laguna temperature gauge fault

I've got a '98 Renault Laguna 2L RT Sport. Every now and then, usually on a longer, rather than shorter run (15 miles plus) the coolant temperature gauge, which normally sits exactly on about 55%, suddenly, in the space of 30 seconds, cranks up to 98%, at which point the a/c cuts out. From then on, it will creep down to about 95%, at which point the a/c cuts in again, then within a minute creep up to 98%, a/c cuts out again, then down to 95%, and so it continues. However, if I pull over, turn the engine off and immediately start up again, it's immediately normal for the rest of the journey, as if it's been reset. First I replaced the gauge temperature sensor and the thermostat, to no avail. Since then it's been to the local Renault dealer, a cooling system specialist, and an auto electrician spent an afternoon working on it, but no-one can find the fault. I now know for sure the cooling system is fine, it's not overheating, the high temp. warning light has never come on, engine diagnostics confirm that the coolant temp. stays at 91 deg. whatever the gauge says, it's never boiled over or used any coolant whatsoever, and this fault has endured for two years now! It almost looks like a software glitch in the engine management system. Has anyone had the same problem? Any solutions? Email me please at snipped-for-privacy@hotmail.com

Reply to
johnwallis75
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My 1995 laguna is the same, but the red is down and its on the top after 30 sekonds, stock in the radiatorwas one idea, waterpump, all shitbrown water, and lots of air in the system. Need vacuum, level the car or dont buy frensch car. Can even be a bad headgasket sometimes

Reply to
Jibb

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