td27 r50 temp raising

vlturbo · Post by **vlturbo** » Mon Sep 21, 2015 5:09 pm

hey guys im new so try to take it easy haha... i have just got my hands on a td27 r50 auto terrano.. its had a new head and headgasket as the last head cracked. but unsure about anything else as it was a friend of a friend. the temp seems to climb as im going uphill or giving it a bit of a bash in soft sand but comes back down just as fast.. any ideas?? thermostat and radiator maybe?? also speedo drops off and on but ks are still ticking over???... thanks any advice will b appreciated

nzlux · Post by **nzlux** » Mon Sep 21, 2015 5:22 pm

If it is not getting overly hot, and then cooling down to barely warm I would suspect that the thermostat is either jammed open or not there.

vlturbo · Post by **vlturbo** » Mon Sep 21, 2015 6:34 pm

yea it has only ever gone to just undr 3/4 on the gauge.. when im driving normal it sits just above the cold line.. even after just hitting under the 3/4 mark it cools right back down... thanks will check thermostat this weekend coming

BlakeNZ · Post by **BlakeNZ** » Mon Sep 21, 2015 6:45 pm

first thing you want to do is get a second water temp gauge hooked up. I'd suggest putting a sender in the top hose to the radiator. This will give you a better handle on what the temp is actually doing, as the factory ones are notorious at not being to scale.
When you remove the thermostat, look for the manufacturing date on it, to see if it has evere been replaced. Make sure you have a replacement with you, because if the existing one in there has been in for ages, you will likely damage the thin gasket whilst removing it.(it's like paper).
water Temp does climb when in sand. Your trans temp will be rising quickly also.
the fact that the vehicle has overheated to the point of damage already is of some concern, making me wonder if they have addressed the issue that caused the overheating. Nearly any mechanic worth his salt would have removed the radiator and had it rodded and flushed while the head was off the motor, so find out who did the spanner work, and confirm with them.

Smurf · Post by **Smurf** » Mon Sep 21, 2015 6:49 pm

I am not a Nissan guy, but Toyota motors of the same era, when overheated can damage the water temp sensor for the ECU. Is it possible to kill a water temp sensor on a Nissan motor due to overheating?

fh2014 · Post by **fh2014** » Mon Sep 21, 2015 7:47 pm

It's definitely missing it's thermostat if normal driving it's only just above cold

BlakeNZ · Post by **BlakeNZ** » Mon Sep 21, 2015 9:58 pm

mine wasn't missing, it was just stuck open(and was 18 years old!!!)

fh2014 · Post by **fh2014** » Mon Sep 21, 2015 10:04 pm

hah yeah forgot to add the /stuck open to that.

Smurf wrote:I am not a Nissan guy, but Toyota motors of the same era, when overheated can damage the water temp sensor for the ECU. Is it possible to kill a water temp sensor on a Nissan motor due to overheating?

I highly doubt this could happen if the sensor is kept within its operating range, more likely damage from corrosion plus heat due to poorly maintained coolant. Maybe if the sensor got like, over 300 deg C.

Most sensors work on resistance, ie how much current passes through them at a certain voltage and temperature of the 'sensing' material/materials (thermocouple). When hot the sensor gets really low resistance, and passes more current. Maybe toyotas ECU's are shorting themselves out?

Smurf · Post by **Smurf** » Mon Sep 21, 2015 10:17 pm

fh2014 wrote:hah yeah forgot to add the /stuck open to that.

Smurf wrote:I am not a Nissan guy, but Toyota motors of the same era, when overheated can damage the water temp sensor for the ECU. Is it possible to kill a water temp sensor on a Nissan motor due to overheating?

I highly doubt this could happen if the sensor is kept within its operating range, more likely damage from corrosion plus heat due to poorly maintained coolant. Maybe if the sensor got like, over 300 deg C.

Most sensors work on resistance, ie how much current passes through them at a certain voltage and temperature of the 'sensing' material/materials (thermocouple). When hot the sensor gets really low resistance, and passes more current. Maybe toyotas ECU's are shorting themselves out?

yes the ECU often fails and needs repairing in vehicles of the same era.
AS for the ECU temp sensor, it is pretty well documented on the net, on overseas forums. I have just replaced the water temp sensor for my ECU on my Prado, which has been cooked twice by previous owners, the new sensor has made a difference to its running.

vlturbo · Post by **vlturbo** » Tue Sep 22, 2015 8:22 pm

hey guys thanks for the help ill try do sum digging to see who done the head.. i hope i dont have to redo it.. will let u know how i get on

vlturbo · Post by **vlturbo** » Thu Sep 24, 2015 6:09 pm

so what i can get from my mate about the truck is the top radiator hose come off smashed the radiator and fan to bits.. they replaced these and was still getting hot... pulled the head off to find gasket had gone and head was cracked... so got a second hand head planned it new head gasket and put it back together... all home job not done by a mechanic.
i can now c the fan is wrong.. looks to big.. and there is no shroud on the radiator.. i cant find any leaks and has used about 250mls of water in the month ive had it... i want to take it from auckland to kaitaia in the next cpl of weeks but dont want to do the truck in.. do u think the water pump might be getting lazy with the bigger fan... ill check the thermostat if there is none should i put one in? cheers guys..

Smurf · Post by **Smurf** » Thu Sep 24, 2015 6:31 pm

No shroud will have an impact on cooling too.

td27 r50 temp raising

td27 r50 temp raising

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