Overheating Hilux - what can it be?

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Hotlux
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Overheating Hilux - what can it be?

Unread post by Hotlux » January 13th, 2014, 11:00 pm

Hi All,

Seeking help/advice on an overheating hilux.

I have an LN106 Hilux which had a 2L-T setup in it which would overheat and boil on the hwy in above 30deg conditions

I have now turfed that engine and fitted a 5L-T setup with a CT20 turbo and PWR WTA inercooler with 8" barrel. This new engine still overheats on the hwy in +30deg temps.

The engine is reco, as are the injectors and mechanical 5L fuel pump. The waterpump, turbo and viscous fan are new and the radiator was re-cored with the highest performance core available and also triple bypassed.

However, I still can not keep this engine cool during hwy use. I have tried removing the the spotties and grill to ensure full airflow but still no joy. EGT's stay below 600deg and the boost is a healthy 12-14psi at hwy speed.

Has anyone come up with a solution for these hilux's, my next thought is to fit dual radiators and a thermo fan setup???

Help please as I have burnt far too many hours and $$$ trying to fix this.

Bevan'n'Katie
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Re: Overheating Hilux - what can it be?

Unread post by Bevan'n'Katie » January 14th, 2014, 12:20 am

this is a bloody strange on mate. im not sure what all the letters and number mean. but is it alloy radiator. because some vehicals will still over heat because the metal is so light and struggles to get rid of the heat. but its strange since its 2 differant motors. you really want to get as much air at the top of the radiator as you can because thats where the water goes first stright out of the motor. make sure your fan shroud is a nice fit. also you not running to much coolant are you ? strong coolant will not help cooling, it will help over heating though. other then that, make sure your fan is sucking and not blowing. other wise you will get kind of a air lock in the radiator. and thermo fans will not pull the air though anywhere near what a car doing 100km will push though.

dhc4ever
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Re: Overheating Hilux - what can it be?

Unread post by dhc4ever » January 14th, 2014, 5:49 am

Whats a triple bypassed radiator?
Whats telling you its overheating, oem guage, engine watchdog tm 2, after market guage, where is its pickup?
Turn the fuel down to a max egt of 550 deg and boost down to 9 or 10 psi.
Fan shroud fitted?
New thermostat?
What under engine bash plates are fitted?
Simply put mate I think you have exceeded the engines and upgraded cooling systems ability to shed the heat you are putting in, tune it back and see if the problem persists.
By tune I mean get it on a dyno and set the egt's, boost and air fuel ratios up correctly.

Hotlux
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Re: Overheating Hilux - what can it be?

Unread post by Hotlux » January 14th, 2014, 7:12 am

To triple by-bass a radiator you put a baffle in the top and bottom tank which forces the coolant to do 3 passes of the radiator. I just had this removed (just to try) and it is worse than ever. It is a brass/copper radiator.

Should've mentioned the thermostat is a new tridon highflow unit and the head is also new (not re-co'd). Fan shroud is all good. Also the block bored .5mm over-sized

Just using the standard gauge but I know that is accurate as when it is in the red the coolant bubbles out the overflow as it is boiling inside (I have not done that to the new engine tho).

Having it dyno'd when I head to Perth next fortnight, I have had someone follow me for the interim (until it gets on the dyno) and the exhaust is completely clean throughout the entire rev range...

I am also thinking the cooling system cannot keep up which I'm not thrilled about.....

Thoughts, thanks.

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Re: Overheating Hilux - what can it be?

Unread post by Peter Aawen » January 14th, 2014, 8:49 am

I'm with dhc4ever on this re the EGT's - it's only overheating at hwy speeds right? When you slow down it drops back in temps fairly quickly, right? If you push to hold speed up a hill or into a head wind it gets hot, right? But again, it drops off as soon as you back off and slow down??

It sounds very much like you are over-fuelling and pushing the EGT's too high!! And with smaller engines like those you are running, there is not necessarily going to be much visible smoke (unless you look at night with a light shining thru it, when you might be able to see it!) Where is your thermo probe?? If it's post turbo ie in the dump pipe, then 600 deg C is too high, 550 is the generally accepted MAX and if you want long term reliability it's best to tune any diesel so that it rarely reaches that under 'normal running' - usually tuning them so they're running in about the mid 300's (or a bit lower) on the open Hwy will give you enough scope to give it stick every now and then without exceeding that magic 550 deg C where things can start melting very quickly.... or just slowly soften things and create terminal damage over time!

