Author Topic: Got a new project, pictorial  (Read 25861 times)

TJ 450

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Re: Got a new project, pictorial
« Reply #120 on: 22 October 2008, 07:06 AM »
It sounds like something's out of whack, like all of a sudden the fuel is cut. :o

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
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koan

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Re: Got a new project, pictorial
« Reply #121 on: 22 October 2008, 12:06 PM »
Do I hear a backfire sometimes when stand on it?

If yes, I'd agree with lack of fuel.

koan
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oscar

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Re: Got a new project, pictorial
« Reply #122 on: 22 October 2008, 01:12 PM »
On the lack of fuel, could vac leak and therefore lean mix be doing the same thing?  I suppose it could.  There's a few things I have to look at for vac leaks but this car has no central locking components and I haven't been able to tell yet whether it's been removed and not plugged.  Was there ever such a thing as a w116 without central locking?

I've also noticed the idle is high.  It was always high but I think it's picked up a bit. 

There was one hint of a backfire at the beginning.  I haven't noticed backfiring on this car but then again, if I floor it when the engine hasn't fully warmed up it will.  In the video the coolant was over 80degC.   Today I'll look for a backfire.  The thing is, remember how the red 280S (with Holley) used to backfire easily.  The way to avoid it was use the accelerator in two half steps when going to full throttle.  I think I'm so use to doing that now that I do it in Povo without thinking about it.

After reading a bit in the manual, I'm positive it has to do with the secondaries, ie lack of fuel from coming thru its jets perhaps but I fell asleep reading it all last night :D I think I'll have to start again.
1973 350SE, my first & fave

craigb

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Re: Got a new project, pictorial
« Reply #123 on: 23 October 2008, 03:39 AM »
It is interesting. Yes seems like you are opening up this big influx of air but not being able to get fuel to it. Vacuum leak alone I don't think would have that much affect. I assume vacuum to the secondaries within the carb is working otherwise it wouldn't behave in this starved manner. And what has changed? Is there a pump jet to the secondaries? I don't think there would be with vacuum secondaries, and even then, I think there would be a stall from not getting the pump squirt but once the other jets cut in you would think it would start kicking back in, which it doesn't. And what has changed for such a sudden impact? With a 4bbl too, to have both secondary jets cut off at once seems a little odd, but maybe they are fed by the same passage. For me, I reckon I would pull the carby off and give it a good clean out - seems a bit of an obvious suggestion! Anyway, just thought I would think out loud about it in case it helps in anyway. Maybe pull the air filter off and get someone to rev it while you watch from under the bonnet and see if there is anything obvious.
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oscar

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Re: Got a new project, pictorial
« Reply #124 on: 23 October 2008, 12:52 PM »
Well I've narrowed the problem down and almost got it back running properly yesterday.  Speaking of secondaries, the flaps above them are supposed to be closed at rest.   At the beginning of Stage II those flaps or air valves remain closed for a short time.  Of course a little air gets past but the vacuum created underneath sucks fuel through the bypass jets.  Then as the vacuum increases and air flow increases, the air vlaves open right up exposing the Stage II jets.  There's a vacuum dashpot connected to the shaft of the air valve.  It's job is to make the transition further moderated by controlling how slowly the air valve opens for full throttle.  So spring tension aside, without it, the air valve can open suddenly and fuel supply through jets is affected adversely.

This is pretty much what's happening with mine.  The spring tension had virtually gone for the stage II air valve.  Plus, the dashpot is leaking but always has.  Add to that, the air valve's shaft was stiff to move.  Lots of crap in the joins and bearings.

So when I go full throttle, the secondary air valve jumps open.  There's no vacuum below the air valve to suck fuel through the bypass jets to begin stage II let alone fuel coming through the stage II jets.  No fuel, no power. 

So I should be able to retension this valve spring.  Easier said then done.  I can't find the sweetspot.  The manual's got a plan for a  custom test tool to calibrate the air valve.  I can't make it.  I'm also wondering whether I can get away with a dodgy dashpot.  The manual refers to stage jump without it, which I don't mind, but the second stage has to be operative.


