strange noise W114 - PeachParts Mercedes-Benz Forum

tc20 · #1 01-30-2006, 09:00 AM

Hi guys,
have noticed a strange noise just in the last week, coming from behind the
instrument cluster of my '72 W114 230. it only appears on start up, lasts a couple of minutes then disappears. the last week it has been colder here, but not below freezing. sound at first was like 2 plastic cogs (?) whirring but not mating correctly. this morning however, it was about minus 2C, and the noise was there again, but accompanied this time by a kind of 'howling'...
seems related to engine speed, and again died out after a few minutes.
any ideas what could be causing this?
thanks in advance.
tony

Mark DiSilvestro · #2 01-30-2006, 09:50 AM

The only 'howling' I've experienced from Mercedes instrument clusters was a noisy speedometer and it only happened when the car was moving. Mine responded to lubing the speedometer shaft bearing where the cable connects, wih ATF, and has been quiet for many years.

Happy Motoring, Mark

#3 01-30-2006, 11:03 AM

The only thing I can think of in the cluster that has much to do with engine speed is the oil pressure guage; not sure how likely this is to cause the symptoms though. No tach in that cluster right? If you pull the thing, make sure not to stretch the tach or speedometer cables, and to hook the oil line back up. If you don't, the thing spews hot engine oil in your lap to remind you something is amiss. Also, you could fix your odometer with a bit of loctite if it has stopped turning.

cheers,
dan

tc20 · #4 01-30-2006, 11:39 AM

Thanks for the tips guys, Mark i think you might be onto something.
all the needles/gauges are working perfectly, no tacho in the pod.
when i said the noise seemed related to engine speed i mean that the noise is only apparent when car is in motion, and the more i press the gas pedal, the louder it gets (the noise)???
im bringing the old gal up to my mechanic on wednesday anyway, apart from the carburretors being all over the place (twin zeniths), he tells me that some of the valve settings are way out, and some are stuck fast. so i guess i'll have some more queries in a day or two for you guys to ponder over

cheers,
tony

Tristar1959 · #5 01-30-2006, 12:44 PM

Concur with Mark and Dan's advice. Have had several noisy "chattering" speedos in W114's and W123's over the years - and all were worst when cold, frequently quieting as they warm. Most were like a cricket.
Your gear noise description is new to me, and can't imagine any "meshing" noises at lower speeds. If you do pull the speedo from the cluster (care with not bending the needle and with aligning the odo reset lever when you reinsert into case), you can remove the cruise control sensor (if has one) with one screw and take off the back, regrease the nylon odo gears, oil the input hub a few drops, and reassemble. Concur with ATF or light oil on shaft end - and tighten the knurled ring only to tight - not overtightened, which can lead to added pressure and misalignment (and more noise).

Another indicator is to see if you can detect a slight "flickering" of the needle whose timing matches the sounds your hearing, especially at low speed just as it lifts off the peg.

One added caution with regard to the oil line on the oil guage. While loosening or final tightening the 10mm fitting on the line from the guage, be sure to use wrench (12mm, I think) on the guage's female fitting - it's quite easy to torque the guage in the cluster, damaging it.

And yes, the hot oil in the lap is a great reminder - Been There, Done That!

Mark DiSilvestro · #6 01-31-2006, 08:47 AM

In the case of my '72 250, it began howling at the start of a mandatory 200 mile trip. After getting off at the next freeway exit, I was able to pull the instrument cluster out just enough to disconnect the speedometer cable and lube the exposed portion of the shaft and bearing with ATF from my power steering reservoir, without disconnecting the oil line or removing the speedometer from the housing.

Happy Motoring, Mark

kpb · #7 01-31-2006, 02:23 PM

Garsh Mark, who needs a garage and special tools for these rudimentary fixes!!?!

Sometimes when I get the urge, I just pull over to the side of the road and adjust my valves (NOT)

Mark DiSilvestro · #8 01-31-2006, 05:23 PM

No way could I put up with that racket for 200 miles. And when my previous W115 220 did the same thing, I tried to ignore it until the vibrations caused the speedometer shaft to snap, then I had to buy a replacement speedometer
If your valves were shrieking like my speedometer, you'd pull over and do something too!

Happy Motoring, Mark

kpb · #9 01-31-2006, 09:05 PM

Gotcha Mark. Just jerkin' your chain. Sorry...

Mark DiSilvestro · #10 01-31-2006, 09:33 PM

No apologies neccessary.

Nearly every Benz that that I've owned has eventually suffered from some speedometer ailment. Often, when the howling starts, it's been accompanied by the needle jerking and rapidly climbing to maximium speed. The first time I experienced this was the only time I ever saw 100 exceeded on my 180b Ponton's speedometer!

Happy Motoring, Mark

tc20 · #11 02-02-2006, 11:58 AM

Thanks for the info guys, will see if i can remedy the noise myself.
Is it possible to just 'tease' the instrument cluster out? there doesnt seem to be anything holding it in place. needles arent jumping allover or anything, just that irritating noise...
was up with Steve, my mechanic yesterday, just chewing over whats next -
when he noticed seepage from the head

Ah what the hell...
we were gonna tackle the valves and carbs, looks like we'll be doing a lot more. there's another paycheck gone.. Oh joy!
just on the subject of valves being stuck, Steve mentioned a 'special tool'
required to get at them. its like a 14mm (just bigger than half inch) spanner, but with a much thicker head. does this ring any bells with anyone who has done similar work,or possibly know where i could procure one of these babies?

Cheers,
tony

Tristar1959 · #12 02-02-2006, 02:22 PM

The cluster is held in by a ridged rubber gasket between cluster and dash hood. Removal entails the oil line, large electrical connector, speedo cable, cruise control/autothrottle connector (if has one); sometimes light sockets which press in and out of their respective holes.

Dunno quite what you mean by "getting at" the valve gear. The ball studs can generally be lowered and raised (adjusted) with an open-end spanner (I speak English, being Hahlf and haff) or with special tool open-end "socket" extension which fits over and around the ball/rocker ends; individual valve springs can be compressed with special tool or flats of a large square-shafted screwdriver levering against the camshaft whilst removing the rockers, tensioner springs, and thrust pieces; normal valve spring compressor used during head rebuild to compress springs whilst removing/installing the split collets under head of valve's shaft.
Really recommend getting yourself (and mech) either good factory manual or Haynes "Mercedes-Benz 230, 250 & 280, 1968-1972 6 cylinder sohc sedan, coupe, roadster" Manual.
If you're pulling the head anyway, seriously consider renewing chain slides/guides and oil tensioner and chain itself, while you're redoing valves - might prevent eating those lovely reground/replaced valves and a piston or two some 20,000km down the road...
And when ya lift/split chain, for crying out loud - make SURE you've got a secure wire attached to both ends - there are a lot of things more fun than trying to "fish" out a lost chain end - and you can use the old to "turn in" a new one.

Nothing is particularly hard about any of this engine work - but the right manuals make it a whole lot easier...

Enjoy!