cliff.b Posted October 6, 2021 Report Share Posted October 6, 2021 Just taken my Spit 1500 out nowhere in particular as it was sunny and hit some stop/start traffic after driving about 4 miles at no more than 50mph. Suddenly, the car started misfiring badly when pulling away, although it was ticking over ok. Sounded like it wasn't running on all cylinders. Pulled into a side road to check things out and the misfire disappeared however, the temp gauge was reading far higher than usual. Drove on and the gauge was still rising, even with the heater on full blast. Then, just at the point where I thought I would have to stop the gauge fell rapidly from over 3/4 to just over 1/4 before gradually climbing to its usual position just below halfway. The car was now running perfectly and I drove it another 10 miles without any problem. So at the moment, I'm wondering if the misfire was caused by overheating, but can't think what would cause that to suddenly happen and then resolve itself. Or is there any form of misfire that could have caused the rise in temperature? This was my first run out after filling the tank with fuel on Saturday (Super Unleaded). A partial blockage in one carb might explain the misfire. Could this result in weak running that would lead to a temp rise. I'm pleased the car is running ok now but don't like it when I don't understand why 🤔 Link to comment Share on other sites More sharing options...
cliff.b Posted October 6, 2021 Author Report Share Posted October 6, 2021 24 minutes ago, Mathew said: Stuck thermostat? Then open!? Actually, there's something I forgot to mention. I have refitted a normal cooling fan but the electric ones are still fitted, they just very rarely come on now. Normally only if I come to a complete stop after driving some distance at speed and then only briefly. But they came on this time, stayed on much longer than normal and on again every time I stopped. The sensor is in the rad return pipe so I assumed I must have hotter than normal water flowing through the rad which would mean the thermostat was open. But you have got me thinking, if the thermostat was stuck closed could that lead to a reverse flow of hot water into the rad via the bottom hose? Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 6, 2021 Report Share Posted October 6, 2021 air lock springs to mind as one idea does the thermostat have a jiggle pin to aid trapped air ,? then as the two events may not be connected was it actually HOT or just reading Hot as mis reading can be a stabiliser problem rather than an engine problem any stry wires around the coil zone , see other post about intermittent frayed wire shorting at the solenoid Pete Link to comment Share on other sites More sharing options...
NonMember Posted October 6, 2021 Report Share Posted October 6, 2021 I agree with Pete - the temperature behaviour sounds like an air lock, and the misfire may not have been connected in any way. Link to comment Share on other sites More sharing options...
cliff.b Posted October 6, 2021 Author Report Share Posted October 6, 2021 2 hours ago, Pete Lewis said: air lock springs to mind as one idea does the thermostat have a jiggle pin to aid trapped air ,? then as the two events may not be connected was it actually HOT or just reading Hot as mis reading can be a stabiliser problem rather than an engine problem any stry wires around the coil zone , see other post about intermittent frayed wire shorting at the solenoid Pete Thermostat does have a jiggle pin. I am assuming it did actually get hot because the electric fans came on and stayed on for some time which never usually happens now I have the mechanical one fitted. Engine has always run smoothly as well since I got it sorted so while I agree it could be a co-incidence, it's strange when two things that never usually happen both occur at the same time. My only experience of airlocks has been after replacing coolant and not on this car. I haven't even needed to top it up since I drained & flushed it in May. Can they just randomly occur? I think I will check everything out and then "force myself" to take her out as much as possible while the weather is ok. If it happens again I will try and gather some more information to hopefully give some clues as to what's going on. Link to comment Share on other sites More sharing options...
Iain T Posted October 7, 2021 Report Share Posted October 7, 2021 17 hours ago, cliff.b said: Then, just at the point where I thought I would have to stop the gauge fell rapidly from over 3/4 to just over 1/4 before gradually climbing to its usual position just below halfway. Cliff, my Vitesse did exactly the same a sudden rise, fall, rise. It was caused by air lock(s). Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 7, 2021 Report Share Posted October 7, 2021 trapped wind maybe a spoonful of senokote would help !!! Ha Pete Link to comment Share on other sites More sharing options...
Iain T Posted October 7, 2021 Report Share Posted October 7, 2021 3 hours ago, Pete Lewis said: trapped wind maybe a spoonful of senokote would help !!! Ha Pete, watch my joke just posted in the Lounge section! Link to comment Share on other sites More sharing options...
cliff.b Posted October 7, 2021 Author Report Share Posted October 7, 2021 6 hours ago, Iain T said: Cliff, my Vitesse did exactly the same a sudden rise, fall, rise. It was caused by air lock(s). Iain Ok, there seems to be a consensus on that and it makes sense. Did you know what caused the air locks on your Vitesse? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 7, 2021 Report Share Posted October 7, 2021 2 hours ago, Iain T said: Pete, watch my joke just posted in the Lounge section! It was solids blocking the intake that I was thinking of there, too... Link to comment Share on other sites More sharing options...
Iain T Posted October 7, 2021 Report Share Posted October 7, 2021 11 minutes ago, cliff.b said: Did you know what caused the air locks on your Vitesse? The rad is too low in a Vitesse and GT6 so so fill without getting airlocks I raised the front end (drove it up ramps) and filled while the engine was ticking over. Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 7, 2021 Report Share Posted October 7, 2021 i just release a top heater hose to let air escape font pull it right off just enough to release air from the highest point Pete Link to comment Share on other sites More sharing options...
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