Intermittent heat gauge rising "overheating"




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  1. #1
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    Default Intermittent heat gauge rising "overheating"

    Guys, please assist here:

    Intermittent over heating situation.

    Ok some back ground:
    Vehicle is a steed 3 2,8 4x4 2008 model with 64000km on theodo.
    It is only used for towing my boat for fishing trips.
    Towing is locally in summer time and then often down to thecoast for fishing trips.

    The vehicle normally stands for up to a month without beingstarted or used, during this time the battery is disconnected.

    Note that several trips down to the coast was done, duringthese trips a boat was towed without any problems.
    Coming back via van reenens pass all was also good.
    The heat gauge indication was always just below the half waymark and would climb to just over the half way mark.

    Over time I have noticed that the normal heat gauge temp wouldnow be sitting at just above the half way mark and not just under it as italways was.

    Last year 2017 on a returning trip it was noted that the vehiclewould start to overheat at van reenens pass.
    The over heating was never close to the red area, but onlyabout to ¾ on the heat gauge.

    On the same day, other vehicles were noted 1, being a Toyotawith a caravan where it stood just after van reenens with its bonnet open. So Ijust suspected the ambient temp was causing some vehicle to start overheating. Sowe proceeded heading to Heidelberg.

    Then another 2 or 3 times on the way to Villiers the tempwould rise again just suddenly for no reason.

    The road section between Villiers and Heidelberg it wasagain found, that out of the blue, that the heat gauge would again rise to ¾
    The speed at the time was about 110km to 120km.
    So I kept my eye on the gauge.
    Just past the Heidelberg toll gates with that long bad uphillit again started overheating going to the ¾.

    So somewhere a problem was starting to brew.
    I did some research but no action was taken at the time.

    Then often over weekends I would tow the boat to the dam “nigel”which is about 20 km from my house.
    It does not overheat during these excursions.

    2018

    In January this year I towed a trailer down to my cottage inst lucia.
    It was at night time and no overheating was found.
    On the way back during day time, I again found that close tobethal the heat gauge again started to rise, this time towing a empty trailer 4meter trailer home “a 2nd venter trailer also basically empty wasloaded on top of the 4 meter trailer” so not the same heavy 1200kg plus towingof the boat

    The heat gauge only went to ¾ and I kept my foot down to seeto where it will go.
    It only did rise to ¾ and nothing more. Keeping my footplanted I then noticed that the heat gauge returned to normal just above the halfway mark.

    So for some unknown reason it did start to overheat and italso did return to the now normal position.
    I thought that the area above sea level could be aindication where the turbo needs to work harder as air pressure is less.

    During easter weekend this year, I again towed the boat downto Durban.
    This time at the marrian hill area the heat gauge againstarted to rise to the ¾ mark. This time it became quite bad as I even startedfeeling a loss in power.
    So when I turned the heater on to try and assist withcooling I found that the heat out of the blower was not hot as was expected.
    I was going with the wind on that up hill, so basically nowind from the front.

    On my return trip from Durban, I left the boat down thereand came back with not much loaded in the bakkie.
    Again at van reenen is found that without towing the vehicletemp started to rise to the ¾ mark.
    Again after Villiers the temp gauge started rising to the ¾ mark.

    So I knew now, that a temp rising without a heavy loadedboat that something was not right as all the other rising in temps was pullingloads.

    With this I started searching the net but could not find a definitiveproblem.

    I decided to replace the thermo stat as it could have been asticky one.
    “initial test of thermo with boiling water over it did not openthe thermo. A seconded boil of the kettle had the thermo open up.
    So I thought I had a sticky thermo switch.
    I also decided, that since the initial running tempo wasjust below the half way mark and now running just past it, to replace the watertemp switch.

