[W126 Coupe] 1- doesn't start in cold 2 - oil pressure strange

[eurotech1 at charter.net]

Hi Richard,

  Well, it almost sounds as if your pump pick-up is momentarily losing suction when the oil sloshes forward during braking. But if the oil level is correct, and you only have 1500 miles on your last oil change (you have checked your oil level?) it probably wouldn't be that.
Is your motor sludgy? I have seen debris in oil pans get sucked into the pick up screen and partially block the flow. Usually though, it will be a constant low pressure condition, not momentary, as you're describing. That's a real headscratcher. Anyone else got an idea? 

                  Christopher Huffine
> From: "Shayegan, Richard" <rishayegan at davidson.edu>
> Date: 2005/01/23 Sun AM 11:01:05 EST
> To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
> Subject: RE: RE: [W126 Coupe] 1- doesn't start in cold 2 - oil pressure strange
> 
> It's not so much that I'm getting sharp fluctuations in readings at
> steady throttle. What happens is this. If I'm driving, all is normal.
> When I'm pulling to a stop, the oil pressure goes a little low (before I
> said 1.5, it's more like 1.8) and then when I come to a complete stop
> the engine will do a quick rev (so little it's not picked up by the rpm
> gauge, but I can hear and feel it), bringing up the oil pressure to
> about 2.8, and the rev is picked up by the economy needle going 1/6 of
> the way to the right and back. Also, sometimes (not all the time, I
> wouldn't even say most of the time), when I come to a stop I won't get a
> rev to bring up the oil pressure. Instead the oil pressure will stay at
> about 2 and the economy needle will come to a rest about 1/10 of the way
> to the right instead of pegging to the left. I'm starting to hate
> vaccuum btw. If only there were a way they could have made it without
> involving rubber or plastic.
> Richard
> 
> -----Original Message-----
> From: mbcoupes-bounces at mbcoupes.com
> [mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of
> eurotech1 at charter.net
> Sent: Sunday, January 23, 2005 1:29 AM
> To: Mercedes Coupes Mailing Lists
> Subject: Re: RE: [W126 Coupe] 1- doesn't start in cold 2 - oil pressure
> strange
> 
> Hey Richard,
> 
>  Your economy gauge is basically just a vacuum gauge ( reads high vacuum
> at idle, vacuum decreases as throttle is opened ), could indicate a
> vacuum leak somewhere if you're experiencing sharp fluctuations in
> readings at a steady throttle position.
> 
>                    Christopher Huffine
> ------------------------------------------------------------
> > From: "Shayegan, Richard" <rishayegan at davidson.edu>
> > Date: 2005/01/22 Sat PM 04:00:01 EST
> > To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
> > Subject: RE: [W126 Coupe] 1- doesn't start in cold 2 - oil pressure 
> > strange
> > 
> > The battery is the official benz battery and is about 2 months old, 
> > has no leaks. Is there a way to check the cold start sensor short of 
> > replacement? As for the oil, it looks clean, has 1500 miles on it, of 
> > which 1200 are highway. Also, I've noticed some more things. The oil 
> > pops backup because the engine does a quick surge (just once, not 
> > picked up by the rpm gauge, but I can hear and feel it). The engine 
> > surge is also accompanied by the fuel economy gauge going from the 
> > left end to
> > 1/6 the way to the right and back to the left end. Also, sometimes 
> > when I stop the engine won't surge, and the oil pressure will hang out
> 
> > at about 2. When this happens, the economy gauge doesn't peg at the 
> > left end (like it should at idle, and most of the time does), but 
> > rather it will stay about 2 economy-gauge-needle widths to the right. 
> > I remember when I once mentioned a problem Jonathan asked what the 
> > economy gauge did at idle, so I'm thinking maybe this indicates what
> the problem is?
> > Thanks,
> > Richard
> > 
> > -----Original Message-----
> > From: mbcoupes-bounces at mbcoupes.com
> > [mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of Sharan Bains
> > Sent: Saturday, January 22, 2005 3:04 PM
> > To: mbcoupes at mbcoupes.com
> > Subject: RE: [W126 Coupe] 1- doesn't start in cold 2 - oil pressure 
> > strange
> > 
> > Richard,
> > 
> > Either the cold start sensor (4-pole switch) on the inlet manifold is 
> > not functioning correctly or you have a weak battery, which in turn is
> 
> > not able to support the cold start system components.
> > 
> > As for the oil sender, may just be dirty oil. Try changing the oil and
> 
> > oil filter and check again.
> > 
> > 
> > talbir
> > 
> > 
> > 
> > 
> > 
> > >From: "Shayegan, Richard" <rishayegan at davidson.edu>
> > >Reply-To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
> > >To: <mbcoupes at mbcoupes.com>
> > >Subject: [W126 Coupe] 1- doesn't start in cold 2 - oil pressure 
> > >strange
> > >Date: Sat, 22 Jan 2005 14:14:25 -0500
> > >
> > >2 things I've noticed as of late. When it's cold out (not super cold,
> 
> > >but like 35F and lower) the car doesn't like to start. First the
> > starter
> > >will spin free since it didn't engage (the strange part is to get the
> 
> > >starter to stop, I have to turn the key all the way to the off 
> > >position and then take it all the way back to the start position - 
> > >jounce bounce the key off the start position basically), then on the 
> > >next attempt (or whenever it finally does engage), I'll have to crank
> 
> > >it for a good
> > while
> > >to get the engine to stumble to life (to get the rpms up to a 
> > >non-stumbling speed I have to give it a little gas). After that it's 
> > >fine. It doesn't do this if it's warm out nor if it's cold out but 
> > >the engine is warm. Any ideas?
> > >     The second thing is that when I hit the brakes (like to slow 
> > >down for a red light), the oil pressure will drop to about 1.5 and 
> > >then when I complete my stop it will come back up to the usual 
> > >2.4-2.8 it does at idle. I know technically even if it stayed at 1.5 
> > >it's ok, but it never did this before so I'm guessing something's 
> > >wrong. The oil level is fine. Any ideas about this one?
> > >Thanks,
> > >Richard
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> > The MB Coupes Website!
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> 
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> Postings remain property of MB Coupes, L.L.C.
> 
> 
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> Postings remain property of MB Coupes, L.L.C.
>