Hilux 2.8 diesel overheating - any thoughts?

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allycol
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Hilux 2.8 diesel overheating - any thoughts?

Unread post by allycol » April 8th, 2018, 8:30 am

I have done just about everything but my hilux overheats. Driving down highway come to a hill and gauge starts to rise, Tested gauge ok. New thermostat, new radiator, cleaned block, timing check, engine runs fine. One time driving up a continuous hill temp right up near boiling, at the top pulled bonnet about a quarter and the radiator was cold the rest - hot how could that happen? New radiator. Any thoughts?

Peter Aawen
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by Peter Aawen » April 8th, 2018, 9:41 am

A few thoughts....
Have you checked the sender & gauge to make sure they are reading accurately? A gauge that goes up to half & then never moves is NOT RIGHT!! The engine coolant temp MUST go up and down as the engine load varies & the cooling system cycles/the thermostat opens & closes/the fan cuts in & out; so if the gauge shows the temp going up & down but manages to remain out of the red, then it is probably all working properly - your engine cooling system isn't 'over-heating' until the coolant temp is up over 110 deg C or maybe even higher depending on the pressure & the coolant you use - anything below that is fine & the gauge SHOULD go up & down as the load varies, but some manufacturers damp that out of their gauges just to keep the sheeple who have no idea calm, but then you risk not knowing things are getting hot until it's too late!! Not a good thing for 4WD'ers, who need to know BEFORE things get too hot, so that they can lift their right boot & reduce the cooling system load!
Have you fitted a new & correct pressure radiator cap? If not or it's a low pressure cap, then the coolant will boil at 100 deg C or maybe even lower if you are above sea level!
Have you checked to make sure that the viscous fan hub is actually working?? If it's not, then the fan isn't pulling air thru the rad & things will get hot under load.
Is the new thermostat OE & opening at the correct temp? While there are some very good after-market thermostats, some systems just don't work the same with anything but the OE unit - or maybe you might need to drill an extra single 1/8th" dia hole in the thermostat flange to let a little more coolant thru when the thermostat is closed? Check your thermostat is correct & opening/closing at the correct temps!
When was the coolant last changed? Did the block get back-flushed then? And when the system was refilled with coolant, was it done slowly with the engine running & was the radiator/block purged once it was all full just to make sure there were no air pockets caught inside?? They can cause overheating &/or throwing all the coolant out of the system!
How about checking the waterpump & coolant flow - the fins inside the water pump might have rusted out; no coolant circulation = engine over-heating!
What about your fuel pump - has the fuel been wound up to give you more power? Too much fuel can easily make a diesel engine overheat! This is especially the case with turbo-ed engines & extra especially with after-market turbos!
Talking about turbos, if you have one, do you have a full turbo exhaust system with little or no back pressure & no choke points like a narrow turbo outlet flange or dump pipe?? Restrictions in a turbo exhaust or the outlet flange/dump pipe can cause high Exhaust Gas Temps (just like over-fuelling can!) and if you've got EGT's over about 550 deg C, 600 max, then NOTHING your coolant system can do will stop the engine &/or turbo getting hot & eventually melting or blowing up, even if the coolant &/or rad are still cool to the touch!!

I hope your problem is one of the easy ones, but overheating as you keep your boot into it going up a long hill is a classic symptom of overfuelling &/or high EGT's - if those are only just over 550 ish, you can sometimes get away with things by lifting your right boot & changing down a gear, & not trying to push to maintain highway speeds.... but often, the only solution is a good diesel tune, setting the timing & fuel delivery correctly, and making sure nothing in the exhaust or dump pipe is creating a choke point & pushing the EGT's up!!

Good Luck!

Oh, & welcome to the Forum too! ;)
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

allycol
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by allycol » April 8th, 2018, 6:07 pm

Hi Peter
Thanks for your post the in car gauge is not working correctly as it only goes to half in any
Condition. I have a SAAS gauge I have checked it with two other gauges it’s correct, I removed the engine and flushed block removed the head all good. Lucky as core plugs where about to leak. The thermostat is after market, I checked it works fine but in some cases genuine is the only one you can use. It only over heats in overdrive going up hill when the motor is at max power or when continues up steep hill. Maybe it needs a genuine thermostat?

