Glowplug Changing Tips

[StevenN]

I have the dreaded glowplug light lasting for about 1min after starting.
It looks like I will have to get the tools out

I have read a lot of horror stories of snapping the little buggers in the head.
So what tips can people suggest?
(I don't want to take it to a garage)

Cheers

Steve

 

[BlackC55]

Get the engine hot and keep your fingers crossed.

 

[corned]

We'll have to have a mini-GTG Steve - mine's recently joined the club!

 

[StevenN]

Hi Keith
Is your engne the one where they hide them just to test your patients’ & dexterity?

 

[corned]

Don't know. I've yet to pluck up the courage to go and look into what's involved. At present I still have 5 in working order, but winter is approaching...

(Mind you, I changed them on my old Pug (the Xantia 2.1TD engine). The left-most plug (viewed from the front) was obscured tight behind the diesel pump. The destructions said the pump had to be removed. I got the b@stard out without having to resort to that, luckily, but it was fiendishly awkward. No doubt Dieselman knows a better way, as he will be intimately familiar with Xantia engines!)

 

[Dieselman]

(Mind you, I changed them on my old Pug (the Xantia 2.1TD engine). The left-most plug (viewed from the front) was obscured tight behind the diesel pump. The destructions said the pump had to be removed. I got the b@stard out without having to resort to that, luckily, but it was fiendishly awkward. No doubt Dieselman knows a better way, as he will be intimately familiar with Xantia engines!)

Weirdly, owning three cars with that engine, I am aware. The last ones I did when the head was off, but that one can be done with a cranked spanner.

 

[Vlad]

I've just done them on a ML270 and at the first try I could feel that they were going to be tough to budge, so over the course of a week, every night I would fill up the wells where the glow plugs sat with WD40...a week later I got the engine nice and hot and they came out with no effort at all.

 

[AMG19]

Grease the one you put back(it's a special grease) and don't over tighten them! They only need to be nipped up.
The mercedes torque recommendation is too tight- trust me! Use feel and common sense and your be fine.

 

[SilverSaloon]

yes put some copper grease on the threads to aid removal for the future...

two of mine were stubburn in coming out last time i did this job on my W124.

i got them past the threads and then I ran the engine with them half out and after a while, they "popped" out like bullets. Seemed the safest way to remove them without the risk of them breaking as they wernt coming out. you need to be very careful when doing this and make sure you are out the way when they pop. persuasion with mole grips during this can also help but wear some golves etc. hopefully you wont have to do any of this! no idea whether this is good for a ML either (engine management etc etc)....

good luck!

derek

 

[AMG19]

No don't use copper grease! The electricity going through the glowplug can react with the copper grease and cause it to seize in even worse! Use a ceramic grease especially for this purpose.

Also if you want a safe way of doing this DONT START THE ENGINE WITH THE GLOWPLUGS HALF OUT. It could strip the thread or worse still take someones eye out!

 

[Dieselman]

No don't use copper grease! The electricity going through the glowplug can react with the copper grease and cause it to seize in even worse! Use a ceramic grease especially for this purpose.

Also if you want a safe way of doing this DONT START THE ENGINE WITH THE GLOWPLUGS HALF OUT. It could strip the thread or worse still take someones eye out!

He means once the plug is unscrewed but still can't be withdrawn.

The best way then is to run the engine at idle and "unscrew" it using a socket and ratchet handle. As the carbon is scraped off the plug it will suddenly blow out but be controlled by the ratchet.

For safety, stand at the front of the car on a longitudinal mounted engine.

Never had a problem with copperslip.

 

[SilverSaloon]

He means once the plug is unscrewed but still can't be withdrawn.

The best way then is to run the engine at idle and "unscrew" it using a socket and ratchet handle. As the carbon is scraped off the plug it will suddenly blow out but be controlled by the ratchet.

For safety, stand at the front of the car on a longitudinal mounted engine.

Never had a problem with copperslip.

yeah i've never had a problem with copper either....

Yes i meant once the plug has been unscrewed from the threads but it still wont come out due to carbon.

The whole method is "very dodgy" but worth trying SAFELY to avoid it breaking in the head if you continue to pull/turn it without this method.

when i did it i had mole grips/plyers on it trying to gently lever it out whilst under pressure from behind by the engine. in the end it gave way and shot out and you tend to drop the tools and move your hand out the way! hence the need for gloves too.

again, not ideal, but better than the hassle of trying to get a broken plug out of the head.

most of the time they usually come out easily by unscrewing them on a hot engine and they either come out no problem or are a little resistant but unscrew out of the carbon build up. the engine running stuff is purely a last resort attempt!!

 

[Dieselman]

The way I suggest, is easy, painless and works. The flash of flame is pretty impressive too.


Disclaimer: At your own risk...

 

[SilverSaloon]

The way I suggest, is easy, painless and works. The flash of flame is pretty impressive too.


Disclaimer: At your own risk...

lol i forgot about the flame

 

[StevenN]

Thanks for the tips lads
Sounds like I should take pictures.
All the way to the Hospital.

I think I will test and soak the culprit in penetrating oil for a while.

Cheers

 

[Danny DeVito]

Is this problem peculiar to mercs ? Only i never had any problems on other cars or forklifts or dumpers or anything.

 

[StevenN]

Hi DD
it's not a problem more than an early warning that trouble is on it's way.
My car starts and runs ok but it's telling me that one or more of the plugs is on its way out.

I have had my Toyota Surf for eight years and it still starts first turn

Steve

 

[StevenN]

Finally got to look under at the engine today.
Can't really tell which plug is on its way out.
The light is now intermittent.
Tested from the connector plug to ground the only one showing a reading just over 1 was plug number 1.
If the numbers follow through to the engine no1 is at the front buried under fuel lines.
I will check again when I have more time.

Do the leads just pull off?
And is it nimble fingers the way for plug number 1?

Ta

Steve

 

[Danny DeVito]

Hi DD
it's not a problem more than an early warning that trouble is on it's way.
My car starts and runs ok but it's telling me that one or more of the plugs is on its way out.

I have had my Toyota Surf for eight years and it still starts first turn

Steve

Sorry i meant the plugs breaking, seems to be mentioned a lot on here

 

[Andrew1068]

A bit of advice................. get them done at your local mb, if one breaks then the head has to come off and then things will get expensive!!!!!! I had mine done and one broke, mb has a tool to remove em properly so it was there problem!!!!
In the end the cost wasnt too bad ( 235 euros or about 210 pound ) and I had all six changed.The price was a complete price parts & labour.