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Thread: Td5 Overheating - your thoughts...

  1. #1
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    Td5 Overheating - your thoughts...

    Just keen to tap into the thoughts of the brains here.

    The D2 has never overheated, I've owned it since new.

    Driving home last week, I was sitting in traffic (well, keep in mind it is a country town ) AC on full cold and it was about 26 degrees (AC isn't spectacular).

    Temp gauge was sitting just over the normal half location so I turned off the AC.
    Lights went green and it was down on power
    Next set of lights the temp gauge went up to just below the hot level and I could only idle.
    I idled around the corner and switched it off.

    No hoses blown, no water dropped, water bottle full, oil correct

    When it cooled I limped it into work (the next block) and it heated up again but not to hot.

    My thoughts at that stage was the thermostat has jammed shut.

    Trailered the D2 home to work it all out.

    When I got it home:

    Engine fault codes were: (probably unrelated previous faults)
    Ambient pressure circuit
    EGR valve stuck open
    EGR valve stuck closed
    Road speed missing
    Cruise control resume stuck closed

    I warmed it up by idling, and the temp stabilised at about 95 degrees which I expect is hotter than it should be given the thermostat opening temps (starts opening at 82, full open at 96).

    Backed it out of the shed and the temps jumped up to 100. Drove it to the end of the drive and the temps jumped up to 110. It cooled coming down the drive a bit and then back up to 110 again as I drove up to the house. At 110 the engine didn't cool off again when idling.

    The viscous fan was unlocked,
    The top radiator hose was hot
    The radiator was cold
    The AC system would cool, but not heat.
    The radiator bleed hose isnt proving the jet in the coolant bottle.

    My thoughts now are the water pump has totally failed as the AC is cold (AC should be unaffected by a shut thermostat) and no water jet from the radiator (water not pumping). I'm guessing the hot top hose is just some degree of coolant or temperature movement. The temp sensor is located at the engine outlet on the top hose which is probably why it was reading hot.

    Just interested if you concur that its the pump or are thinking something else?

    Thanks for any input.

    Here is my poor girl...

    Attached Images Attached Images
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  2. #2
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    I'd be thinking pump impellers are gone, most of what you said lines up with that.

  3. #3
    discorevy is offline ChatterBox Silver Subscriber
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    Assume the coolant was checked at the top hose bleeder as per the other thread ?


  4. #4
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    Could be the water pump drive key from the power steering pump. Not unknown on high mileage engines. Maybe remove the power steering pump as it is easy before the water pump.
    Hmm. Did you change the thermostat? If so are you sure the pipes are on the correct way? The "no heat from airconditioning is a worry" as the thermostat directs hot water to the heater when cold but if no circulation I guess that could be the cause.
    Pretty unusual stuff!
    Regards PhilipA

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    Quote Originally Posted by Slunnie View Post

    Temp gauge was sitting just over the normal half location
    Factory gauge? I find that unusual. With mine it's "Nothing to see here, ...fine... fine... fine... HOT
    ​JayTee

    Nullus Anxietus

    ​Getting involved in discussions is the best way to learn.

    2000 D2 TD5 Auto: Tins
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    discorevy is offline ChatterBox Silver Subscriber
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    If it has coolant at the top hose bleeder when the expansion tank is raised, then starting the engine and checking to make sure there is a flow of coolant out the top bleeder is the quickest way to check if the water pump is working.

    I have seen a couple with no impeller blades left, none with the pump drive stripped.... yet.

  7. #7
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    Quote Originally Posted by discorevy View Post
    Assume the coolant was checked at the top hose bleeder as per the other thread ?
    Argh, I haven't...

    Quote Originally Posted by PhilipA View Post
    Could be the water pump drive key from the power steering pump. Not unknown on high mileage engines. Maybe remove the power steering pump as it is easy before the water pump.
    Hmm. Did you change the thermostat? If so are you sure the pipes are on the correct way? The "no heat from airconditioning is a worry" as the thermostat directs hot water to the heater when cold but if no circulation I guess that could be the cause.
    Pretty unusual stuff!
    Regards PhilipA
    I haven't really touched anything on it at this stage, but it will be interesting to see what and where the damage is. Its probably still the original thermostat thats still in it.

