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  • Highspeed overheating after 4WD/mud tracks

    Hello everyone,

    I have a overheating problem similar to some I've seen on this and other forums, but mine has a very specific cause so I would like to ask for your input. Thanks in advance.

    problem: temperature-gauge keeps on rising on inclining roads or when driving over 60 mph. Used to be steady as a rock no matter what I did. Controllable when slowing down or putting heating on.

    cause:

    I went on a 4WD roadbook including 3 medium-deep mud pools (which I took effortlessly, hooray). However I neglected to clean the radiator after and on a high-speed section overheated the engine. (very stupid) This was obvious with following consequences: needle in red, an empty coolant reservoir, boiling sounds and steam (through reservoir cap).

    pictures happy, not so happy:

    https://photos.app.goo.gl/v7bEWbTeeirjY6qW8

    After this we cleaned the radiator and topped up radiator + coolant reservoir with plain water.

    Coming home I gave the car a thorough clean but since then I have the problem as described.

    I was thinking viscous hub or water pump but those seem to be 2 problems that seem to be unrelated to the mud in the radiator thing. I am hoping not head gasket or worse, cylinder head itself but I am hopeful because I am not losing any coolant since I've topped it up.

    I would be very greatful if someone could point me in the right direction.

    Thank,
    Peter


  • #2
    From the photos it's a non intercooled KZ.
    Did you remove the radiator to clean it's fins as well as getting at the aircon condenser to clean it?
    If you did all the cleaning properly and it still overheats there's an excellent chance you've cracked the head.
    If the viscous hub was working previously as well as you mentioned, it wouldn't have instantly died from a mud bath.
    But a KZ head, they don't like getting hot.

    Comment


    • #3
      You can test the viscous fan clutch - with the engine off the fan should be turnable but you should feel a resistance to turning, and once you have turned it, the fan should stop almost immediately. If it just freewheels then the clutch needs a service/repair. Good idea from carco to remove and thoroughly clean the radiator. Good luck...

      Comment


      • #4
        Thanks for your replies. Although I am pretty confident about the cleaning I will dismount the radiator to be sure.

        As for testing the clutch, I suppose I should do this with a hot engine for the clutch to be filled with oil thus providing resistance?

        Still hoping for a non cracked head but if so, any tips on reliable suppliers for an aftermarket replacement?

        Comment


        • #5
          Peetn checking the clutch is done cold, it should be as I described when cold, and if you did it hot should be a lot harder if not impossible to turn without turning the engine.

          Comment


          • #6
            The fact you're not losing coolant is a good sign.
            I find the easiest way to test the fan is to start her from cold and rev to about 2000rpm.
            You'll hear the fan roaring and then after a minute or so you'll hear the noise subside as the viscous hub starts to slip.
            That roaring noise is what you have to hear when you're on the road and she's getting hot.
            If she gets hot and you don't hear the roar, the hub isn't locking at max.
            Adding silicone oil is easy but it's hard to know how much to add. Too much and the fan will never freewheel, engine will run cool but you'll use a bucketload of fuel and it eats horsepower.
            Your reply sounds like you didn't actually remove the radiator. If that's the case, you'll find the space between radiator and condenser is still blocked with mud.
            Radiator out is very easy and the best way to clean the fins.

            Comment


            • #7
              Originally posted by carco View Post
              The fact you're not losing coolant is a good sign.
              I find the easiest way to test the fan is to start her from cold and rev to about 2000rpm.
              You'll hear the fan roaring and then after a minute or so you'll hear the noise subside as the viscous hub starts to slip.
              That roaring noise is what you have to hear when you're on the road and she's getting hot.
              If she gets hot and you don't hear the roar, the hub isn't locking at max.
              Adding silicone oil is easy but it's hard to know how much to add. Too much and the fan will never freewheel, engine will run cool but you'll use a bucketload of fuel and it eats horsepower.
              Your reply sounds like you didn't actually remove the radiator. If that's the case, you'll find the space between radiator and condenser is still blocked with mud.
              Radiator out is very easy and the best way to clean the fins.
              I have indeed not taken it out but I will!

              I'm thinking replacing hub rather than refilling when necessary as they seem quite affordable.

              Comment


              • #8
                In most cases that Iíve come across, overheating issues are from partial blockages in the radiator fins. Mud covering some of the outside was probably what tipped it over the edge. Those radiators in the 90 typically last 10yrs then youíre up for a new one. If it wasnít going to be mud, then maybe a decent hill climb later on in the year wouldíve exposed the problem. Itís always one day with no issues, then the next it presents itself from nothing to something.
                2005 120 series V6 Grande, 2 inch susp lift (King/EFS combo), 32 inch MT’s, Safari Snorkel, rear diff lock, breathers, Light Force spotlights, UHF, dual batteries.

