hi i checked the fuse for the aux fan and its okay. how can you check if the thermostat is working or not. and also how will you know if the fan clutch is working. thanks.
overheat
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86 300E manual
overheat
i have a 86 300E.it overheats when istop as soon as i drive it goes back to normal . i just change the waterpump but it didnt solve the problem. i notice the aux fan turns slow. what else is there to check. thanks.
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From: LI, NY
02 W163, 84 W123, 03 E39, 98 E39
Overheating troubleshooting
Check coolant level. Low level can cause intermittant overheating problem. Adding Atifreeze/water mix can take a while to work as coolant works through system from reservoir.
Aux fan should come on when A/C on and or engine hot. If not use a multimeater to see if Aux fan is getting 12V when the engine is hot. If no voltage first check fuse box. If fuse OK may have an problem from switch in engine that turns on fan. Can have a mecanic trouble shoot problem or if want a cheap solution you can power Aux fan with a relay you mount. On my 300D I used the A/C compressor power to switch on. I powered the relay directly from the battery. Alternately you could mount a switch in the dash.
Don't know if your model might have the main fan that has a vicous clutch to keep "robbing" power at high revolutions. Does your main fan turn very easaly or does it have some friction to it?
Your radiator could be clogged. Try flushing it out if it hasn't been done in recent menory.
Last but not least check/replace engine thermostat.
In emergency you can turn on high heat in car and use heater as an auxillary radiator to keep from overheating.
Aux fan should come on when A/C on and or engine hot. If not use a multimeater to see if Aux fan is getting 12V when the engine is hot. If no voltage first check fuse box. If fuse OK may have an problem from switch in engine that turns on fan. Can have a mecanic trouble shoot problem or if want a cheap solution you can power Aux fan with a relay you mount. On my 300D I used the A/C compressor power to switch on. I powered the relay directly from the battery. Alternately you could mount a switch in the dash.
Don't know if your model might have the main fan that has a vicous clutch to keep "robbing" power at high revolutions. Does your main fan turn very easaly or does it have some friction to it?
Your radiator could be clogged. Try flushing it out if it hasn't been done in recent menory.
Last but not least check/replace engine thermostat.
In emergency you can turn on high heat in car and use heater as an auxillary radiator to keep from overheating.
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From: Germany
'00 S320 W220, '98 A160 W168/ sold in 2005 '86 260 E W124 '90 260E W124
One of the previous posters leads maybe the most probable issue. It is the fluid clutch of the radiator fan. As soon you enter stop and go traffic or just slow speed A/C ON and hot outside make you engine temp. climb., since the clutch is not engaging the fan good enough. No big deal to replace. Loosen the fan cawl and open the 5 or 6 mm allen screw in the center of the clutch and put on a new one. There is a little notch on the circumference of the clutch to apply a 5-6 mm rod to hold the piece for loosening the screw.
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From: LI, NY
02 W163, 84 W123, 03 E39, 98 E39
Thermostat
Thermostats are relatively inexpensive. Under $25 as best as I remember. If you are going to pull the thermostat out, you can test it by putting it in a pan of water with a thermometer that goes up to 100C. Your thermostat has it's opening temp printed on it. Mine is 80 C. It should open at that temp. Take the water to boiling, then let it cool. The thermostat should close near that temp also.
When you take the thermostat out, note the orientation. Is the thermostat spring toward the engine? I always forget the correct orentation.
Have you been able to get your auxilliary fan to turn on? If you warm your car up and then while parked watch it with the AC on with the temp as cold as possible the Aux fan should cycle on. If it is not ever coming on you may have a problem.
I am not very familiar with the main fans with the fluid or viscous clutches to advise how to trouble shoot that. It would seem that if you have some resistance when you turn it your self with the engine off, and it seems to turn well with the engine running, it would seem OK.
When you take the thermostat out, note the orientation. Is the thermostat spring toward the engine? I always forget the correct orentation.
