Resucitating the M117

[tadhaggard]

Have a situation here that will be familiar to some, but not I.
I have a M117 motor in a W108 that was running, (very well a while ago) with little required for the job to be complete and the car on the road again. Then I got crook, the car was left, fuel in the tank coolant in the system battery removed (fortunately). When I finally recovered enough to re-aquatint myself it was a sad situation. I drained the tank and with fresh fuel and a new battery tried to start the motor. It did fire but was spluttery and stalled after starting several times it refused to do so any more.
I pulled the plugs and they were fouled, running rich it looked like, cleaned and reinstalled them and the motor fired again but the same result.
Then life got in the way. sold business, moved state, covid, house hunting, family etc. Shipped the car to my new abode and looked at it but did not touch for more than a year.
I am back at it now and with less pressures upon me I am going to finish what I have started. I have de-cluttered the engine bay and have made a list of what is needed to the best of my abilities. I want to start the car but don't want to make it worse than it now is.
What would be the best process to go through before turning the key. I had advice from John Green as to how to get the car going in the first place (vacuum line connections, electrical connections and fuel system alterations, there was a 3.5L M116 in it originally) which it did, well, as I said.
I am sure that I will have to replace the seals in the fuel distributor and clean out the fuel lines. Will I need to replace pump,filter or any of the other fuel delivery parts? Is there an accurate way to test them for delivery volume and pressure? Is the cold start regulator an integral part of the system when the cold start injector is disconnected? Would I need to replace the seals in this (CSR) and could a faulty(ie stuck open) cold start injector be responsible for the motor running rough and rich? How would I test this?
Any previous posts that have dealt with this issue I would be glad to have myself pointed at, and any advice, particularly warning against naivete that will beget catastrophic results, will be received graciously and result in me willing good fortune upon the messenger.
I want to love it back to life not love it to death.
Just throwing this out there as I have need.
Cheers
Tad Haggard

[John Green]

I would start with a clean tank, pull out the gauge sender and have a look inside, if al all suspect, take the tank out and steam clean it. . Once it has fresh fuel in it, and if the pump runs use it to flush 5lts of it though to the line that connects to the fuel divider, this will clean out the pump and lines. If pump doesn't work, new pump and then still flush the lines. I presume that when the conversion was done they used a k-jetronic pump? This is important as k-jetronic run at a way higher fuel pressures than nearly all other injection systems. The pump needs to be able to sustain 6-7 bar.

Then hook up the supply line to the divider and remove the return line back at the tank, run another 5lts of fuel though to flush the divider and the return line. Then hook it up and see if it starts. The injectors are most likely gummed up but quite often they come good once some fresh fuel goes though them.

Also I would buy a fuel pressure gauge like this one https://www.amazon.com.au/CTA-Tools-342 ... B008FJXA3M and learn how to use it and how k-jetronic works, there is plenty of info online.

[tadhaggard]

Thanks for the heads up John.
I had purchased all the M117 fuel delivery parts when the motor was changed, I think it was you that told me what to buy. I have taken your advice and studied up on K Jet fuel injection. I have drained the tank and removed the fuel gauge sender and the fuel tank is very clean inside. When removing the boot floor covering and spare tyre I noticed a rust problem where the bumper bar bolts to the body next to the tow/winch attachment hoop. I'll have to remove the tank to weld the replacement sheetmetal into the boot floor. I will use 1.6mm steel as it is a structural area. there is also rust in the floor-pan on the drivers side front but not much anywhere else. The tanks coming out anyway so I will steam clean it, just in case. I removed all of the fuel delivery parts and bench tested them. they worked fine but I did not pressure test the pump. Turns out the auto electrician who installed the pump had reversed the wires so the polarities were wrong. I corrected this and I now have fuel to the Distributor and the Cold Start Injector but I haven't checked the return line yet. I do not have fuel going to the injectors, at the distributor so I don't know if the injectors are sound. I have ordered a rebuild kit and will rebuild this. As I said I did not check for the fuel pressure. If the pressure was too low would this cause the distributor to block delivery or is it, as I suspect, just gummed up from sitting. I will order the tester you recommended and check pressure first before rebuilding but will rebuild anyway. I do not have the cold start injector connected electrically nor the WUR and the thermostatic valve gadjet between it and the Cold Start Injector has one hole blanked so would have minimal impact on running. Do I rebuild the Warm Up Regulator and do I blank off the line to the Cold Start Injector? (this does not leak fuel thankfully). Clearly I have a bit more study to do on K Jet injection.
I have put some before and after de-cluttering photos, I like the colour, I call it "Not Quite White". I think it is Ivory.
Cheers

