Quick history - Went on holiday pulling #8,000 lb 5th wheel holiday trailer through mountains, very steep grades in the rockies and very long. Factory gauges, water temp hit 250 F on several occations nearing the top of hills (1st gear, auto, on the floor, 20 MPH), crested hills and truck cooled off great. The idiot light (check gauges light) came on a couple times while hot, anyone know what temp this light comes on at?


So now after being home a few days the low coolant light has been coming on, filled it a couple times now but after sitting overnight fluids down another gallon, not losing it out the cap as the overflow tube is dry as can be. Will let it sit for a bit here now that i'm at work and pull the oil drain plug and see whats on bottom, if nothing then it must be going out the tail pipe. What do you guys think? Head Gaskets http://www.dieselplace.com/forum/smileys/Pinch.gif, Heads http://www.dieselplace.com/forum/smileys/Cry.gif or Block http://www.dieselplace.com/forum/smileys/Throw Up.gif?

check your engine oil and transmission fluid levels. if they are high, you might have antifreeze going into places it shouldn't be.

Well no foreign fluids in the engine oil or tranny (not sure why one would check the tranny but i did). Held a paper over the exhaust on hi idle, dry as a popcorn *art, but i guess fluids could evaporate before the tail pipe. I'm starting to suspect cracked head or bad gaskets, any other suggestions? If i have to pull the heads what would be some good mods to do at that time. This truck is my office so i need its use on a daily basis, put on 250km/d.

Stupid question, maybe, but have you checked for coolant dropping just to ground? Such thing can happen with a broken water pump.

If the water comes out at or drops onto some hot location under the hood, it may even evaporate before it hits the ground.

Tranny cooler is inside of radiator, one leak and fluid exchange.

heads can be worked in the intake and exhaust passages for better flow.

No external leaks Lee but thanks.


QM i knew about that cooler but thought it would be a long shot. But did check the tranny fluid, no increase in level and even smells good still.


Thanks for the input.

A gallon seems like alot to me. It has to be going somewhere.

OK, dumb question time. Is it possible the thermostat has stuck and its blowing the fluid out the filler jug but only down that 1 gallon each time and then staying there? I haven't really run more than a day to see if it stays there, keep refilling it. Gauge temps seem normal while driving all the time and the dump tube on the jug also seems to be dry, maybe it dries up before i get a chance to look at it. I'm going to fill the jug to the cold level and put the overflow line in a pop can on the way home and see what happens, maybe pull the thermostat tonight or tomorrow as time permits.

Maybe its going out you tailpipe...which would mean its time for new heads.

Well... topped up the H20 and put the pop bottle under the drain, ran 5 min's on high idle and the bottle was full and bubbling, temp only @ 165 - 170 F, bad rad cap, i doubt it, blown head gasket is starting to look suspicious but will test the cap ASAP.


Could the heads have warped?

no way, its a 6.5 man, they're CRACKED!

Well, blew just over a gallon out the water jug on the way home, with finger on the vent tube there is a steady blow.


TDG & QM Your both fairly knowledgable. Gaskets or Heads? Being the weekend and all i'd like to know weather or not to pick up some heads tonight or just gasket sets.


Am also contemplating an entire engine because of the high mileage. I can't be down for more than 2 or 3 weekdays to get this done. Lose big $$$ without my truck.

with the high miles a replacement engine would not be a bad idea, just a weekend swap then, if heads are cracked, whick is likely as stated above, then they must be replaced and top of engine dissasembled, which then runs the risk of getting dirt in the engine and while a small bit is normally a non issue, the high mileage parts may not take well to it and it COULD develop a lower end problem... Again, not likely it will happen, just weighing out the possibilities

Thanks for the info. Wish i knew what the problem is before i pull it apart. I'm thinking gaskets (maybe hoping instead). Funny thing was it never started using the fluid until a week after the hard pulling, does that tell anyone anything? Its getting worse too, had to fill the rad twice in the 100km drive home.

better pull the heads or you'll have to do a short block too