stanisicb Posted January 8, 2012 Share Posted January 8, 2012 Hi guys i gotta 2004 granite with 460 hp,with viscous fan and she runs hot on the highway in about 10 min driving her steady at 1800 rpm the temp goes up to 200 than fan kicks in and cools her back down, and over and over.... city driving no problems she never get hot i put in a new rad and air to air and it didnt help, please guys help me out this is driving me insane, thanks everyone Quote Link to comment Share on other sites More sharing options...
Mackpro Posted January 8, 2012 Share Posted January 8, 2012 Follow the lower radiator pipe from the radiator to the engine, on the engine you will see a rubber "Y" hose, remove the "Y" hose and in it there should be a metal screen where the "Y" pipe meets the engine oil cooler. I would remove it , clean it, replace it or just throw it away. Most all ASET engines had this , the AC engine in the CX/CH and the AI engine in the CV/LE/MR. Here is a Mack service bulletin that is about the AC EGR engine but this is the same screen as on your truck.sb214056.pdf Quote Link to comment Share on other sites More sharing options...
stanisicb Posted January 8, 2012 Author Share Posted January 8, 2012 i replaced Y hose at mack dealership not too long ago, and they didnt say anything about the screan but ill pull it down and check it out, is there anything else that i shuld check out thermostat maybe? Quote Link to comment Share on other sites More sharing options...
Higgy Posted January 8, 2012 Share Posted January 8, 2012 If they put a new y hose on it, they almost surely checked the screen, it basically falls out when you pull that hose down. I would not throw that screen away. If it's dirty or broken (sometimes they get so plugged the top gets pushed out from the pressure) it should be replaced. That screen is there to protect the oil cooler core from becoming plugged with trash. Not a bad idea to replace the thermostat. Do you have any other symptoms? Does it push coolant from the radiator cap or from the pin hole in the center of the expansion tank cap? If you have been adding coolant and can't find any external leaks, you should pull the piping off the egr cooler and have a look down those pipes as shown in the service bulletin posted above. Quote Link to comment Share on other sites More sharing options...
stanisicb Posted January 8, 2012 Author Share Posted January 8, 2012 i add lilbit of coolant but nothing major and i couldnt find no leaks, other syntoms all the temp get higher on highway such as engine oil, trans,axle temp, turbo temp., alot of black smokePS Quote Link to comment Share on other sites More sharing options...
Higgy Posted January 9, 2012 Share Posted January 9, 2012 So from what I understand, it is not actually overheating. Your fan is cycling excessively to keep it cool? By excessive I mean on/off/on/off/on pretty quickly.. right? This is usually caused by poor airflow across the radiator for one reason or another. Your fan is working hard to keep it at temp. I know you said you have a new CAC and Rad in there. Check for anything that would cause poor airflow like the radiator fins plugged with dirt, fan clutch itself may be weak, make sure belts are in good shape, tensioner allowing belt to slip on fan pulley, fan shroud missing or broken, . Also possible you could have an internal cooling system restriction such as stuck closed t-stat. Macks seem to have a lot of casting sand in the block that has been known to cause internal restrictions after the engine gets some hours on it. I have seen this sand crap plug the elbow fittings for the bleed lines to the surge tank and cause running hot complaints. This is also another reason that screen is in front of the oil cooler inlet. Make sure the weep hole in the water pump is not leaking, if it is, change it out. That's about all I can think of. Good luck to you, sir. Quote Link to comment Share on other sites More sharing options...
Higgy Posted January 9, 2012 Share Posted January 9, 2012 The black smoke may or may not be related, could just be a boost issue causing the smoke. Trucks are hard to fix over the internet. Quote Link to comment Share on other sites More sharing options...
stanisicb Posted January 11, 2012 Author Share Posted January 11, 2012 no the truck is not overheating, but the fan is on and off all the time i changed the water pump last year and its not leaking at the same time i changed the clucth fan, all the pullys and tenseners look good, non of them are making any noise, its gotta be interlnal plug somewhere, rad and air to air are 2 days on the truck so no way air flow can be restricted between them, but the thing that i dont understand is how come it never does it city driving? thanks alot man for your help Quote Link to comment Share on other sites More sharing options...
Higgy Posted January 12, 2012 Share Posted January 12, 2012 (edited) I would imagine it is because your engine is typically under constant load when your rolling on the highway. City driving would give it time to recover at stop lights and what not. If I were you I would drain your coolant, put a new set of t-stats (can't hurt) in it and take a look at that screen that MackPro was talking about.If you do pull your t-stats, you can test them in a pot of water on the stove and a thermometer in the water. I think they are supposed to start opening at about 170 and be fully open at 195 or so. Can't remember exact temps. Edited January 12, 2012 by Higgy Quote Link to comment Share on other sites More sharing options...
Mackpro Posted January 12, 2012 Share Posted January 12, 2012 I would unplug the AC compressor and see what happens, this time of year people use their defroster alot and with the defroster on the A/C compressor runs. If there is a A/C high pressure issue the fan clutch could be coming on due to this. Last winter I had a CV with a stuck expansion valve, Everytime he turned the defroster on the head/high pressure would build up and turn the fan on. Also if the water pump was changed have the dealer double check that they put the correct one on. There is one for the AI engine and one for the AC engine, they both look the same and will bolt on but the pully slightly different in diameter. On the thermostats, I would change them and the new improved thermostat kit will have better o-rings and one thermostat opens at 180 and the other opens at 185 to help prevent coolant surge. Quote Link to comment Share on other sites More sharing options...
stanisicb Posted January 12, 2012 Author Share Posted January 12, 2012 thanks alot guys ill do the thermostat and ill check the screen hopefully thats gonna solve my problem, Quote Link to comment Share on other sites More sharing options...
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