Black death / Seized injector removal.. post mortem/findings

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miggit

Active Member
Joined
Mar 25, 2016
Messages
102
Location
Milton Keynes UK
Car
2000 ML270CDI Manual
Hi all, just thought that I'd share a few findings after replacing my injectors on my 270cdi.

My engine was suffering with major black death, which translates into leaky injector copper washers and injectors glued in place by a tar / coal like substance.

2 of my injectors came out without any issues, 2 needed a bit of wiggling at normal working temperature with some grips and they also came out... but number 4 wasn't having any of it, well and truly stuck fast.

In the process of discovering that it wasn't going to play ball I broke the fork clamp (don't ask me how as I haven't the foggiest.. 1 minute it was there, the next PING, broke in 2 and departed the engine bay, D'OH!!) At this stage I was left with a working engine, minus an injector clamp, and total despair. I decided to regroup the next day and surf the web for answers.. leaving the injector in a puddle of WD40.

The web wasn't any use at all, every specialist offering a hydraulic puller service in my area didn't have the tooling for the 270cdi injectors, stating that they normally fall out the head. So I purchased a slide hammer/puller kit like this
product_13055.jpg

A day later it turned up, I rushed out to the car and gave it a go...10 minutes later the injector hadn't moved and I'd pinched/cut my little finger.

So I had a re-think, started the engine and got it hot, about 78/79 (just below the 80 mark) and had another go... this time I was careful not to pinch my finger.. instead I managed to knock a large chunk out of my thumb on the other hand. It was then time to call it a day!

The next day I was faced with an injector that wouldn't move and a lot of plasters on my fingers!! Scratching my head and leaning into the engine bay wondering if it would ever come out, I noticed that the WD40 had disappeared! Spurred on by this revelation I soaked the area with WD40 and started the engine again and waited...

As the engine got hotter there was a tiny amount of gasses bubbling up around the injector, rather than reach for the puller I thought that I'd just leave it running at about 1250 RPM and see what happened, remembering that this injector had no clamp! As the engine got nearer to 80 the bubbles stopped. At this point I was getting a bit nervous about sending my injector into orbit, so I decided to cover it with a few rags. The engine got to around 90 and still no movement, but the bubbling D40 was back. I let the fan cycle a few times 3-4 and then switched off. Removed the injector pipe, fuel return and harness, and had another go with the slide hammer.. after a few minutes it moved! After a few more minutes it was about an inch out the head, but had stopped moving. I tried to knock it back into the head, but it wouldn't move. I then had another go with the slide and it came out further and then stopped, after another rest I managed to get it out.

Findings.. if you have black death then a slide hammer / puller is worth the investment (under £30)

If you've got Black Death, then remove the engine cover and as much of the coal / tar deposit before running the engine... When its cold it is hard and easily chiseled with a screwdriver, when its hot its like treacle and sticks to everything.

Do one injector at a time, run the engine until it is very hot (90ish) By getting the engine hot the clamp bolt will come out without any worries, and hopefully the injector too! You may be lucky and get them all out in 1 go, but if there is a dealy you might have to run the engine to extra hot again before continuing.

I also found that it was easier to clean the engine when it had got cold again, using a cleaning kit like this
71BawEJsbuL._SY355_.jpg

The last thing is I've used inserts on all my head clamps... the first time that I did an injector seal I spent hours cleaning up the threads for the clamp bolt, 80k later it blew out the top of the head... if there is any black death / tar around the clamp bolt I personally would think about using an alternative to the stretch bolt.. I now use 35mm long M6 12.9 cap head bolts torqued to 20nm.. easier than the 80 mm originals, but you must use an insert!

Oh and hot WD40 is a life saver!
 
If it helps someone stay sane it will be worth it..
The fact is the injectors don't get seized very often and as such there is no information available, until now!
 

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