I removed the inline fuel filter thinking it might be a restriction.  I couldn't find anywhere in manuals where the fuel filter is on these carby cars.  There's nothing in the back like the FI cars.  There's just the screen in the fuel tank and a pre filter in the Solex.




Pre filter in Solex




View of the Solex




What needs adjustment




Removing and cleaning the air valve componets made a big difference.  Before it would bind when moved.  It needs to be frictionless almost for an attempt at calibrating to be worthwhile.

« Last Edit: 23 October 2008, 12:57 PM by oscar »
1973 350SE, my first & fave

oscar

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Re: Got a new project, pictorial
« Reply #125 on: 27 October 2008, 07:49 AM »
 
For me, I reckon I would pull the carby off and give it a good clean out -

I didn't want to but it's the best thing I've done so far.  The Solex is back and better than ever. ;D  I found a bucketload of info on the web the other night, mainly from BMW forums but although nothing pinpointed my problem there was enough info out there to give me the courage to take it off and strip it.   Three problem areas existed.

1.  It was full of crap and crud.  Little tiny metal shavings came out of the fuel bowl plus lacquer in the primary jet valves and the secondary fuel valves were binding. I used a can of carb cleaner and it did wonders.  I blew out all the jets and vents and flushed any bit of sediment out or off the carb.

2. The float valve is adjustable by way of bending the arm going to the float.  To me this seemed too far bent thus causing a restriction of fuel during high loads. 

3. Most importantly, there is a bakealite cam connected to the secondaries' air valve shaft.  When they open, the cam operates a lever to open the secondary fuel valves.  My thinking is that the binding of the secondary fuel valves and the forced mechanical movement of the secondary air valve has led to this cam breaking.  The result is that the fuel valves remain closed and no fuel enters the secondary barrels. 

The first picture shows the extent to which I pulled the carb apart.  Note to the left of the pliers is the air valve shaft, then the lever to operate the secondary fuel valves. 




The second shot shows the broken cam that is mounted on the secondary air valve shaft and sits inside the "U" shaped section of the lever for the secondary fuel valves.  A bit of Araldite and a few hours wait it was right to go.




Third shot is what happens to a nokia when left on a rag soaked with carb cleaner :(



So although the camera still works,  I wasn't in the mood to take anymore shots or video of the test run but by midnight I had the carby back on and went for a spin and the result is fantastic.  The car runs smoother at lower speeds and the full acceleration is back.  There is still a little bit of tweaking to do , especially to the idle mixture and spring tension to the secondary air valves but I'm happy for the moment to know it's working again 8)
1973 350SE, my first & fave

koan

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Re: Got a new project, pictorial
« Reply #126 on: 27 October 2008, 08:27 AM »

Third shot is what happens to a nokia when left on a rag soaked with carb cleaner :(


Funny about that, I did the same thing with the portable house phone a couple of weeks ago.

Do you reckon the glued up cam is up to it? What about a bit of brass and a few hours with files etc.?

koan
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oscar

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Re: Got a new project, pictorial
« Reply #127 on: 27 October 2008, 08:38 AM »
Although the secondary fuel valve is very light to operate I've got my doubts how long the cam will last to be honest.  Furthermore I can't find these cams available anywhere and they're not available in the rebuild kits.  So I think brass would be a perfect replacement.  I think a thick brass shim or thin plate etched to the correct shape would do the trick.
1973 350SE, my first & fave

oscar

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Re: Got a new project, pictorial
« Reply #128 on: 06 November 2008, 05:30 AM »
The cam is surprisingly holding together.  The cars done maybe 100km's since then on a few trial runs and is still opening the secondary fuel valves.  Haven't had a chance to make brass ones like wanted and instead have attended to other need to do things.  Primarily the steering box and vacuum dashpot for the solex.

