Author Topic: K-jetronic pressure testing (troubleshooting)  (Read 2795 times)

rumb

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #60 on: 14 December 2020, 04:39 PM »
The vent line can go either place. The rubber fitting or under the intake manifold.  There is a drain hole in the block to let anything that get in there out beneath the car.  Draining to the rubber hose it will either put gas in your oil or make your car run rich, neither things I would want. The EPA has different opinions.....
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #61 on: 15 December 2020, 12:15 AM »
Rumb; thanks for quick response. This is interesting.

Can you tell me a bit more about the drain hole in the block? Where do I find it? The idea is to guide the hose into this hole, or let the leaked fuel flow find its way into the drain hole?

Do you by chance have a picture of this drain hole?
1975-mod W116 450 SE with 6.9 engine

raueda1

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #62 on: 15 December 2020, 09:31 AM »
Rumb; thanks for quick response. This is interesting.

Can you tell me a bit more about the drain hole in the block? Where do I find it? The idea is to guide the hose into this hole, or let the leaked fuel flow find its way into the drain hole?

Do you by chance have a picture of this drain hole?
It's about 1 cm dia and at the low point at the rear of the block in the "valley" of the V.  It's very close to the oil pressure gauge fitting.  It's very difficult to see with the intake manifold in place.  It's even more difficult to see if it has been obscured by years of junk, dirt, etc.  Mine was completely blocked with fuzz from what seemed to be an old mouse nest.  I was horrified.  Good luck!
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #63 on: 15 December 2020, 10:49 AM »
Thanks, raueda1

I will search for the drain hole at the weekend. I have currently access to a borescope, maybe that helps.

So the solution is to put the hose a few inches into the hole, and make sure it stays there? No fire hazard associated with this alternative?
1975-mod W116 450 SE with 6.9 engine

daantjie

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #64 on: 15 December 2020, 09:58 PM »
Rumb; thanks for quick response. This is interesting.

Can you tell me a bit more about the drain hole in the block? Where do I find it? The idea is to guide the hose into this hole, or let the leaked fuel flow find its way into the drain hole?

Do you by chance have a picture of this drain hole?
It's about 1 cm dia and at the low point at the rear of the block in the "valley" of the V.  It's very close to the oil pressure gauge fitting.  It's very difficult to see with the intake manifold in place.  It's even more difficult to see if it has been obscured by years of junk, dirt, etc.  Mine was completely blocked with fuzz from what seemed to be an old mouse nest.  I was horrified.  Good luck!

Nice one Dave!  I did not even know about this drain hole.   I went and checked mine and it was gunky of course :o
The drain exits just aft of the sump on the driver side.  I saw this hole before and thought it was a bolt hole, who knew 8)
Daniel
1977 450 SEL 6.9 - Astralsilber

raueda1

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #65 on: 16 December 2020, 07:41 AM »
Rumb; thanks for quick response. This is interesting.

Can you tell me a bit more about the drain hole in the block? Where do I find it? The idea is to guide the hose into this hole, or let the leaked fuel flow find its way into the drain hole?

Do you by chance have a picture of this drain hole?
It's about 1 cm dia and at the low point at the rear of the block in the "valley" of the V.  It's very close to the oil pressure gauge fitting.  It's very difficult to see with the intake manifold in place.  It's even more difficult to see if it has been obscured by years of junk, dirt, etc.  Mine was completely blocked with fuzz from what seemed to be an old mouse nest.  I was horrified.  Good luck!

Nice one Dave!  I did not even know about this drain hole.   I went and checked mine and it was gunky of course :o
The drain exits just aft of the sump on the driver side.  I saw this hole before and thought it was a bolt hole, who knew 8)
And you just completed the puzzle!  I never figured out exactly where the exit was, there was just dripping of solvents etc from someplace under the engine.  The whole damper design seems pretty cockeyed to me given that failure seems to risk hydrolock or engine fire.  Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #66 on: 17 December 2020, 01:48 PM »
I searched for the drain hole today, without luck. I need to use a camera with USB to the pc, I guess.

Another try at the weekend.

raueda1; is it possible to take a photo and point in the right direction?
1975-mod W116 450 SE with 6.9 engine

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #67 on: 17 December 2020, 02:10 PM »
A great day today - all parts have arrived. The whole assembly is new - except damper cage, large bracket, small bracket for the tank hose and metal connection from accumulator to feeder hose/fuel line.

Notice the little pre-pump inline filter 14 mm next to the tank hose. Will keep the pump clean.

A few more things to check and clean and then we will fire up the old man. Exciting times .....
1975-mod W116 450 SE with 6.9 engine

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #68 on: 17 December 2020, 03:10 PM »
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.
1975-mod W116 450 SE with 6.9 engine

raueda1

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #69 on: 17 December 2020, 06:47 PM »
I searched for the drain hole today, without luck. I need to use a camera with USB to the pc, I guess.

Another try at the weekend.

raueda1; is it possible to take a photo and point in the right direction?
This is the best pic I have and is the best I can do right now (car is in storage).  I'm pretty sure it was taken with engine removed from car.  Anyway, you can identify the oil pressure gauge line, circled in yellow, which is snapped off at the top.  The other larger tube is the brake booster line.  The red line follows the border between the block and transmission flange.  The plugged blue hose is where the heater hose would normally be.  Finally, the green scribble shows approximately where the drain is - except that it's under the intake manifold so not visible.  Again, it's very close to the rear of the block at the low point.  Very, VERY difficult to see.  I didn't even know it was there till I had the heads off and the block totally exposed for cleaning.  The bottom of the block "V" just collects dirt, grime, rust flakes, mouse nests and all manner of garbage.  The layer on my car was about 0.5 cm thick back there!  I guess the point is, that it might not be visible at all if it's clogged like mine was. Maybe a stiff, bent wire to probe around?  Good luck and cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

Jan S

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Re: K-jetronic pressure testing (troubleshooting)
« Reply #70 on: 18 December 2020, 07:20 AM »
Fantastic, thanks a lot!
1975-mod W116 450 SE with 6.9 engine