Help! Prado 95 series overheating on highway, fine stationary and around town.

[Fizbne Lurker Find all posts View Profile Close Fizbne]

Hey guys,

First post here and unfortunately it's a cry for help! We're here in Aus on a year holiday and we've bought a 95 Series Prado (1998) to get us around. It's the petrol V6 and so far so good. Right until our actual Road trip started.

To cut to the chase: 3 people, roof racks have two swags, and the boot is full of stuff so we're pretty heavy. Around town and when idle, the car is perfectly fine. Going uphill at highway speed, the car starts getting hot. On level road it'll slowly start to come down to temp. Either that, or we need to stop at the side if the road and let it idle to bring the temp down.

I'm thinking thermostat maybe? I have tools and I'm alright with a spanner so roadside repairs should be alright.

Thanks.

[t303 Senior Member Find all posts View Profile Close t303]

A couple of questions:
How does the radiator core look?
What colour is the coolant, is it a rusty mess?
One thing to try is when it starts to overheat, turn on the heater and open the windows. If the temp comes down it is a cooling capacity problem and I would be looking seriously at radiator, possibly fan hub clutch. I have never personally had a thermostat crap out on me on a well maintained system, but I do change them at the same time as the radiator.

[Fizbne Lurker Find all posts View Profile Close Fizbne]

The radiator core looks OK, have seen worse. The fan comes on when you the start the car as normal but the most recent time the car overheated and we were at the side of the road to let it cool, the fan was not running fast.

Coolant colour - we bought the car 3 weeks ago and the coolant was brand new. Will check colour later tonight and update. The oil is clean so no head gasket issues as far as I'm aware.

With heaters on full blast and windows open the car still overheats.

[Fizbne Lurker Find all posts View Profile Close Fizbne]

Stopped again. Just FYI the car has done 250,000kms, not sure if it's an original radiator, but the top is very discoloured. Just hoping it doesn't explode haaaaaaaa.

[t303 Senior Member Find all posts View Profile Close t303]

If the engine is hot the fan should be hooked up solid and "roaring" when revved. Unfortunately it will probably require refurbing all the components to be sure; I would probably start with another tube of oil in the fan hub (cheapest, there are tutorials floating around) but you may end up doing the radiator as well.
cheers
Steve

[Bobba Junior Member Find all posts View Profile Close Bobba]

When the car is hot feel the centre of the radiator - it could be blocked up and you won't notice it until it's under load. That happened to us last summer with air con on and coming up our steep hill - was fine everywhere else. The radiators have a certain life span (can't remember what our mechanic quoted but he's Toyota trained) and you need to replace them.
Hope you get it sorted!
Cheers,
Mark.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

If it has a thermo fan isit working ok?

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

Does it lose coolant?

[Brett1979 Avid PP Poster! Find all posts View Profile Close Brett1979]

My petrol 95 wa overheating a few weeks ago. It was the thermostat o ring losing coolant through it at a healthy drip rate. Car overheated at idle but when driving it went back to normal operating temp. The top core didn't have coolant in it due to the thermostat losing it so fast. So at idle the coolant wasn't pumping through the top radiator hose. At revs it was and that cooled the car back down. I get the impression yours isn't losing coolant otherwise you would've mentioned so which throws a spanner in the works. If you have a blockage then it should overheat quicker with higher revs/working the car harder creating heat. If it's at idle that tells me you've got a low level of coolant or there's an air flow issue. After its overheated and you switch the car off. If you turn it back on after 1 minute is it still reading hot or does the temp gauge show the temp back at normal? If it takes a while for the temp to go back down then it's a partial blockage in your radiator fins most likely as theyre smallest openings for your coolant to pass through. I'm wondering if someone had stop leak in the radiator some months before you bought the car. Stop leak will in fact stop the leak, but it will inevitably block your fins a few months to a year down the track. As soon as stop leak goes into a radiator you will be up for a new radiator eventually. The standard plastic core radiators last 10 years on average before they crack.

I had to edit spelling in this due to typing too fast for the iPad. It throws in words and full stops I didn't even type.