The dashpot has simply got a leak so I thought why not cut it open and repair it.  I cut a small patch from a kids tyre repair kit but it wouldn't hold despite the surface being cleaned.  I was going to give up and I just used what I had on hand which was araldite.  Competely wong product to use but I did and it's working, though I need to change it.  It's slowly leaking again  from the same spot I hope, after working well for a while.  Need to use something with a bit more flex like silicone.  I put it back together using two blobs of solder which is holding well.  The cut was on the vented side not the suction side so no need for an air tight seal there.








The big job was the power steering box.  It took me about 12 hours over 3 days.  Most of that was due to being a first timer and lessons learnt along the way.  Undoing all the bolts and things isn't too bad, it's the wrestling with the box and alignment that I had difficulties with.

Although I have removed and replaced a coupling before and had real trouble with the allen bolts, these looked like they were going to give me hell too when my tool slipped in one of the heads so I soaked both in INOX then did something else for a while.



I took off the pitman arm.  All that muck is due to the steering fluid leak from the box.  The nut is a 36mm big one so I had to go buy one of those.



In order to remove the coupling though I had to allow the shaft to be withdrawn.  I just took off the inner and outer circlips that hold that bearing and subsequently the shaft.  I then mount the steering wheel and by hand apply the 22m retaining nut and give the steering wheel a pull.  That should free the coupling from the steering shaft or the steering box.  Either way the coupling can be slid or prized off both shafts afterwards.


Next thing is to remove the high pressure and return lines from the box then remove the three bolts, accessible in the driver's side wheel well, that hold the power steering box to the engine bay.  In a 280 the box was removed by lifting it up throught the engine bay.  Took a fair while of manipulating it to fit past hoses etc.  The manual suggests removing the ball joints of the track rod and the drag link from the pitman arm.  Would've made it easier to ease the old box down rather than lift it through the engine bay.  Here's a pic of replacement(left) v old.   On the ground the the old one's freeplay was noticeable by hand, feeling a knock when it changed direction.  The replacement felt smooth.


So putting the new one in, I lowered it through the engine bay and rested it on whatever was in the way to stop it from falling on the ground.  I slid under the car and held the box in one hand and applied the bolts with the other.  Surprisingly, although the box is heavy, this took no time at all and although I thought I might have needed assistance from another person, it wasn't needed.
When I came to put the Pitman Arm on I struck a bit of trouble.  It was too hard with the track rod still attached.  It was physically limiting my movement of the Pitman Arm making the alignment of the notches impossible no matter which way I had the alignment notch facing on either box or arm.  So I removed that ball joint and got the alignment I was after then screwed on the big 36mm nut.



I took out the bolt that covers the alignment hole for the shaft.  Seen below is a gap in the box's piston where an alignment bolt would go to get the box in dead centre.  No idea where to get that bolt so I just viewed it and turned the input shaft as necessary.  The pic below shows it not quite centred yet.


Be damned if I could get that coupling to go on right though!  In the process of getting the steering shaft and the box's input shaft far enough into the steering coupling so the clamping bolts clamp over the right indents, I had inadvertently shortened the steering shaft.  These shafts are telescopic and a few blows with a mallet at the end whilst trying to put the coupling on will shorten the steering shaft.  Whilst you can adjust the length in situ,  I decided to remove it, it seemed easier.


Seen here is the hole on the left being obstructed by the thinner part of the shaft telescoping into the thicker part.  I adjusted it back by putting the thin part in a vice and hitting laterally the thick section at the point where the thin section meets.


Once lengthened I loosely put the shaft back in the steering column then attached the shaft to the coupling.  With the box in alignment I then made the alignment notch on the steering shaft (at the end facing the driver) point straight downwards (straight upwards for LHD cars).  It appears in a pic further above.  The shaft and coupling were then prized onto the steering box's input shaft.  No hammers or mallets, the shaft and coupling are prized onto the box's shaft by levering at the notch at the left on the shaft towards the firewall with a long screwdriver .  Once the notch become fairly visible I had to use something to act as a pivot between the end of the steering column jacket for my long screwdriver. 


