Cat D6D

[jook]

I have a D6D my radiator has a leak if i run it for 4 hours it starts to heat up.check the coolant level still has coolant up to the neck .I stop it before it gets in the red zon,would the leak cause it. No air bubbels in the rad.power shift trans runs about half when it gets that warm.Not working hard nocking down small brush.

 

[BCnT]

pressure raises boiling point of coolant so in theory,a leak could cause overheating without coolant loss.
i'd check more obvious things like belt tension and good coolant flow...could be your radiator needs cleaning inside and out and leak repaired.

 

[NCWayne]

Not really understanding the post exactly. You start by saying the radiator has a leak and that it's overheating because of that, but then go on to say that when it overheats the water level is still in the neck. Stands to reason if you actually had a leak the water level would be going down, you'd see the leak, etc, etc. One thing though, don't let those tanks fool you. They are made with a baffel in them and they can look like they have water 'in the tank' and all it will be is water on top of the baffle while the tank is dry below it. Regardless I'll give a little advice as to how those radiators are designed and hope it helps you solve the problem.

That said, a coolant system can carry away/handle more heat when it's under pressure than it can at atmospheric pressure alone. At atmospheric the water will still boil around 212 degrees, but under pressure it will soak up more heat before it starts to boil.

Now that machine should have a completely sealed screw on top for filling the radiator, etc, and a seperate device that operates as the 'pressure' cap. First thing to check is the seal rubber on the large screw on cap. Those tend to get hard and cracked and then don't seal the tank. The rubber seal is easily replacable and not very expensive. Simply remove the little snap ring holding the thin 'keeper' and the seal in place and remove both. The keepers are pretty thin and tend to crack over time, and may fall apart when you tak it off. In other words go ahead and get both the seal and the keeper when you place your order.

What's typically overlooked is the actual 'pressure cap'. Looking at the tank from the seat it'll be the small round object to the right of the screw on cap, and will be held down with a couple of bolts. There are several parts to the assembly. The part that comes up when you first unbolt it will be the outer casing and will have what looks like the spring/seal assembly out of a normal radiator cap pressed into the center of it. To replace it pry it out and the new one will go in sort of like putting in a freeze plug. Now the area around the spring/seal tends to accumulate dirt, rust, etc and needs to be cleaned out at the very least. The last one I pulled was stopped completely up with crud. With everything clean, look at the spring/seal. More than likely the seal is screwed up and will need to be replaced. Alot of people don't even know the pieces are there and it's not uncommon for them to be origional to the machine. Next under the top piece is a thin metal piece with a raised seat for the seal made into it. Those usually don't 'go bad' but just insure the sealing surface is in good shape. Using a thin screwdriver, putty knife, etc slip it under the ring that has the seal on it and remove it. Under it should be a screen into the tank that will come out also.

Once everything is removed make sure that the top of the tank is clean, the top and bottom of the seal surface is clean, and the bottom of the top piece is clean. Going back together it will be the screen resting in a pocket in the tank, then a gasket, then the seat, then another gasket, than the top piece.

If all of those pieces are good then the next thing to check is the thermostat to make sure it's operating. If it's stuck open or stuck shut either one it can cause the engine to overheat. Typically though if it's stuck shut it will overheat almost immediately but stuck open, or partly so, will cause it to heat over time if the outside air temp is high enough. Beyond that all I can say is feel free to ask any other questions as you look further into the problem, and good luck. Wayne

 

[jook]

I was wondering if the leak could cause it to what to over heat.I have been adding 1/2 gallon or less a day depending how much i use it.I know where the leak is it is the top seal on the tank.Just trying to finish a job then fix it thanks

 

[AJ.]

Don"t chance cracking the head when you have a known problem with the rad,have it out and get it repaired and cleaned now rather than when the head is cracked,those machines will not tolerate anything wrong with the cooling.
AJ

 

[Anonymous-0]

When it's hot check the top and bottom rad temp. If both are about 10 to 15 deg different the rad likely needs external cleaning. If they are more different then the rad may need internal cleaning or the temp regulator may be bad or missing. If the temp regulator is missing coolant can go freely through the bypass and not the rad. Be sure to check easy stuff first, Dirty rad core, slipping belts, dammaged fan blades. Or one blade the wrong way on reversaable blade fan.
Later Bob

 

[jook]

Thanks for the info.I plan on taking it out to fix it i don't let it get in to the red zone. The cost is to much.

 

[bob plumadore]

Are you sure you have a leak? at a half gal a day, filling it to the top ot the cap opening you are replacing the overflow
it should be filled 1.5 to 2 inches below the top. If the Tem regulator (Thermostat is missing that can cause overheating because the water is traveling to fast to pick up heat or to give it off. Read Wayne's posting he is giving good advice.

 

[jook]

thanks i took it out today to get it fixed,Should know 4or5 days.Going to put new therm. stat in to.

 

[jook]

Got a call on my rad souds like it was plugged inside I don't think the rad had ever been out the bolts were rusted on twisted off.So i think that was the problem,thanks for all the replies,good advice.ps. going to get a new core cat is a 1979.