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280S ALIVE, but help needed.

Started by oscar, 01 December 2006, 09:49 AM

oscar

The good news is the 280S is alive.  I spent a few hours on it just to see if I could get it ticking over.  Firstly, I drained the oil.  Holly crap.  With oil filter still attached I placed a 10litre container underneath and it overflowed by a good margin.  Max is supposed to be 6litres :-\ .  With new oil I went to the igniton side of things.  Cleaned plugs and checked compression which was as follows:

Cylinder         1      2      3      4      5      6Press' (Bar)  <11   <10   >8    >9   <10   N/A

Couldn't measure No.6, too hard to get to with my guage.  They should've put No.6 in front of No.1 :D
Not bad figures IMO.

Anyway new battery and a bit of pumping and the old girl kicked in but it sounds a bit agricultural with idle problems and an exhaust leak, there was a bit more to do.  Even when warm the car wouldn't sustain an idle.  For starters I found the igniton to be set at a whopping 20oBTDC :-[.  I mucked round with idle for a fair while and unfortunately, unless I drive with both feet to keep it going, it'll stall.  Incidentally, S class talked about the diff earlier.  I now know what you mean. To add, the whole drivetrain really grabs, too hard IMO.  If idle's too low (set normal @ 750rpm) it stalls not long after going into R or D.  Rev higher around 1000rpm or the idle was initially 1180rpm, kick it into R, and the rear weels will screech a bit.  You end up standing on the brakes a bit harder, then give in and let it go.  The engine doesn't labour, it's almost as if the car has a manual transmission and the engine is in constant mesh with the rear wheels.

Once on the road, my only real complaints would be the reluctance for it to go from 2nd to 3rd gear (assuming I have normal 3spd, not the hidden 1st gear type 4spd A/T gearbox), the inability to stop at a giveway without reverting to neutral first, and the general roughness of the engine at idle.  Once you get over the 60km/hr mark, and the revs stay high, it's quite smooth.  I like it :). But down low, apart from the grabby A/T, the idle is a bit rough.

EDIT: I forgot to add, I tried identifying misfiring cylinder/s by removing igniton leads in turn from the dizzy's cap whilst the engine was idleing.  2, 3, 5 & 6 each saw the rpm's drop a little.  However, when 1 & 4 were pulled, the engine died completely. Any ideas why?

There's a few more things so please click and refer to the pics and q's:
I've found some answers, shown in blue.  Still having problems working out other bits and the idle problem.  Changed dwell today to the recommended 40o. A little improvement but still rough at idle with misfiring plus the stall problem.

There's a yellowish lacquer substance covering parts of the engine bay, particularly noticeable here on the radiator shroud. Any idea what it is?


There's 2 female 2 pronged plugs hanging here between the solenoid and the engine.  They connect to the main harness near the solenoid.  Any ideas where they're supposed to be attached?? Just found out these plugs are for a Solex carburettor.  They activate idle mixture cut off valves not present in this form on the Holley



This metal bit in the fuel line just before the carby.  What is it and should there be a hose attached to the bottom bit? Is in fact a draw-off valve. It's upside down, hopefully blocked and usually vent fuel fumes into a Solex carby.


Side of the Holley carb.  Wish I had a Solex original although a Holley may be cheaper to service.  It's lacquered and dirty inside.  Any idea what this loose lever is supposed to be attached to?  It looks like a spring should be attached to the end.





Red advance and white retard vac lines are still attached to the vac switch on the firewall but cut from dizzy and plumbed together.  Got no idea why?  Dizzy's advance and retard diaphragms hold a vac. Actually they haven't anything to do with the dizzy.  I found out these are connected once again to a Solex carby, and mediate the choke via a vacuum and the switching valve on the firewall



Still attached, should there be a third line in here?  No, read above.


Engine is oily below head. Does this mean anything drastic?  It drips oil to the floor as it did on the trailer on the way home.


Previous manifold repair.  Can't pinpoint another leak that I can hear.


Check out the engine mounts.  Right then left.  Does anything look odd??  Should those threads be visible as if there's bolts missing?  The mounts look dodgy.



The odd lead on No3.  Anyone seen one like it?


Guys, there's a lot of info I'm asking for starters here.  If you can compare the pics to your own or have thoughts about what's causing the engine problems please don't hold back :) Thanks.  I'm starting to think the Holley carb may be part of the problem with a few of the subsystems designed for the Solex disabled.  I'm sure the auto choke works fine but not sure how. ie it's connections.

