Stan Posted May 6, 2017 Share Posted May 6, 2017 Bit of a wierd one but this has happened since I've owned the car. If I am in heavy traffic or just letting it idle on my drive, the engine will get to temp (i.e the needle reaches about 1/3 way up) and I will get hot air from the blowers, and it will idle around 800rpm which I assume is normal? If I start driving at any speed without hitting traffic, the needle will drop to almost the bottom line and I will get lukewarm air out of the blowers, and when stopping the idle will get up to about 1000rpm as if it doesn't realise the engine is hot and is trying to keep the revs higher. This even continued after I replaced the radiator with a mishimoto and had the coolant replaced. Any ideas? It doesn't bother me too much as I only use it as a warm day car anyway, but it'd be nice to get an answer. Quote Link to comment Share on other sites More sharing options...
Dracostan Posted May 6, 2017 Share Posted May 6, 2017 Water thermostat failed open, by the sounds of it. What oil temperatures do you get? Quote Link to comment Share on other sites More sharing options...
Stan Posted May 6, 2017 Author Share Posted May 6, 2017 Not sure how to check oil temps? Quote Link to comment Share on other sites More sharing options...
88 Zed Posted May 6, 2017 Share Posted May 6, 2017 (edited) How much water / coolant did you put in? Sounds like it's low on water, or thermostat stuck open. Edited May 6, 2017 by 88 Zed Quote Link to comment Share on other sites More sharing options...
Stan Posted May 7, 2017 Author Share Posted May 7, 2017 The garage did the replacement rad so not sure, however it existed before the rad change so maybe it is the thermostat? Quote Link to comment Share on other sites More sharing options...
catman Posted May 7, 2017 Share Posted May 7, 2017 Yes, sounds like the thermostat to me. It doesn't do the car any good if it's faulty, it's not just about the heater. Tim Quote Link to comment Share on other sites More sharing options...
Dracostan Posted May 7, 2017 Share Posted May 7, 2017 Oil temperature will be one of the triple gauges on the dash - normal running should be around 90-100degC. Water level check - WHEN THE CAR IS COLD (important!) open the radiator and expansion tank caps and check levels. Leaving the caps off, start the car and let it warm up to running temp. Check levels again and top up as necessary. Stop the car, let it cool, replace the caps and go for a run to get the car back up to temp. If the issue continues, it's you thermostat - replace! Draco Quote Link to comment Share on other sites More sharing options...
88 Zed Posted May 7, 2017 Share Posted May 7, 2017 Oil temperature will be one of the triple gauges on the dash - normal running should be around 90-100degC. Water level check - WHEN THE CAR IS COLD (important!) open the radiator and expansion tank caps and check levels. Leaving the caps off, start the car and let it warm up to running temp. Check levels again and top up as necessary. Stop the car, let it cool, replace the caps and go for a run to get the car back up to temp. If the issue continues, it's you thermostat - replace! Draco Oil pressure is one of the triple gauges you mean? Quote Link to comment Share on other sites More sharing options...
Stan Posted May 8, 2017 Author Share Posted May 8, 2017 Yes, sounds like the thermostat to me. It doesn't do the car any good if it's faulty, it's not just about the heater. Tim I thought a dodgy thermostat only caused overheating, not underheating? However for the sake of £50 maybe I'll just get it done anyway Quote Link to comment Share on other sites More sharing options...
Olly350z Posted May 8, 2017 Share Posted May 8, 2017 Yes, sounds like the thermostat to me. It doesn't do the car any good if it's faulty, it's not just about the heater. Tim I thought a dodgy thermostat only caused overheating, not underheating? However for the sake of £50 maybe I'll just get it done anyway It can do either depending on which way its stuck, either open or closed. Easiest way to check if a thermostat is goosed is dangle it with some string in boiling water. Youll see if it opens or closes Quote Link to comment Share on other sites More sharing options...
catman Posted May 8, 2017 Share Posted May 8, 2017 Most thermostats fail in the open position, causing under heating, but either is possible. While it is possible to test it, it's easier to just replace it, if you've gone to the trouble of removing it. Tim Quote Link to comment Share on other sites More sharing options...
Dracostan Posted May 8, 2017 Share Posted May 8, 2017 Oil temperature will be one of the triple gauges on the dash - normal running should be around 90-100degC. Water level check - WHEN THE CAR IS COLD (important!) open the radiator and expansion tank caps and check levels. Leaving the caps off, start the car and let it warm up to running temp. Check levels again and top up as necessary. Stop the car, let it cool, replace the caps and go for a run to get the car back up to temp. If the issue continues, it's you thermostat - replace! Draco Oil pressure is one of the triple gauges you mean? Should have been clearer - .... will be one of the triple gauges on TOP OF the dash .... Draco Quote Link to comment Share on other sites More sharing options...
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