i installed a zerostart block heater the other day in the lower radiator hose. it's a 600w unit and after about 3 hrs plugged in the thermostat housing is very hot to touch. the upper radiator hose and radiator seem warm. but after starting the engine is still cold. i ran it for 5 mins and blasted the heater but the motor is still cold. there wasn't any movement at all in the temp gauge. just looking at how the flow of the coolant system is setup seems as if it would be more logical to install these in the upper radiator hose. any ideas? do i need to leave it plugged in longer? 3hrs and no movement on the temp gauge just doesnt sound right.

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83 300d euro
85 944

Heat rises. The heater needs to be installed as low as possible for the heat to spread.

is there two different styles? my lower hose goes directly to the thermostat. i'll post pics in a min.

83 300d euro

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83 300d euro
85 944

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83 300d euro
85 944

it's going on 7hrs plugged in now. radiator cap, front of thermostat, and upper radiator hose are all warm. engine temp still reads cold at 100F.

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83 300d euro
85 944

100 degrees is all you need. The heater is not to get the engine HOT, its to keep the engine above freezing temperatures so it will start easily.

good enough. thanks!

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83 300d euro
85 944

My Zerostart lower radiator hose heater in the 85TD does not move the temperature gauge as much as the block heater in the 77d but it's enough to help starting on cold days.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Ditto, I was disappointed to find out that the lower hose heater didn't really help the heater get warmer quicker.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

Yeah its not going to do much for making the heat warmer quicker (maybe slightly) but its main use is to take off the edge of the cold temps, and help the engine start ok.

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The block heater in our '87 gets things real hot fast. I've got a dedicated outlet right there next to the car with a control switch in a handy location inthe kitchen. Plug it in when the wife gets home and wait until early a.m. to throw the switch on. Only take about 2 hours to get the thing nice and hot so why leave it on all night or go out in the early a.m. dark and cold to plug it in?

Gotta pat myself on the back for that one.

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300TD W124, Two VW TDI Passat Wagons,Cummins Ram 250, Kubota Tractor
23 cylinders sipping the sweet sauce of the soy bean

I installed a zerostart tank style heater less than a week ago. Gets the engine up to 40C easily in about 3 hours. I was originally going to install one like you did, but couldn't really figure out if I would be heating the engine or the radiator... I have my heater on a timer set for 3am, and my remote start alarm on a timer at 6:20, so my car is already nice and warm inside by the time I get in it..

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Ich liebe meine Autos!

1991 Mercedes-Benz 560SEL | Megasquirt MS3-Pro | 722.6 transmission w/ AMG paddles | Feind Motorsports Sway Bar | Stinger VIP Radar | AntiLaser Priority | PLX Wideband O2 | 150A Alternator | Cat Delete
1981 Mercedes-Benz 300SD | Blown engine, rebuilding someday...
1981 Mercedes-Benz 300SD | Rear ended, retired in garage.
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