If this is the case, I don't think ANYTHING you do to the cooling system will solve the 'overheating' - it's not a factor of the cooling system being up to it, in fact, if you have done all those things that you mention your cooling system is probably somewhat better than original AND has much more heat tolerance than most, but the engine itself is cooking because metals are reaching untenable temps. You could try adding an aftermarket coolant temp, but all that will do is confirm your overheating and give you some more accurate temps to run with, the bubbles sound pretty conclusive, and the pattern of 'overheating' is pretty much the same!! Wind the fuel back a little now! Then when you get the dyno done, get it tuned so that sustained max throttle under load conditions doesn't ever push the EGT's over 550 deg C!!

Good Luck!
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dhc4ever
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Re: Overheatin Hilux

Unread post by dhc4ever » January 14th, 2014, 9:15 am

Put the baffles back in before you get it tuned, the baffles sound like an excellant idea and every bit will help.
Another thing that might help is rearward facing bonnet vents, have a mate with an xj jeep that over heated at the mention of the words cunninghams gap, he fitted rear facing vents at the rear of both sides of the bonnet and dropped temps by 25 deg with no other mods. Now yours is a slightly different issue but improved airflow through the engine bay and radiator may help.
Cheers

mydmax
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Re: Overheating Hilux - what can it be?

Unread post by mydmax » January 14th, 2014, 9:34 am

Hotlux
The triple pass radiator with baffles effectively makes the flow area 2/3 smaller than the original flow because there are only 1/3 of the tubes presented to pass the flow.
A normal radiator running normally will be cool at the bottom and engine temp at the top and with ALL the core tubes able to carry flow.

I cannot see how the baffles would be any advantage and possibly will be a distinct disadvantage with only 1/3 of flow ability and effectively three times the length of tube to have to push the water through causing flow friction losses as well.

Definitely not my cup of tea.

i agree with Peter and think it is a fueling issue and possibly expecting a small engine to pull too high an overall gearing ie big wheels etc which will cause internal engine heat to be more than normal.

The engine cooling system doesn't have any control over the temp of the internal combustion and gas flow, all the cooling system can deal with is what is conducted to the water..

Peter Aawen
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Re: Overheating Hilux - what can it be?

Unread post by Peter Aawen » January 14th, 2014, 10:34 am

Be a little careful with ANY bonnet vents or scoops on these vehicles - they work on a thermo-syphon system of cooling that uses the air flow thru the radiator and then down and out UNDER the car (due to the slightly higher pressure area created at the top/back of the engine bay) to suck more air than the fans alone can suck or the forward motion of the car alone would generate. Disturb that carefully engineered thermo-syphon system and you can create massive cooling issues by simply disturbing the designed air flow paths!!! So I wouldn't go cutting into your one and only bonnet before removing any other possible cause, and even then I wouldn't be doing it without careful discussion and consideration of the direct experience of others, not just anecdotal info off a forum!! I've seen too many vehicles with major issues from silly little things like just lifting the rear of the bonnet on a couple of washers to think there will ever be an easy fix of any cooling system by doing something like fitting scoops or vents!

That said, I'm still convinced that you would find your over-heating issues reduced somewhat by winding the fuel back a tad, and massively reduced if not totally resolved by properly tuning the fueling & I/P system to make sure that your engine won't ever exceed 550 deg C with a thermo probe after the turbo - you might not get quite so much power, but you won't blow up or melt the engine or turbo either, and you may well even get better fuel economy and better driveability into the bargain! ;)
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CASH476
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Re: Overheating Hilux - what can it be?

Unread post by CASH476 » January 14th, 2014, 7:21 pm

As the others have said, don't go cutting holes in the bonnet etc, this will not solve the cause of the problem & may make it worse.

Some of the earlier 5 speed utes were too high geared in overdrive and had to work harder (using more fuel) in 5th than if you left it in 4th. Provided the revs are not too high, try some highway work in 4th & see if it makes a difference. It will not solve the problem but will give some valuable info. Definitely get the tune done & the pump set to a safe setting regardless of the outcome.

mydmax, A triple bypass radiator has a baffle at the top & bottom of the radiator to direct the water down through the first 1/3, up through the middle third & down through the last. This is fairly common in heat exchangers to keep the flow as even as possible through the whole thing. With a radiator with such a wide area across the top & bottom tubes it can make a big difference to the efficiency.

