Hi, I've got a mk 2 gti 1.8 8v. When driving for a while water temp goes to 3/4 on the dsh and oil temp goes up to 126 - 128. Any ideas as to why? and how I can fix this. Also what can be done to the engine performance wise? Any replies are much appreciated. Matt
Those numbers aren't over the top, but maybe a little higher than average. The water gauge can be a fickle thing - and if it's not overheating and you're not using coolant, then 3/4 isn't too bad. If you want to have a look, try refreshing the coolant system - drain fully, flush, replace thermostat etc - and see if that makes a difference. It could be that your system is a little tired and just needs servicing. The oil temps are a little higher than normal for an 8V, but well below the VW owner manual suggestion, that states 'The engine speed should be reduced if the oil temperature rises to +145C.' How old is your oil? What brand and specification is it? Sometimes, retarded ignition timing can have a detrimental effect on engine temps. Has the car been properly serviced recently or the timing checked? Just a thought, as it's not hard to check. Performance wise, there's a few bits you can do to the engine (depending what year - whether it's a K-Jet or Digifant fuel system) but you're not going to get a big increase in performance without spending quite a bit of money. A common upgrade to the 1.8L GTI is to replace the bottom end with a 2.0L bottom end from an Audi, Mk3 GTI or Passat (engine codes 3A, 2E or AGG.) This gives a really good increase in torque and a bit more power. A lot of people have done this and it gets a big thumbs up. Use the search function - there's a lot of information about tuning the 8V GTI engines, what to do, not to do etc. There's a current thread by a user called Phil Hall, who's just replacing his bottom end for a 2E - with progress photos etc. Good luck!
Sounds like a stuck thermostat or a dead water pump. Those oil temps are way too high for everyday use. Sometimes the impeller can come loose from the water pump shaft.
yep get a new thermostat and water pump then use a good coolant.i also got a new radiater for around 35. my oil temp. never goes above 106 and water temp sits just below half.
