1984 W126 500sec help needed

[neil.b]

hello all, i have a few things wrong with my car and was wondering if any of you guys could help me out

problem 1: cold start

my car is lousy at cold starts, i have to push and hold the accelerator pedal to get my car to start when its cold , then i have to keep revving it till its a little warm before i can let off

problem 2: higher idle speed in neutral/park than in Drive

as above really, having read a couple of posts i think this could be something to do with the idle air valve? any further guidance on where this is and how to fix it would be great

problem 3: belt butler/ rear screen heater fuse

basicly the fuse keeps blowing, i put a new fuse in and then a few days later it blows again, any idea what could be causing this?

problem 4: only the passenger door window works

all the other windows make a horrible gringing noise when i opperate them, although at least the motors work, is it a big job to replace the worn gears?

problem 5: this is the biggy that really has me worried

when i first bought the car i got home and noticed a water leak of some kind so i opened the bonnet to find water spewing from the radiator header tank overflow, i decided to let it cool down and topped up the coolant, i also noticed the big thick hose going to the top of the radiator was full of air so i disconnected it and filled it with coolant then re connected it. after i did this it seemed mostly ok although it has pressurised up a couple of times since and i have to keep an eye on the coolant level as it sometimes needs topping up, any ideas?


any help with any of these problem will be greatly appreciated, thanks in advance

 

[Mikesmerc]

Hi Neil
my 560 is having similar problems but I will have a stab at your Qs
1. Cold start injector not working.
2. Idle Air Valve sticking(as mine) Relacement usually the only answer but check posts that I have placed re this matter.Some good answers there.
3. Duno
4.Haven't had that problem(yet)
5. The coolant system is supposed to pressurise. Perhads its a faulty filler cap(broken seal or weak spring). Just check the cap for oil deposits as it may be a blown head gasket over pressurising the system.
Hope this is of some help to you.
Regards
Mike

 

[neil.b]

there is no oil in the water and i dont think there is any water in the oil so im hoping its not the head gaskets, could it be something to do with the rad fan not working properly, although when it does start spewing water out the engine temp dial reads normal

 

[Mikesmerc]

When you say not working properly is the fan cutting in when the temp rises? How hot does it get?
I have had heads crack on some of my older mercs which pressurised the cooling system because the crack was in the combustion chamber and so giving no trace of oil at all. Every 2 or 3 days I would have to top up with a pint or two.
The only other reasons I can think of for high pressure is overheating or faulty cap or the above. Hopefully not the heads

Regards
Mike

 

[neil.b]

[prays]please god not the heads lol[/prays]

the temp reads at about 80-90 degrees C, could it be the viscus(spelling) thingy on the fan, is there any way to check if this is working ok?

i will replace the rad cap as a matter of course even though upon close inspection it apears to be ok

its going for an mot on monday so i hope it passes, i just put new discs and pads on the front and gave her a quick check over and nothing seems obviously wrong to me so fingers crossed

 

[Mikesmerc]

Hi Neil
when she is at this temp. the viscous fan should feel stiff to turn by hand as opposed to when she is cold it turns freely by hand. Not exactly sure at what temp the fan starts working at.
Enine turn off when checking :lol:

Regards
Mike

 

[Mikesmerc]

Hi Neil
when she is at this temp. the viscous fan should feel stiff to turn by hand as opposed to when she is cold it turns freely by hand. Not exactly sure at what temp the fan starts working at.
Engine turned off when checking :lol:

Regards
Mike

 

[neil.b]

yes, i like my fingers atached to my hand

 

[jaques2k]

Does anybody know if the 560SEC from -87 have electric clutch on the fan or not (not the extra electric fan of course)? I had mine running on idle for a few minutes while listening to the beautiful sound =D and the fan suddently cutted in for a short moment and then cutted out again. The sound when the fan cut in was noticeable, e.g. it started to spin faster (turned around somewhat all the time though). Did they change from viscous to electric in 85? Just curious...

 

[Mikesmerc]

Im sure my 1990 560SEC is viscous.

Regards
Mike

 

[guydewdney]

if you have a look at this site - http://pages.prodigy.net/jforgione/MB_S500.html you can see that there is a bi-metallic clutch thing for the fan - maybe the sec has the same?

i'd suspect a split in the hose for the leak..

also check / replace temp sensor(s) - not expensive (15 quid?)

take door cards off and lube motors etc with spray grease / GT85 (NOT wd40)

lube belt butler (good name! - actually called belt handover arm) - maybe its getting stuck and the motor is drawing too much current? maybe the heated window wires are shorting out?

 

[spanners]

Problems

The 5.6 litre 107 engine always had a viscous fan which has a bi-metalic clutch built into it.

For some reson they do some times cut in when the engine is cold for a short while when you first start up. Don't know why.

Neil

Most garages should have a simple carbon dioxide tester which can tell if the pressurising is due to blown headgasket/s or not.

You may even be able to buy one yourself.