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Discussion Starter #61
Djenka - thank you so much, the info you share is always very helpful and I learn a lot from your good self - thanks for taking the time to share!

So it looks like my TTS is spot on in terms of specs - and we already know it works as expected in hot state given the CSV doesn't spray fuel. What I'll do today is measure the coolant temp and then measure the timing how long the CSV sprays in this cold state. If the flooding theory is to check out then I expect the CSV to spray longer than it has to given the coolant's temp, even if it's all "eye times Pi".

Re voltage regulator in the alternator - looking at the notes from the previous owner the VR was replaced in 2010 (ca. 7k miles ago) as the battery voltage was 12.5 when the engine was off, 14.5 when the engine was first switched on & then rising to 17.5 when the engine warmed up. The 17V were messing up the radio and blowing bulbs, so he replaced the Bosch part 0192 052 008 with Bosch 1197311090 - it looks like the first p/n is no longer available but both are specced for 14.1V. So again you're on the money Djenka :) I'll remove the alternator today to get it tested and rebuilt if needed, and I found a VR by a German crowd called Monark which seem to have a good reputation. The battery light could have been temporarily on before & I don't think I'd have spotted it given I drive the car primarily during the day, but the last time I drove it at night 2 weeks ago the light wasn't on for sure.

Now, onto your baby - first of all sorry to hear that! But as you pointed out, it's better to fix it rather than have it auto-disappear and come back to haunt you when least expected. The downside is that sometimes it's like chasing a ghost in the machine, and it's hard unless you're a Ghostbuster ;) What's your next steps - fuel pressure test? Or play around with the TTS / CSV and see if that makes a difference? Does she run & start ok once warmed up? That's been my experience anyway, i.e. issue only in cold start state leading me to believe that I've mix ratio problems rather than insufficient fuel supply as I've excluded compression, ignition, air and timing from the equation.
 

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Discussion Starter #62
Ladies and gents, mystery solved! Or at least I like to believe so, I could be gone crazy at this point.... Here's my findings:

- I measured the coolant temp - 16C, and the resistance of TTS indicated the contacts are closed.
- I removed the TTS to check p/n and I could tell the coolant where the switch is inserted was actually much warmer. Bottomline - the switch shouldn't spray ANY fuel at this point, even if the spec on it reads 15C +/-3C.
- I reinstalled the TTS and disconnected the CSV, pointing it to a bottle. I cranked the car after a few spins she fired up perfect, no hesitation, straight to idle. I checked how much fuel CSV sprayed and as you can see approximately 2-3ml; not much, but I assume it sprays much more fuel as coolant's temp decreases. This also explains why she starts fine every day as long as she ran recently, but will not fire after sitting in a garage for a week - at which point the coolant temp is equal to outside, probably 8-10C, and the CSV stays on for too long given the conditions and floods the engine.
- I then confirmed the CSV doesn't spray once TTS contacts are open, explaining why there's never any issues with hot start.
- Lastly, the alternator is putting out 13.75V so for now I'm leaving at as-is; dash light didn't come on, for now I assume yesterday was a result of messing with bits & pieces. Definitely need to watch out for that in the future.

To summarize, my conclusion is that while TTS works perfect in the higher temp range it doesn't do so at the lower temp spec, energizing the CSV for longer than needed given the actual conditions.

Now, onto the last pickle today (I hope:)) - I could use help confirming the correct part number of TTS as I still have no access to EPC due to upgrade to Xentry. There seem to be two p/n in circulation, 0045459124 and 0045459224 - one opens at 15C, the other at 20C, and some online portals list the as interchangeable but that's probably not the case given the different spec. Looks like mine is 15C, unfortunately the MB or VDO p/n is not on the switch itself.... So I'll appreciate some advice as I want to order a new TTS asap. :)

EDIT:Of course, video evidence below :)

 

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Discussion Starter #63
TTS part # is 004 545 9224, confirmed & ordered through local stealership = 鈧100 with the loyalty discount, could be worse!
 

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Discussion Starter #64
Ladies and gents, the switch arrived today and turned out to be 004 545 9124 i.e. equivalent to 9224 - it has larger body and shorter pin, but specs are the same. At any rate, I swapped the switch, reconnected the wire, cranked the engine and after 1-2 sec she fired up as if she just rolled off the factory line back in 1979 :D I am one happy camper today, it's beer time - or whatever's your poison!

I'd like to sincerely thank everyone for your thoughts, inputs, comments and guidance over the last few months - couldn't succeed without you, and the always useful "The Encyclopaedia Germanica Volume 107"! :bowdown::bowdown::bowdown:

 

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Discussion Starter #65
Djenka, Ted, any updates gents? Are ye back on the road?

I haven't driven my girl much, but I did start her up every 3 days to ensure the coolant's got a chance to reach ambient temp, and happy to confirm she starts on the button every time. Yesterday the temp dropped to 4 deg C, she cranked for 3-4 secs and came to life like a spring lamb. Runs perfect, no hesitation, happy days again :D
 

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nope, barely 2 bars system pressure will not run it.
trying to analyse to the N-th degree in false expectation to pinpoint the culprit. In the end it will be the elbow grease that fixes it.

diggin in.. as time allows.
 

