Over heating???

[D22Nav_Man]

Anyone had any dramas with there zd30 nav over heating.....mine over heated yesterday on the way back from Byron bay doing 110 on the highway..... Pulled over let it cool Down and had to put 3ltrs if water In it to fill it back up....after that the temp was all over the place the whole way home...since yesterday I've flushed the coolant and changed the oil.. Took it for a drive tonight and once again doing 110 on the highway the temp started to go up and sat about 10mm above half. Soon as I slowed down to 90-100 the temp dropped straight away back to its normal spot just below half......could it be the thermostat on its way out? Any help would be great cheers

 

[ben85]

sorry mate cant really help ya.

mine overheated about a month back.
it was on the forum day trip. all was well then she just overheated. stopped and topped up with about the same 3lt water.
temps have been fine ever since.

i have had to top up the radiator a few times since.
too much coolant always seems to be going into the overflow tank.
and i assume it fills up then overflows out the top.
sometimes it leaks after stopping, and i have found the overflow full and coolant all around the area so i guess thats whats happening.
if i dont top the radiator back up it seems to stop leaking out.

engines running perfectly.
but i'm trying to get a mechanic mate to have a look at.

not sure if any of thats relevant to you. but thought id post anyway.

 

[Saitek]

A bit of help

the way you describe the temperature being all over the place sounds really worrying. try driving on bost and seeing if it causes the over heating problems or off boost and no over heating. try the basic things as well, check for air locks, flow, blockages in front of radiator/ condensor, make sure your fan still spins with the motor as the rpm rises and falls(However your engine fan wont offer you cooling when your cruising at 110 so that shouldnt have caused the problem) and try driving with the air con on and off as the condensor fan may help with a bit of extra cooling, also when bleeding make sure the heater is on and that it gets hot as the car warms up, a simple way to get an indication of the thermostat working is to start the car from cold leave warming up or use idle up function to heat it up and check the temperature of both radiator hoses one should be warm as the vehicle starts to heat up and one will remain fairly cool for a long while as your thermostat opens the should both heat to a similar level also use the heater hoses as a temperature guide as the allways have coolant flow regardless of your thermostat being open and above all else THEY CAN GET VERY HOT BE CAUTIOUS WHEN TOUCHING THESE ITEMS AND WORKING AROUND MOVING PARTS. also was there any water in the oil or oil in the water or was there or is there now any moisture in the oil or a thick shake like looking substance under the oil cap, or is the car hard to start after driving it and getting it up to operating temperature stopping and trying to restart it if so you may have blown the head gasket out or warped the head good luck with the trouble shooting

 

[Old.Tony]

I don't have a ZD30 but the problem sounds similar to what others have described in the past - the cooling fan clutch. Get the engine up to normal temperature, turn the engine off, pop the bonnet and try to turn the fan over by hand.

If it's really easy to turn, the clutch is gone and that's the cause of your overheating - the fan won't drive at full speed because the clutch keeps slipping.

 

[D22Nav_Man]

Thanks guys...do you mean the engine fan or the thermo fan?

 

[Old.Tony]

The engine fan. The thermo fan is operated electrically and may activate when the engine is off - do NOT touch that one! If you DO touch it and spin it, it'll turn easily anyway, because there's no clutch because it's just a blade driven by an electric motor.

The engine fan changes because it's mechanically driven, but in order to not cool the radiator too much when the engine hasn't finished warming up, there's a clutch in it that slips when the fan isn't needed, so the fan isn't driven as hard.

The test is as described. If the engine is good and hot, that clutch ought to be fairly firmly engaged. If it's not, it needs attention.

 

[D22Nav_Man]

Tested the fan today....seemed about the same to turn it when its was hot and cold....... I don't understand why the fan would cause it to over heat. At the speed I'm doing when it over heats there is plenty of fresh air flowing through it, I did notice there is a but of mud and shit on the front of the radiator so I will pull it out and clean it up. But I'm still leaning towards the thermostat because it only over heats when its revving around 3 grand for long periods of time. The temp is fine when driving around town in traffic and slow speeds.

