I brought the 4450SLC into a local Mercedes Shop today. I have done business with the shop for 10 years or so. The owner was trained by a local mercedes dealership, as two of his three techs, he was services BMW as he worked for a BMW shop which was owned by the Mercedes dealer, that being said. I took the car in for a general inspection of the drivetrain and to fix some problems. One of them is the off center steering wheel. Earlier this morning, he put the car up on a lift and was amazed how clean it was. but there is a slight shimmy in the front wheels, and the steering box needs to be tightened to were it is held to the frame. He suggested changing out the tie rods. the car had new tie rods installed in 00 and has only been drive about 2K miles since then. the shimmy in the wheels is not bad and I asked how about a front end alignment, he said lets see what I can do with the steering wheel first, playing with teh tie rod adjustments might bring it back straight, as it is off when driving to the right, but the tracks straight and even when you make a quick hard stop the car stops in a straight line. and only pulls when you try an turn the wheel straight. I was going to pull the wheel and turn it a notch or two to the left, but decided that doing it the right was with the chamber is better. Also, there is a bit of play in the wheel I measured roughtly 2inces right of left, which according to the shop manual is withn tolerance but should be about 1 1/2 inch either way plus or minus 1/2 inch. the shop owner thinks the steering box has enought adjustment in it to compensate. Also the idle is high when the engine is warm it is around 1000 to 1100RPM in Park or N and in gear around 800 RPM. This was after my son and I tightened the linkage and adjusted it as best we could according th the shop manual. before the tightening and adjustment the idle in Park was 1300 and in gear 1000. The owner said sometimes about the cold idle valve which cost around $600. might be the problem or a vacuum leak. I tend to think it is a vacuum leak. Since we got the car, I have replaced a lot of vacuum lines that were cracked or worm. Also, we installed the ACC servo yesterday and after bleeding the system, we now have a lot of heat. But when the Type II HVAC is on and I hit the Auto HI or Auto Lo buttom there is a squeal behind the unit, when I hit defrost, the squeal disappears, I have a feelin this is also vacuum. The previous owner had a Sony radio installed, one with a removal face plate and I am not sure how to take these out, any help here? Other then that the car runs very good, eats gas, but I feel that could be from being out of idle and perhaps a fuel/air and co2 adjustment might help. Also, the cruise doesn't work, in the owners manual it says to make sure you replace the stop light with the proper bulbs as this could effect the operation of the cruise control? any ideas about that statement? Thanks as always. I have to got to work today, God the thought of this is killing me. Be back on board tonight.

 

on the steering, the pitman arm shaft got adjustment screw to minimize the play.

if the tie rods got no play, no need to replace it.

you don't pull the steering wheel to make adjustments...just on the toe or camber.

squeal could be the blower motor? or leaking vacuum element?

stop light bulb affects the cruise control they say? does their face turns red while saying it? if not, you better whoop their ***.

 

Thanks for the advice on the steering. I am goin to pass along your comments to the mechanic.

Seriously I have read both in Mercedes literature and in retail literature that the wrong stop light bulb can in some models effect the operation of the cruise control. Also, on the MBCA Technical Forum there was a long string about this. it seems the wrong stop light bulbs effects older Mercedes benz cars then new ones. Also, I the factory service manual there ia a short sentence in the troublehooting section on the cruise and it specifically says first thing to check that the stop light bulb is of the corrrect wattage and correct bulbs number. I have read the wattage effects the cruise and other have said the bulb itself, wattage does make some sense as part of the cruise is electirc, but the bulb itself, unless the writer forget to mentione the wattage?

the mechanic also told me the idle control valve might need replacement, and quoted me $1000US for the part, I did some checking last night on line and a genuine new idle control valve on the sights that I looked at were price $239 to 289, and it is not rocket science to install. I am kinda disappointed as I have done business with this shop for years, and wouldn't expect this from the owner. unless he has some other part in mind or a later model SL? But I left a post on the MBCA board and the answer came back the the last thing to check is the idle control valve, vacuum leaks were number one, and the writer noted even a cracked valve cover gasket could cause idle problems. I tightened and adjusted the accelerator as close ot factory specs as I could, gave is a lube job, but I noticed the kickdown switch seems to me to be too far down, and I can't bend down there to look. These adjustemtn help bring down the idle, Also after reinstalling the ACC servo, heat is nice in the winter, the idle also came down a bit. Long story short I told the mechanic is it is the idle control valve to note it and I have to bring it back. I'll buy one myself and install it. Sleepwalker am I on the right track here with my thinking about how to cure the idle problem? Thanks for the imput, your advice is always taken very seriously by me, and I am going to take along your comments about the pitman arm and tie rods.