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Discussion Starter #67
ooopss, sorry to hear that Djenka. I guess the only good news is that at least you know what the problem is, hopefully it's something simple between the pump and WUR. Let us know how you get on, always good to talk!
 

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Well crikey, 10l of fuel and she fired up again.
馃く damn it, these cars won't run on fumes from the tank

In defence of my stupidity, i blew through the return line and could feel the air struggling to push the fuel through the pipe (and some air gushing back after I stopped) which made me believe there was some fuel there.
System pressure 5bar, should be a bit more.
Control pressure 0.5 then within seconds 1.2 which is a bit low for 25掳C ambient in the garage.
Will look into it again tonight... at least she runs.
Julia Roberts smile.
 

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Discussion Starter #69
Well, if that's all it took to fix the situation then you're one lucky Mercedesoholic Djenka 馃檪 fantastic news, though interesting still - curious if the pump isn't on the way out, I'd think that as long as you're about reserve level it should fire up...

And 25 degree ambient is a welcome change I assume after the 40+ heatwave 馃檪 here in Eire we're about 5 degree this week, looking forward to the summer!
 

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Still troubleshooting. Replaced almost everything fuel and ignition related. It will start for a few seconds and then die. I think the control pressure is too high. Focusing on the WUR now.
 

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Discussion Starter #71
Sorry to hear you're still having issues, but sounds like some progress since last update Ted - were you able to pinpoint which component was responsible for the car failing to start? Also, is the car stalling on its own or does pushing the throttle make any difference?
 

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LOL... I stopped being excited when she runs as she does not want to start again... until I left her for a 4 days now she runs.
ATM my theory is that intake was flooded (because I was priming the WUR at baffle plate) and that goes similar to your experience of CSV being opened for too long AND/OR ignition timing goes out of wack by itself. Must get that green dizzy wire replacement from the resident bad parts supplier to keep sanity.

She runs again last night.
The timing was retarded by 30deg (i remember fiddling with timing following the last road drive). Could this create no start? I corrected this for standard version to 0deg (+/-3deg) with both vacuums at dizzy and will see later today how she starts. Want to do one thing at the time so that I can pinpoint the culprit and gain the confidence, rather than a scatter gun effect and hope for the best.

Revised K-Jet pressures: 0.8bar at cold start, 3.5bar at full warm, vacuum enrichment working and enough vacuum at idle to disengage it, 5.2 bar system. Barely passes and cold start is set too rich (by the table cold should have ~1.8bar at the 25*C-ish temp in the garage.
WUR adjustment is on the list once she becomes reliable runner.

But danm, she never ran this solid ever. The loss of power at ignition wires made her burn bad and although I had her tuned for good run it was a tiny balance of things. Now she has good idle with 2 plugs disconnected (just for test) and idle will not get her warmer than just above the 80*C mark (87*C thermostat if I remember correctly)
Will write a 'road to fix' story to share with others when I consider the problem gone.
 

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Discussion Starter #73
The symptoms you describe sounds like my flooding issue alright - I didn't touch the timing at all either before or after. I'm in the US this week but I fired her up on Saturday morning which was really cold, maybe 5deg C, and all worked as expected so my confidence is all time high that the TTS was the bad boy.

Good to hear the progress Djenka, do keep sharing how you get on. Hope for the best, prep for the worst, expect some surprises :D
 

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Just wrap it up, over last two weeks she started instantly no matter what condition and purred like a kitten as warming up and whilst hot.
Fuel starvation was the main culprit and I am yet to investigate further as she seems to cut out on a slope with estimated ~5-7L in the tank or bout half the reserve (but more fuel and she purrs again ).
But otherwise.... engine runs better with every passing minute ran. I need to pamper her not to spin the wheels atm, and she feels as if most of the 215 horses have returned (and I can see the rest of them coming back),
 

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Discussion Starter #75
That's great news Djenka, I'm delighted for you! Out of curiosity, do you often run on reserve or just got caught as a once-off which highlighted this issue?

As a rule of thumb, I tend to top up tank when I've approx a quarter left, not just for SL but the other cars too. Not sure if it actually makes any difference but in my head I convinced myself that it does no harm :D

My old lady is defo recovered too, I've just replaced the whole fuel package this past weekend which included flushing the tank etc. and after everything was put back together I cranked her twice, approx 6-7 secs each time, she started perfect and I'm a happy camper again - perfect time for the summer! :p
 

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Out of curiosity, do you often run on reserve or just got caught as a once-off which highlighted this issue?
whn I used to drive it more often, the reserve light gave me 50km city drive confidence
Never ran it more unless to the first fuel pump. I did the shame walk to fuel pump twice in life and the feel of stupidity prevented me from allowing this again. But I never shied driving on red reserve neither I panicked filling up early. I fill up full and drive until red reserve light, even decades before when I paid for the fuel from my own pocket.

