Coolant Temperature / Dashboard Gauge

[Tony]

Ok, so now I have a fancy Madman Indicator of all the vital signs and I take a long ride out for the weekend, and watch this gadget like a hawk!! The coolant temp seems pretty constant at around 91 / 92 degrees .... and then we travel up that little (steep) pass just before Vaalwater, and the coolant temp starts to rise up to 105 / 108 and the alarm goes off (it was set at 115 degrees by SAC) at this point the gauge is pretty unstable and jumps up and down from 108; 111; 105 and then it came down slowly, but never returned to 91 / 92 it remained up at 96 /98 for the rest of the trip. Every climb thereafter it increased, and on a number of occasions set off the alarm. Throughout the trip, the water temp gauge on the dash remained well below half (closer to the quarter) mark, and never moved. I recently had issues with this gauge rising steadily with any uphill driving, and after replacing visco fan & water pump with no success, I replaced the radiator (which was pretty badly blocked up) and the thermostat (for good measure). Thereafter it has not moved and I assumed all was 100% in the cooling dept. I am now wondering just what my temp. should be, and what would cause the water temp on the engine side be so different to the radiator side??? Does the thermostat have anything to do with it or could some dirt have found its way through and caused a blockage - or maybe water pump failure. Does one have a warranty on parts?? Without the Madman I would'nt have known a thing - this might have been going on for some time.

[ricster]

Wow .... i'm intrigued by this !!!

Where is your Madman pickup sensor fitted? The temp gauge ( on the dash ), on the 4.2 diesel is sitting just in front of the thermostat, so the reads the temp before the thermostat opens even.

On a climb up a hill, you will get a temp increase, I saw on Grant's 4.2 turbo diesel on an uphill a temp climb of 106, which I have heard is still ok, but cools down relatively quickly when the ground levels out or goes downhill.

What kind of Antifreeze/coolant did you put in? I was told by many guys here not to mess around with cheap antifreeze/coolant. Use genuine Nissan, or I had Silverton radiators supply me their stuff. They know radiators, and should know their product. I would try a good flush and replace with a 50/50 coolant /water mix ( or as recommended ). My patrol takes 14 litres of water.... so was expensive putting 7 bottles of expensive antifreeze in.... but so far ....so good.

[Tony]

Thanks Cedric, I'm going to give them a call this morning.

[Tony]

I just recalled the maximum values from the Madman unit, and those temps are scary:

Voltage : 16.1
EGT: 576
Boost: 1.5
Coolant Temp: 137 degrees

Those are the max figures - I think it's more than just coolant. Not sure if that's an accurate reading though as the gauge was pretty erratic when she climbed beyond 106. Even the voltage very seldom comes down to maybe 14.5v it is usually happy at the 15v mark, but jumps about a lot and the alternator was removed just the other day and tested and she's as steady as a rock on the test bench, but back in the car she's erratic again - weird!!

[Bruin Beer]

This sounds almost like a grounding issue on the MAD Man.
Should maybe verify this connection.
Bruin Beer.

[ricster]

16 volts...... wow
EGT at 576 if probe is PRE turbo is fine.... if POST turbo... that for me is a bit high by about 60 deg (max out at 520-530 for VERY short burst)
Boost... cannot comment, don't know enough about that
Coolant temp... something doesn't sound right that is way too hot !!!

[Peter Connan]

Tony, I also think you have an earthing or connection problem somewhere. But please tell us where the temperature sender for the Madman is mounted?

You sort-of indicated that it was on the radiator, but the temperature of the radiator should never reach those kind of levels. The reason I say this is that if the temperature of a vessel reaches boiling point, it will remain steady untill all the water in the unit has boiled, and only then will the temperature start climbimg again. If the sender is on the engine, it is theoretically possible for the temperature to exceed boiling point as it would be in contact with the engine's metal components and thus can measure heat conducted through the metal, but this would not happen if it was on the radiator.

Furthermore, at 137 degrees, a lot of water would have boiled away out of the system, and you should definately see a huge drop in your water level, much more than the header bottle can accomodate. If you have not lost massive amounts of water, then your Madman is lying to you WRT temperatures.

16V should also fry a battery in short order. You can easily verify that with a multimeter though.

[Tinus lotz]

Tony 16v is not cool !!!!!!sounds like regulator or earth not lekke send grootseun a pm and he can give u some atvice
The temps sound exsessive but let's see were senders are ............

[Tony]

The probe for the coolant temp. appears to have been put directly onto the metal casing of the thermostat - yesterday I spent some time at Silverton Radiators, and they tested the water pump, thermostat and also checked for a possible cylinder head gasket leak (which would cause exhaust gasses to heat up the cooling system). Everything checked out ok. Next up I will return to SAC and get Mynhardt to check the unit out, it's probes as well as the grounding. Will try for Thursday - keep you all posted, and thanks for all the input guys.

[Tony]

Sorry, the EGT temp probe has been fitted before the turbo - it looks as if it's been put directly on the outlet manifold.