 

[bods]

Thermostat would be a good start and if you don't know or haven't I'd replace the radiator cap too, that can cause coolant pumping out into the overflow bottle. It will also lower the boiling point of the coolant as the system can't run at the right pressure if the cap is worn out because it will be letting coolant out before it should be.

 

[Farmer Joe]

If you are loosing water from your radiator it may be worth trying it with another radiator cap just in case yours is stuffed, but make sure you get one of the same rating.

 

[D22Nav_Man]

Yeah was considering doing the radiator cap as well...would like more info on the fan clutch if anyone knows??

 

[Infernal]

g'day mate, have a quick look over here, ive written some thing up.

http://www.navara.asia/showthread.php?t=16175

If it heats up at low speeds and cools down at higher speeds then thats a fan/air flow issue.

If it heats up at higher speeds/load conditions but cools down at slower speeds, thats Radiator internally blocked.

This will affect your viscous hub, because their wont be any hot air coming off the radiator to heat the temperature sensing Bi-Metal spring on the front face that controls the valve, and thus wont lock up.

 

[bods]

There have been quite a few threads on here about fan clutches, but if you only have overheating problems on the highway I'm not convinced it is an issue, as said above they don't generally operate on the highway. I'd start with a new thermostat, new coolant and a new radiator cap after a good flush and give it a good run and see hoe that goes. If you want to / can, when you drop the coolant you can pull the radiator and take it to a radiator shop and get them to clean and pressure test it, but that's up to you...

 

[Infernal]

Mine was doing the same.

Here is the 411 when it comes to over heating.

If your vehicle is getting hot at slow speed, but cooler at higher speeds, then you have an air flow issue, and that's the Viscous hub.

If your vehicle is over heating at High speeds/working, but cools when it slows down you have a internal blockage.

If you have an internal blockage in the same place mine was, in front of the fan hub, then you wont have any hot air flow coming off the radiator to heat up the temperature sensing Bi-Metal spring on the front face that controls the valve, and therefore your fan wont lock up.

Get your vehicle hot, stop the engine and run your hands over the radiator, the temp should be almost the same all over, if you have any cold spots, then you have an internal blockage, get a new radiator, not amount of reverse flushing will make it as clean as a new one, also there is risk that there could be corrosion.

The longer you leave it, eventually the seals will go in the tanks.

Change your thermostat at the same time, they are cheap.

A Viscous fan hub should stop with the engine when you turn it off at operating temp, check your radiator out first, because the fan is fixed to the water pump, one out all out.

 

[D22Nav_Man]

Still over heating grrrrr!!!!! Changed the thermostat this Arvo and hosed the radiator out aswell..... A shit load of mud came out but nothing has changed at highway speed. Will try a new radiator cap tomorrow but after that I'm at a loss...

 

[Farmer Joe]

Did you reverse flush the inside of radiator while you had it out?

 

[D22Nav_Man]

Yeah mate hosed it top and bottom.... Just want it fixed :-(

 

[Old.Tony]

I'm still saying it's the fan coupling.

If the coupling from the drive of the fan to the fan itself doesn't go firm, the fan won't be spun hard enough to really draw the air through the radiator quickly enough. That's why it needs to harden up.

The coupling changes like that because when the engine is cold, you don't want the fan drawing hard and cooling the radiator too much.

 

[WillieD22]

Get the head tested to see if the gasket has gone. If not Take the radiator to someone and get it professionally cleaned or buy a new one.

 

[fourocker]

This might be worth a mention, the bottom radiator hose should have a wire coil in it that helps keep it from collapsing, at higher engine rpm especially for extended periods the water pump can suck the hose flat which is the same as a major blockage, check if it's ok while you're mucking around with all the other stuff.

 

[D22Nav_Man]

Thinking it may be fixed I replaced the radiator cap this Arvo and took it for a drive on the highway and left it in forth gear so it was revving hard for about 20k and the temp didn't move.will keep an eye on it but let's hope its all fixed