i have a 92 300d 2.5 with 181k which is making a little noise behind the passenger air bag. it is a constant hum, which sounds a little like static. when i disconnect a fuse (i think it was 7, it was the one the auxilary water heater is on) the noise stops. the noise doesn't change with different speeds, nor stop with highway driving.

this car also didn't get up to temp this winter. at barely creeped past 40 if i was driving on the highway, and couldn't get to 60 if i warmed it up in the driveway, and only drove on backroads. i figured the thermostat was bad, and have a replacement. now that it is warmer, the temp got up to just under 80, and i'm thinking maybe the thermostat isn't bad after all.

i need to mess with the coolant as i'm putting in a veggie kit, so i'll replace the thermostat anyway, and check the old one with some hot water, but i'm interested in the noise that might be from the water heater. any thoughts?

thanks

david

I want to say aux pump, but other issues may be involved.

PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1992 Mercedes Benz 300D Turbo 2.5
Part: Auxiliary Water Pump
Note: Year: -2/1993
G3050-13421 Auxiliary Water Pump Bosch IN STOCK $208.24
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1HS1BNMYH1HS1BNVTX&year=1992&make=MB&model=300-DT-003&category=G&part=Auxiliary+Water+Pump


PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1992 Mercedes Benz 300D Turbo 2.5
Part: Sampler Blower Motor
Note:
For Temperature Sensor Ventilation on roof rail. Draws air from a specific location in vehicle to sample the temperature and relays information to control unit which takes action to correct to desired temperature setting. Optional with 000 830 96 08.
R3011-70122 Sampler Blower Motor IN STOCK $52.92
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1HS1BNMYH1HS1BNVTX&year=1992&make=MB&model=300-DT-003&category=R&part=Sampler+Blower+Motor


PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1992 Mercedes Benz 300D Turbo 2.5
Part: ACC Mono Valve
Note: Heater Valve
With heating water feed in bottom of heater core. Electromagnetic heater valve.
Year: 4/1990-1/1993
R3022-26888 ACC Mono Valve IN STOCK $95.06
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1HS1BNMYH1HS1BNVTX&year=1992&make=MB&model=300-DT-003&category=R&part=ACC+Mono+Valve


Have a great day.

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

have a great day!!?? with all those dollar signs??

i'll replace the thermostat, and then see from there. truth is, i have to pinpoint it more, but i was hoping someone could tell exactly what i needed from my short description. i was also hoping that it would be someone who lived nearby, had the part, and would come over and put it in while they drank my beer, but haven't gotten those responses yet.

thanks for your help

david

did the plumbing of my frybrid kit and replaced the thermostat. no problems with temps now, it moves quickly to and hovers right above 80, and although i haven't driven the car tons, i haven't heard the same noise coming from behind the dash.

we'll see.

david

__________________
newfane, vt
84 300td 223k modified greasel conversion (sold)
92 300d 2.5 185k with frybrid kit

I don't know the 90's cars at all, but I have heard tell of the little aspirator fan for the climate control sensor making a noise like that. It would be located in that general area.

__________________
Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

i'll be looking into it more once it starts happening again.
thanks for the help.

david

__________________
newfane, vt
84 300td 223k modified greasel conversion (sold)
92 300d 2.5 185k with frybrid kit