart.co.uk/categories/?search=glow+plug+removal+tool

Robert G8RPI.
 
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The usual procedure for glow plug removal is to get the engine as hot as possible before removing them then spray a lot of penetrating spray into the area then very gently work the plug back and forth as soon as you feel some resistance tighten them back up a little way before undoing again

Sort of. :)

In my experience.. older designs
( previous ducato included..) the glow plug was desinged in a similar way to a sparkplug.

Modern motors..everything is so tight for space..they have shrunk :eek:

M14 Thread becomes M8

13 hex becomes 8 hex

But... the functional length remains unchanged so it all becomes thinner walled.. for longer lengths.

I had a passenger car with these tiny plugs.. spent a week pre.soaking..as access was ok.

Then on the day for removal got motor HOT
stripped a few necessary obsructions
(2 minutes..'well drilled' ;) )

Tool at the ready spray tealease fluid into the socket of the cylinder head that the plug disappears into... attempting to cool:shrink the skinny lightweight plug away from the major heat soak of the hot block

Great fitting tools.. and set up so you have 'great feel' as direct..and 90' SQUARE to the plug as possible.

It took reasonable effort to get it moving..

I used a technique akin the tapping a threaded hole.. 1 x rotation.. then back a half.turn

At any thight point.. spray..then back in.. to the bottom.. more spray

( at this point.. you are battling carbon build.up on the tip of plug..rather than corrosion on the main thread)

I got 1 out.. a straight wind

1 took more 'back and forth'


I am an engineer.. been hands on for 40 years.. so have 'feel'

Any clumsiness will soon shear these tiny tubes of metal :(

Write up of the plug removal..winter 2019

Im going to mention glow plugs..

On a FIAT..

OK. got warm.. coaxed the mj into life.. drove for 40 mins.. uphill..

Stopped.. covers off.. wound out 2 plugs..BERU.. replaced with Bosch.

The stuck lead played hard to get.. then came away.. leaving the connector rusted onto the plug :(

Next plug..only moved 1/8 turn.. so left it.. :(

Car starts as badly as ever.. so was probably relying on the lead I snapped :(

Looks like some mew wiring is required.. :)
couldnt find mew connectors for sensible money .. so will try bullet females

At least they are 10p.. not £10 each.. :)

Charlie
 
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