But for better understanding the car was not registered for 5yrs now and I ran her around the block until the fuel pump rust seized in late 2016... replaced by the Easter 2017 which gave me about 1hr run on 10L fuel on an empty tank (replaced full fuel pump package) prompting me to think there is a fault with a real cheap fuel pump I got because I could not clean the tank at that time. Time was MIA and I could not spend more than 30 min randomly,combined with apartment garage etiquette ... until recently as my circumstances changed and I decided to burn some midnight oil for several nights... and here we are.
I have a bore scope and I will look in the tank to see if there is fuel varnish causing premature fuel starvation but generaly IMO running a stronger concentration fuel injector cleaner and some italian tune up fixes that. When the FP could not achieve more than 2-3bar I blew down the return line and it felt hard, much harder than anticipated but it was not clogged. I felt blowing into liquid and it would breathe back (as fluid filled up the pipe) but system pressure still did not want to go above 4bar until I topped up another 10L fuel.
Last week I took her outside and she stalled on the kerbside where the nose was ~10deg down but I poured another 10L and she started again.
I could be wrong and perhaps these cars can offer only ~3-4hrs of cold start to warm run at idle equaling .5-3L/hr (vs my modern car starting at 2L/hr to 1.5L/hr within minutes and then ~1.2L/hr at normal temp). I f this is true than we have a case of maladjusted expectations. I have no problem running her only with a full tank (and she handles better that way).
Either way, clogging will clean itself with use and I will replace the filter at first sign of problem.

I am actually quite happy I had this problem as otherwise I would not even look for ignition issues where I fixed *a major* problem. Now I'm keen to replace the timing chain as I *really* love noiseless idle.
Carby cleaner down the throttle until she chokes, rinse and repeat after 5min until empty 400ml can removed most of the tappet noise. Some tappet noise comes up with the throttle but I am saving some bucks to replace all 16 valve compensatators whilst replacing the timing chain (most prominent noise now) and then replace rusted out exhaust with stainless... and register her.
Amazing how silent these engines can be at idle, with a closed bonnet one could only know she runs because of the exhaust noise.

I see the pics of the fuel pump package and I am of belief that it is not consistent for a 1979 build. My car is 1979 builf CKD in 1980 and has metal link from FP to filter to accu (as seen on alu block engines) with a disabled overpressure valve which is integrated in the alu FD. but this could have been replaced/upgraded earlier in the life of my car.
Apparently they changed from setup as per your pics to allow quicker cold start as the accu gets to be filled up through a smaller dia pipe and fuel goes from pump to filter and to engine. Your setup will achieve system pressure a milisecond later and I believe it was abandoned in 1977-ish. I could be wrong.
 

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Discussion Starter #78
Got it, thanks for the detailed background Djenka. I think you're on the money with the fuel consumption at cold, all those horses are definitely thirsty.

What's wrong with the chain - is it slapping on the covers etc.? Maybe you'll get away with replacing the chain tensioner - I've ordered a new MB one today just to learn none are in stock in Europe and it's on backorder, no estimated delivery date. Some of us discussed our experience here https://www.benzworld.org/forums/r-c107-sl-slc-class/3017380-1979-450sl-117985-chain-tensioner-pickle-2.html incl. my latest faux pas with Febi tensioner; a big no-no.

You're right re fuel pump package and the benefits of the latter, which was changed for the set up you describe in Feb 1979. The first one to get the upgrade for chassis 107.044 was 53366, and mine is 53271... This is a good write up https://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Engine/107/M117_45/073-282.pdf I considered upgrading mine but in the end I opted to keep it as-is given negligible benefits and the higher price tag of the whole upgraded package. I took her out for a spirited drive yesterday and I'm delighted with the responsiveness, replacing all the bits & bobs over the winter months resulted in a smooth drive - I don't want to overdo it, but I honestly feel she hasn't ran this good since I got her in July 2015.
 

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What's wrong with the chain - is it slapping on the covers etc.?
I know the chain is stretched 6deg at the rhs cam and about 3-4 at lhs and I saw sprocket sharpen a bit.
Chain and cams will die prematurely with poor oil and one of the first things I had to do after purchase was to replace shaven camshafts but chain was assessed as usable. Overseas parts were not as easy to get to South Africa at that time i17 years ago and dealership was debilitating expensive.

I got Febi tensioner and Iwis chain several years ago and at that time there was no concern with its quality, I believe. I will bear in mind your experience.

For fuel pump upgrade all you teed is the metal pipe #26 and if your FD is aluminium, you do not need pressure compensator it is even easier.
You can pinch one from wreckers (any 126, 123 should have the same)
Fuel accu you have can be used with upgraded pump package, it is fitted oposite direction and you'll need to plug the outer hole (any fuel and hydraulic store will have the plug).

Bottom line, I find a lot of fun chsing these things, especially when the results are obvious.
 

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Discussion Starter #80
Got it Djenka, well in that case it makes sense to replace the chain although the stretch seems minimal? I should probably do mine too, given 68k on the clock and 40 years of usage as I've no evidence of the chain ever being replaced. I haven't checked how far off it is but given I don't get any symptoms that could be associated with stretched chain (backfiring, rough running, rattle, etc.) I expect it to be off somewhere between 5-10 deg, analogous estimating based on other folks' experience.
 
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