Offroad-Express

PR wrote:

oldblue wrote:About 12 months ago, I had the same problem, looked at all the "easy " and cheapest things to try.
tryed new themostat , increased the amount of wax in the viscus, cleaned the outside of the radiator, etc, at a cost$$$$$$$$$ no joy.
The end result was the inside of the radiator needed to be cleaned out, which cost less than the money on all of the above.

I have had the radiator cleaned inside and out by pros, have had engine flushed for 2 hours with a fire hose change the themostat so the only thing left is the viscus fan

Like has been said before if you are experencing o/heating at high speed, the problem wont be the fan there is more than enough airflow through the front of the vehicle at 100kms to cool the radiator.
A faulty fan will cause o/heating at low speed not high speed, which is why most race cars dont run a fan.


If the radiator is ok then it would have to be flow of coolant through the system, which can be waterpump, themostat or a blockage somewhere.

For the cost of a thermostat its not worth messing around just chuck a new one in. You cant just leave it out either as that can be even worse than a faulty one.

If that doesnt fix it then look at the waterpump.

mines doing all of the above, at 100k it sits half way on the gauge ,round town and offroad sits at 1/4 on the gauge, had someone look at it and i have a wee bit play in my water pump,
rang for prices
BNT =$110
ripco =$120
and genuine nissan part wait for it $128
from cockram nissan,i am going with genuine nissan at that price,will be fitting new pump next week,will post back and tell yer how it goes

vince

PigFmr wrote:mines doing all of the above, at 100k it sits half way on the gauge ,round town and offroad sits at 1/4 on the gauge, had someone look at it and i have a wee bit play in my water pump,
rang for prices
BNT =$110
ripco =$120
and genuine nissan part wait for it $128
from cockram nissan,i am going with genuine nissan at that price,will be fitting new pump next week,will post back and tell yer how it goes

vince

Cheers vince let me know pleaseeeeeeeeeee

PigFmr wrote:mines doing all of the above, at 100k it sits half way on the gauge ,round town and offroad sits at 1/4 on the gauge, had someone look at it and i have a wee bit play in my water pump,
rang for prices
BNT =$110
ripco =$120
and genuine nissan part wait for it $128
from cockram nissan,i am going with genuine nissan at that price,will be fitting new pump next week,will post back and tell yer how it goes

vince

If your thermostat is working, then it should sit on the same temp regardless of where you drive it. A low reading around town and offroad suggests thermostat opening too early.

The viscous fan may need it oil changed. When the motor is cold the fan should feel harder to turn that when it is at operating temp. In time, the oil's viscouity reduces and when you are trucking down the road the air rushing through the grill can slow the fan down therefor reducing the cooling efect it has in the engine. Any good radiator shop or mechanic will be able to send the fan away to have it re-oiled. Just check the fan when the engine is cold, if it spins freely, send it away to be re-oiled.

Jon wrote:The viscous fan may need it oil changed. When the motor is cold the fan should feel harder to turn that when it is at operating temp.

I think you have that backwards.
If the viscous coupling is in good condition it should spin most freely when cold and stiffen up when warm.

well, its been a month or so since i fixed up my overheating... i removed the solid wall of mud between the aircon rad and engine rad, removed the rad and reverse flused it, flushed out the eninge block and refitted it all with a new genuine toyota thermostat and new coolant. now it hardly gets above half, and if it does a quick blast with heater on full hot brings it back, so im happy with it currently as it made the rallywoods trip then the whanga road trips with no real issues!

has any one cleaned the air-con condenser in front of the radiator,getting all the bugs out off external fins?
if you dont want to run thermostat make a plate the same size as the thermostat and diff a 15mm hole, all good

350cruiser wrote:if you dont want to run thermostat make a plate the same size as the thermostat and diff a 15mm hole, all good

Why would you want to do that?

making a plate with a 15mm hole in it slows the coolant down to maximise the systems cooling potental, the same as as a thermastat without the hassles of thermastat failure.

350cruiser wrote:making a plate with a 15mm hole in it slows the coolant down to maximise the systems cooling potental, the same as as a thermastat without the hassles of thermastat failure.

There's no way a 15mm hole can flow as much water as a healthy thermostat.
There is also no way a 15mm hole can regulate temperature. It flows too much when cold and too little when hot.