    With the new switch fitted, the vehicle is still indicatingjust over the half way mark.
    I then found that oil was dripping from the turbo oil returnpipe area, so I thought seals.
    I even removed the turbo and also split it. “not the core”
    All did seem fine with not too much play etc. I found that theoil return pipe was cracked “rubber” and caused oil to drip as it leaked out. Sothat heart scare was over….lol.
    I also checked the water pump, it does spin freely considering water is still present in the system.
    no play in bearing on water pump.
    with radiator cap removed, revving engine water movement is clearly observed.


    So next came another fishing trip, the long weekend in April.
    I set out to Durban and found that the heat gauge stayedjust over the half way mark.
    All seemed normal again.

    After the fishing trip I again towed the boat back home.
    Again at van reenen it started to heat up and keeping therpms high it only managed to get to the ¾ mark.
    Between Villiers and Heidelberg the temp again rose to the ¾.
    This strange all is well then suddenly a temp rise for now apparentreason was clearly frustrating.

    Thinking about this sudden for now reason heating problem….ithought ok, well maybe the wind was not coming onto the radiator properly “likehaving a side wind or something” this for the no reason sudden temp rising.

    Back at home some more research was done.
    Eventually I removed the viscus fan to check it.
    Comparing viscus fans it seems like mine is locked up.
    So always spinning/ engaged.
    It does not free wheel and it does not make a roaring soundwhen the vehicle is started in the morning or ever.

    Another search on the internet indicates that a locked upviscus fan would not cause a engine to start to overheat.

    Where does all of this leave me…..still a vehicle which forno apart reason starts to overheat.
    Again the blower on heat inside the cabin is never hot aswould be expected.
    This could indicate a blocked aspect within the water system….or something.

    But would a blocked radiator not cause constant overheating?

    This is clearly a intermittent problem and sorting it outseems to be much harder.
    I need to sort this out before it ever gets to the red area.

    Fuel consumption while towing back from Durban to Heidelbergwas around 6-7km/l
    It now sits at 6km/l. I know that the locked up viscus fanwill increase fuel usage. So it could be the reason for the higher consumption.

    I have not yet stripped out the radiator to check for debrisobstruction the air flow I also don’t drivein areas where grass and stuff could get into / between the 2 to interfere withcooling so I suspect all is good there.
    The intercooler is also in front of the aircon radiator.
    Also when at idle and a stand still with the aircon on, coldair is not coming out, only when driving will the aircon blow cold air.

    So any advise willassist as I am at a loss for now.

  2. #2
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    Default Re: Intermittent heat gauge rising "overheating"

    6km/L is quite a lot.

    It sounds like the engine is over-fuelling slightly under load and that will cause an increase in exhaust gas temperatures which will cause an increase in coolant temperatures.

    I suggest you fit an EGT probe and gauge so that you can see what is happening when you are towing.

    Two other things I would do:

    - find out how to blank off the EGR
    - fit a big bore free flow exhaust (76mm will work)
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  3. #3
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    Default Re: Intermittent heat gauge rising "overheating"

    egr has been blanked off for ages now.
    no cat or dpf in line.

    just standard exhaust.

    also thought about a egt probe. have looked at madman.

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    Default Re: Intermittent heat gauge rising "overheating"

    From what I can gather, I don't think your problem is intermittent. It is related to the load you place on the engine and the ambient temp.

    You are asking more of the cooling ability than what it can offer you. It wasn't like that initially, so something has gone "bad".

    1) Have you installed something on the car's nose? I'm thinking spotlights, winch, bullbar etc.
    2) A properly functioning viscous fan is very important. I can't quite figure out what you say about the fan on your car, but I get the impression it isn't "normal".
    3) You fitted a new thermostat. That is good, but you won't be the first guy to get a defective one.
    4) A free spinning water pump doesn't mean it is operating to capacity. A pitted or worn impeller will result in reduced flow and reduced cooling power.
    5) Is the cowling between the fan and the radiator still fine? Same goes for whatever seal exists between the radiator and the body.
    6) Is your coolant still at the correct mix? On some makes this can be absolutely crucial. Further to this point, do you need to top-up coolant after a trip where you experianced the overheating?

