Overheating

20

Asked by Aug 28, 2016 at 01:39 PM about the 1999 Buick Century Custom

Question type: Maintenance & Repair

I have a 1999 Buick Century with the 3100 engine,
it ran hot on the interstate so flushed with hose
while running and went out of state, came back 3-4  
days later and it overheated again, found a crack in
the neck of radiator, now I have replaced the
radiator, new cap, new water pump, new hoses top
and bottom, new heater hose that comes off water
pump, new thermostat, new temperature sensor at
thermostat housing, went ahead and bypassed
heater core, bled air out of both bleeders numerous
times...does fine at 35-40 mph in town, get on the
interstate, it still runs hot...HELP ! ! !

5 Answers

58,915

Usually when an engine heats up at expressway speeds it's a coolant circulation problem. Did you flush out the system with a chemical cleaner? Might be a good idea. You might have partially clogged passages in the engine causing poor circulation. Any signs of a blown head gasket? White "goop" on the oil dipstick, for example. If this is a high mileage engine you may be looking at a worn timing chain as well. But I'd only go there as an absolute last resort. HTH. -Jim

1 out of 1 people think this is helpful.
20

Car doesn't show typical blown head gasket symptoms ie: oil looks clean, not watery or milky, no smoke in tailpipe, no water at tailpipe, runs strong, not missing, head could be blown between cylinders I guess and not shown signs yet. I have now taken the thermostat out and car seemed to get real hot even faster. I see that these 3100 engines are notorious for blowing intake manifold gaskets...anyway, water seems to get hot (boiling) and just blows right out overflow reservoir, then temp gauge inside the car of course pegs out and temp light comes on, at that point, if I open bleeders, nothing but steam or just hot air...

1 out of 1 people think this is helpful.
58,915

The system could have air in it. It's actually the 3800s that have the intake gasket failures. The 3100s do oftentimes blow head gaskets. If it was blown between cylinders you'd have a misfire condition with both those cylinders due to lack of compression. Use a cooling system pressure tester and pressurize the system to 15 PSI. It should hold for 15 minutes minimum. If not, you've got a leak somewhere. Also, with the system under pressure from the pressure tester start the engine. If the needle on the pressure tester gauge bounces, the head gasket is blown. HTH. -Jim

20

Thanks Jim...I will definately try the pressure tester...

1 out of 1 people think this is helpful.
58,915

You're welcome. Glad to help. Please keep us posted on your findings. -Jim

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