Hey everyone, I recently bought a old CAT D6 8U dozer which I am repairing but I am struggling with the cooling system. The oil and the water was combined at first but I repaired that problem and it used a lot of oil but now it doesn't use oil anymore and also the oil and water stay separate. The radiator pushes out the water and the machine gets warm fast. I don't know what this problem could be but I thought a thermostat but I don't know if it still has one in. Any help would be greatly appreciated, thank you.
I f bubbling in radiator could be leaking pre combustion chamber. Is it missing on any particular cylinder?
No it idles quite nice. I removed the head to check the head gasket and I saw no cracks in the head and head gasket also good. Any other suggestions?
If the radiator tubes are blocked, the water pump will circulate the coolant faster than it can flow through the tubes, so this will lead to coolant being "pumped" out of the cooling system. The precombustion chambers are notorious for developing holes in them when the cooling system goes rusty. But a leaking precom should show combustion gases in the top radiator tank, when the engine gets warm.
Should the water shoots out like a volcano if there is a leak in the pre combustion chamber?
No, it won't shoot out like a volcano from a perforated precombustion chamber, it will just produce bubbles in the top tank. If the precombustion chamber is badly holed, the coolant will run through to the cylinder, and when you crank the engine after an overnight stop, the coolant buildup in the cylinder will cause hydraulic lock, as the piston rises to TDC. The engine will crank for about one revolution or less, then stop dead with a big CLUNK.
Okay thanks for the help and advise.
You need to drain the coolant until you can sight the top of the tubes in the top radiator tank. You generally can't see many of them because of the cast plate in the top tank, but you can usually see a few of them through the hole in the cast plate. Use a flashlight to check out as many as you can see. If the ones you can see, show signs of being plugged with rust, muddy gunk, or any other material such as white calcium deposits, you will need to pull the radiator out and unbolt the tanks, and either treat the core with an acid bath and pressure wash, or maybe even rodding the tubes, to clean the blockages out. You would also be well-advised to add some cooling system cleaner to the tractor before you do anything major. You can use commercially-available products, or you can use muriatic acid. Be very careful using muriatic acid, you don't want splashes on your skin or in your eyes, and don't use any stronger acid solution in the cooling system than about 3%-4%, or you will damage the metals in the engine via acid etching. I prefer citric acid (about 5%-10%) as a rust-removing solution, it's a lot safer, and it does not etch metals. If an engine has a faulty thermostat that doesn't open properly, this simply leads to the engine getting hot very quickly. No thermostat installed means the engine will take a long time to reach operating temperature - and this can also cause overheating - although slowly - as the coolant circulates faster than it can be cooled. Always make sure you use good quality coolant with additives and anti-freeze, if needed.
I have a wheel loader without thermostat which cools good although it has no thermostat. Do I need to replace the whole head if it's a leak in the pre combustion chamber?
No, the precombustion chambers are easily replaced individually. New precom chambers are not expensive. You need a special Cat tool to remove and replace them. Earlier precombustion chambers were 2-piece design, later ones (and current replacements) are 1-piece design. The main tool required looks like a splined bolt, they're not expensive to acquire.
Okay thanks I'll check it out.