1986 300E weird sounds when startup - PeachParts Mercedes-Benz Forum

muybweno · #1 11-29-2004, 06:31 PM

hey everyone. this problem has stumped me for a while and i can figure it out. maybe i should probably just take it to a mechanic instead but oh well..

anyways, i put the keys into the ignition and when i turn it to the first position, i can hear this clicking sound. Its very annoying and it used to go away before after i start the car up..but now it continues to keep clicking well after first position on the ignition. The sound is comming from the under part of the air filter housing, really close to the ignition coil that mounted on the side block of the engine. When the car is at go, i can still hear the clicking sound but it seems to go away when i apply breaks. anyone got any clues or had this problem before?

J.HIDALGO · #2 11-29-2004, 10:32 PM

It may be loose causing that noise but, since you said the noise is there even before you start the car, the fuel pressure regulator comes to mind as well as the idle control valve. Check those items...

muybweno · #3 12-01-2004, 10:48 AM

thanks for the replies...
I checked my sparks the other day..and holy S@#t!!!. they're hardcore coated with oil and carbon deposits, to the point where the electrode is almost grounded with the contact point of the spark plug

I guess its time for valve stem seals and guides to be replaced...do you think its related to that ignition coil not firing enough to the sparks to cause this oil deposit buildup on the spark plugs? or can it be related to bad timing, or perhaps that fuel pressure regulator or idle control valve..??

I really dont want to replace valve stem seals and guides...i've heard lots of stories that give mechanics nightmares about it.

samiam4 · #4 12-01-2004, 01:33 PM

??I really dont want to replace valve stem seals and guides...i've heard lots of stories that give mechanics nightmares about it.??

What nightmare stories? Occasionally a loose valve guide, but everything else is pretty straight fwd. 200k on a 86', I think it might be time. I think when I asked Mark Langston about what the valve job interval was for an early model, his reply was something like 50-160,000 miles. Or something like that- it was a big range based on oil changes and operation.

Michael

nglitz · #5 12-01-2004, 01:44 PM

The clicking noise is from the fuel system. It will go away if the cold idle mixture is adjusted a little richer.

How long have the plugs been in there? From your description, they seem to be working well. New plugs are cheap, and cleaning them is even cheaper. I've found a quick glass bead job helps a lot. Just be careful not to overdo it and round off the electrodes. I think blue smoke on acceleration after a long idle is more of an indication of the need for valve stem seals.

Best of luck,

muybweno · #6 12-02-2004, 01:02 AM

will a compression test tell me if i need a new valve stems and seals? But replacing them....i dunno if i can do them myself. I'm hella scared on doing on my 300D 78 that really needs it--litterally drinks about a qt of oil per 2 fill-ups; so i'm pretty sure i dont want to touch that job on my 300E. Some mechanic that i know stated that they had to pull off the camshaft, springs, timing chain, the whole 9 yards just to replace those $5.00 guides and seals. If i had the knowlege of doing the right way, then i'd take it up. But for the average joe thats use to spark plugs, oil, tranny, and coolant changes...thats a hmmm and studder for the moment.

BTW--Good point about the blue exhaust smoke! ; i'll look out for that the next time i drive.

so should i invest on replacing that idle control valve and fuel pressure regulator...not to mention a new fuel filter while i'm at it..??

samiam4 · #7 12-02-2004, 12:59 PM

For a pro wrench it is an easy job!

What is your oil consumption like? If it's low, then just leave things alone. I don't think the compression test will show valve guide wear unless severe.

early M103s are known that the valve guides are a weak point. Any 20 year old car, the valve seals will most likely be baked crispy.

For you 617 engine- it is NOT difficult to replace seals. I doubt you will find much difference in oil consumption when replacing them. Pull the rocker arm shafts, set piston on the cylinder you are working all the way up. Then unscrew the valve adjusters, remove spring, remove oil seal, install new seal. Do all 5, setting the adjusters for max clearance and reinstall rocker arms.

Then again- put new sparkplugs in the car and see how long it goes...

Michael