1973 350SE, my first & fave

s class

Wow you've been busy Oscar.  No kids?

Q1 : yellow lacquer substance - I dunno, but is it waxy-  could it be some sort of tectile type rust preventative that's been carelessly applied?

Q2 : plugs - you answered that

Q3 : draw-off valve - answered

Q4 : extra levers on the holley carb - I know nothing about holley carbs.  Are you considering gonig back to the original solex?  It might be much simpler to get it operating properly.  How much is one at a breakers yard?  If its very expensive, I will offer you my 280S carb and related bits gratis - it will just be a question of postage.

Q5 : vac lines - you answered this.  Again it sounds like these mods may be contributing to your idling problems.

Q6 : excess engine oil.  I'm assuming the high oil level hasn't helped this issue.  I suggest you clean it and then see where its leaking from.  The photo you show the location of the temperature switches where they scre into the top of the head.  Be aware that this car has an engine assembled as follows : (from bottom to top)

small sumnp
main sump box
block
head
cam box
tappet cover.

The gasket you see next to thos temp swithces is not the head gasket, but rather the gasket between the head and the cam box.  You can replace this gasket but it is a bit of an exercise because it means disconnecting the chain.  Also bear in mind that 50% of the cylinder head bots are exactly that, the other 50% are longer and pass through the cam box, through the head and into the block.  Attempts to remove only the cam box and thus result in the head gasket integrity being disturbed. First verify if this is the locatoin of your leaks, and then I gan give you some more suggestions

Q7 : manifold leak.  Oh brother man I pity you.  THis is a miserable design and I guarantee you you will not find a permanent fix.  Problem 1 : the gaskets between the 2 three-into-one headers and the top of the Y-piece fail due to expansion and contraction.  You can replace them but it is a miserable job and it doesn't last;
problem 2 : the Y piece distorts over time so the top gasket mating surfaces no longer are in the same plane and they don't meet the headers as required
Problem 3 : the y piece tends to split.

SOme years ago I spent AUS$150 for a new Y-piece which solved problems 2 and 3, but only temporarily.  Eventually I gaveup and substituted 280E manifolds which have a different, problem free, arrangement.  If you are interested I can provide close-up photos of the problem areas of the standard system, and close-up photos of the modification I made, and how to route the exhaust pipes. 

Incidentally I'm a determined type, and I only gave up on the standard arrangement after some 5 years of concerted effort to overcome it. 

Q8 : engine mount bots - mine look the same

Q9 : ignition lead supressor - this is acheap spares shop type.  I have them on my car and they are 'okay' but they are very susceptible to problems with moisture getting in when driving in the wet.  Get Bosch or Beru.

Ryan



[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

oscar

MAN!!! I just lost my reply post, I hit shift and something else and the screen went back to the thread GRRRRRR! this happened the other night too.....

Anyway, Ryan, thanks sooo much for your input.

Quote from: s class on 03 December 2006, 03:49 AM
Wow you've been busy Oscar.  No kids?

I've got kids, 4 of 'em; 5yr old daughter, 8yr old son, 33 yr old 350SE and now a 31yr old 280S  :D But I also have a DVD player with lots of kids movies to babysit :-\  I'm also a bit of a nightowl, doing all the quiet non-powertool jobs overnight.

Thanks so much for the offer of the Solex. The Holley seems very much like the Solex in design and function ie 4 barrel, 2 stage. I'm going to persevere with it and will pull it apart eventually.  There's plenty of info about them, just have to identify what model I've got.  If all else fails, I'll be happy to offer you some $$$ for your Solex.

Q6 & Q7, Thanks again for this info.  If you do have those manifold pics, you can email them to me at simnat@ozemail.com.au.  They will come in very handy.  As for the head, it's black with oil and I mistook it for the block but you're quite right about the boundaries between the engine assemblies/components.  I retightened some tappet cover bolts but two spark plug area gaskets remain wet with oil. It seems obvious to me that it would do a world of good just to replace all gaskets.  I'm looking forward to removing the head, the M110 seems far less intimidating and easier to work on than my M116.

My progress today. Replaced spark plugs with NGK BP6ES (old were DENSO w6.....something, never heard of 'em), isolated accessory vac system due to no vac locks working or vac in main reservoir, replaced ignition wires with 6 of the best used BERU wires I had spare on hand, plumbed vac line for dizzy and fuel draw-off valve to the inlet manifold where the accssory line was. 