It's a wives tale that fast moving water doesn't cool properly. If I hit you with a high pressure hose containing cold water travelling very quickly, you'd cool down much faster than using a low pressure hose.

before you get all fired up and squirt me with a hose again have you tryed it or just raining on my parade? without a thermastat, your heater doesnt work properly because the coolant is moving to fast. i have been using this old wives tale for quiet a while with no problems as have a few of my mates with no problems, one of them was a winch chalenge truck. believe what you like i know what works. SORRY SORRY. ive just gone back to my spec sheet and the hole size ranges from 16mm to 19mm.

350cruiser wrote:before you get all fired up and squirt me with a hose again have you tryed it or just raining on my parade? without a thermastat, your heater doesnt work properly because the coolant is moving to fast. i have been using this old wives tale for quiet a while with no problems as have a few of my mates with no problems, one of them was a winch chalenge truck. believe what you like i know what works. SORRY SORRY. ive just gone back to my spec sheet and the hole size ranges from 16mm to 19mm.

Without a thermostat there's two problems.
First one is not enough restriction to make water flow in the required direction (it takes the easy way out which probably isn't through your heater), second one is overcooling.

It's not because the water is "moving too fast". The faster water moves, the better the heat transfer because it's more turbulent.
But the faster the water moves, the more even the temperature is going to be. It'll lose less temperature through the radiator and gain less in the engine. But it's shifting way more heat.
It's a bit tricky to get your head around but it's as simple as 10 people carring a 10L bucket each and walking slow vs 10 people carrying a 3L bottle each and moving 5 times faster.

The faster people are carrying less each time but getting 50% more done.

KiwiBacon wrote:

350cruiser wrote:making a plate with a 15mm hole in it slows the coolant down to maximise the systems cooling potental, the same as as a thermastat without the hassles of thermastat failure.

There's no way a 15mm hole can flow as much water as a healthy thermostat.
There is also no way a 15mm hole can regulate temperature. It flows too much when cold and too little when hot.

It's a wives tale that fast moving water doesn't cool properly. If I hit you with a high pressure hose containing cold water travelling very quickly, you'd cool down much faster than using a low pressure hose.

i know the point your tring to make ... but dosent that come dow to jet impengment cooling ...
http://www.ctvr.ie/docs/PHO_Pubs/UKHeat ... pt2005.pdf rather than speed etc
and isnt the reason it dosent cool faster the more speed due to boundry layer effects on the walls

vvega wrote:

KiwiBacon wrote:There's no way a 15mm hole can flow as much water as a healthy thermostat.
There is also no way a 15mm hole can regulate temperature. It flows too much when cold and too little when hot.

It's a wives tale that fast moving water doesn't cool properly. If I hit you with a high pressure hose containing cold water travelling very quickly, you'd cool down much faster than using a low pressure hose.

i know the point your tring to make ... but dosent that come dow to jet impengment cooling ...
http://www.ctvr.ie/docs/PHO_Pubs/UKHeat ... pt2005.pdf rather than speed etc
and isnt the reason it dosent cool faster the more speed due to boundry layer effects on the walls

Yes, more speed also creates more turbulent flow. The more turbulent flow stirs up the boundary layer better, this is in addition to the higher mass flow.

Things start to go backwards when your pump is adding more heat to the flow than you're removing with faster flow. But in an engine your water pump speed is set by engine speed so that's not so relevant.

if fan working and engine temp seem ok but the temp gauge read different it could be electrical ! 24v do funney things when not earthed . cheak the earth between battery and cab allso cheak the connection between the 2 battery.

I have done the same after a new radiator new thermostat several flushes it was the viscous fan I disagree with what some one said above, fans do cool !!! Only gets hot on long and steep hills now(with 35s)

PR wrote:

oldblue wrote:About 12 months ago, I had the same problem, looked at all the "easy " and cheapest things to try.
tryed new themostat , increased the amount of wax in the viscus, cleaned the outside of the radiator, etc, at a cost$$$$$$$$$ no joy.
The end result was the inside of the radiator needed to be cleaned out, which cost less than the money on all of the above.

I have had the radiator cleaned inside and out by pros, have had engine flushed for 2 hours with a fire hose change the themostat so the only thing left is the viscus fan