I put the steering hub back together and applied replacement race steering wheel.


The result was that it drove fantastic and didn't float around on the straights.  Steering was much tighter, not just due to the smaller diameter wheel.  Freeplay is still there but nothing like before.  I don't notice it.



I also replaced 3 main coolant hoses up front, changed engine oil, Super Dot4 brake fluid bled in, new PS fluid and before I put the new oil in I tool off the old dented sump and replaced it.  The newer one is a w123 style with a much smaller bolt for a plug rather than the trditional bigger 14mm allen plug.





1973 350SE, my first & fave

koan

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Re: Got a new project, pictorial
« Reply #129 on: 06 November 2008, 06:32 AM »
Lot of work and expense there oscar, must be seriously depleting the 6.9 fund ;)

Don't understand what all belting and prising of the steering coupling is about, it should just slide on and off.

The bolt shank won't slip over the splines on the steering box, the bolt needs to be removed completely.

koan

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oscar

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Re: Got a new project, pictorial
« Reply #130 on: 06 November 2008, 07:05 AM »
You know, last year I had a couple of chances early on to buy sub $2k 6.9's but I opted out since we were building at the time. If I was given the same opportunities in May this year before I acquired Povo we might be discussing 6.9 issues not Solex's.  Not to worry I suppose, I've well and truly compensated by indulging in this pursuit since then and the cheap 6.9's have all but disappeared.  Will do an approx tally of costs soon but I don't think I could race, keep the 350 and have a mediocre 6.9 needing attention.  One would have to go.  I dread the thought of having to choose.  What's that saying, -- you wont miss what you haven't got -- What bollocks! ::)

Steering coupling - The clamping bolts were removed but although the shafts of the box and column were clean and undamaged I couldn't get either to go all the way in.  They slid in half way no problem.  That's when I banged the steering shaft from inside the cabin and consequently shortened it.  Then after removing and lengthening it I found the notch that could be used as a levering point and that worked really well.  It drove the coupling and shafts into place so then the clamping bolts could be inserted into the right spots.  Maybe because the coupling was a used one it was a bit tighter than a new one.  I had similar probs with the 350's and reusing the old coupling.  Just a real snug fit is all and not enough room to grab it by hand and shove them all together.
1973 350SE, my first & fave

koan

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Re: Got a new project, pictorial
« Reply #131 on: 06 November 2008, 02:56 PM »

You know, last year I had a couple of chances early on to buy sub $2k 6.9's


If I had the room I'd collect them at that price.

Quote

Steering coupling


When I think about it I have had to jam a big screwdriver in the clamping split to get it off.

That closeup of the coupling is excellent - it shows it correctly installed with the coupling extending beyond the start of the spline on the steering box shaft. It's all to easy to get it wrong and have the clamping bolt go through above the shaft rather than in the groove.

koan
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TJ 450

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Re: Got a new project, pictorial
« Reply #132 on: 06 November 2008, 08:09 PM »
That's coming along nicely, Oscar. I reckon you'll have one of the cleanest 280s' around by the end of this exercise.  8)
It's amazing the difference a fresh sump makes in terms of appearance.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

John Hubertz

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Re: Got a new project, pictorial
« Reply #133 on: 08 November 2008, 07:26 AM »
Wow - congrats.

And the wrinkle-finish on the Nokia doesn't look too bad.

Melt ALL the phones IMHO - I despise telephones.

This one has its merits - I wish all the bluetoothers had to have this model:

John Hubertz
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oscar

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Re: Got a new project, pictorial
« Reply #134 on: 08 November 2008, 12:38 PM »
hehe.  Now that's making an anti statement.

TJ, wish I could make the rest look like that.  But I'd love to see the internals be spotless too.  I was surprised to see the hard baked oil deposit on the upper half of the sump.  Plus the general colour of components.  If you remember ages ago seeing Carl J's 280's engine it was clean as new.  Amazing.  A testament to frequent oil changes.
1973 350SE, my first & fave