I assume it is easier for car makers to just put bigger radiators in than mess around with this system. Also, the triple bypass could block up quicker than the single.

Scantek
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Re: Overheating Hilux - what can it be?

Unread post by Scantek » January 14th, 2014, 9:47 pm

G'day Hotlux

I'm thinking maybe you have a restriction in the coolant flow somewhere.
Take off the radiator cap and run it up to temp.
If you rev the engine slightly you should be able to see the coolant flowing across the top tank of the radiator.

If you cant see that happen first thing remove the thermostat. It may be faulty or set too high and not opening enough.
Try running it again. If you get flow go for a drive and see if it overheats.

If you have any of the tubes inside the radiator that are blocked or if the core is too small you may have a water pump trying to suck more coolant through the radiator than it can handle.

Mmmmm just a thought. Your bottom radiator hose isn't collapsing is it?

You may have to put an internal spring inside it to stop that happening. If it is collapsing it will restrict the coolant flow and will cause overheating.

Just a couple of thoughts and things to try.

Russ

Hotlux
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Re: Overheating Hilux - what can it be?

Unread post by Hotlux » January 14th, 2014, 10:13 pm

Hi guys,

Thanks for all the info, no holes in the bonnet for me - hence why I have a WTA intercooler.

As expected it runs a bit hotter without the bypass but I had to give it a run.. It was only 35 on the way home from work so a bit hard to tell how much difference it made.

Should've mentioned I set the timing to standard spec (0.64mm plunger stroke). 5th is 3000rpm at 110km/h.

I've backed the fuel off an extra half turn (I don't think I'll have to worry bout 110km/h now) and will see how that goes tomorrow.

When the outside temp is below 30 my EGT's don't go over 450-500 and also for the first 10-15mins of driving on a hot day.
After 10-15mins at hwy speed on a hot day that is when the temps start to rise and will not lower till I back off to 70-80km/h.

Another thought we had, could the CT20 turbo not be capable of flowing the 5L's exhaust gasses therefore creating the high temps - however the temps do not rise in below 30 deg days.

More fuel for the fire (less for the hilux tho)

Thanks

75workhorse
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Re: Overheating Hilux - what can it be?

Unread post by 75workhorse » January 14th, 2014, 11:17 pm

Try to lock the fan if it still over heats
2 things are wrong
blocked rad or internal
that is all you can do to save your motor
If it is called common sense
then why is it so uncommon

dhc4ever
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Re: Overheating Hilux - what can it be?

Unread post by dhc4ever » January 15th, 2014, 7:50 am

Hotlux wrote: When the outside temp is below 30 my EGT's don't go over 450-500 and also for the first 10-15mins of driving on a hot day.
After 10-15mins at hwy speed on a hot day that is when the temps start to rise and will not lower till I back off to 70-80km/h.
That description is heat saturation, after 15 minutes everything in the engine is hot and in your case the cooling system cant keep up and so the temps start climbing. If the 2.8 block had larger coolant galleries and a greater coolant capacity in the it may be able to handle your current load, but thats not the way they made it.
Post the results of turning the fuel down, if everything else checks out it should make a difference.
Cheers

dod28
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Re: Overheating Hilux - what can it be?

Unread post by dod28 » January 15th, 2014, 4:23 pm

In your opening post you say you've got the highest performance core available, what's the difference between the new an old cores?
A standard LN106 3 core rad has approximately 40 tubes per row spaced at about 12.5 mm. My upgraded core has 60 tubes per row spaced at about 8 mm. I don't know the fin count other than to say you can clearly see the upgraded core has a lot more fins than standard. Also each tube is significantly larger than standard which results in the whole core being a lot thicker than standard, somewhere near the size of a 4 row core.
How does your new core compare to how I've described mine?

Also I'm presuming with no hole in the bonnet your intercooler is mounted in front of the radiator reducing airflow and increasing the temperature of the incoming air before it gets to the radiator.

Have you got air conditioning? More airflow restriction and heat.

dhc4ever
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Re: Overheating Hilux - what can it be?

Unread post by dhc4ever » January 15th, 2014, 8:04 pm

Dod,
Water to air intercooler, generally fits across the top of the tappet cover, no bonnet hole required and no obstruction of the radiator.

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