Emrys Parry Posted February 7, 2022 Report Share Posted February 7, 2022 I have just replaced the headlight panel on my '81 TR7 DHC, I have also replaced the radiator whilst I was at it. I refilled the system with Prestone coolant and now find that, when the engine is running, the temperature gauge rises to high level and the low coolant light is constatnly on. I have filled the system with the recommended volume of coolant so I suspect that either (a) the thermostat has packed up or (b) there is an airlock somewhere in the system. My particular model does not have the filler system on the top of the thermostat housing. Can someone please give me some advice as to the best way to check and remedy the problem. Quote Link to post Share on other sites
jerrytr5 Posted February 8, 2022 Report Share Posted February 8, 2022 Sounds like an airlock. Make sure the heater control is on hot to open the valve. Start it from cold and leave the radiator cap off. You could try squeezing the rad hoses to make it 'burp', but watch your hands on rotating components. Put the rad cap back on as it warms and the level rises. Jerry Quote Link to post Share on other sites
Emrys Parry Posted February 8, 2022 Author Report Share Posted February 8, 2022 5 hours ago, jerrytr5 said: Sounds like an airlock. Make sure the heater control is on hot to open the valve. Start it from cold and leave the radiator cap off. You could try squeezing the rad hoses to make it 'burp', but watch your hands on rotating components. Put the rad cap back on as it warms and the level rises. Jerry Thanks Jerry, I'll try that and, hopefully, it'll do the trick. Quote Link to post Share on other sites
HowardB Posted February 8, 2022 Report Share Posted February 8, 2022 I used a cut down 2l plastic drinks bottle pushed into the header tank to allow me to create a head of water when filling the car - then when you squeeze the hoses you can see the level drop down as the air is vented. Quote Link to post Share on other sites
Propshaft Posted February 9, 2022 Report Share Posted February 9, 2022 Yes I also used the drinks bottle fitted into the header tank I also left the car for a 24hours with the clutch pedal wedged tight down finished up with a good hard pedal Quote Link to post Share on other sites
DaveR Posted February 9, 2022 Report Share Posted February 9, 2022 Refill the system both through the header tank and the thermostat housing with the thermostat removed. Dave Quote Link to post Share on other sites
Propshaft Posted February 9, 2022 Report Share Posted February 9, 2022 Foreget the last part of my earlier reply getting different operations mixed up think they call it an age thing Quote Link to post Share on other sites
Emrys Parry Posted February 15, 2022 Author Report Share Posted February 15, 2022 Gents, thanks for your suggestions; I eventually driled and tapped a M8 hole in the top of the thermostat housing, cut down a M8 bolt and, along with a copper seal, inserted that into the tapped hole, I also replaced the thermostat. I then started the car from cold, removed the expansion tank cap and slackened the M8 bolt; when I saw coolant start to seep out of the tapped hole, I tightened the bolt and squeezed the top hose several times. The expansion tank level dropped a little and the temperature gauge showed just over the half way mark, the electric fan cut in and the gauge remained stable when the engine ran for about 5 - 10 minutes. I'm happy that my 'bodge' appears to have worked. Quote Link to post Share on other sites
BusheyTrader Posted February 26, 2022 Report Share Posted February 26, 2022 Sounds more like a post factory air bleed modification than a “bodge” Quote Link to post Share on other sites
Emrys Parry Posted March 20, 2022 Author Report Share Posted March 20, 2022 Som e photo;s of my 'bodge' job. Quote Link to post Share on other sites
Andy Moltu Posted April 4, 2022 Report Share Posted April 4, 2022 Some of the thermostats have a small hole with a jiggle pin in to allow air to bleed through - if the stat doesn't it might be worth drilling a smal hole - makes refilling after a coolant change much simpler. Quote Link to post Share on other sites
Emrys Parry Posted April 6, 2022 Author Report Share Posted April 6, 2022 Thanks Andy, appreciate your input but my 'bodge' as per the photographs seems to have worked quite well. Emrys. Quote Link to post Share on other sites
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