Hi I have a problem with a 89 gti it was fine temp wise smack bang upright on the gauge would go a little over then the fan cut in , but now I have done a new water pump a new thermostat (88 temp not a 92) put a sensors for the gauge and ecu. Since I have done this temp will sit under half but a little and fan will not cut in. I have put the old sensors back in and it will only sit just after first bar once doing 60 then once in traffic go back up to dead centre then fan will cut in is this right ?! Getting fed up with this now please help?!
If the new stat was jammed open or opening too soon (sometimes you do get faulty ones) it could be your problem. When the car is warming up but not fully up to temp (about 1/4 on the temp gauge), feel the top and bottom radiator hoses and see if there's a big difference between them. Either switch the engine off, or make sure you don't get caught in the belts... better to switch off really If the bottom hose is properly warm before the stat should open (about 1/2 way on the gauge, but every gauge is different) then it's faulty.
The lower thermostat is doing exactly that lowering the temp. The fan kicks in at around 97c I think but you fitted thermo rated at 88c which is opening earlier than the 92. The fan wouldn't work if temps never got high enough hope this explains it.
Thanks for ur replys much appriciated , I have checked in the Haynes manual and got a genuine VW number and I worked at a motor factors so crossed the number and my car should have a 88 deg in from Standered so that was good !. I have just changed the new stat for the old one and the old one is gen VW. Changed it over and it works ! Gauge sits just under half in this weather then in traffic goes to half then just over and fan kicks in so fingers crossed its fixed guess ur thero for a dud stat or a gen VW stat is worth the extra money thanks again
rad fan shouldn't kick in till temp gets to around 3/4 on the gauge anyway, it'll only kick in if you're sat for a while in traffic plus with it being quite nippy out that'll help keep it cool. no need to fit a low temp thermostat, beleive it or not VW knew exactly what they were doign when they designed the cooling system and so the engien works best with the standard stat in it you only want a lower temp one if you have a heavily upgraded engine, and even then sometimes only required when using it on the track