I'd ge a new radiator ordered at a destination you'll be heading to. Fit it yourself to save a couple of hundred dollars. I'm confident that will fix the issue.

At around the 250,000km mark I had a few consecutive problems with my car all happening within a short period of time of one another... Radiator renewal, alternator renewal and starter motor renewal.

[topic97 Senior Member Find all posts View Profile Close topic97]

First off, I would be looking at replacing the radiator asap if the top tank is brown & discolored - this is the plastic breaking down & will ultimately fail sooner rather than later.
And usually its a spectacular fail - like fittings exploding off etc.

The issue you are having will be caused by the fan clutch(viscous fan), it will have leaked oil and will work at low revs but be cutting out at high revs.
You will be able to tell by looking at the front of it & it will have a dirty, oily residue on the front.

Change that and the radiator and you should be all good!

[pradosteve97 Junior Member Find all posts View Profile Close pradosteve97]

I don't think its the fan as you say you have to pull over and let it cool down you should be able to drive at 100ks and the air passing thru the radiator should be enough to do the cooling on everything else I play with the thermos don't run after 60ks the prado having a clutch fan shouldn't the said clutch be slipping by 100ks. Go to a radiator joint and get them to pressure test the cooling system would be my first move.

[t303 Senior Member Find all posts View Profile Close t303]

I repeat my usual warning:
diagnose carefully before throwing $$$ around, and only change one thing at a time. Despite the fact that it sounds like the rad has to be changed anyway, I would still fix the fan hub first and see if it improves somewhat. If you change just the rad you may still have a stuffed fan hub, but the effect will be masked until the rad degrades again, or you hit the 45C + temps that are somewhat common here up north. You may then start second guessing your rad again.
cheers
Steve

[Fizbne Lurker Find all posts View Profile Close Fizbne]

Hey guys, thanks for the advice.


The centre of the Rad is ice cold, coolant hose at the top feels really solid.

Regarding the fan, it just doesn't lock when the car gets hot and spins freely and slowly when idling. Turning off the car and turning it bacm on again after 5 mins and the fan works again for like 30 seconds.

The faster I go, it doesn't help at all.

Think it may be a new Rad and new fan thing.


Just need to make it back to Albury, via Mt Kozsciuszko, which we are stuck on ahahaha.

Ohhhhhh Fml.

[Fizbne Lurker Find all posts View Profile Close Fizbne]

Forked out for a new rad. $$$$$$$$$$$$$$$$$ but whatever. Still *kind of* in our budget.

The V/C for the fan we're gonna keep on the car as is. In theory if the car is moving, air should go through the rad and keep it cool yup? Not really fussed if it's not working on idle as it's still technically spinning.

Guy in the rad shop suggested that the fan *may* not be locking as the sensor hasn't ticked as the middle of the rad is cold, buuuuut I think he might be a little bit wrong.

Will keep everyone updated. We're driving to Melbs straight after we get the car from the shoppe and go from there.

[topic97 Senior Member Find all posts View Profile Close topic97]

No, what he says is quite a common occurrence.
If you have blockage in the radiator, the coolant will either be flowing too slow - meaning its over cooling - or not at all.
If the fan hub isn't getting the right temperature it wont lock on correctly, as it uses the heat from the radiator to heat up the oil which engages the clutch.

Usually the symptoms for this will cause overheating at any speed, which is why I suggested fan hub first.
But in any case, if the plastic was deteriorating on the radiator, you were better off fixing it as soon as you could.

Earlier model ford couriers were notorious for blocking over the centre of the radiator where the fan contacted them.
99.9% of couriers we used to have come in overheating were due to the centre of the radiator blocking - we could never figure out why they would do it, apart from perhaps the factory coolant was reacting and bonding to the tubes.
But every single radiator we pulled out, we would always remove the top tank and flow test & it would only flow through the outer tubes on either side where the fan didnt contact them.
It was bizarre.
Couldnt clean them out either because it seemed to bond to the tubes - whatever was occurring.