I have a 1991 940 turbo. I just changed the oil with royal purple ordered spark plugs, New harmonic balancer, What things should i replace the car has 186,000 miles i just installed a mbc pushing 10psi i dont want to go any higher till tune up is complete. now what kind of thermostat should i get and also what kind of fuel filter and how hard is it to install fuel filter.

 

Going into winter, a stock temp thermostat should be fine. Wahler is a good brand. As for fuel filters, the type is pretty well dictated by the fittings unless you want to do some plumbing. Bosch # is 71 005 with the outlet fitting, # 71 039 w/o the fitting. Get the fitting as well as copper crush washers for the banjo bolts. If you still have the o.e. turbo and intercooler you needn't try boosting over 12-14. Anything more and you'll be blowing hot air and increase the detonation.

 

what do you mean by blowing hot air because when im on the highway hot air comes through vents even though the heat is not on unless its just the air blowing in through grille.