    Quote Originally Posted by Tins View Post
    Factory gauge? I find that unusual. With mine it's "Nothing to see here, ...fine... fine... fine... HOT
    I was reading the temps from the Nanocom but it is just the factory gauge (MY2000.5). When it started to get warm it sat not much above the normal position, I was stopped in traffic and looking at it though rather than a glance when driving. It did swing up to hot pretty quickly from there but not past the hot line by the time I turned the motor off.

    Quote Originally Posted by discorevy View Post
    If it has coolant at the top hose bleeder when the expansion tank is raised, then starting the engine and checking to make sure there is a flow of coolant out the top bleeder is the quickest way to check if the water pump is working.

    I have seen a couple with no impeller blades left, none with the pump drive stripped.... yet.
    I haven't yet checked it via the bleeder but it will be interesting to see what the impeller in this looks like... and where the bits have gone!

    I've had a chat to Davis Performance Landys, they're gold as always. Interestingly he said that often when the pump goes bad that they also lose coolant. They're organising and sending me pump parts and thermostat parts to get it sorted. Hopefully sometime in the next 4 -5 years when I get the job done I'll show what the pump and thermostat come out looking like. It'll be good to have the Disco back on the road.
    Cheers
    Slunnie


    ~ Discovery II Td5 ~ Discovery 3dr V8 ~ Series IIa 6cyl ute ~ Series II V8 ute ~

  8. #8
    discorevy is offline ChatterBox Silver Subscriber
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    Quote Originally Posted by Slunnie View Post
    Argh, I haven't...


    I haven't really touched anything on it at this stage, but it will be interesting to see what and where the damage is. Its probably still the original thermostat thats still in it.



    I haven't yet checked it via the bleeder but it will be interesting to see what the impeller in this looks like... and where the bits have gone!

    I've had a chat to Davis Performance Landys, they're gold as always. Interestingly he said that often when the pump goes bad that they also lose coolant. They're organising and sending me pump parts and thermostat parts to get it sorted. Hopefully sometime in the next 4 -5 years when I get the job done I'll show what the pump and thermostat come out looking like. It'll be good to have the Disco back on the road.

    If it is the original 22 year old thermostat and water pump then yes, they are due for a change, I change the pump housing to block O ring (err6711) while I'm at it, hopefully they sent you that 1 as well.

    Water pumps usually lose coolant due to the bearing wearing out and leaking coolant past the seals
    TD5 pump bearings have an easier life than most because they are driven off the P/S pump and have almost no radial load compared to a pump driven directly off the belt, which is 1 reason they last so long.

    Both of the pumps I have seen with no impellers left had corroded and I didn't find any trace of blades left.
    (both also didn't have any evidence of coolant either, only she'll be right rusty water)

    It's worth diagnosing if the water pump is indeed the problem using the method above.

  9. #9
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    In regards to the water pump. I just replaced mine this week because my car has always run hotter than it should. I was expecting the pump to have the vanes eaten away but they looked good with the exception of being very pitted. Temperatures are now normal with the new pump and my theory is that the pump will cavitate well before the vanes physically dissolve if the surfaces are pitted and this disrupts coolant flow. The cavitation in my case was bad enough that it has caused minor erosion of the inside pump's cover (it looks like porosity).

    The sudden shift to overheating, even at idle, scenario would make me suspect either a total water pump impeller failure (has this ever happened?) or, perhaps more likely, a collapsed radiator hose or even a clogged radiator as the more likely culprit.

  10. #10
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    I can't remember on which vehicle it happened but I've had the shaft of a water pump break just in front of the impellor. I vaguely recall that the pump had a failed bearing too which probably caused the impellor to jamb in the housing.
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
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