Have been taking a bit of a break again while I sort my ongoing back saga out. In my downtime I have had lots of time to think about and plan my next move on the path to getting the engine back in working order.
I have been watching heaps of the you tube video that Kent Bergsma has put out including everything he has done on fuel injection. Really feel much better prepared to tackle the issue I currently have with the bad over fueling issue.
In particular I have been very suspicious of the injectors. In two of Kents videos he talks about over fueling being a notorious issue on 'old' Mercedes and suggested that a good proportion, if not majority, of these problems can be put down to dirty injectors that are not atomizing, leaking at low pressure or both. His video, which I have a link to below, is quite compelling. If you haven't watched it I highly recommend you have a gander along with all his other gems.
In his videos he describes how he can test and clean the majority of faulty injectors at home with a simple hydraulic pump setup. He sells the kit for around 150US. To me that represents about the sum it would cost here in New Zealand to get the job done professionally. However as he pointed out if an injector is simply worn out no amount of cleaning will fix it and you may end up tipping your money into a black hole. At least with the pump you know what part of the ball park your in before you send them out for professional attention.
Fortune has smiled on me this week and while browsing a local ebay type site here in NZ I came across an almost identical unit for only 30USD. I decided to go for it and picked it up this afternoon. It came with all the fitting to mate up directly to the MB injectors which was another relief.
Screwed up the first one and already I think I have identified the issue. The injector seems to release a squirt of fuel without the gauge even registering. It would seem its stuck open. These should take around 250psi to even begin to open and should hold pressure indefinitely at just under this pressure. Take a look at the video for a demonstration of this.
I dont yet know if the rest will have the same issue or if they will be recoverable. I first need a gauge with a much lower pressure range. This unit was designed for diesel injectors which operate at thousands of psi. Kent uses a gauge with a full scale deflection of 600psi. I could get a 300psi gauge but you would end up risking blowing its brains out during the cleaning phase where you swap diesel for carb cleaner and pump the hell out of the unit to pulse the cleaner through the injector. So am on the hunt for a very cheap gauge now.
If your interested in the videos.
1) How to clean the fuel injectors using the pressure tester. http://youtu.be/Fb3fHKiVF4o
2) Testing of the W109 6.3 injectors http://youtu.be/za-5sW2QOIo
This one is interesting about the rescue of the red 113 they called Lucky. Of interest is that they got it so cheap because it had a burnt out wiring loom caused by those dodgy failing insulation of the wires around the alternator and the starter motor that I was talking to you about the other day. https://www.youtube.com/watch?v=wM55ZalsAcI
The same unit that I purchased second hand can be landed for about 120 US
http://www.aliexpress.com/item/PS400A-Diesel-Fuel-Injector-Nozzle-Tester/32274075667.html or you can just buy one off Kent for 170 which comes with a video instruction CD.