how to flush 3.0 liter ohc 6 cylinder engine

I need to know how to properly flush the FUEL system on my '89 3.0 liter over head cam 6 cylinder engine in my '86 Mercedes 300e. My previous post didn't distinguish that from the coolant system. Sorry!
rgman@wi.rr.com
Most articles and faq's I've found only provide pieces of the puzzle, I need the whole damn puzzle to do this right.

[sixto]

I'm trying to say this in a kinder, gentler way (without invoking a thousand points of light) - you really need a manual if it's too much work for you to piece together the advise in the archives.

That said, it's a job you can trust to good instincts and advise. The manual says nothing about converting an old thermostat into an always open bypass port blocker so you can flush the engine without getting to operating temps, or that citric acid is much cheaper at a [plant] nursery than an MB parts counter.

The procedure is something like set the ACC to defrost, drain the coolant through the radiator petcock and the block drain just ahead of the starter (remove the reservoir cap and thermostat to ensure max draining), install the reworked thermostat if you're going that route, fill with citric acid solution (I don't have the concentration spec handy), run for x minutes, drain, flush with water enough times that you're comfortable that water coming out is about as citric acid solution free as you'll get, fill with deoiling solution (don't have the concentration spec handy, but it's just dishwashing soap and water), run for x minutes, drain, flush with water enough times that you're comfortable that water coming out is about as oil and dishwashing solution free as you'll get, install a new thermostat, fill the system with fresh MB or aftermarket G05 coolant (if you're going by the book) and water in whatever concentration you choose.

If what comes out the first time is fairly clean coolant, flush a couple of times with water and fill. There's obviously no scale or oil to remove. If what comes out is green, flush until what comes out is no longer green unless what you'll be putting in is green in which case we've found a major difference in philosophies.

You can try Redline water wetter and a 20/80 coolant/water solution. From what I understand from Redline, water wetter's benefit don't manifest as well with a 50/50 coolant solution. Just thought I'd toss in another piece of the puzzle

Oh, these posts help more folks in the tech help forum.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

[sixto]

Boy that's egg on my face. I saw flush and went on a tear. No wonder I have so many posts to my credit

You can't flush a K-Jetronic system because all the sensitive parts are downstream of the fuel filter. You don't want to get dirt in the fuel distributor. If there's already dirt in the fuel distributor, you're out of luck because you can't flush it and not many shops are qualified to service it.

Chevron Techroline (Techlorine? ) is okay and I understand Redline fuel injector cleaner is okay as well.

If it's not running right, there's lots of information in the archives on testing the EHA, idle valve, O2 sensor and other bits of the puzzle. If you want a really puzzling problem to solve, look for posts by Ron Johnstone.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

[Eberhard Weilke]

Cleaning the fuel distributor at the K-Jet is possible. I did it myself. I try to write a how-to-do tonight.

Kind regards
Eberhard

[Eberhard Weilke]

First of all: You shouldn't use engine flush on a K- or KE-Jet. All the parts are down the fuel filter. There is actually a chance to damage the system when you push the flush through the filter to dilute the dirt in there...

One thing to do is to replace the fuel filter and this pressure storage thing above the fuel pump.

What you also can do is to clean the fuel distributor to get the piston working freely again (and check first if you have a K- or KE.Jet, I don't know about the younger models)



The fuel distributor is the part at the right side of the pic. Get a clean cloth and put it on you workbench. Use WD40 (or similar) to brush with an old toothbrush to whole area around the fuel distributor. You don't want to have dirty stuff falling into anything.

Unscrew all the fuel lines, the one coming in and the six leaving and put them aside.

Unsrew the two or three screws on top, which you can see between the fuel lines.

Now lift the whole thing carefully and take care not to loose the rubber sealing ring below the distributor.

Put the distributor upside down on the clean cloth. On the bottom you will find a littel metal clamp which holds the piston. Push it carefully aside so that the piston can slip out (if it is not moving freely we very likely have found the reason for a bad running engine ) Be very carefully not to scratch or twist the piston, the smoothness of this system is dead important!

Clean the piston with a piece of cloth. Blow the dirt out of all the openings carefully (there is a spring on the bottom which we don't want to have flying through the workshop! You will be surprised who much dirt you will find. Also cars, which have been sitting for a while, are likely to have a stuck piston in the fuel distributor.

Then put everything together in the opposite direction. Carefully. Don't forget the sealing ring


You may want to check the even pressure of the fuel lines. But that is a workshop work, you need the right tools. The fuel nozzles in the intake manifold hardly ever break. You can check them visually by bending one fuel line and attach them one by one. They should have an even cloud of fuel. But better stop smoking and have a big fire extinguisher handy



Kind regards
Eberhard