                Comment


                • #9
                  update


                  So this novice apparently mistook the condenser for the radiator.

                  I now took the radiator out and it was still very very muddy. Almost all fins blocked. Pictures at the bottom of this post. I hope this is the cause it was still heating and I also hope no further damage was done. @carco thank you for being so gentle with me as I obviously had not cleaned it well. To give you an idea about the type of mud look at the picture of the inside of the skid plate.

                  Did the fan clutch test like you described @RedAdventureWagon and it feels 'normal' like you put it.

                  I guess the next question is whether it's worth putting the old radiator back in. Not that many fins left. Thus @Brett1979 I hope you are right and it's a simple problem.
                  Full disclosure on my stupidity I also probably rinsed it too hard, I could see the fins fall off with the water. Although one might think if water can do that the strength was already gone. Also, I rinsed the radiator inside with plain water from a well, which is probably not very good.

                  Next question is about the condenser it is in a very bad shape, you can actually see through. I don't care much for aircon, it's never worked as long as I own the car. But while I have the radiator out it seems like a good time to put a new one in as well, or can i just take it out giving the radiator more breathing space?

                  Last worry I have is the small hoses on the radiator (cooling tubes for the automatic gearbox?), seemed to be having more oil coming out of them than coolant (see picture), is that an issue or normal at this age? I have 160k miles.

                  I only use this car for 4wd and some heavy lifting doing about a couple of thousand miles a year.

                  pictures here:

                  https://photos.app.goo.gl/8RjtmmwV2YZxW4Hw6


                  So I guess my questions are:

                  1. new or old radiator?
                  2. replace or remove condenser or leave as is?
                  3. should I worry about the gearbox?
                  4. will I have to take the radiator out after every mud bath?
                  5. do you guys use original Toyota coolant, the red, "old" version?

                  Again, thank you so much for your advice.

                  Peter
                  Last edited by Peetn; 10-07-2019, 05:22 AM.

                  Comment


                  • #10
                    I would:
                    1. New. Best replaced early as you don't want an ATF/coolant soup disaster later on down the track.
                    2. I would probably leave as is until the AC gives up especially if it's not that important to you. Just my opinion on this though I imaging leaving it dry for a time would eventually cause damage.
                    3. Yes definately, if you do change the radiator swap the hoses, then start engine and then check and top up ATF using the cold marks on the dipstick. Once that is ok go for a drive and re top up according to the hot marks. Remember to cycle the shifter from P to L few times as part of topping up, stopping at each section for a few seconds
                    4. If it's as severe as the pic you had earlier maybe but I'm not really qualified to comment with my lack of mud off roading.
                    5. My mechanic flushed the coolant at my last major service and he just used green coolant recommended by an aftermarket supplier. Likewise with ATF I just used aftermarket recommended by Penrite, these old transmissions are not as sensitive as newer ones IMO but I'm no Toyota qualified mechanic.

                    Hope you get it sorted mate and hope your engine is ok.

                    I'm assuming that battery cable draped across the pulleys is just whilst you work on it and not always there? Looks a bit precarious.

                    Would say as well even when you have the ATF level ok hot, check after 200km or so. After a recent ATF leak and replacement I got an extra litre in after that distance due to air bubbles etc.
                    Last edited by RedAdventureWagon; 10-07-2019, 06:13 AM.

                    Comment


                    • #11
                      If that was the original radiator the fins tend to corrode and any decent water blast will bend them, new radiator would be the go. Plenty on eBay but none are as good as that original.
                      Aircon is so handy I'd be reluctant to remove it. Is the condenser still in situation, you haven't removed any of the refrigerant pipe work?
                      So long as you can clearly see through it, it won't offer a huge restriction to airflow. If it's fins have been bent like your radiator, it would need replacing. They're not expensive, the vac out and re-gas will cost as much.
                      Too late now but you should have plugged both those hoses when you removed the radiator. You will have lost a LOT of trany oil. Blocking them also stops any chance of dirt entering your auto.
                      These cars are not designed for mud baths. If you want to continue this activity, you'd have to look at everything that will be immersed. Diff breathers, gearbox transfercase etc. Alternator will probably start giving trouble soon judging from the amount of mud on the engine, thrown up from the fan.
                      Dedicated mud bashers will have the radiator relocated we'll clear. Most will have the engine bay semi sealed as well.
                      Don't mix coolants. If she had Toyota red coolant, use that. If she had some green stuff, use that.
                      From the photos I think you've dodged the bullet. A big clean, new radiator, new coolant, refill and check trany oil, she might be OK.
                      Good luck.

