lack of power and overheats

[Soniczs]

hey i gotta question , im having the excact same problems with my 89 240, i thought it was a head gasket, and still think it is. But i too also have an aftermarket air intake, and i too thought it was my maf. I also have a bad backfire. noow when i ran water in my car for the summer the temp was normal, i had water in the winter 2 weeks and the temp sisnt budge at all, put antifreeze in it and for a 2-3 weeks it was great. well minus all the above problems. i also have a turbo muffler. ive changed:

radiatorwater pumpthermostatclutch fanbattery and cablesstarteralternatorspark plugs and wiresrotor and capbeltsand the head has been replaced b4 i bought the car

now my problem is, i have all the above wrong, and now i have to turn down my heat cuz my car will fluxuate from normal temp to extreme hot. ive checked all around the head and block and have found no oil leaks and no cracks nor am i losin anit-freeze. kinda funny cuz i know the thrmostsat is fine, i actually pulled it out and boiled it to open up. Now i know i have a bad O ring, and my buddy told me b4 i pull the head (which is kinda hard cuz i dont know the order of bolts) i should do a compression check. obviously thats the easier way to tell if you have a bad head gasket. but i do know that the car will be runnin normal for a good amount of time then youll feel the rpm drop about a 500 or so and the temp gauge automatically shoots up, so ill turn on the heat and she'll cool down but its not explaining the rpms cuz theyll go up and down. Normal, not normal. fluxuate. im extremely hessitant to pullin off the head. im gettin terrible miles to the gallon and no i havnt changed the fuel filter. i love this car so much but these things are worse than porsche! im jus thinkin about sayin screw it and throw in carbuerated 305 and gears haha.. so if you could please help!!!!!!

[Soniczs]

oh and where can i find online "how to take the head off" tips?? ive basically been screwin with this thing on my own and god knows theres no help in cleveland lol

[NISTECH]

I made your thread seperate from his. Posting in his thread is thread jacking please dont do that. do a search in 240 technical on head replacement. There probably isnt anything detailed out but there are some tips. your best bet is to drop some coin and pick up a factory service manual before you attempt it. It has good diagrams of what is involved and torque sequences. To me it sounds like you have a restriction somewhere in your cooling system. can you give anymore details as to when it happens. every time it happens are there some charicteristics that are common to every event. like it always happens in stop and go traffic but not when at cruising speeds? stuff like that

[NISTECH]

oh did you put the fan on backwards? it happens. when you throttle up does the air from the fan blow back over the engine or back through the radiator?