Diesel injector dramas

Alexsdad

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Hi all,

Spent today attempting to replace a injector seal on my 2002 C270. Ordered a new copper washer and stretch bolt, and began the task needing to be done. Injector 2 was ‘chuffing’ sounded like a steam engine!!

Removed the old injector quite easily, cleaned up, and fitted the new one. Problem now is that I’ve got diesel bubbling from injector 2, no chuffing noise though) Now I’m not sure if this is me being over cautious, and not tightening the stretch bolt enough (I tightened it to 8Nm and a bit more), or if the new washer didn’t seat properly, or a combination of both.

Has anyone every had the same issue? I removed the injector to check for issues (and dropped the copper washer in the process ) so I’ve got to order another kit anyway.

Any advice please
 

bembo449

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oh these are a git ! ( not what you wanted to hear ) I think the torque setting is summat like 7ftlb but I don't think its enough personally , are you the hole / seat were perfect , clean with nothing missing out of the hole the nozzle fits into ?
 

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You have to clean the cylinder head injector seat at the bottom of the injector housing
and the injector nozzle collar/seat where the copper sealing washer sits against.

Do not use an injector seat cutting tool.

Mercedes Injector cleaning kit
W 611 589 006 800
Mercedes Injector grease
A 00 198 942 511

MB ceramic grease should be applied to the injector body only, not the nozzle.
The new injector stretch bolt should be fitted and torqued to 7nm +90' +90'
 
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Alexsdad

Alexsdad

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Thanks for the reply’s so far. I’ll have another good clean up of the injector and the seat. Was worried about tightening the bolt too much, you know.... steady, steady, steady... BANG!!! I’ve got to get another copper washer, so will get the cleaning kit at the same time.
 

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Steve@Avantgarde

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Cutting the cylinder head is only required if you can see corrosion on the seat itself. The same for the injector seat on the injector body.

I will disagree with Westheath above regarding the stainless steel bolt. I have never seen a stainless steel bolt hold these injectors for a long period of time. Usually lasts a couple of months at best. I've also had to spend many afternoons tidying up this kind of repair and putting it back to the original design. The reason M6 stretch bolts are used is so they expand at the same rate as the alloy engine block maintaining the correct torque. Stainless steel will not expand with alloy meaning it will lose torque and leak or fly out, as i have seen on many occasions, I would never advocate it or do it.

In any case, its never the bolt that gives trouble, its the copper washer is what fails.

If you clean everything up properly, torque it with the original equipment to 8nm and 2 lots of 90' it will seal just fine. My success rate is 100% every time.
 
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Alexsdad

Alexsdad

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Many thanks. The seat looked fine, once I fished the old copper washer out of it, same as the injector. Maybe I just wasn’t brave enough on the torque front. I tightening it to 8Nm, then gave the bolt a ‘nip’. I found it odd the diesel was bubbling around the injector without any of the traction engine noise I had to begin with. Sound these bolts be tight as hell when trying the do the 2 90’s after the torque had been set.

It doesn’t help this being the first Mercedes diesel I’ve had the pleasure of trying to work on
 

om613

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Remember to clean the bolt threaded hole fully!
The bolt stretch on the 90 + 90 is part of the (not great) design, if not clear of debris, that's when the thread might shear.
Take your time and be meticulous and you'll be fine.
 

mersum1es

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Did you check injector nozzle holder is solid? Does not sound normal diesel bubbling at at that phase of repair when there was no such symptoms before. Cracked holder nut will 'alaways' cause that. Just a question; you didn't open enything of injector itself? Surely diesel is coming bottom, not top of the injector?

Fully agree Steve about M8 allens. Won't work.
 
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Alexsdad

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Thanks for the question. No I didn’t open the injector, just cleaned the muck from the outside of it, high temp greased it up, and refitted it.

It does seem the diesel is bubbling from the copper seal, and traveling up the side of the injector, causing it to bubble on the top.

I’m thinking I just didn’t tighten the stretch bolt down enough, and the copper washer didn’t seat correctly.

