Posted: 1/12/2011 9:45:36 PM EDT
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Trying to help a buddy here. He has an 86 Ford 460.
New water pump, radiator, hoses, etc... the heater core has been flushed and flows with no problems, but the truck constantly overheats..... take the thermostat out and it never gets hot, but does lose coolant, it seems to build pressure and pushes it out the overflow sometimes.With the thermostat in it will sometimes suck the upper hose completely closed... 5 thermostats, all different temps have been tried, even drilled holes around one of them to keep a constant flow and it still overheats under a load.The clutch fan is working properly, the waterpump is working, when the water is low you can actually see it coming across the radiator fins from the passenger side... so it's going the right direction. Any ideas? |
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"The coolant has boiled more than once. With the thermostat out the gauge never gets past the N on normal and the temps say around 130 with an IR gun... can physcally lay my hand on the radiator after driving 300 miles. Put the thermostat back in... take off... 5 miles with the trailer and it's pegged, but I didn't have access to the IR gun at that time. Both fuel pumps are new, ignition module is new, coil is new, plugs, wires, cap, all new.
With the thermostat out the flow is constant and the upper hose does not collapse, with it in, it collapses and overheats... the collapsing hose is the biggest issue that can't seem to get figured out. " |
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Would that collapse hoses, and cause it to overheat with thermostat in and not with it out? Secondly, he has no coolant in oil, and no coolant in oil. Only explanation I can come up with is that the thermostat is causing an air bubble, which can slow/stop fluid flow in the system. It can cause a pressure buildup that causes fluid out the overflow, and you can get boiloff in the engine. It's not the most likely scenario, but it's the only thing I can come up with. |
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Temp sender is new... it has never run so hot it shuts down, but the gauge pegs and the coolant has boiled more than once. With the thermostat out the gauge never gets past the N on normal and the temps say around 130 with an IR gun... can physcally lay my hand on the radiator after driving 300 miles. Put the thermostat back in... take off... 5 miles with the trailer and it's pegged, but I didn't have access to the IR gun at that time. Both fuel pumps are new, ignition module is new, coil is new, plugs, wires, cap, all new.
The radiator, cap, waterpump, hoses, all are new. I believe the timing is set about 9 degrees BTD C9VE block timing set is a 69 lincoln |
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It is a new "new hose"? (not that I don't believe you, just double checking) Usually the tell tale sign is they swell near the hose clamps, but I have heard of them getting soft enough to collapse. I think so yea. He also stated he drilled holes in the thermostat, and tried that too. |
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Not related to that engine but a friend had a Dodge diesel that was overheating, short story is belt tensioner was weak allowing belt to not run water pump as normal. Replacing tensioner fixed his overheating. Sort of a stretch but worth looking at unusual things. |
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Have you checked the oil to see if it has any lung butter in it? Any thick white goo in the oil filler tube, radiator good,spark plugs look normal? ETA: has he ran the truck with the filler cap off the radiator with the heat on full blast while keeping the radiator topped off to bleed the air out of the system.
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Have you checked the oil to see if it has any lung butter in it? Any thick white goo in the oil filler tube, radiator good,spark plugs look normal? Plugs are new, he no mixture of coolant and oil in any direction. Water flows the correct direction. From what I can understand it doesn't do this if he removed the thermostat. He has tried 5 thermostats, and even drilled holles in one. |
| If it is an air bubble, its pretty easy to fix, just park the truck and let it run with the radiator cap off and put some more fluid in if need be. Second, you may have a blockage in your radiator. I had a similar problem with my Jeep and it ended up being sludge in the radiator which came out with a water hose and taking the drain plug out of the radiator. If nothing else works get a radiator flush or get a new radiator. |
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I'm leaning toward head gasket or cracked head. Had an Olds that did the same thing, turned out to be a tiny crack in the head. He doesn't have coolant and oil mix, and only occasional exhaust smoke. I will let him know though. That was the crazy thing, neither did I. It pressurized into the coolant jacket, but no antifreeze ever got into the engine. Or not enough to be readily apparent. I'd get the little puff at start that I wrote off to Qjet+cold humid air. |
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I'm leaning toward head gasket or cracked head. Had an Olds that did the same thing, turned out to be a tiny crack in the head. He doesn't have coolant and oil mix, and only occasional exhaust smoke. I will let him know though. You don't always get coolant in the oil. It depends on where the crack in a head or head gasket goes. I had a crack in a head that went from a water jacket hole to a valve port. Coolant never got to the oil journals. Coolant can be lost internally to the cylinders and "burns" out with the exhaust and doesn't get past the rings to the crankcase thus getting the occassional "exhaust smoke" and no coolant in with oil. The proper test to do to check for cracked head or gasket is to test for exhaust gases in the coolant system. Napa has a test kit. If coolant is going out to a cylinder, then there is exhaust gases going the other way into the coolant system and causing an "air bubble" that lockes up the flow of the coolant. That's why you test for exhaust gasses in the coolant system. And with the thermostat in place it will be in a closed position until it heats up. But the coolant heats too quickly and overheats before the thermostat opens up. That also keeps flow from happening. I'm not there and can't actually see your problem but this was my experience and I ended up havng cracks on both heads. Hope this helps. |
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I just had the exact thing happen on one of our vehicles. It turns out the head gasket was blown. It was small enough that no coolant was in the oil, but it did test for exhaust gasses in the radiator. Had the heads pulled, and sure enough the gasket was blown.
I did the same thing with thermostats, etc.. I was pulling my hair out. Had all the fans/senders/pump/radiator changed, and still had the problem. It was extremely frustrating to know what was spent before the problem was finally found and fixed. |