Author Topic: K-jetronic pressure testing (troubleshooting)  (Read 4756 times)

daantjie

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #75 on: 10 April 2021, 05:09 PM »
Nice one  8)!
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #76 on: 10 April 2021, 05:26 PM »
Nice work!  It's a great feeling when it all comes together you're back on the road.
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

UTn_boy

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #77 on: 11 April 2021, 06:47 AM »
Took some borescope pictures of the damper cage today (the inside).

It's an old Bischoff 116 470 0516". It's hollow :-)

Pic 1 shows the zylinder wall and the round surface. One piece of metal that is bend. Fairly clean.

Pic 2 shows the opposite side. Two metal pieces are connected. We can see some rust. Confirms that stainless steel can rust, as expected :-)

Pic 3 shows the 14 mm inlet port. Fairly clean.

Pic 4 shows the leak port from accumulator. Full of particles that will go straight into the pump.

I'm considering ultrasonic cleaning. The damper is not that bad, but I have never tried it before, and this might well be an interesting opportunity to test it.


These damper cages are not stainless steel.  They are regular stamped steel, and were painted black when new.  And stainless steel does not rust.  It will stain, it can have deposits grow on the surface of it, but will never rust. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #78 on: 11 April 2021, 11:42 AM »
UTn_Boy: interresting that the damper was black when new. All gone now  :)

Are you saying the damper will eventually rust?
1975-mod W116 450 SE with 6.9 engine

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #79 on: 11 April 2021, 11:54 AM »
Great day today!

Tested the system pressure and control pressure during warm-up again. All good!

1. system pressure 5.2 bar (design spec says 5.2-5.8 bar)
2. Control pressure:
- Cold: 1.3 bar (design spec at 10 deg C 0.7-1.1 bar)
- after 10 min: 2.25 bar
- after 20 min: 2.90 bar
- after 30 min: 3.10 bar

Will probably go up to 3.2-3.4 bar when engine is really warm.

Also installed a new fuel hard-line between pressure damper and WUR. A bit tricky but worked out fine.

The car is transformed after the new fuel assembly! Engine starts immediately both cold and warm and idle is very good, although a bit high (approx 850-900 u/min, would love to have 750 u/min). AND, after the test drive today, I believe the car has more power, this is subjective  :)

On to next maintenance item.
1975-mod W116 450 SE with 6.9 engine

UTn_boy

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #80 on: 13 April 2021, 12:14 AM »
UTn_Boy: interresting that the damper was black when new. All gone now  :)

Are you saying the damper will eventually rust?

If left bare with no paint, then yes, it'll rust just from the moisture in the air.  Since it's already put together maybe brush some paint on it?  Just throwing out an idea. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1971 280sel Black/black leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #81 on: 13 April 2021, 11:54 AM »
Strange .... this damper has been out in the wet for 46 years and no signs of rust (nor paint).
1975-mod W116 450 SE with 6.9 engine