There was some improvement in the decrease in misfire.  But what I found was after warming up, the engine would become starved of fuel.  I had to depress the accelerator then let go to pump more fuel, idle would stay high then slowly come down and then die if I didn't pump fuel again. Clamped draw-off valve to no avail.  This sounds carby and/or fuel pump related.

Lastly the A/T.  thanks for your info you posted in your A/T thread.  So I do have the 4spd.  It clearly needs work.  I adjusted that accelerator pushrod according to your post and the online manual.  I did it both ways to no avail.  Going from P to R is violent with revs up over 1000rpm. There's the 0.5 of a second for the A/T to engage but then it grabs and the engine dies not long after.  Same for N to D.  I'll go after the linkages like you suggest.  Whatever the A/T's problem, there's still no excuse for the engine to die under load at a high idle.  There's some form of regulation not happening. 

Back to it tomorrow. I lost hope at one stage today and started looking at the trim again to see what I could replace on my 350.
1973 350SE, my first & fave

s class

Oscar,

The functioning of the A/T is strongly affected by the engine performance.  I suggest you get the engine running correctly first (ie correct vacuum performance) before you make conclusions about the A/T

Ryan


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

Mforcer

I have nothing to contribute to help you other than thanks for the great, detailed posts. It seems you have quite a puzzle before you which should be a lot of fun to solve! :)

And in future, I find that doing a quick copy of any text I have written online before posting allows me to 'paste' it somewhere else should something go wrong.

Keep the posts coming! :)
Michael
1977 450SE [Brilliant Red]
2006 B200

oscar

Thanks Mforcer,

A little update, the idle mixture screw was wound all the way in, thus starving the engine at idle.  Found a complete Holley catalogue with good tips, that helped.  S class I think you're right too.  The A/t behaved better today with this constant fuel supply at idle figured out.  Still haven't got a vacuum gauge which is imperative to properly tune the carby but there's also a slow leak from a float chamber gasket since this idle screw has been adjusted.  A set of seals/gaskets and a proper tune will eliminate the carby as a problem IMO.  Will come back with details when I've figured out how to do it.  Cheers. 

PS, also found an accessory vac attachment to the carby which is unconnected and unplugged.  That's another problem that should be easily sorted out.
1973 350SE, my first & fave

s class

Goodness,

It sounds like this car was seriously badly set up.  It suggests that half of the A/T's problems will also be setup issues.  How's the PO enjoying these progress postings?

Ryan


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

oscar

Not sure yet.  I've been meaning to contact him again but I keep finding little things to fix or adjust on top of the engine problems.

Whilst I'm getting closer to solving engine problems, there still remains the issue of regulation of engine speed at idle under load.  The car now idles in D and R without stalling and without a high set idle before the load.  With the A/C on it will still stall whilst in D or R.  But I really think that plugging the accessory vacuum port on the carb will overcome power loss at idle to the point where one more warm idle rpm adjustment and idle mixture adjustment will see the engine running smoother under all loads.  Still need to properly tune the carby with vac guage though.  If all that works out, I don't think too much will have to be done to get it on the road again.  I don't know whether the manifold and oil leak problems would see it knocked back for road worthy, nor the non functioning central locking.  Probably wont be seeking registration until next year sometime.  Still have to pay for rego and repairs on the 350.

BTW, are these A/C systems noisy?  My 350 still on R12, although now leaked dry, was quiet.  The 280 has the vertical type compressor with top cover plate visible, still R12 and working.  You can hear it work away but the noise whilst the gas circulates is like a churning bubbling sound that can be felt in the cabin and thru the steering wheel.  Is this because it's just an old design, low on charge? Just curious if it needs looking at.  I don't want to have it evacuated if I can help it.  I don't know any auto-electricians well  enough to give me R12 if it has to be evacuated.
1973 350SE, my first & fave

s class

#8
The V8's use a sort of recirculating ball or vane type of A/C compressor.  I'm not sure what the proper name is.  The 280 engines use the old York compressor.  Its basically an in-line 2-cylinder machine with the pistons arranged vertically.  Mine was always nopisy as you describe, and eventually I decomissioned it because it sounded terrible.  It turned out it had piston slap due to bearing problems.  Unfortunatley there is no overhaul kit available for this compressor.  I replaced my compressor with a brand new one, at a cost of about AUS$900.  At the time I also replaced the drier, and had the system flushed and evacuated, and properly relubricated.  It works very well and has the best cooling power of all my cars, but it is still noisy, in fact it sounds the same as the one I replaced.  - basically gurgling and grinding.    I guess that's just how they are. 

