Hello, Im new to this forum, so I did a search before I posted this question but could not find any answers? My father and I have an older Cat 966 I believe its from the mid 60's. Great machine and very well kept. We use it for plowing in the winter. Last season the heater unit in the cab went so we replaced it. The heat was great until recently. We replaced the thermostat, checked the valves of the two lines that are hooked up one the the engine and two to the radiator. When the machine warms up and the heater is put on only one of the two lines that enter the heater heats up, the bottom one? So yesterday we had the water pump rebuilt and installed it. Still no heat? Anyone have any idea on what it could be??? thanks in advance Peter
Hey Pete , bad time of yr to have heater trouble . Either your heater inlet / outlet hose is kinked , or the heater inlet tube is blocked ,or the valve at the block return is blocked . I would take the hoses loose at the engine and backflush the heater with a garden hose (not full pressure ) . If that seems good then check the valves again . Hopefully you'll find something . I once found a wad of silicone in a heater tube that came from a quickie gasket repair . Just a process of elimination I guess ......
Why not take hoses off the heater and connect them, and see if the hot water is now circulating, if so its the heater core. And also sometimes it takes a while to get the air bubble out. My Trojan is on the roof (to blow on the glass) and now on shut down it seems to flow back to the radiator then into the overflow. So I have to take the overflow bottle a gallon and put back in the radiator. My Ford backhoe the heater also is up on the roof it works fine. So we all got problems sam
Actually, hot coolant should enter the heater at the top, and exit at the bottom. Switch the hoses around and try that. Many of these heaters have a temperature control cable running to an inline valve, generally right near the heater. If that cable is broken, rusted, or bent, the valve may be closed or partially closed. Check that. The other ideas here are also good. I've found many the same problems over the years. Good Luck!
heater I would go with the heater valve not open Is both heater hoses hot? If they are both hot, I would think the heater core is full of dirt/dust(external) If it had a filter, I would say it was stopped up. I think someone said to take the hoses off at the heater core and see if there is a good flow out one of the hoses. If you have good flow then, as stated hook up a garden hose to one side of the heater core, with low pressure, keep an eye on what comes out of the other port. If all this is OK, the return(heater hose) has a problem, hook up the water hose to this and see if you have flow, it should be coming out the other heater hose. This should be simple to troubleshoot, but Im thinking heater valve. I had to replace a cable on one of my trucks last week, it was broke in the housing Good Luck