So I bought this truck a week ago and it started running hot. So I thought it was the fan clutch because the temp would go back to normal when you start driving it and only ran hot at idle. So I replaced the fan clutch. Now every once in a while it will run hot but as soon as I give it gas the temp drops right back down to normal. If I dont give it gas it will run very close to the red, but again soon as I give it gas it drops right back down. Im wondering if it could be a water pump? But It is not leaking from the water pump. Im frustrated trying to figure out what the problem is. I have opened the radiator and topped it off completely but it still does it. Any ideas on what the problem could be?

 

could be any of several things:
rotted out water pump impeller
sluggish/partially closed thermostat
bad radiator

 

Ditto replace water pump and thermostast and go ahead and replace timing chain while your in there with a double roller. I would flush the radiator at really well before reinstalling.

 

+1 on above.

 

dang, he only bought it a week ago and y'all have already got him tearing the front of the engine off, lol.

since i'm lazy and cheap, mostly lazy, i'd flush the radiator and cooling system first and replace the t-stat with a nice new Stant Superstat. stock is 195, some people use a 180, but some of them get a CEL from that and less heat, so make your own decision. if you do this, while the t-stat neck if off, grind off the big stupid tab that says "front". prestone makes a chemical flush that might help. follow the directions. if your coolant is really really nasty and you're not in a cold climate (tampa) you might drain and replace it with distilled water first. don't use tap water due to risk of hard water calcium which kills the **** out of radiators.

edit - by the way there are pipe plug block drains on both side of the engine hiding behind the engine mounts. they can be a bitch to remove due to poor access angles and risk of rounding off the heads so be careful to avoid that. i had to use real good vise grips on one side. penetrating oil like pb-blaster might help.

 

I think just replacing the parts would be easier than doing a flush, but that's just me. However i have torn the front of the engine off several times and know the routine now.

 

Gonna try the thermostat first and flush out the radiator then if tat doesnt work il do the water pump. Thanks for the advice. Not too much worried about the timing chain right now because march or april im going to find a another motor to drop in. I can tell the motor has a lot of age in it.

 

So I took the thermpstat out and put it in a pot of boiling water.... and the thermostat opened up. So now i know the thermostat is fine. So the only thing left is a bad radiator, bad water pump, or I bought a this truck with a blown head gasket. There are really no signs of a blown head gasket. No water in the oil.... no water in the coolant.... and no smoke out of the exhaust.

 

One more question.... Did the Ram 1500's with the 5.2 litre come with electric fans? Someone told me they did..... But mine doesnt have one.

 

no they do not come with electric fans, but a nice upgrade to do. I replaced my water pump and left the mechanical fan off and installed a single 19" electric fan in the stock fan shroud and it worked great. only cost about $90.

one way to check the water pump is to take your serpentine belt off and grab the fan and tug on it to see if there is any play in the bearings in it.