Ryan


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

oscar


Thanks for that, you've put my mind to rest on this one.
gurgling and grinding, that's definitely a more apt description.

A bit of clarification sorry- I understand then you got the same type York compressor ?  Also, still R12 refrigerant?  Just wondering if a GM type on the V8 would mount in the same spot.
1973 350SE, my first & fave

s class

I guess anything is possible.  You would probably need to manufacture a custom mounting braket, and be aware that on the York compressor, the hoses enter at the top, whilst on the V8 type compressor, they enter from the rear, so youwould need some custom plumbing.  My opinion is if your A/C is working fine, stick with it.  If you ever need compressor replacement/overhaul, it might be a cost effective option to do the swop.

Ryan


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

Papalangi

On my 450SEL, and thus I assume on your car, when the A/C is on, a vacuum change over valve on the firewall changes the vacuum signal to the retard/advance cans on the distributor to bring the idle up and prevent stalling.

I think you still have some vacuum leaks to find and fix but it sounds like you are on the right track.

I found that if I tightened the air cleaner mounting stud, it would warp the baseplate and kill my idle.

Michael
'83 300SD, I'm back!  It's the son's new car (12/2020)
1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023
1976 280C
1970 250/8

oscar

Thanks Papa, you've got me thinking.

I've seen (photos) of 116 firewalls that have more than one vac switch.  Especially some Californian specced cars with extra emission controls seem to have at least three.  Form the manual, my single vac switch is supposed to control a Solex carby choke whereas my 350's single vac switch (in the same spot) controls retard, and advance is controlled by intake manifold pressure for both.  That's from memory but I'll recheck.  PO stated a new dizzy had been put in which by the looks and condition of it is a used 280se's as there is a retard and advance port connection. A carbied 280S has only an advance port.

Two things; you're right about vac loss in all regards.  I also used advance vac line that is too thin for advance.  Fix the leaks and ammend the line will see more improvement I reckon.  I'm a few days off remediying all that thanks to work. 
Oh, a third point; screwing the air cleaner down.  I need a new seal around the top of the carby which is worn/squashed, which means the cleaner gets screwed down further to make a seal.  I'll make some closer observations considering your finding.  Thanks for the tip.
1973 350SE, my first & fave

Papalangi

I just noticed your location.  My US spec '76 280C (W114, not W116) with the M110 and Solex A1 had a dual can distributor which controlled idle speed and emissions.  The retard side may not have made it to the AU spec 280S W116.

Do you have the idle shutoff solenoids in the carb base and if yes, do they both work?

Michael
'83 300SD, I'm back!  It's the son's new car (12/2020)
1976 450SEL, 116.033  Sold it to buy a '97 Crown Vic.  Made sense at the time.
1971 250C, 114.023
1976 280C
1970 250/8

oscar

#14
Quote from: Papalangi on 06 December 2006, 02:55 AM
I just noticed your location.  My US spec '76 280C (W114, not W116) with the M110 and Solex A1 had a dual can distributor which controlled idle speed and emissions.  The retard side may not have made it to the AU spec 280S W116.

Do you have the idle shutoff solenoids in the carb base and if yes, do they both work?

Michael


Hmm.  I honestly thought a Solex carbied M110 had a single can dizzy whereas d-jet and k-jet might be doubled.  According to a pic in the online manual 7.5-510 shows a pic of a single can distributor.  But like many pics, it could be generic or an older photo from a W108 or similar used for illustrative purposes.  The other anomaly is that my dizzy has the rev limiting type rotor (as does my d-jet 350) like the top photo and the pic in the manual shows a regular rotor like the one in the bottom pic.




I forgot to mention the retard side of this dizzy is capped with what looks like a proper rubber cap, not some homemade fix.  So despite the anomalies with the dizzy, it looks like it has been adapted to fit the car. It's also Aus delivered not an import.

Re: the idle shut-off valve solenoids, being a Holley carb: list 8007, there is no valves (in this form).  I edited my first post after I found some answers to what some unattached bits were. The plugs to activate the solenoids were left to dangle in the 2nd pic (first post) and I subsequently found their sole purpose  is to return to their natural resting state (closed) and basically cut fuel supply when the ignition is turned off.  It makes sense that if these were faulty or working intermittently, the engine would be starved for fuel.  I'd have to delve too far into schematics of the Holley carb to see how the same thing is achieved but it looks like a vacuum and ball bearing valves could be involved.
1973 350SE, my first & fave