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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by Peter Aawen » April 8th, 2018, 6:28 pm

Yeah, that 'only overheats in overdrive going up hill when the engine is at max power' bit REALLY SCREAMS over-fuelling tho!! What happens if you back off & go slower?? Or change down a gear & don't use max revs?? I reckon that if you stick an EGT gauge on it & check the exhaust temps with a probe within about 150mm from the turbo outlet/exhaust manifold to exhaust connection you'll find the EGT's are topping 550 deg C and that will almost certainly be from too much fuel or too much of a restriction/a choke point somewher in the exhaust or outlet - and if that's the case, ABSOBLOODYLUTELY NOTHING you can do to the cooling system will stop things over-heating!! :eek:

The give-away is the significantly raised temps while you are pushing to maintain hwy speeds on an extended climb; temps that drop off fairly quickly once you change a gear, or once you lift your right foot, or once you crest the top of the hill & start to coast down the other side...... But EVERY SINGLE TIME your EG temps hit 600 you WILL have started to damage something just a little more inside the engine or turbo and that damage is accumulative and irreversible - you simply cannot get it back/recover from it without an engine rebuild!!

Sounds awfully much like you need a good diesel pump/injector tune & to get your fuel tuned better to the volume of air you are getting into the engine!! Less fuel WILL mean a little less power, but it also means your engine isn't likely to be slowly destroying itself - or doing that quickly!! ;)
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

allycol
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by allycol » April 9th, 2018, 7:38 am

It sounds like you're right about the standard temp gauge not showing the right temp. I wonder if all gauges on other cars my Hyundai gauge never changes in any condition.

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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by Peter Aawen » April 9th, 2018, 11:03 am

If the gauge goes up to half way or thereabouts & then never moves, chances are that the manufacturer has damped the gauge response so that it doesn't go up & down & worry those people who don't realise that going up and down as engine load varies is what your coolant temp actually does & is what they are meant to do - but the needle should stay out of the Red or at least keep within the normal range!! ;)
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

allycol
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by allycol » April 9th, 2018, 6:46 pm

Do you know if the rear drive axels are the same length, do they fit both sides.

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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by Peter Aawen » April 9th, 2018, 8:35 pm

Yeah Nope, sorry. :( Those 'newer' Hilux's aren't really my cup of tea... :p Regardless, generalities, maybe I can help; specifics, not so much! ;)
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

allycol
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by allycol » April 10th, 2018, 6:46 am

Mine is a 1992.

dod28
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by dod28 » April 11th, 2018, 5:50 pm

allycol wrote:
April 8th, 2018, 8:30 am
about a quarter and the radiator was cold the rest - hot how could that happen? New radiator. Any thoughts?
Is that supposed to read, about a quarter of the radiator was cold?
If the top of the rad is hot and the bottom is cold that's what they're supposed to do.

Is it turbo'd? Search some of my previous posts for info on upgraded radiators.
if it's not turbo'd then it's a system fault somewhere

allycol
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by allycol » April 20th, 2018, 4:43 pm

The complete quarter of rad was cold maybe the thermostat isn’t opening enough. One thing I
Think it needs is a high flow thermostat. I will figure this out and I will post. Cheers

cuzza_wa
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by cuzza_wa » May 8th, 2018, 4:32 pm

Was it overheating before?

New radiator.......new thermo.........only stories i have read about overheating in mostly replaced cooling systems and due to not burping it after topping it up, ie you've got air in there somewhere.

Have you bled the cooling system?? ( ran car with heater on and rad cap off until thermostat opens?)

If it wasn't doing it before, and its doing it now, and you've only replaced a radiator, then i cant see how its fuel related unless you busted something when you put the radiator in.

allycol
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by allycol » June 8th, 2018, 8:02 pm

I have fixed my overheating problem, I removed the turbo. I just returned from Cape York was a great trip, done the telly track. The old hilux never missed a beat. At 1992 it must have been the oldest 4x4 up there.

Headonz
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Re: Hilux 2.8 diesel overheating - any thoughts?

Unread post by Headonz » September 13th, 2018, 8:19 am

Thats interesting , was there a significant power loss without the turbo ??

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