[John Green]

A couple of points:

1) you need to wire up the warm up regulator as it needs power when the engine is running to warm up the bi-metalic spring inside it, this is what leans off the mixture as it warms up.

1.5) I would be checking if the warm up regulator works (using those gauges) before touching it. "if it isn't broken, don't touch it"

2) I would strongly advise against a DIY overhaul on the fuel divider, that is unless you have a Bosch test bed to set it up once you have cleaned every thing out. Same story and the warm up reg, run the engine and see what you have first.

3) cold start injectors very rarely leak.

[T-Modell]

...2) I would strongly advise against a DIY overhaul on the fuel divider, ...

Hi,
I was surprised too, that you can do this. I had a "presumably" overhauled fuel divider in my "new" M117 and it was not. Sent it to a "real" specialist and he found out, that the o-rings had never been changed. Unfortunately I cannot help you with a specialist in Oz, but after my repair (it was over 500 EUR) the motor ran surprisingly on all 8 cylindres

Regards
Thomas

[tadhaggard]

I have undertaken several restorations and have picked up the habit of replacing rubber but upon reading more on the K jet I can appreciate the more conservative approach. I have a history of loving things to death.
I presume that I wire the WUR to the W108 fuel pump relay to the equivalent pins to the W116. Further engine work will have to wait for the gauges. I intend to take some time on the body work
Cheers all

[tadhaggard]

Hi all.
The pressure tester turned up today and I connected between fuel distributor and warm up regulator as instructed. Pressure was 5bar or 72psi. When the tap was open or shut. I checked injectors and they appear to be working well.
I checked for spark and no joy. Seems my mechanical fuel injection problem is electrical. I'm such a goose. I have attached a pic of the ignition set up for any advice. The control box is still voodoo to me.
Cheers.

W108 ignition wiring.pdf

[Chai]

I have attached a pic of the ignition set up for any advice. The control box is still voodoo to me.

The text in your supplied PDF states "Green with Yellow Stripe and Brown from Alloy Control box not connected anywhere".
I've based the following statements on the (newer) W116 electric wiring diagram, which shows the transistorised ignition switching unit wiring:

• The brown wire is the Earth/Negative connection. (This colour is true for all MB car wires.)

• The green with yellow wire runs to both the (unused) diagnosis plug socket and the tachometer - via a connector that splits that one wire to both mentioned items

Connect the brown wire to earth and that should (hopefully) provide the needed spark.

[tadhaggard]

Thanks Chai,
We have spark. Up to my neck in rust repairs so potential explosives out of the way for welding. Will try and start after that.

[tadhaggard]

Hi All,
I have a question.
I have delved deeper into the mysteries of the K-Jet, I no longer find it mystifying, and have come to appreciate it, a lot.
Still I cannot get the motor to run.
I replaced the Accumulator which was defective and was in the process of changing the flap (it's not really a butterfly) that controls the air intake, which was bent slightly and I have a sound replacement, and decided to have a look inside the manifold.
Imagine my surprise to find a pool of fuel almost to the height of the butterfly attached to the throttle linkage in the bottom of the intake manifold. I then pulled the dipstick and have fuel in the sump (telltale smell and increased volume of oil). I am beginning to think I have a serious mechanical problem and suspect I am about to do some in depth dismantling.
I will remove the rocker cover and see if the push-rods are pushing. I have thoroughly inspected, prodded, cajoled and repaired the fuel injection and the injectors are injecting wonderfully. This fuel is making it into the manifold and no further by the looks except to leak down into the sump.
Could I have a camshaft chain broken or skipped a tooth (but if this was the case why the fuel build up?) I'll no doubt find out when I pop the rocker covers.
Is there anything that the collective has experienced that would point me in the right direction.
I have disconnected the coil and removed the battery. I have fuel and compression, add ignition to that and I have a bomb.
I know this is a bit of a "Hail Mary" but I am almost at my wits end. On the bright side I have been enjoying learning about K-Jet fuel injection.
Cheers
Tad Haggard.
Check the photos, reflection of the roof indicates depth of sump fluid and the other down the throat the pool of fuel.

