Robert Lewis

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


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.
Robert Lewis

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.

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

Robert Lewis

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

1 out of 1 people think this is helpful.

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

Your Answer

Add photo

Related Questions


Looking for a Used Century in your area?

CarGurus has 1,269 nationwide Century listings starting at $3,295.


Search Buick Century Questions

Buick Century Experts

#1 John Saffrahn
John Saffrahn
Reputation 840
#2 Tom Demyan
Tom Demyan
Reputation 640
#3 LtColumbo
Reputation 300
View All

Related Models For Sale

Used Buick LeSabre"
19 Great Deals out of 2,612 listings starting at $1,950
Used Buick Regal"
190 Great Deals out of 10,672 listings starting at $2,195
Used Chevrolet Impala"
934 Great Deals out of 35,696 listings starting at $1,500
Used Buick Park Avenue"
612 listings starting at $5,995
Used Toyota Camry"
1,590 Great Deals out of 98,367 listings starting at $895
Used Ford Taurus"
363 Great Deals out of 23,112 listings starting at $1,400
Used Honda Accord"
1,258 Great Deals out of 78,695 listings starting at $1,400
Used Chevrolet Malibu"
1,146 Great Deals out of 72,965 listings starting at $695
Used Nissan Altima"
1,347 Great Deals out of 87,445 listings starting at $1,095
Used Pontiac Grand Prix"
30 Great Deals out of 4,357 listings starting at $1,995
Used Lincoln Town Car"
51 Great Deals out of 2,364 listings starting at $1,542
Used Mercury Grand Marquis"
46 Great Deals out of 2,557 listings starting at $1,300