strange over heating prob

Joined: 04 Mar 2008 Location: u.k

can anyone help Crying or Very sad

my truck seems to over heat from time to time BUT only when off road and not all the time off road,

its fine when on the road cant get it to over heat at all even when stuck in trafic

its fine when crusing around off road apart from when im really giving ot some to get ot of a mud hole or some deep mudded ruts or giving it full beans to clim a big slope

has anyone had simular??

where do i start to look?

viscos fan?
thermostat? top and bottom pipes feel hot when it does over heat
blocked rad?

any help would be much appreciated

Joined: 20 Mar 2008 Location: Aus

when was the last time u cleaned the radiator fins out? dont use a high pressure hose u will bend them all..

Joined: 04 Mar 2008 Location: u.k

im pretty good with cleaning my rad, always tend to do it every other off road session, so keep on top of it

and ive just been using hose pipe with my finger over the end,
rad looks in ok conditon

it just seems if im not going anywhere fast/moving with high revs it over heats Rolling Eyes

Joined: 18 Nov 2004 Location: New Zealand

You have a 3 inch body lift - have you adjusted the radiator to fit the fan?

Sounds to me like a viscous fan or blocked radiator issue. Thermostat is easiest to change so do that 1st.

To clean the radiator out, take it right out of the vehicle to a professional, they take the top and bottom tanks off and 'rod' it clearing it.

Joined: 04 Mar 2008 Location: u.k

ive had the 3" body lift for over a year now with no probs,

i can stop the viscous fan from spinning very easy is this right??

i will take the rad out first then and see if i can swap it with a spare rad my mate has,

changing the thermostat, is there a how to or link on the site showing how to do it on a 4D56? im no mechanic but a fast learner Laughing

thanks for help so far

Joined: 11 Jan 2004 Location: Adelaide

cms wrote:

i can stop the viscous fan from spinning very easy is this right??

Not while it's hot - no.

I'd start by doing something about that. Either replace it, or some have had success with re-filling the silicone oil.

Joined: 11 Dec 2007 Location: Perth

stop the fan and hold it for a min or 2 while holding the revs bout 2 -2500 rpm then let it go if it comes on strong straight away its ok but slow get it replaced or refilled, done a few , think can only buy it gen toyota silicone stuff, though ive heard its getting hard to get, if theres a non gen fill id like to know

Joined: 15 Jan 2008 Location: Cooma NSW

CMS:
It sounds as if you have reached the limit of your cooling system's capacity if it only happens when you are working hard at low vehicle speeds - eg low range, hilly or boggy stuff. This would most likely be caused by partially blocked cooling system, thermostat or the fan not pulling enough air to cool it all. The fact that it doesn't overheat in traffic is probably just coincidence, because you probably move a bit and get enough air to cool it down - it may be just below the point where the gauge would have started to climb when you start moving again and cool it down. Overall, you have an inadequate cooling system.

Check the fan first, then the thermostat and finally flush out the cooling system passages. This is probably the order of things anyway, but it is also the easiest sequence to do it because it involves less dismantling. Be careful when stopping the fan. Remember that the fan coupling seems to grab strongly when first started, then it settles down to allow more freewheeling. I had a Range Rover with a stuffed coupling and I could stop it with a wooden stick quite easily.

Best of luck...

Joined: 04 Mar 2008 Location: u.k

cheers guys great info Smile

im going to remove viscous fan all together and fit a KENLOWE electric fan which im told are very good, which should hopefully improve the cooling system and fix my prob,

been meaning to look at getting one for awhile now anyway

see how it goes from there and will keep u posted #Fade in

Joined: 04 Mar 2008 Location: u.k

im going to also fit a new thermostat just for good measure,

as said above i may have reached the limits of the cooling system with the set up i have,

do you think it would be worth my while changing the mitz thermo that opens at 95oc to one that opens at 76oc??

would this help the cooling or is it to low?

cheers Smile

Joined: 04 May 2008 Location: melton

I awlyas clean my radator after a sesion in the mud.

I was Very suprised when I pulled out for another reason and found the fins half full of mud.

