So I have put in a new OEM thermostat, replaced the waterpump and the radiator. The car just loves to sit at around 98deg c. Why? It has a front mount on it, but also an underbody tray. It's driving me nuts why it runs so hot anyone got any ideas?

 

Maybe you need an upgraded radiator? Do you still have AC in place? I noticed a significant drop in temps when I removed my AC condenser core & fan in front of my radiator.

 

double check your timing and be sure it is set correctly, be sure there is no unecessary airflow restrictions through the radiator. upgrade the radiator if you are running a larger turbo, make sure your fan is pulling enough air through the radiator, yadda yadda. those were things missing from your post that need to still be checked off your list.

some cars just run hotter than others, i can't explain why even though all things are equal from one car to the next. if all of the above doesn't cure it, coring the thermostat likely will.

 

What is your fan setup? You have the stock clutch fan? Is the fan clutch locking up properly?

 

How clean is the rad itself, between the fins?

I clean mine by removing the fan and shroud and then soaking the fins with aluminum rim cleaner (as in the stuff meant for your wheels) and letting it sit for 10-15 minutes and then rinsing with all with a hose. Cheap, quick, easy and it works very well.

 

Sorry should have added. Im running a 55mm core PWR radiator with a SPAL 3000cfm curved blade thermo, in a shroud that I made myself. The a/c is still in the car but not currently connected. And the radiator has only been in the car 6 months so it's still clean

 

Show pics of the shroud. I would think ducting alone could make or break your cooling.