Have you been able to get your auxilliary fan to turn on? If you warm your car up and then while parked watch it with the AC on with the temp as cold as possible the Aux fan should cycle on. If it is not ever coming on you may have a problem.
I am not very familiar with the main fans with the fluid or viscous clutches to advise how to trouble shoot that. It would seem that if you have some resistance when you turn it your self with the engine off, and it seems to turn well with the engine running, it would seem OK.
Last edited by sph17; Jun 21, 2003 at 10:39 PM.
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86 300E manual
hi, my A/C is not working so my aux fan i cant get it to work. i check the main fan it seems alright but there is no resistance when i turn it but it seems like when the engine is running when i step on the gas it doesnt turn fast.thanks.
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From: LI, NY
02 W163, 84 W123, 03 E39, 98 E39
Aux & Main Cooling Fans
I believe your Aux fan should turn on when your temp goes up, even if your AC is not on. If your aux fan dosn't go on when you overheat, then you could rig an inexpensive "fix" by putting a switch in the dash to turn it on/off using a relay you mount in the engine compartment near the aux fan.
It sounds like your main fan might need to have the clutch replaced. Have never don it, so don't know what the suggest. There are two different fan clutches depending on wich version of the 3 L engine you have. You can check MB parts by going a Google search of "mercedes benz parts" Places have the clutch listed but no prices or they say it is not available. You can always have yor car checked by a mecanic, or check with a dealer for pricing of the clutch.
Maby some one else has more information or a better suggestion?
Good Luck
It sounds like your main fan might need to have the clutch replaced. Have never don it, so don't know what the suggest. There are two different fan clutches depending on wich version of the 3 L engine you have. You can check MB parts by going a Google search of "mercedes benz parts" Places have the clutch listed but no prices or they say it is not available. You can always have yor car checked by a mecanic, or check with a dealer for pricing of the clutch.
Maby some one else has more information or a better suggestion?
Good Luck
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From: Germany
'00 S320 W220, '98 A160 W168/ sold in 2005 '86 260 E W124 '90 260E W124
The aux. fans of the A/C dont come on when A/C is off. Unless you are driving in Death Valley and the outside temp. is like in hell. The problem in your case is most probably the fliud clutch of the radiator fan. The test is simple but not very acurate. Just try to turn fan when the engine is hot (engine OFF!!!) Push the fan and it should not move more than 90 degrees on its own. To test it properly you need to measure the speed increase during the the engine's warm-up with a stroposcope lamp. Or the simple task just swap the part. The function of the fluid coupling is that with increasing temp. the viscosity of the filling of the clutch increases and so the fan speed increases too. To replace it, just loosen the fan cawl and loosen the centre screw (5 or 6 mm Allenscrew). To prevent the coupling from turning you need a 5-6 mm rod which goes into a groove on the circumference of the clutch. The rod needs a 90 degree angle (like a hook) of about 0.5 inch. My guess of the part's price is roughly $180-200.
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From: LI, NY
02 W163, 84 W123, 03 E39, 98 E39
Powering up Aux Fan
What I did was take a heavy gauge wire from the battery to the left front wheel well area near where the Aux Fan has a connector at the left bottom edge of the radiator. At that point I mounted a relay that I purchased from an auto supply store that could handle 20 amps. I used the power coming to the AC compressor to "switch" the relay on, and the power coming out of the relay I soldered to one wire of the Aux Fan. I soldered another heavy gauge wire to the other wire from the Aux Fan and grounded it. With my set up, when the AC compressor is energized (IE the clutch is energized to turn over the AC compressor) the relay is energized and my Aux Fan works.
Since your AC dosn't work, you need to take a hot wire into your dash area, mount an on/off switch and then run it to the "switch" terminal on the relay. You can take power from under your dash if you know where to look, like mabe the cigar lighter power if it is "switched". It would be better to find a "switched" power supply that turns off when you turn your car off so the aux fan dosn't run when the engine is turned off.
