1993 Merc 1.8 190e Overheating

I have had a problem with overheating. My 1993 Merc 1.8 190e is overheating in traffic. It is fine on a run, say on the motorway or uninterrupted driving.
As soon as I am caught in traffic the temperature shoots right up. On inspection I have found that the fan is not coming on. It is obviously turning (freewheeling) when on the motorway and keeping the engine cool, but it isn't coming on in traffic, thus overheating. What will this be??? Sensor...fan...thermostat... Help!!
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waldorf wrote:

Waldorf Well you hit the nail on the head, first off check your a/ because the electric fan has 2 modes and runs the fans because its always cycling. Then replace that thermostat if its actually overheating. Remember the fan is designed to come on at 110 degrees +/- 5 degrees while in motion. The fan will cycle on slow because of the low speed with the a/c. If you can see its overheating its not the sensor, you see it therefore the car knows it.
Jason
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hi i would check the fan thermostat switch located between the air filter and rocker cover in cylinder head its two black push on plugs if you bridge the two wires with the ignition on you should hear the fan click in I have put in a switch from them two wires to bring the fan in early i think the temperature setting is a bit high before the fan kicks in.hope this helps frank
"macdrone" wrote
> waldorf wrote: > > I have had a problem with overheating. > > My 1993 Merc 1.8 190e is overheating in traffic. It is fine > on a run, > > say on the motorway or uninterrupted driving. > > As soon as I am caught in traffic the temperature shoots > right up. On > > inspection I have found that the fan is not coming on. > > It is obviously turning (freewheeling) when on the motorway > and keeping > > the engine cool, but it isn't coming on in traffic, thus > overheating. > > What will this be??? Sensor...fan...thermostat... > > Help!! > > Waldorf > Well you hit the nail on the head, first off check your a/ > because the > electric fan has 2 modes and runs the fans because its always > cycling. > Then replace that thermostat if its actually overheating. > Remember the > fan is designed to come on at 110 degrees +/- 5 degrees while > in > motion. The fan will cycle on slow because of the low speed > with the > a/c. If you can see its overheating its not the sensor, you > see it > therefore the car knows it. > > Jason
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frank133 wrote:

Do you mean join the two wires together with a separate wire??
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frank133 wrote:

Frank you were spot on. I took off the two wires and bridged them and BINGO!! On came the fan. I had a play around with the sensor(cleaned it) and it seems to be working fine now, although i'll change it in the near future. Many Thanks Frank Hey, this guy knows his stuff ! Cheers Waldorf
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If I had to guess I'd say water pump.
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The fan is an electric one so it will freewheel. So first thing I would check is the fuse in the fusebox. Take it out and inspect it... while you are at it, replace it with a new one.
I don't think fuse is the cause so next thing to check is thermostat... when you drive on highway, did it ever go below 80 degree? If no, then thermostat is fine.
So the real reason is the thermoswitches that controls the two electric fans you have. I believe there is three of them on your car... dealer will tell you how many you got... one is two prongs, possible one is three prong and then there is one prong red (not black... which is for the temperature gauge). Don't forget to get all new aluminum washers for these thermoswitches.
Replace these parts when engine is cold... little if any coolant will spill out so change them quickly. Do not change these when engine is hot or otherwise, hot coolant will shoot out and possibly you ruin the aluminum threads for these sensors.
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Tiger wrote:

When you say "bridge the wires" do you mean join them together with a separate wire?
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Tiger wrote:

When you say "bridge the wires" do you mean join them together with a separate wire?
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Tiger wrote:

When you say "bridge the wires" do you mean join them together with a separate wire?
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Tiger wrote:

When you say "bridge the wires" do you mean join them together with a separate wire?
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sorry mate yes the two wires that go to the temp sensor on the head just connect them together with a piece of wire all you are doing is making a circuit instead of the temprature switch if the fan clicks in with the ignition on thats your problem hope this help
"waldorf" wrote
> Tiger wrote: > > > The fan is an electric one so it will freewheel. So first > thing I would > > check is the fuse in the fusebox. Take it out and inspect > it... while you > > are at it, replace it with a new one. > > > > I don't think fuse is the cause so next thing to check is > thermostat... when > > you drive on highway, did it ever go below 80 degree? If no, > then thermostat > > is fine. > > > > So the real reason is the thermoswitches that controls the > two electric fans > > you have. I believe there is three of them on your car... > dealer will tell > > you how many you got... one is two prongs, possible one is > three prong and > > then there is one prong red (not black... which is for the > temperature > > gauge). Don't forget to get all new aluminum washers for > these > > thermoswitches. > > > > Replace these parts when engine is cold... little if any > coolant will spill > > out so change them quickly. Do not change these when engine > is hot or > > otherwise, hot coolant will shoot out and possibly you ruin > the aluminum > > threads for these sensors. > > When you say "bridge the wires" do you mean join them > together with a > separate wire?
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