Joined: 26 Jul 2007 Location: Crawlorado, USA

cms wrote:

im going to also fit a new thermostat just for good measure,

as said above i may have reached the limits of the cooling system with the set up i have,

do you think it would be worth my while changing the mitz thermo that opens at 95oc to one that opens at 76oc??

would this help the cooling or is it to low?

cheers Smile

A lower temp t-stat won't help you if you are having overtemp issues. While it will open at a lower temp, the issue causing the overtemp will still have the temp climbing. If you're climbing above 95oc, a 76oc t-stat won't matter. Sounds like the fan clutch or a good rodding of the radiator is needed.

Joined: 11 Jan 2004 Location: Adelaide

CapnCrunch wrote:

cms wrote:

im going to also fit a new thermostat just for good measure,

as said above i may have reached the limits of the cooling system with the set up i have,

do you think it would be worth my while changing the mitz thermo that opens at 95oc to one that opens at 76oc??

would this help the cooling or is it to low?

cheers Smile

A lower temp t-stat won't help you if you are having overtemp issues. While it will open at a lower temp, the issue causing the overtemp will still have the temp climbing. If you're climbing above 95oc, a 76oc t-stat won't matter. Sounds like the fan clutch or a good rodding of the radiator is needed.

I agree - your cooling system is working properly while you have airflow through the radiator. Fix your fan before you go playing with anything else.

I would never fit a lower temperature thermostat to my Pajero. I've had it slogging at low speeds through soft sand in 40 degree temperatures and the temperature gauge didn't budge. The cooling system design is good enough - you don't need to "improve" it.

Joined: 25 Sep 2003 Location: "Shit"ney

Head down to Toyota and get a tube of the replacement oil for the fan coupling - remove the fan from the vehicle, dismantle the coupling and get rid of all the old fluid inside - replace with the new tube of oil and reassemble and refit.

I chases an overheating problem for ages and this solved it - and for under $20.

And before the Flames suits go on ......... Mitsubishi looked at me with stupid faces when I asked about the coupling fluid..the boys at Toyota reached under the counter and produced it with a smile.

Joined: 22 Aug 2007 Location: melbournes west

don't under estimate the importance of a good fan shroud, it doubles the effectiveness of the fan, and if you have opened up the bottom of it and offset the fan from the shroud to suit your lift then it's effectiveness goes out the window.

Joined: 04 Mar 2008 Location: u.k

cheers, thats a good point about the shroud, going to looking in to getting that back spot on!
ta Laughing

Joined: 07 Jul 2006 Location: perth, WA

Have you tinkered with the injector pump at all? I found my 4d55 overheats when you are dumping too much fuel in when at max boost with wastegate open. (i have been tinkering Embarassed

) With the wastegate open iit appears to severely decrease engine efficiency, so more heating load. i have still not solved this issue on my beast. once a week i have to drive up this very long hill and i find (using boost gauge) that if control throttle to maintain 11psi (ie not passing a whole lot through wastegate), then i get the same steady state speed up the hill, as when i go full throttle and the boost creeps to 13-14psi. The difference is that i get no temp rise at 11psi, but i get a sudden rise if i drive full throttle with boost at 13-14 and wastegate clearly passing. The only times it is a problem is when i drive at full throttle along boggy beach, or up a long hill, or at high speed >120kph. Otherwise the car has no issues in traffic or at low speed 4wding etc. So i find i can thrash teh old girl however i like as long as i don't spend much time overboosting. i'm interested if ayone has any experience with this issue btw, or if we have any bosch VE experts out there. btw, don't change/remove your thermostat, its there for a reason

Joined: 18 Aug 2004 Location: packahoonaham

gday mate,

when i did my body lift - only 2" - i move the radiator down 2" so it was same position in relation to motor again - then all hoses/shroud/etc fit the same - just had to notch a little around cap to make it easier to get on and off. The shroud is there for a BIG reason - amazing the effect it has.

Regards,

Haydn

Joined: 04 Mar 2008 Location: u.k

cheers for the help guys, got rid of the viscous fan for an electric one,

had a good test run and all seems fine... so must of been the viscous fan

the kenlowe fan is very good and cools it quickly also has a boost mode if needed! and an isolator switch to cut it off when wading Laughing

truck seems to run smoother and rev more freely aswell Laughing