    In my book, if a temp gauge climbs but it doesn't push coolant out, then the engine didn't overheat. If it is not normal (usual), like in your case, then it is sending a clear warning. If I were in your shoes, I wouldn't like to stop until I got to the bottom of this.

  5. #5
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    Default Re: Intermittent heat gauge rising "overheating"

    Possibly a dodgy injector not atomising correctly?

    Maybe pull the injectors and send for testing?
    Any minority that advocates for gun control is either wilfully ignorant, or has never opened a history book.

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    Default Re: Intermittent heat gauge rising "overheating"

    Quote Originally Posted by RoelfleRoux View Post
    From what I can gather, I don't think your problem is intermittent. It is related to the load you place on the engine and the ambient temp.

    You are asking more of the cooling ability than what it can offer you. It wasn't like that initially, so something has gone "bad".

    1) Have you installed something on the car's nose? I'm thinking spotlights, winch, bullbar etc.
    nope, all still standard, as I bought it. it does have a nudge bar on, nothing obstructing air flow into/ onto the radiator.

    2) A properly functioning viscous fan is very important. I can't quite figure out what you say about the fan on your car, but I get the impression it isn't "normal".
    I took it out, it seems to be locked up, meaning always engaged. a normal viscus on startup would have a roaring sound and then the clutch will disengage. and spin freely on a cold engine. mine does not, what ever the rpm is, of the engine it will run the same rpm.

    I have taken it out. placed it in a drill, bliksem daai fan spin kwaai, lol.
    If I hold it "blades" it will disengage and when I let go it will start spinning and engage.
    nogal nice om te sien en te hoor.

    3) You fitted a new thermostat. That is good, but you won't be the first guy to get a defective one.
    true but it still doing the same thing at times.
    so the replaced one seems to be ok then if both are doing the same thing.

    4) A free spinning water pump doesn't mean it is operating to capacity. A pitted or worn impeller will result in reduced flow and reduced cooling power.I would agree here. but a worn out water pump will cause, imho constant overheating and not sudden over temp at times. I might be wrong here, but pulling this water pump is not easy....let save it for later.

    5) Is the cowling between the fan and the radiator still fine? Same goes for whatever seal exists between the radiator and the body.
    yip cowling is in order, not broken etc. properly secured.
    a aluminum adapter is present moving the fan closer to the radiator. but at first when I bought it it was fine, over time the problem started. thus the added coupling length cannot be a factor in my mind, as all has been left as it was bought.

    6) Is your coolant still at the correct mix? On some makes this can be absolutely crucial. Further to this point, do you need to top-up coolant after a trip where you experianced the overheating?

    think coolant is about a 50/50% mix.
    nope, not boiling at all.
    no need to fill up on coolant as such.


    In my book, if a temp gauge climbs but it doesn't push coolant out, then the engine didn't overheat. If it is not normal (usual), like in your case, then it is sending a clear warning. If I were in your shoes, I wouldn't like to stop until I got to the bottom of this.

    its is only a rise in heat gauge temp as indicated by the heat gauge.
    and only to about 3/4.
    it did loose power during a hill in Durban and the last one in Heidelberg after the toll gates, which tells me, either the ecu saw it and dealt with the problem to remove fuel as such.

    I have fitted a boost gauge to check boost.
    that was before the easter trip.
    boost is around 0,9bar, it will peak to about 1 bar but settle at 0,9bar.

    also what I have noticed on the boost gauge is:
    diesel is needed to get boost.
    when the engine started to heat up, boost started dropping. there is no leak on the intake system. I don't have the factory fitted couplings, I have the proper blue rubber pipes with proper clamps.

    in any case, when the engine started heating up, boost started dropping. this tells me, that the ecu either saw the temps and cut off diesel supply to get egt down, cause that is the way to do it.
    if this steed does have this recognizing facility then it is great.

    maybe they are not that dum as everyone thinks...lol.

    if it is not clear, then I would try and explain more.


