[W126 Coupe] Hydraulic Compensating Element question

[Chet Hwilka]

Hi Attila,

 

According to the oil gauge, I say the pressure is great.  On start up it
snaps to the top and stays there, even at idle (550-600rpm).  And the cam
lobes look and feel perfect, not a blemish on any of them.  I have not
enlarged the oiler holes, but when I did the valve job a few years ago, I
made sure the tubes were clean and holes were not blocked.  

 

BTW, the couple of days the temps here in New Jersey have been in the upper
90's.  I keep the car in an attached garage that is at least 15-20 degrees
cooler and the engine has been quiet as a mouse.

 

Thanks for the input and hope you're doing well,

Chet

 

  _____  

From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]
On Behalf Of Attila
Sent: Tuesday, July 06, 2010 6:32 PM
To: 'Mercedes Coupes Mailing Lists'
Subject: Re: [W126 Coupe] Hydraulic Compensating Element question

 

        Does the oil pressure bar jump up to 3, immediately,

on start-up??

        Does it go below 2, at idle.  If so, it's not the HCE.

        Have you enlarged the oiler holes on the bars across the 

top of each camshaft bank??

        The cam-lobes themselve(s) may be worn, as unseen

by the naked eye.

Put in 2 quarts of straight 50 weight (remove 2 quarts

first).  If the duration of the noise is less, you may have

a pressure issue. 

I'll keep reading and keep you posted.

 

  _____  

From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]
On Behalf Of Chet Hwilka
Sent: Tuesday, July 06, 2010 3:53 PM
To: 'Mercedes Coupes Mailing Lists'
Subject: [W126 Coupe] Hydraulic Compensating Element question

 

Hi All,

This one has me thoroughly stumped. I've followed the procedure in the
manual for testing the HCE (that's the hydraulic ball stud that the valve
rocker arm sets on) and have not been able to determine the bad or weak one.
The HCE basically performs the same function as a hydraulic lifter,
automatically adjusting the intake/exhaust valve clearance using the
engine's oil pressure.

I've got a valve clack for the first minute or so after the car has set over
night.  The colder it is, the longer it takes to quiet down.  Once the oil
warms up it purrs like a kitten.  The procedure calls for checking the play
of the rocker arm while the cam lobe is in the up position (opposite the
rocker arm), also using the butt end of a hammer handle to press down on the
HCE and noticing how fast the HCE collapses.  All the rockers have the same
amount of play side-to-side and nothing up-and-down.  (I did replace 2 of
them a while ago hoping to get the bad ones.   Those new ones have the same
play as the others.)  No matter how much hand pressure I put on the hammer,
I can't get the HCE to collapse at all.  I would think there isn't a problem
with the HCE's.  Also the cam lobes and rocker arms look like new.  Not a
wear mark on them.

The clack sounds like it coming from the left bank, but I can't narrow it
down where.  And by the time I really get to probing around the clack
stops..

Does anyone have any other suggestions??  I'd hate to have to just shotgun
the whole set (at about $50 a piece) when it only sounds like a single valve
clack..

BTW, I change the oil every 3k miles or so and the chain, guides, sprocket,
cam, valve cover look great..

Thanks

Chet

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