 

please tell me the VIN. i think the system is k-jetronic? i need to know your engine.

idle speed control and coldstart/warm up regulator is one unit.

 

VIN 10702412028087 and according to what I have information on it is mechanical FI? I could be wrong, won't be the first time. engine numnber is M 117.985

 

yes, it is CFI and got warm up regulator (governor). there is a big chance that your problem was from that and the mechanic can be right for he might have done some tests already.

the idle speed couldn't be high when engine is warm but too low when it is cold.

basic things first. put all adjustments to normal including the air/fuel mixture by using gas analyzer. 9eg. CO <1.5%, HC <100ppm, etc.).

if possible, put it in normal idle speed and check the ignition pattern using oscilloscope. (eg. start of combustion line is 0.6 - 12 KV, combustion duration 1.9 - 2.5 KV, etc). adjust ignition timing before doing it.

vacuum leak cause the high rpm, so better use gauge to see. not only for external vacuum leak but also from inside the engine such as engine timing, pcv, piston rings, valve seals, etc. common external leak on your engine is from the injector seals. pour water around those to see if the engine running changes.

does your engine got no electronic idle speed control? (a screw on the idle speed air valve which used to adjust idle speed). if no, electronic idle speed control cannot adjust the idle manually... which i think the one you got for you did adjust from the linkage.
you have to adjust the idle speed from the fuel distributor but that is included in setting the mixture i mention earlier.

anyway, doing your engine involves many things which is easy if you understand the system, but very difficult to discuss and explain.

narrow down the problem to avoid unecessary time.

check that idle speed contact switch too and the return spring on the

was the car hard starting?

was your cruise control unit number is 016 545 77 32? if yes, remove ground jumper from socket 12 to socket 14. connect ground lines or ground socket 12. socket 14 is no longer used.

 

I picked up the car last nite and the shop owner told me the idle was caused by a couple of things, the acclerator linkage was way out of adjustment, missing clips stop, etc., there was a vacuum leak in a line, which he didn't say and he had to also make a bushing for the kick down switch. He also fabricated new bushings for the shifter,and replaced the right valve cover gasket. Also, change the tranny fluid, and filter, engine oil and filter. He said "Al this is a great car, you got yourself a good deal." The other thing he found were the Flex joints aka guibo joints on the axle both front and rear will need to be replaced. Also got the aux fan working it was wired backwards. He replaced the stop light bulbs with the proper 21 (32cp) bulbs and now the cruise control works. Haven't paid him yet, as it was closing time so, I'll find out what the damage is tomorrow.

 

I've read that business about the improper stop light bulbs affecting cruise control before, but I have trouble buying it.

The cruise control works by latching a small relay in the controller when you turn cruise control on. The relay gets it's ground thru the bulb filaments on both bulbs. When you apply the brakes, the bulb filament becomes + (positive) and turns off the relay (and breaks the latch) because it is no longer grounded.

For the life of me, I can't see how one bulb versus another can make any difference whatsoever as long as one or the other bulbs don't have a broken bulb filament.

I say BS-it's an old wives tale.

John

 

And you've got 5 stars and also called a wizard??

You answered most of your own questions.
Vac leaks . Must ALL be fixed. Behind dash, on engine etc. Can play havoc with idle and HVAC.

Steering. Never move wheel off centre as box gets looser either side of centre so you will pull into a tight spot if freeplay adj after wheel moved. This is why there are 2 adj tierods.
If side light globes used instead of stop light globes their resistance is wrong for latching relay. 18 to 21 w should both be ok.

Bazzle