not a bloody leak off pipe

[Lobo]

Thanks Rick, all good still, just checked it again with no clips in sight.
You got a theory on why i'd have diesel squirting out under load?
Do you think dirt or carbon build up could affect the internal seal allowing some higher pressure diesel to be forced into the low pressure leak off line?
As I said since I've cleaned it the problem has vanished.

 

[solarman216]

The leak off on and injector is just that, it is what leaks past the needle in the injector body, running at around 2000 psi the machining needs to be good, very good, in order to only get a drop or two a minute, it is such that if you strip an injector and take the element which is the nozzle and the needle, remove the needle and hold it in your hand for a few mins and place the nozzle on a cold surface such as a vice, on a good element you will not be able to insert the needle until the temperatures pretty much equalise, so for your injector to squirt it would have to be very worn, stripping it and re assembling would not cure this, I would think the most likely cause of a squirt is a slack injector pipe nut, Rick

 

[solarman216]

Just re read your post 5, I guess if the needle was not seating, in theory combustion gas could pass the needle (easier than fuel) and so could cause spitting, but as an ex diesel engineer I have never experienced this, as if the seat was that bad then the fuel would not atomise and so would not burn any sense, Rick

 

[Lobo]

Should have posted a pic of the needle pre clean as there was a carbon deposit around at least a quarter of the tapered section of the needle which I guess would tally with your theory that the needle was unable to seat properly.
As I have only cleaned the injector and put it back on and the symptom has gone it does point towards that theory being correct.
Reluctant to put clips on as they aren't standard on any diesel I've come across and the pipes shouldn't leak if they are in good nic.
Plus putting the clips on is a fiddly job at best.
Good to know your well qualified on this subject Rick, thanks again:.
:clap

 

[Lobo]

Well what can I say, the fault returned, ticking and power loss, after about 50miles so took off all the injectors for testing. Most diesel specialists will test these old style mechanical injectors for free, I took mine to Droitwich diesel and Tim the owner duly tested them and the verdict was "they are ok but not brilliant..."
So spent some time researching on the interweb and found a website called mercedessource which specializes in old Mercedes and their maintenance.
The injectors used on the models in the late 80's early90's are the same Bosch ones used on the maverano just a slightly different nozzle.
There are a few videos on the testing ,cleaning and maintenance of these injectors on there.
I followed the advice on there which involved scraping away heavy deposits with brass square section tubing and a brass bristled brush (brass is softer than steel so won't damage or score injector), boiling the disassembled injectors in water and dishwasher detergent except no 1 with the lift sensor which I left the top half of the injector out of the boiling process instead cleaned through with carb cleaner and a brass bristled brush and fine brass wire , 'lapping' all the mating faces with 2000 grit wet and dry with thin mineral oil. Cleaned all again with carb cleaner and put straw into base of injector nozzle to check spray pattern.
Blowing through all openings with a compressor and then reassembly.
New copper sealing washers and heat shield crush washers all torqued to the manuals spec.
I would have used new Bosch nozzles available for £16+vat each on line but couldn't stretch to that at this point so reused the old ones as they passed the visual inspection test described in the manual.
Have now done over 100 miles and it truly is like driving a new car, quieter, smoother and more power. Still early days and didn't have them retested before fitting but the procedure for testing and bringing them back to the manuals spec is straight forward using shims to recalibrate the opening pressure back to what it should be which is around 130 bar (which is etched into the side of the injector which you can see after cleaning).
So if you have time and a little knowledge I would heartily recommend having a go yourself as you have nothing to lose before forking out a fortune for new replacements.
:clap:clap:clap

 

[Blocky10]

Quality post this is. Sounds like everyone would benefit from doing this :thumbs

 

[terranosaurusdoug]

Well what can I say, the fault returned, ticking and power loss, after about 50miles so took off all the injectors for testing. Most diesel specialists will test these old style mechanical injectors for free, I took mine to Droitwich diesel and Tim the owner duly tested them and the verdict was "they are ok but not brilliant..."
So spent some time researching on the interweb and found a website called mercedessource which specializes in old Mercedes and their maintenance.
The injectors used on the models in the late 80's early90's are the same Bosch ones used on the maverano just a slightly different nozzle.
There are a few videos on the testing ,cleaning and maintenance of these injectors on there.
I followed the advice on there which involved scraping away heavy deposits with brass square section tubing and a brass bristled brush (brass is softer than steel so won't damage or score injector), boiling the disassembled injectors in water and dishwasher detergent except no 1 with the lift sensor which I left the top half of the injector out of the boiling process instead cleaned through with carb cleaner and a brass bristled brush and fine brass wire , 'lapping' all the mating faces with 2000 grit wet and dry with thin mineral oil. Cleaned all again with carb cleaner and put straw into base of injector nozzle to check spray pattern.
Blowing through all openings with a compressor and then reassembly.
New copper sealing washers and heat shield crush washers all torqued to the manuals spec.
I would have used new Bosch nozzles available for £16+vat each on line but couldn't stretch to that at this point so reused the old ones as they passed the visual inspection test described in the manual.
Have now done over 100 miles and it truly is like driving a new car, quieter, smoother and more power. Still early days and didn't have them retested before fitting but the procedure for testing and bringing them back to the manuals spec is straight forward using shims to recalibrate the opening pressure back to what it should be which is around 130 bar (which is etched into the side of the injector which you can see after cleaning).
So if you have time and a little knowledge I would heartily recommend having a go yourself as you have nothing to lose before forking out a fortune for new replacements.
:clap:clap:clap

That merc diesel guy has loads of vids on youtube, usually a good watch. I think he uses a brand/company called Monarch for replacement nozzles, I've been tempted for a while to have a play with me injectors but the most I've done is run some diesel purge through. How did you connect to injectors to test opening pressures?, and the centre console looks amazing btw :thumb2

 

[Lobo]

He definitely knows his onions with regard these injectors.
I think the boiling with dishwasher detergent is aimed primarily at the vet oil users but can't hurt for the non veggies.
I didn't pressure test mine after reassembly as I don't have a test pump and as Tim at Droitwich diesel didn't flag them up as being too far out of the normal operating pressure I didn't feel it necessary. (I still would have liked to just out of interest and will do further on down the line).
You can buy the test pumps for around half the price of a new injector which I will be putting on my wish list although my son has access to one at work.
Full instructions on inspection and testing of injectors are on page EC313 of the manual.
I think Kurt the Mercedes guy is on commission from monark nozzles as he rather likes them but I struggled to find a uk supplier and they are more expensive than genuine Bosch ones.
Cleanliness is also key through the whole process as even the smallest bit of grit can bugger things up as the tolerances are very fine.
I did the whole lot inside a day including adjusting valve clearances but almost paid the ultimate price when management arrived home early from work to find me boiling the injectors in our old kettle on the cooker (I used a mesh basket set inside the kettle to keep parts together and not touching the base) in my defence I did have the windows and back door wide open but she still flounced off muttering something about coldest day of the year.
Still, that pales into insignificance compared to some of my DIY mechanicing antics over the years and she hasn't left me yet!