Need Help 57 Cat D6 Cooling and Dumb Question

I just bought a 57 D6 9U that appears to be in very good condition except for a possible cooling issue. Temperature gage stays green, but after running long enough to get hot, it vents fluid from radiator cap. It never seems to get close to top of green on temp gage even if you continue to use it. When you add water next day it takes between half a gallon and a gallon to get to where you can see water in radiator. Am I over filling or do I have a problem.

Second question - fan blows lots of air volume out thru front - opposite of car which sucks air in thru radiator and past engine front to back - is this normal?

Ace.I plead ignornance when it comes to your machine, however logically it seems that the fan is pulling HOT AIR from the engine, pushing it into the radiator core causing the water to boil over yet not affecting the guage reading. Like i stated I plead ignorance to the problem, and there are others on here that are a whole lot more knowledgeable then me, Hope you get the right information, regards LOU.
P.s. I either read or heard SOME of the fans can be turned from a push air to a pull air type,but which ones I can't remember,others will know.

every dozer i been around pushed air thru radiator to keep dirt buildup at a minimum...buy,borrow,steal a thermo gun to see what true engine temps are...may be a replacement gauge of unknown quality.

On a dozer, normal direction on the fan pushes air through the radiator like yours is doing, so no problem there.

As far as the issue of water being forced from under the radiator cap I ask this. Is the water actually coming from under the screw on cap, or from under the pressure relief valve that sits on top of the tank, near the cap? The way CAT does the older equipment the actual screw on cap should seal, and not leak at all, unless the seal is shot. Instead they have a pressure regulating valve on the top of the tank to relieve any excess pressure. So,typically, if the cap is leaking then the seal on it is worn completely out, or worn such that it is letting the coolant past at it a lower pressure than the actual relief. This, in turn, usually happens because the relief is stuck from getting packed with dust and dirt over the years. There are either 4 or 5 bolts (been awhile) that hold the assembly to the tank. Carefully pull those bolts (they tend to be rusty and will twist off easily if your not careful) and you should be able to take everything apart and clean it up. You might find the actual valve seal is shot and you'll need another, but often you'll get lucky and be able to reuse the old one. Either way clean it up and reassemble it in the same order it all came apart. Once together it should relieve pressure on the radiator, instead of the cap seal doing it, unless the seal on the cap is shot as I said earlier.

Beyond that, if you are topping the tank completely off, most systems will spit out some coolant and 'seek their own level', regardless to any of what I said above. In other words what is happening may also be perfectly normal as long as it's happing through the relief and not the cap.

Hope this helps.

toss a thermometer in it when you get it spittin water ,, guage could be wrong and radiator could be plugged , summer fan should push air forward , winter work reverse blades to share heat with engine and operator quickest best way I found to flush radiator fins is to idle motor way down and douse fan blades with simplegreen ,, then take a hose oand rev up motor and suck the soap thru the fins with water ,, worx quick and does a good job

Unless it's equipped with a Huber, or other brand, of reversible fan it's going to push forward through the radiator summer and winter. Usually the main reason for reversing the direction during the winter, at least around here, had to do more with operator comfort (ie- heat for the operator on an open cab machine) than anything else.

Unfortunately with those old Cats a lot of times it is combustion gases leaking into the cooling system that cause this. I ran an old 9U once that if you ran it wide open it would start puking like that but if you backed off the throttle a bit it would behave pretty good. The big question is if the coolant will stabilize at a lower level and not overheat or can you run a shift without adding coolant.