[Chai]

Hi Tad,
You previously confirmed that the spark plugs are now firing. Can you please confirm that the distributor was NOT removed and then reinstalled from the engine?
I'm guessing that the spark plugs are not firing at the correct time needed for ignition to occur, so the unburnt fuel mixture in the cylinders have condensed, with the petrol then seeping past the piston rings and into the sump.
I'm not familiar with the K-Jet setup, so another guess for the source of the petrol in the intake manifold is the cold-start injector.

[tadhaggard]

Partly there Chai,
Checked injectors to see if they worked but didn't check to see if they stopped. Two were working overtime. I presume this is the cause of the fuel leakage. This of course became obvious after changing the Accumulator.
Have not changed the distributor as wiser heads caution against this.
I have another K-jet distributor and air intake that I can swap over to try if this one doesn't work.
Popped a rocker cover to find OHCam so no pushrods and cam and chain fine.
I will go through the protocol for setting up K-jet after sonic clean of injectors, oil change, and suck up all remaining fuel with air powered brake bleeder vacuum.
On the up side I am getting well acquainted with parts of my car.
Will still have to do brakes, spray rust repairs and air conditioning.

[John Green]

Partly there Chai,
Checked injectors to see if they worked but didn't check to see if they stopped. Two were working overtime. I presume this is the cause of the fuel leakage. Have not changed the distributor as wiser heads caution against this.
.
I will go through the protocol for setting up K-jet after sonic clean of injectors, oil change,

New injectors are under $40 each, so I wouldn't bother with the ultrasonic cleaner. https://www.supercheapauto.com.au/p/bos ... 18393.html



When you say "two were working overtime" do you mean two were injecting heaps when the others weren't? If so two possibilities

1) the other 6 are partially blocked
2) the fuel divider has either got blocked filters in the outlets, or someone has attempted a home rebuild and got it very wrong.

It is the adjustment of the divider to be 100% equal between all cylinders that is the difficult part for the home tinkerer to get right.

[tadhaggard]

Thanks John,
I've taken your advice and delved into the fuel injection system. By working overtime I meant they didn't stop. They are leaking, so yes I will also avail myself of the injectors you mentioned, at $40 ea I'll probably buy eight of them. So far the system has served up an Accumulator that was faulty, a stuck plunger in the distributor head (wasn't coming all the way down) and I noticed that the 3mm Allen Key bolt that is supposed to adjust the mixture at idle was not connecting with anything. The flap had a threaded protrusion hollow like a cup or tyre valve immediately beneath the idle mixture screw location so I am a bit worried that something has dropped off and fallen into the air intake. I have a gimmicky mini camera on a wire that plugs into my phone so I will shove that into the manifold nooks and crannies and see if there is any errant debris in there. Today I found that the inlet to the Warm Up Regulator had a filter that was so blocked it could only be called a plug, that's in the sonic cleaner as we speak but I will source another. I also discovered several small cracks in vacuum hoses which I have replaced and when I popped the valve covers I noticed that the oiler clips were past it also. These I have ordered. Fortunately the cam chain and tensioners and cam lugs are all fine. This whole process has had me find many missing rubber mounts, bolts, nuts, clips and all manner of other small problems which I am obsessively rectifying. This is going to be a well sorted car.
The rust repairs proved less onerous than I expected and I just have to put a final skim coat and finishing paint job on them. Does anyone have a recommendation for a paint matching place in Adelaide? I'm in Murray Bridge but it's only a hop from here.
Thanks for all your help and thanks for the nudge to get me onto the pursuit of knowledge with regards to my vehicles function, it is fundamentally the answer to all questions ("Teach a man to fish....etc.).
Cheers
Tad Haggard