Hot running

Discussion in '16-valve' started by theboysmiffy, Oct 1, 2020.

  1. theboysmiffy

    theboysmiffy Paid Member Paid Member

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    Hi all.
    My temp gauge has not been working for a year or so, mechanic said it was the gauge and it would need replacing so I put it off thinking it would be hard to source.

    During lockdown I have been spannering more so changed the gauge switch and it’s now working, unfortunately it’s also highlighting my overheating problem.

    The temps are fine when I’m driving even when driven hard but when I am stationary the temps start creeping up nearly to the red sometimes. The fans kick in but it is too close for comfort.

    I have replaced pretty much the whole cooling system which now looks a little hasty. I have replaced the gauge switch, fan switch, low temp stat, water pump, expansion tank and cap, all Febi/OEM. I have also fitted a full width Pro Alloy rad with twin fans and all the hoses are silicone. Obviously new G13 too! I have some lower temp fan switches I could fit but worry that might just be covering up the problem.

    Engine is 2.0 16v, shedhead, Schrick 272, Twin 45, Dta S40, Ashley exhaust mani. Surely my cooling system should be able to cope. Has anyone any ideas apart from HGF? There is no mayo anywhere and the gasket was done two years ago with the head and cams.

    Hope you can help!!
     
    Last edited: Oct 1, 2020
  2. costel1969

    costel1969 Paid Member Paid Member

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    I don't know what you mean by the low temp. but have you replaced the actual coolant mechanical thermostat - this in my opinion looks like it's stuck and it's not opening to allow circulation and cooling
     
  3. theboysmiffy

    theboysmiffy Paid Member Paid Member

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    Do you mean the stat in the bottom of the water pump housing? I used a stat that opens at a lower temperature, 75degs vs 87degs. The radiator is never to hot to touch and the engine always feels much hotter. Bottom hose is not cold tho.
     
    Last edited: Oct 1, 2020
  4. costel1969

    costel1969 Paid Member Paid Member

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    OK looks like that has been covered - this is a strange one, have you bled the system thoroughly? I've heard before that any degree of air trapped within the cooling can create problem. To be fair to you you've changed and replaced a lot of gear and I'm just wondering if it's as simple as that?
     
  5. theboysmiffy

    theboysmiffy Paid Member Paid Member

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    I think I have bled it correctly. Started the car from cold with the heater on hot and the cap off. Squeezed all of the hoses whilst the engine warms up and put cap on before it gets too hot but after stat has opened.

    Just checked the car after parking up three hours ago. Took the cap off and there was no pressure release so must be fairly cool but the coolant level is definitely higher than before I took it out.
     
  6. costel1969

    costel1969 Paid Member Paid Member

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    Might be worth bleeding it again just in case but if it's not that, then I'm a bit stumped but hopefully others may have some more insight
     
  7. rubjonny

    rubjonny Administrator Staff Member Admin

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    the temp sensor may not be reading quite right if its a pattern unit, common issue I've seen vs genuine. if its got the MFA what does the oil temp say and if its possible check the DTA with a laptop see what the ecu coolant sensor is reporting.

    but if gauge is reading right but the radiator isnt getting hot this suggests as mentioned a bad thermostat, airlock or waterpump issue
     
  8. theboysmiffy

    theboysmiffy Paid Member Paid Member

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    I performed a sniff test on the coolant this evening and the results were negative, tho I know these diy kits are not conclusive. I also re-bled the system.

    I left the car idling for 20 minutes occasionally giving it some revs. The fans are kicking in at about 3/4 up the gauge and the oil was a steady 90 on the VDO gauge. The coolant temp never got up to the red.

    Unfortunately I haven’t had the chance to test it out on the road. I guess it is possible that more heat builds in the engine after being driven and this is harder to cope with when stationary compared to just idling.

    The temp gauge sender was from Heritage but I can’t remember the brand. Unfortunately I don’t have the software to read the ecu. I have replaced both the thermostat (Febi) and water pump (Meyle) so they should be good. The bottom hose heats up so stat is opening.
    Should I be able to touch the rad?
     
  9. rubjonny

    rubjonny Administrator Staff Member Admin

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    from your tests that sounds perfect so fingers crossed its all fixed now.

    once the stat opens the rad will start to warm up then eventually should get just as hot as your rad hoses, the fan will only kick in when the fan switch gets hot so it needs to get nice and toasty round the switch
     

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