rover p6 3500 temp gauge

life on mars

life on mars

Member
Hi i am new to the forum SO PLEASE be gentle. I would like some help to identify a problem with my temp gauge.
When i start the car and the engine works up to operation temp the gauge slowly rises to the 85 deg
as it should do .I presume at some point the thermostat opens because the NEEDLE drops just in between
the grey and green section of the gauge, the car is fitted with an electric cooling fan and this cuts in after about 7=10 Min's of normal idling

1975 ROVER 3500 AUTO MONZA RED WITH BUCKSKIN INTERIOR
 
life on mars said:
Hi i am new to the forum SO PLEASE be gentle. I would like some help to identify a problem with my temp gauge.
When i start the car and the engine works up to operation temp the gauge slowly rises to the 85 deg
as it should do .I presume at some point the thermostat opens because the NEEDLE drops just in between
the grey and green section of the gauge, the car is fitted with an electric cooling fan and this cuts in after about 7=10 Min's of normal idling

1975 ROVER 3500 AUTO MONZA RED WITH BUCKSKIN INTERIOR
Click to expand...

Hi LOM

Seems okay to me :D , what's the problem?

Dave
 
Hello LOM,

It is possible that your thermostat is in the process of failing, as I have seen the situation that you describe before, and the next step is a thermostat which fails to open... :shock:

Best best would be to fit a new thermostat. Where abouts in the world are you?

Ron.
 
Hi Ron i live in sunny Norfolk in England. as regards to the thermostat it was replaced last November for the correct opening temp which at the moment eludes my poor monkey type brain, me thinks it was 87or 90 deg one. All the pipes get hot so all the coolant is circulating around the system AND the rad was re cored last November as well, as it had a leak from the middle probably from a stone. The think is the temp gauge shows no movement at all after it has dropped back in between the grey/start of the green section the car is fitted with an electric fan and the fan thermostat switch is screwed directly in to the rad approx 5/6 inches down from the top hose. when driving the car again no movement on the gauge,stop in traffic for 20 secs and the fan runs and will not cut out until the car moves again AT SPEED not a craw through the traffic, as i have no way of telling if the car is overheating i feel very reluctant to use it. PS the fan is located at the front of the car behind the honeycomb grill and seems to blow air through the rad into the engine bay Worth a mention regards Dan
 
Hi Dave me thinks i may have one!! :( please read my reply to Ron. may be i should replace the temp gauge for a new one?
 
life on mars said:
Hi Dave me thinks i may have one!! :( please read my reply to Ron. may be i should replace the temp gauge for a new one?
Click to expand...

Hmmmm yes it would appear that you do.

So the temp gauge rises to 85 degrees until the thermostat opens then drops back a bit. Which is what it should do so that seems ok. An 87 or 90 degree thermostat seems a bit high for sunny Norfolk though. An 82 degree one would be better.

Anyway, back to the problem.......after the thermosat opens and the temp guage needle drops, it stays where it is but the fan kicks in when you're stationary and doesn't shut off until you start moving. That suggests the coolant temp is rising but the temp gauge does not register the rise, which we know it should do as it does so before the thermostat opens. Is it maybe just a sticky needle? Have you tried tapping the gauge to see what happens? The only other test would be to get a hold of an IR thermometer and check the temp of the engine that way. However, as I said earlier, the fact that the fan kicks in suggests the coolant temp does rise so this test woould only serve to confirm that the guage is probably on the way out. Remember though that the temp guage is merely an indication of what the engine temp is doing. They're not particularly accurate.

Hope that helps

Dave
 
There is one possible problem. The V8 likes the sort of thermostat that has a "pilot" hole so that a very small amount of coolant ciculates even when it is shut. Fitting one without this could lead to the rise and drop back effect you describe.

Chris
 
:D :D Hi just to update you all after a long process of elimination i replaced the temp sender unit,this cured the temp gauge problem, and gauge works as it should. Fan cuts in at 87-95 deg approx although fan seems not lower temp it stays there :? And as soon as car is on the move temp drops to 85deg :D
 
life on mars said:
:D :D Hi just to update you all after a long process of elimination i replaced the temp sender unit,this cured the temp gauge problem, and gauge works as it should. Fan cuts in at 87-95 deg approx although fan seems not lower temp it stays there :? And as soon as car is on the move temp drops to 85deg :D
Click to expand...

Glad to hear the gauge is working. The subject of V8 cooling and electric fans has been done to death on the forum. Suffice to say that your car does the same as my own car in that the electric fan holds the temp steady once it comes on and it takes some forward movement to increase the airflow mass sufficiently to reduce the temp. The difficulty is in the size of fan you can fit on either the front or rear of the rad as there are clearance issues which seem to vary from one car to the next. Obviously the bigger the fan the better. Anything 14" diameter or bigger seems to be the best option.

My own car has a front mounted 14" fan that pushes air through the rad simply because I haven't got enough clearance between the rad and the nose of the water pump to fit it to the rear of the rad. Hope that helps.

Dave
 
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