For the last few months now i have had to top the coolant up on my truck every couple of months which is a 2002 4.7.

Now that the cold weather is here i noticed last night that at idle the heater was blowing cold air in to the cabin. When revved the heat would come through. I naturally suspected that the coolant was low again. I topped back up again. Since then i have done 15 miles,and the heater went cold again at idle. Four litres of water again to top up.

Now ive checked the obvious. The oil is as good as the day it was changed three months ago,with no hint of contamination. Temp gauge reads just below half. Where it has been ever since i have owned the truck(Never ever read above this) There is no lumpy running and the engine runs sweet. I have also checked for excessive condensation coming from the muffler. But this burns off after a few minutes once warmed up. The only thing i have noticed is that there has been some small drips of water coming from an over flow pipe in the passenger side bulkhead(does this when the aircon is not switched on) But doesnt show any signs of coolant.

Anyone with any ideas??

 

You said it runs sweet-Do you mean it runs well, or do you literally mean that the exhaust smells sweet (coolant)?

Every time I see one of these kinds of thread it gives me bad memories of when I blew that head gasket in my 4.7 lol. Always seems like the same symptoms too, but my truck idled rough and threw a CEL for a misfire in the 1st cylinder.

The 4.7s are known to blow head gaskets though, so I wouldn't rule it out. If you can, I wouldn't drive the thing until you figure out what the problem is...That coolant is going somewhere...

 

Sorry. Sweet= Well. Ive put my nose near the muffler,and no sense of the sweet smell of coolant.

 

Check for any radiator leaks. I have a leak that took a while to figure out, on the bottom drivers side of the radiator, where the plastic crimps onto the coils. It drips steadily right there. The radiator was replaced already (and recent) when I bought the truck and had air in the system. I topped off one day at work and happened to walk back outside about 15 minutes later and saw a puddle under front of truck. I bled the air out and ever since than it has only been a steady drip when truck is not running.

 

Ive just checked on what you said. And there seems to be some trace of coolant on the ribs of the end cap on the drivers side of the rad. It couldnt have been from where ive been topping up. But no signs of coolant under the truck. B.t.w do the end caps of the rad split. As they seem to be made of plastic??.

 

I dont know that they split, but the seal between the plastic and metal does start to leak for whatever reason. Some people had a bunch of coolant spray all over everything depending on where it is leaking. Some leak a whole bunch at once, mine just dribbles out steadily.

 

get that checked out quickly or youll end up another 4.7 down the drain....check tstat for bad spots on the radiator maybe a heater core.....theres a few diff reasons ....

 

the best way to figure out where its leaking would be to buy (or if you have one) a coolant pressure test gauge and put the cooling system under about 15-16 psi and let it sit and see where the coolant leaks from (if its not an internal leak). You could also do a compression test on all the cylinders and see if any of them are low.

 

My 05 4.7 QC did the same thing you describe. One of the heads was cracked and had to be replaced. It ran fine with no signs of a problem other than having to top up the coolant every 2-3 weeks.

 

You can get these on loan from Oreily's as well, so you don't have to drop a bunch of money on the entire tool set.