  7. #7
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    Default Re: Intermittent heat gauge rising "overheating"

    Thanks for clearing up my questions.
    You are clearly thinking this through in a thorough way. I'm sure you will get to the bottom of this.

    My new car does the following:
    It has a heat gauge as well as a standard digital readout. Needle normally sits at 3/8 position and the temp number on 79C. This is also the coldest temp the thermostat will allow. No matter what I do on a downhill (keeping in mind the car is auto - so neutral is not an option) the temp will not drop below 79C or move down on the needle. It will just sit at 79C for hours on end. BUT, if it is hot outside and if a keep the cruise at say 140, then on very steep and long climbs the needle will move to 4/8 and the readout to 90C. It will just sit there until the pass is topped and then it drops back to the "thermostat minimum". I have done a fair amount of research and it seems "normal" for my car is with the needle on 4/8. This whole experience was new to me, because my previous cars (mostly Pajeros) had boring temp gauges. They just parked off on about 3/8 and never ever moved. No matter what I did.

    The reason I'm sharing this with you is because I have no doubt that engine temp (and the coolant temp) will rise if it has to work hard. Most cars have "buffered" gauges, so the needle doesn't move with acceptable temp variances. Maybe your's is behaving similar to mine. You are not losing water, so the car hasn't overheated. I am a little worried about the pseudo limp mode you experienced.
    Last edited by RoelfleRoux; 2018/05/16 at 06:54 PM.

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    Default Re: Intermittent heat gauge rising "overheating"

    Please consider reading this post. It may help you to better understand the workings of a viscous fan

    http://www.4x4community.co.za/forum/....php?p=3890798
    Last edited by RoelfleRoux; 2018/05/16 at 06:59 PM.

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    Default Re: Intermittent heat gauge rising "overheating"

    Quote Originally Posted by RoelfleRoux View Post
    Thanks for clearing up my questions.
    You are clearly thinking this through in a thorough way. I'm sure you will get to the bottom of this.

    My new car does the following:
    It has a heat gauge as well as a standard digital readout. Needle normally sits at 3/8 position and the temp number on 79C. This is also the coldest temp the thermostat will allow. No matter what I do on a downhill (keeping in mind the car is auto - so neutral is not an option) the temp will not drop below 79C or move down on the needle. It will just sit at 79C for hours on end. BUT, if it is hot outside and if a keep the cruise at say 140, then on very steep and long climbs the needle will move to 4/8 and the readout to 90C. It will just sit there until the pass is topped and then it drops back to the "thermostat minimum". I have done a fair amount of research and it seems "normal" for my car is with the needle on 4/8. This whole experience was new to me, because my previous cars (mostly Pajeros) had boring temp gauges. They just parked off on about 3/8 and never ever moved. No matter what I did.

    The reason I'm sharing this with you is because I have no doubt that engine temp (and the coolant temp) will rise if it has to work hard. Most cars have "buffered" gauges, so the needle doesn't move with acceptable temp variances. Maybe your's is behaving similar to mine. You are not losing water, so the car hasn't overheated. I am a little worried about the pseudo limp mode you experienced.
    yip, have not been rushing this.
    it has been a while considering all aspects.
    some eliminated, some not....but we will get there

    I have read many internet posts about diesels overheating/ running hot when towing heavy loads
    so it is not a uncommon aspect.
    even our local guys towing heavy loads have some troubles coming up van reenen or ithelijuba near Pongola.

