1hz overheating

Gotta agree steve

well I had the hub to bits and bought new oil from Toyota . seems to be Cracking and when stopped has good resistance .

Sam,
if you don't here the fan coming in when it starts to i=overheat that will be the problem. You should here it roar.

We changed the viscous fan and it sorted our overheating problems.

Try that before putting in a new radiator.

Steve

Same on my 80, topped up the oil etc, but in the end replaced the viscous fan and have not had problems since. As slowone said, you should hear it roar when it kicks in.

Sam,
if it is found to be the fan that is causing the problem, do yourself a favour and pay the extra for a genuine toyota fan hub. If it is the radiator also do yourself a favour and buy a genuine dense radiator, you can often get a good price on ebay for a genuine one.

Gone Bush is on the money - but it's the lower hose that sucks flat, not the top hose.

If you haven't been maintaining your coolant quality with exceptional care, then the tubes in the radiator core become partly-plugged with a buildup of gunk.

As the water pump sucks from the bottom of the radiator and pumps the coolant through the block and head and into the top tank, the core flow blockage is where the problems start.

It's almost impossible to have a flow blockage through the block and head, as the coolant passages there are huge (compared to radiator tubes).

Bottom radiator hoses should be stiffly reinforced or contain a spring, to prevent flattening under high water pump flow levels.
If you find there is no spring and you desire to install one, make sure you select a stainless steel spring, to combat corrosion.

Bottom line is, if the tubes are partly congested, a trip to the radiator repair shop is the order of the day, to have the tubes cleaned out.

If the tubes are blocked exceptionally badly, the radiator crowd will have to unsolder the top tank and physically clean the tubes.
Usually an acid-bath dip, followed by a pressure flush will clean them out.

Cooling systems should only be filled with the manufacturers recommended coolant - or coolant additive plus pure water.

In the case of Toyotas, the proper Toyota coolant additive added in the ratio of about 40% additive to 60% pure distilled water, or clean rainwater (NOT tap water!) - and then changed out every 3 years - will ensure your cooling system stays in excellent condition.

The genuine Toyota coolant additive isn't cheap, but you have to look on it as cheap insurance.
Always carry a supply of premixed coolant for any top-up, and never add just plain water to a low cooling system.

Cheers, Ron.

I would add to what Ron has said regarding radiator blockages.........

Many years ago I had serious overheating of my V8 whilst on a trip. A country radiator repairer diagnosed radiator blockage. Opened the top tank to reveal a small piece of rubber blocking each and every tube. One (or both) of the hoses had disintegrated on the inside wall to produce pieces of rubber to pass through the system. Removal of the blockages fixed the problem. Plus new hoses of course!

I had not heard of it before but it was no surprise to the radiator bloke.

My recommendation is to get the cooling system checked by a radiator specialist before doing more trial-and-error fixes.

Yep. For sure. I've seen several threads on this forum and others. I've had a 1HZ with an overheating problem (cause not mentioned so far) and posted to at least two threads hereabouts.

There isn't a silver bullet, there's a whole magazine of the dang things and you need someone capable of going through the list.

Cheers
Mark

I'm with Mark.
And you may never find the problem after throwing time and cash at it.
Workout what you are prepared to spend and what you are prepared to put up with.
A compromise might be - if you have to turn off the aircon and limp up a hill, so be it. Drive to the temp gauge not the speedo.

If you are doing a lap around Australia, for more than half of it you wont see a hill (and that's the warmer half of the country).

Good luck, I hope you find a silver bullet.

yep
very much so the fan can be an issue buit hes done that - besides doing the fan can mask a blocked radiator for a bit longer but the truth comes out
new radiator is about $700 fitted approx

Hi
Remember to check for blown head gasket .
Either a TK tester ,checks for exhaust in coolant [changes colour ]
pressure test cooling system to 18 psi and pull out glow plugs ,if there is water coming out when u turn over ...blown...

swampfox

Swampfox

Are you sure you didn't miss anything.!!!!


Sam's Oz tour will be over by the time he gets though "THAT" list.
I will stick to Allan's Thoughts ( R A D I A T O R ) Blockage .

Cheers

With a diesel if you have a cracked head you well and truly know it

hi
If this were not standard procedure check list for a work shop u would not be doing your job properly.
Guessing does not happen at my work shop
There is no replacement for thorough procedure when spending someone elses money .
A comprehensive cooling service does not stop at the radiator /coolant level
Hair line fractures in the cylinder head typically do exist and cause no issues . But it will not be long b4 the head needs removal.
All the above items are carried out in a mornings work
If 95% of this list was not carried out where I work u would be sacked

swampfox

Rojac

Yep its heading to one conclusion.
The radiator.


Cheers

Suppose I should have added the needle still moves but rarely goes past the half way mark and then when the incline finishes reverts to its std position at the bottom end of the scale

Cheers