Mixture control unit? Fuel Distributor? Does this mechanic know?

[kaoskingnd]

Ok.... I have a 300 SEL with 172,000 miles, new plugs and filters. It has the cold start problem, and I went to a local import shop to have it diagnosed. He said the " mixture control unit was leaking internaly" I guess he could be right but it would seem that the cold start valve would be responcible for regulating this function. I can smell gas when I start it (pump a few times) once warm it runs great...best car I have ever had.
He also said "I need a new vac pump in the drivers side back door for my key fob to work?" but all the locks go down when I use the key the back ones are a little slow. Opinions.....
Can the o-ring on the fuel distributor be the cause of a leak? 500.00 bucks for a distributor is alot of denero. Would like second opinions.

Thank you in advance

[Mike Murrell]

Your personal info shows you as being in North Dakota. If you were making this post in December, the cold start valve might become more of a culprit.

Check out what M.B.Doc had to say in the thread below. While in there, scroll down to a post I made. There's another URL in that post that will take you to some comments Steve Brotherton made about a quick way to check fuel pressure. This might give you an idea if things are really hosed up.

I would hire someone to do a fuel pressure and system pressure test. Fuel pressure about 60 psi to open injectors. System pressure around 90 psi.

I would start with this before shelling out $$$ on an expensive part.


http://www.peachparts.com/shopforum/showthread.php?t=156354&highlight=cold+start+valve

[kaoskingnd]

I have a magic coolant loss, about half the res every 3-4 days, checked hoses, and res, no plug problems,no coolant in oil or tranny,
I keep hearing about mono-valves could this be the culprit? Is there a place where it could just sit and not drain?.....

[Duke2.6]

The "monovalve", which controls coolant flow to the heater core is a common leakage item. Unless the HVAC system determines that heating is required it is off.

If it's leaking, coolant will drain into the HVAC plenum and through a drain above the transmission. If it's leaking you can can usually see coolant residue on the trans. If so, the monovalve is suspect and should be inspected for leakage, which will likely be readily apparent when you see it (wet). The heater core is the other suspect, but if it's leaking it will usually leave a film on the windshield and an antifreeze odor that you can smell when in heat or defog mode.

Not sure about your model, but on my 190 I have to remove the cowl HVAC inlet screen to see the monovalve - just a couple of screws or clips as I recall. The W/S wiper arm does not have to come off - just slip the screen out from under the rubber boot. The monovalve easy to R & I and a good opportunity to do a coolant change with Zerex G-05 if you are close to due.

Duke