If you still have power going to your AC compressor, but the AC just dosn't work, you could disconnect the electric connector going to the AC compressor. Find which wire is energized when you push the button on your dash for AC, and use that disconnected wire to swithc the relay as I did to power your Aux fan. Disconecting the wire from the AC compressor effectively shuts down your AC compressor and thus you AC.
If this isn't clear let me know.
Since your AC dosn't work, you need to take a hot wire into your dash area, mount an on/off switch and then run it to the "switch" terminal on the relay. You can take power from under your dash if you know where to look, like mabe the cigar lighter power if it is "switched". It would be better to find a "switched" power supply that turns off when you turn your car off so the aux fan dosn't run when the engine is turned off.
If you still have power going to your AC compressor, but the AC just dosn't work, you could disconnect the electric connector going to the AC compressor. Find which wire is energized when you push the button on your dash for AC, and use that disconnected wire to swithc the relay as I did to power your Aux fan. Disconecting the wire from the AC compressor effectively shuts down your AC compressor and thus you AC.
If this isn't clear let me know.
Last edited by sph17; Jun 23, 2003 at 09:55 PM.
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86 300E manual
thanks for all the advice ill try to do it this weekend. after this problem i got another one. seems evrything breaking apart. now its my starter. evrytime you turn on the ignition all you hear is click. might as well start a new tread.
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From: LI, NY
02 W163, 84 W123, 03 E39, 98 E39
Click, Click, Click
The most natural thing to assume is that you need a new starter. You may well need one. But always check the easy, cheap things first, even if it ddosn't seem like it is the problem.
Check to make sure your battery posts & contacts are clean. A corroded connection may pass enough current to operate the gauges and lights, but not enough amperage to turn over the starter.
Next, make sure your battery is in good shape. Try a jump (with heavy gauge cables) and see if that works.
If all the easy stuff is ok, then you may need a starter.
Let me know how things work out.
Check to make sure your battery posts & contacts are clean. A corroded connection may pass enough current to operate the gauges and lights, but not enough amperage to turn over the starter.
Next, make sure your battery is in good shape. Try a jump (with heavy gauge cables) and see if that works.
If all the easy stuff is ok, then you may need a starter.
Let me know how things work out.
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From: LI, NY
02 W163, 84 W123, 03 E39, 98 E39
MB Parts
Many parts I purchase from dealer. Some things I get from local Auto Supply place like Auto Barn or PepBoys (on LI, NY). Interestingly, my bother can find re-built parts in TN sometimes easyer and less expensive than I can. He was able to find a re-built master brake cilinder 1/2 the price I could.
I replaced a starter about 10 years ago for a 83 240D re-built for about $135. About 5 years ago got re-built one from MB dealer for a 84 300TD for about $175?? Re-built not available from either place anymore. MB now cost about $300 is my best re-membrance. You can do a Googel search for mercedes benz parts and take your pick of places. On some of the other forums some people comment about mail order places they have purchased from. I don't have aby experience purchasing mail order. Good luck
I replaced a starter about 10 years ago for a 83 240D re-built for about $135. About 5 years ago got re-built one from MB dealer for a 84 300TD for about $175?? Re-built not available from either place anymore. MB now cost about $300 is my best re-membrance. You can do a Googel search for mercedes benz parts and take your pick of places. On some of the other forums some people comment about mail order places they have purchased from. I don't have aby experience purchasing mail order. Good luck
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From: Germany
'00 S320 W220, '98 A160 W168/ sold in 2005 '86 260 E W124 '90 260E W124
Quite simple, you just have to bridge the red pressure switch on top of the dryer bottle of th A/C and ignition on, if the fans are okay they will run. The fan(s) are A/C pressure activated.
Originally posted by doodski
thanks. ill try that. about the aux fan what kind of relay should i put so i can make it work if needed. and how do you do it. thanks.
thanks. ill try that. about the aux fan what kind of relay should i put so i can make it work if needed. and how do you do it. thanks.