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    Default Re: Intermittent heat gauge rising "overheating"

    Quote Originally Posted by RoelfleRoux View Post
    Please consider reading this post. It may help you to better understand the workings of a viscous fan

    http://www.4x4community.co.za/forum/....php?p=3890798
    I have been through them, silverton radiators etc.

    my viscus fan is a BorgWarner type. it cannot be serviced at all.
    it is also not leaking oli as such.

    researching BorgWarner viscus fan, they do have a method of testing the viscus fan.
    so I have read it.

    my viscus does not relax at all.
    the speed it is doing is 1:1 with my electric drill.

    the thermos spring was also inspected, I unhooked it and even turned the valve completely open and or closed.
    with the temp quite cool, the viscus should not be locked up.

    if I grab hold of the viscus and using the dril to force it to slip, then it would eventually start slipping.
    as it is cold "not in a engine environment the viscus should still have slip "the above link also refers to this, letting the engine run efficiently and air needs to be pulled through the heat exchangers as needed."

    so I would ref up the drill with it slipping then I would let go.
    the fan which is still connected will start to turn the same way as the drill and just like that it would engage and slip no more.
    the drill would suddenly start to labor as it now needs to turn a much heavier weight.

    so it clearly engages. sweet but when cold, it should also have slippage.
    mine clearly has no slippage.

    my question also is, if it has no slippage when cold, and seems to be locked up. could it be that the viscus is staring to slip at higher temps.
    this could be it.
    as stated according to the net a locked up fan clutch will not cause overheating.... but is this proven?

    again as stated, I never have a roaring sound.....which is normally associated with fan clutches.

    on a hard test drive before my 2nd trip I did drive the living day lights out of it and then only did I hear the fan clutch on high rpms.

    thank you for the replies so far.
    I am sure many of you do not have answers and many of you are scratching your heads, just like I am doing.
    but I am sure, we will get there.

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    Default Re: Intermittent heat gauge rising "overheating"

    I managed to source a new fan and clutch from the agents.
    It was fitted yesterday.
    the new fan is more prominent in hearing it.

    I still need to do a leak back test on the injectors, just to see if all of them are ok!!

    with the cold weather around I don't think a towing test will bring me closer for now.

    I also replaced glow plugs as 1 was mike tango.

    will keep you guys updated....it might take a while

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    Default Re: Intermittent heat gauge rising "overheating"

    Had a similar problem on a Fofd Bantam at around 70k and again at 140k km. Temp would climb quickly, a bit of mild reving and temp back to normal. On both occasions replased water pump, thermostst and the plastic thermostat housing, flushed system and problem solved.
    Found two things, the plastic thermastat housing gets brittel and breaks leaving bits in the water system, the water pump impeller housing breaks off in front of the impeller, therefore somtimes good flow and somtimes not.
    Also depending on the thermostat design spring tension could control the pressure in the water system, better heat conduction under pressure vs no pressure

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    Default Re: Intermittent heat gauge rising "overheating"

    I had a 2.8tdi Pajero, that when I towed my big offroad trailer, would do something similar. As Roelf mentioned the cooling system has a reserve abilty which I think in your case is diminished due to some problem. ie it is fine until that reserve ability is called upon and due to a problem cannot perform.
    In my case, looking at the radiator externally it looked clean. I removed it to check and clean it internally. Once it was out I noticed the core had quite a lot of grass seeds stuck in the core. Now would I recognize the telltale hairs that stick out of the core. The core was clean internally.
    Getting the grass seeds out is only really effective by two means, one of which is by one seed at a time which will take ages. No compressed air water pressure etc gets it out. This also could damage the radiator.
    The best way is to have a large water surface such as a pool or jaccuzi and holding the radiator flat, smack the radiator against the water surface. You cannot believe how easily it gets the grass seed out and without any damage to the core. This sorted my problem.
    Failing this make sure the coolant / water mix is not more than 50%/50%. Neat anti freeze is a definite no no.
    Check the radiator for internal blockage. You should have a differential temperature top and bottom of 15 degrees. If you haven't a hand held laser to measure the temp, feel the top and bottom hoses.
    Failing this, water pump, fuel pump timing, etc.
    Keep us posted.
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