                      Comment


                      • #12
                        If your aircon isnít working & you honestly donít give a stuff about it, just pull the condenser out and cut the aircon pipes with a cutting disc on an angle grinder. My aircon was shagged a few yrs back in the 90. Just stopped working all together. Spent $250 on Natradís auto elec trying to diagnose issue & they were stumped. They told me to try Toyota. Spent $600 with Toyota unsuccessfully diagnosing the fault. They asked to keep the car for another day and for me to spend $1,000 on the diagnosis while they delved into it further with no guarantees of fixing it or what any replacement parts might cost extra. I told them not to worry. I ripped out condenser, cut the pipes back on the engine bay, removed the compressor to make the car 15kg lighter and to make the next DIY timing belt change quicker because the prick of a compressor has to be removed to do a timing belt change (on a the petrol engine anyway). The radiator gets much more airflow to keep it cool without the condenser in the way blocking the wind. And PLUS you can keep doing your mud bashing and the radiator will be exposed front and centre for easy inspection & cleaning. If aircon isnít important to you like back in the 80ís just take it out. If youíve gone long enough without it it wonít matter. I did without it for 7yrs & it was fine. Got it in my 120 now and love it, but when you havenít got it, you get over it & donít think anything if it.

                        With your replacement radiator, donít use any water other than demineralised and coolant. Tap water, bore water, well water will corrode the spindles in the water pump. You wait till you remove it when youíll see. The cheaper eBay radiator will do just fine provided youíre not towing 1.5T or more up mountain ranges during the hottest days of summer. Much cheaper than the genuine Toyota radiator, is the same as Natradís radiator and youíll get 10yrs out of them still. Just has a smaller top core but if not towing heavy stuff itíll cope with everything you throw at it just fine. Trust me on this as I know from experience. Use Dex 3 transmission fluid to top up the auto transmission. I used a plastic syringe from super cheap with the clear plastic tube, inserted that into the tranny dipstick hole, take out the plunger part and insert a funnel spout into the top of the syringe body. Simples!
                        Last edited by Brett1979; 11-07-2019, 10:15 PM.
                        2005 120 series V6 Grande, 2 inch susp lift (King/EFS combo), 32 inch MT’s, Safari Snorkel, rear diff lock, breathers, Light Force spotlights, UHF, dual batteries.

                        Comment


                        • #13
                          You guys are the best!!

                          I have plugged the tranny hoses so that's OK.

                          I am very much in doubt about the aircon. Do you think there's a way to remove the condensor put leave everything else and plug those tubes properly? I live in Belgium and these cars go to Africa at the end of the cycle. All they care about is a running engine and a working aircon....

                          As for tranny oil, I'd already ordered this one, presuming it was backwards compatible unless you say no go:

                          https://www.autoonderdelen24.be/aisin-12862923.html


                          I'm definitely going for a new radiator!

                          I'm thinking I'll flush the coolant system with demineralised water. I suppose fill up, run engine hot, drop water?

                          Ps learned to love this vehicle and 4WD in your country where we spent a few years. If ever in Belgium drop by for a few thank you beers!



                          EDIT: Oil level: measure stick seems fine but no oil to be seen with lid removed. Is that normal? Car is slightly uphill.

                          https://photos.app.goo.gl/XssWzo82ZaFgdD729
                          Last edited by Peetn; 12-07-2019, 05:14 AM.

                          Comment


                          • #14
                            Peetn trans oil looks fine to me, says Dexron III which is important plus lists Prado 90. I'd use it.

                            As for the oil filler cap it's perfectly normal to not see any under the cap especially if the valve cover hides the cap from internals. There's only a few litres of oil in most engines and when they are off this falls back into the sump. I've never owned one of these particular engines however. As long as the dipstick reads ok you should be ok.

                            You could probably plug the AC lines but I have not done much with AC to comment really. If working AC will improve future value plus make it nicer for you on hot summer days maybe it's best to just get it working right now.

                            These 4wds can go for a long time, how many km do you have? My petrol 5VZ-FE has 389,300km so far.

                            Cheers mate glad you are on the way to recovery.

                            Comment


                            • #15
                              Hello all,


                              fitted new radiator yesterday. Flushed cooling system. Have not been able to overheat system since.

                              So far so good.

                              ATF: topped up with 1 liter. It was getting dark so was hard to see what I was doing. Might have to add some more. I used thick straws and baking paper. Worked like a charm.

                              https://photos.app.goo.gl/omgDBUiTEgaRZQVE8

                              I ended up not fitting new condensor, although I have bought one. I removed tube and dryer and will close of remining two lines. I was thinking heat shrink tubing or maybe just a condom, a plastic bag and a zip tie.

                              Ive 267.000km and pretend to convert it into a overland travel truck over time. There's a long way to go but I've designed a pretty cool and extremely simple system to convert loading area into a bed with interlocking panels and no screws. I'll post some pictures separately, you never know it's good to someone and I can return something to this community.

                              I am very happy with your help. Makes me want migrate to your country even more

                              Cheers

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