overheating

Post by **SIERRA BANDIT** » Wed Sep 30, 2009 10:26 am

hi all i know this has probably been covered a few times but i couldnt find ant answers.
i have a 03 79 series landcruiser 1hz and when im dioing highway speeds. over 110kmh the temp gauge rises to 3/4. i have had the radiator cleaned out, replaced the fan hub with a genuine toyota one and replaced the thermistat.
but i replaced the thermistat with a non genuine, i have been told they are dodgy as shit. the old thermistat was scaled up so it wouldnt open fully, i know this as i put it in a pot of water and heaated it up to almost boiling temp. i also put the new aftermarket one in and it didnt open until 85 deg c or so even though it has 76 written on it.

so the question is do you think the thermistat is the problem and should i go get a genuine toyota one? or is there another thing i should look at.
i dont have big spotties or anything restricting the air flow

cheers

Post by **dabulg** » Wed Sep 30, 2009 11:07 am

I just did some work on my cooling system as a result of findind a bit of grass coming out from the space between the A/C condensor and the radiator. I was pulling it out as it appeared but it just kept coming. I pulled the radiator out and it was chocka a block with spear grass and seeds. I held the radiator up to the sun and could only see through about 20% of the core. How it was cooling at all I don't know. I half filled a 10 litre bucket with grass and crap.

The A/C condensor fins were also blocked. This sits in front of the radiator and also offered resistance to the flow of air. Could your core also be blocked or the A/C condensor blocked ? Belt onto the water pump OK ?

Post by **yamaha__308** » Wed Sep 30, 2009 11:37 am

To test if its the thermostat, cut the valve part out of it and just put the housing back in. It'll take longer to get up to temp, but should be able to tell when its warm if its a flow problem.

Post by **SIERRA BANDIT** » Wed Sep 30, 2009 2:20 pm

dabulg wrote:I just did some work on my cooling system as a result of findind a bit of grass coming out from the space between the A/C condensor and the radiator. I was pulling it out as it appeared but it just kept coming. I pulled the radiator out and it was chocka a block with spear grass and seeds. I held the radiator up to the sun and could only see through about 20% of the core. How it was cooling at all I don't know. I half filled a 10 litre bucket with grass and crap.

The A/C condensor fins were also blocked. This sits in front of the radiator and also offered resistance to the flow of air. Could your core also be blocked or the A/C condensor blocked ? Belt onto the water pump OK ?

yea i had the radiator out and cleaned out all of the grass seeds, while it was out i cleaned out the condensor, there was afair bit of seed between the two so i thought i found my problem but the temp gauge still goes up. The belts are nice and tight also.

Post by **Chucky** » Wed Sep 30, 2009 4:30 pm

had the same problem in my 80, it turned out to the be viscus hub on the fan.
Pulled it out, and using a write up I got off the lcool website, refilled the hub with the fluid needed (Was about $18 a tube from toyota and used two tubes).
I'll see if I can find a link to the write up on how to do it.

Fixed the problem.

Post by **howesy** » Wed Sep 30, 2009 4:46 pm

A problem often overlooked with overheating on highway speeds is the bottom radiator hose. Most have reinforcement inside to stop them sucking in and cutting flow on extended higher revs. Replace the bottom hose with a reinforced newy and see if there is a difference it wont hurt any and you've already spent 3 times that much so what have you got to lose.

Post by **twocs** » Wed Sep 30, 2009 5:11 pm

The same thing has just started happening to mine. Looking into it now.

Post by **SIERRA BANDIT** » Wed Sep 30, 2009 9:22 pm

howesy wrote:A problem often overlooked with overheating on highway speeds is the bottom radiator hose. Most have reinforcement inside to stop them sucking in and cutting flow on extended higher revs. Replace the bottom hose with a reinforced newy and see if there is a difference it wont hurt any and you've already spent 3 times that much so what have you got to lose.

this sounds like something i should look at.
cheers

Post by **SIERRA BANDIT** » Wed Sep 30, 2009 9:31 pm

just had a look and my botom hose its verry soft. might be onto something

Post by **twocs** » Sat Oct 03, 2009 8:23 am

twocs wrote:The same thing has just started happening to mine. Looking into it now.

I've been told more than likely just a blocked radiator. Bit costly though, need a new top tank once they remove the old one apparently....

Post by **SIERRA BANDIT** » Sat Oct 03, 2009 11:21 am

i had my radiator pulled apart and cleaned out, they reused the old top tank. cost $120

Post by **twocs** » Sat Oct 03, 2009 8:17 pm

SIERRA BANDIT wrote:i had my radiator pulled apart and cleaned out, they reused the old top tank. cost $120

Thats good to know. I'll look for some where else and get another opinion. But didn't fix the problem then ?

Post by **SIERRA BANDIT** » Sun Oct 04, 2009 10:12 am

twocs wrote:
SIERRA BANDIT wrote:i had my radiator pulled apart and cleaned out, they reused the old top tank. cost $120
Thats good to know. I'll look for some where else and get another opinion. But didn't fix the problem then ?

nah didnt fix the problem. starting to lean towards the head gasket, was told that it can leak so little you will only notice the water usage over a long period of time, ive only had the car for 20 000 and have droped the water a few times in this peroid, so i cant really say if its using any.

i havent changed the bottom radiator hose but i checked out a mates and it seemed to be the same softness and he isnt having any over heating problems. ill give it a go tho.

Post by **chunks** » Sun Oct 04, 2009 10:32 am

How many kms on it? Waterpump impellers could be worn or the belt slipping. I'd be changing that thermostat again as well if it didn't open when it was supposed to.

Post by **BJ73** » Sun Oct 04, 2009 11:30 am

You could try spacing the bonnet out from the hinges with a couple of washers each side. Just enough to create a bit of a gap but not so much that it's too noticable.

This allows the air to flow in through the grill then out the back of the engine bay.

Also, if there is that rubber seal at the back of the bonnet, rip it out to facilitate air flow.

However, these things are only of help for mild overheating problems.

Post by **dexter09** » Sun Oct 04, 2009 12:57 pm

if it's with highway driving, your vehicle could be over fuelling, turning the fuel up gives you extra torque but also extra heat and when your on the highway, usually your foot is down bout halfway so if your fuels set a bit high it can heat up after a period at high revs. does it blow alot of diesel smoke when you put your foot down getting up speed?

Post by **SIERRA BANDIT** » Sun Oct 04, 2009 1:01 pm

dexter09 wrote:if it's with highway driving, your vehicle could be over fuelling, turning the fuel up gives you extra torque but also extra heat and when your on the highway, usually your foot is down bout halfway so if your fuels set a bit high it can heat up after a period at high revs. does it blow alot of diesel smoke when you put your foot down getting up speed?

i havent really noticed it blowing alot of smoke. ill try get a mate to follow me and check it out.

Post by **twocs** » Fri Oct 09, 2009 5:25 pm

Any verdict yet ?

Post by **SIERRA BANDIT** » Sat Oct 10, 2009 5:44 pm

twocs wrote:Any verdict yet ?

nah but i bought a genuine thermistat and ill give that a go. got 2 new hoses aswell.

i was told the botom hose will only suck in if your radiator is blocked. but i might as well change them over.

got 2 hoses and a thermistat for $80 all genuine toyota.

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