I’ll check with the main dealer this week, to make sure there’s not more than one type of copper washer for my 02 C270, guessing I’ll have to buy another stretch bolt for a second attempt.
 

Westheath

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Cutting the cylinder head is only required if you can see corrosion on the seat itself. The same for the injector seat on the injector body.

I will disagree with Westheath above regarding the stainless steel bolt. I have never seen a stainless steel bolt hold these injectors for a long period of time. Usually lasts a couple of months at best. I've also had to spend many afternoons tidying up this kind of repair and putting it back to the original design. The reason M6 stretch bolts are used is so they expand at the same rate as the alloy engine block maintaining the correct torque. Stainless steel will not expand with alloy meaning it will lose torque and leak or fly out, as i have seen on many occasions, I would never advocate it or do it.

In any case, its never the bolt that gives trouble, its the copper washer is what fails.

If you clean everything up properly, torque it with the original equipment to 8nm and 2 lots of 90' it will seal just fine. My success rate is 100% every time.

I have repaired diesel engines for over 30 years why do you think the "black death" is only apparent on these CDI engines with those ridiculous bolts.

No other diesel engines use such a sh*t bolt.
Regarding the bolt upgrade:
With the best of respect fella but you don't know what your talking about in this department as there's no direct contact between the bolt and the head material.
I have had to repair hundreds of these bolts due to multiple attempts of fitting the OEM bolts and customers giving up because of the "this way or no way attitude" given to them.

Read the Mercedes OEM repair manual regarding cutting the injector seat, they never recommend it and advise against the practise.
;)
 
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bob 6600

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I have done mine on a couple of occasions (all 6) once because of failed washer and once because I was stripping for a repair. I have never cut the seats but did clean them and cleaned and cleaned the bolt holes etc. Not had a problem.

Also, previously someone had stripped a thread (probably more than once) and fitted an M10 bolt poorly.The head was touching the injector so I replaced it with an allen-headed bolt - can't remember if S/S or high tensile. That was a few years ago and it has never leaked or failed.

I'm not saying others are wrong but it worked for me on this occasion
 

alexanderfoti

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My method on these is

Remove injector!
Clean seat thoroughly with cleaning tool
Clean injector sealing surface thoroughly
MB special grease injector
New stretch bolt 7nm then 90,90

Always works first time.

I only cut the seat if its impossible to clean properly.
 
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alexanderfoti

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An evening lubrication hiccup?
Presume that was meant to be 'remove injector'?

Haha yes! Although It would be a good job I removed the head every time!
 
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Alexsdad

Alexsdad

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Thanks for all the info people. I’ve ordered another copper washer, and stretch bolt. I’m going to clean the area up while waiting for the new parts to arrive. I think I firstly didn’t clean all the build up out crud out of the bolt holes etc enough (I’ll find out tomorrow) and didn’t tighten the bolt down enough. I only gave it 8Nm on the torque wrench, and a slight bit more (in fear of hearing the dreaded SNAP). I’ll let you all know how much more muck I removed, and when the next part gets here how brave I was tightening it up!! Got to say the 8Nm was a struggle, which now makes me think there’s a lot more crud in last bolt hole. Wish me luck... if you here on the news a man from Suffolk has been arrested for smashing up his c class with a torque wrench during next week, you’ll know it didn’t go according to plan!!
 

umblecumbuz

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To thoroughly clean the bolt hole and thread, use your existing bolt - as you intend discarding it anyway - cut grooves up the entire length of the threads (a Dremel is great for this) and liberally fill them with grease, with the exception of one groove. Wind the bolt up and down the thread several times, washing it and replacing the grease each time.

Keeping one groove free of grease allows air to escape, so that the bolt will reach the bottom of the hole without hydraulic lock intervening.
 

alexanderfoti

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I must admit I have chickened out on the second 90 deg...I got it to about 45 deg :)
If it snaps, then the thread isnt cleaned properly, or there is diesel/oil down the thread hole :) Cleaning them out is imperative.
 


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