Losing coolant
Question:
I have a 89 GMC pickup truck w/ 305 V-8 engine. For about the last year it has been loosing coolant. No external leaks. I’m thinking it’s either a bad intake manifold gasket or a bad head gasket. It seems to lose the most cooloant when I make more short trips rather than long trips. Is there a simple way to tell if it’s a head gasket or a intake manifold gasket. Or any other suggestions are welcome. The engine has 168,000 miles, but I’ve changed the oil about every 3,000 miles since it was new. The engine runs ok still. Haven’t done a compression check. Only put in about half a quart of oil between changes. Any suggestions would be appreciated. Thanks
Response:
David, Check the dipstick for any whitish deposits. If so, coolant may be leaking into the crankcase. Then have your mechanic do a cooling system pressure test. This will reveal any cooling system leakage. Then do a cylinder leakdown test. Bubbles in the coolant mean a bad head gasket. Note that some external leaks never result coolant under the truck. The leak may occur at a clamp, freeze plug, block heater, etc. only during warm-up or cool down, when the truck is moving. Dean – Hide quoted text — Show quoted text – > I have a 89 GMC pickup truck w/ 305 V-8 engine. For about the last year it > has been loosing coolant. No external leaks. I’m thinking it’s either a bad > intake manifold gasket or a bad head gasket. It seems to lose the most > cooloant when I make more short trips rather than long trips. Is there a > simple way to tell if it’s a head gasket or a intake manifold gasket. Or any > other suggestions are welcome. The engine has 168,000 miles, but I’ve > changed the oil about every 3,000 miles since it was new. The engine runs ok > still. Haven’t done a compression check. Only put in about half a quart of > oil between changes. > Any suggestions would be appreciated. > Thanks
Response:
Ditto on the internal intake leaks BUT most of the time the leaks are external. The intake manifold gasket almost always leak in the corners on this engine. Also with high mileage engines, the head gaskets leak externally. Both leaks evaporate so quickly, they don’t reach the ground. Look for scale build up at the intake corners and near the rear of the left head. RJL
– Hide quoted text — Show quoted text -> I have a 89 GMC pickup truck w/ 305 V-8 engine. For about the last year it > has been loosing coolant. No external leaks. I’m thinking it’s either a bad > intake manifold gasket or a bad head gasket. It seems to lose the most > cooloant when I make more short trips rather than long trips. Is there a > simple way to tell if it’s a head gasket or a intake manifold gasket. Or any > other suggestions are welcome. The engine has 168,000 miles, but I’ve > changed the oil about every 3,000 miles since it was new. The engine runs ok > still. Haven’t done a compression check. Only put in about half a quart of > oil between changes. > Any suggestions would be appreciated. > Thanks
