AbelTwo
Newbie
I have a 1994 GMC Sierra K1500 with the 4.3 l V6, TBI, and a 5-speed manual transmission. The truck has 180k miles, the last 15k of which are mine and I drive it gently. I bought the truck two years ago from a guy that did not offer that he had a shop put in a head gasket, water pump, and radiator before listing it for sale - until I noted fresh RTV on the water pump. He then produced a receipt for the job from a shop in northern Idaho. I presume that means that before he had the head gasket replaced, the truck overheated at some point. My first 11,000 miles in the truck included righting many of the wrongs dealt to the truck by neglect by its former owner and included a couple of ~1500 mile trips to Montana and Wyoming from eastern Washington. Last Fall I drove it again to eastern Montana, where it cracked a cylinder head, overheated, and spent the winter in a local shop over there getting a new-to-me cylinder head . I have driven it 3000 miles since March, when I got it back from Montana.
This morning I discovered that it was low on coolant, somewhere between a cup and pint low - on the eve of another trip to eastern Montana. I am starting to suspect that this rig has a long-standing leak that slowly reduces coolant levels until the engine overheats and that has so far avoided detection. I fear getting stranded again in eastern Montana.
I'd like some help determining where the coolant could be going. Is this amount of loss "normal" for these rigs? If so, that will take some adjustment in vigilance by me; I have been lulled by a 1995 Honda Civic with 400k miles that never needs topping up of oil, or coolant - ever. It really seems unlikely that this coolant loss would be considered normal, but this is my first truck and I am surprised that it requires a cup or so of oil per 1500 miles.
The truck doesn't leave puddles of coolant and the engine bay seems dry. I have felt around the rear of the intake and looked for leaks back there, but nothing is apparent - and the engine has a new intake gasket from the shop in Montana last winter. The heater does not leave puddles on the floormats. In short, I can't see any external leaks and that makes me suspect it is running coolant through the cylinders and out the tailpipe.
About 30 seconds after startup on a cold morning, the truck does produce some vapor from the tailpipe. The amount of that vapor increases considerably with RPMs until the temp gauge in the dash shows that the engine has reached about 160 degrees (on its way to 195 degrees) and then the vapor wholly disappears. The engine runs smoothly and pulls without complaint - to the limit of the 4.3, which I find a little too gutless for a full-size truck. There is no trace of coolant in the oil, nor is there oil in the radiator.
I am headed out to the shop to pull the spark plugs and to look for evidence of coolant fouling. Can anyone point me toward other ways to figure out where the coolant is going? Or maybe suggest chronic weak points that deserve special scrutiny? Thanks!
This morning I discovered that it was low on coolant, somewhere between a cup and pint low - on the eve of another trip to eastern Montana. I am starting to suspect that this rig has a long-standing leak that slowly reduces coolant levels until the engine overheats and that has so far avoided detection. I fear getting stranded again in eastern Montana.
I'd like some help determining where the coolant could be going. Is this amount of loss "normal" for these rigs? If so, that will take some adjustment in vigilance by me; I have been lulled by a 1995 Honda Civic with 400k miles that never needs topping up of oil, or coolant - ever. It really seems unlikely that this coolant loss would be considered normal, but this is my first truck and I am surprised that it requires a cup or so of oil per 1500 miles.
The truck doesn't leave puddles of coolant and the engine bay seems dry. I have felt around the rear of the intake and looked for leaks back there, but nothing is apparent - and the engine has a new intake gasket from the shop in Montana last winter. The heater does not leave puddles on the floormats. In short, I can't see any external leaks and that makes me suspect it is running coolant through the cylinders and out the tailpipe.
About 30 seconds after startup on a cold morning, the truck does produce some vapor from the tailpipe. The amount of that vapor increases considerably with RPMs until the temp gauge in the dash shows that the engine has reached about 160 degrees (on its way to 195 degrees) and then the vapor wholly disappears. The engine runs smoothly and pulls without complaint - to the limit of the 4.3, which I find a little too gutless for a full-size truck. There is no trace of coolant in the oil, nor is there oil in the radiator.
I am headed out to the shop to pull the spark plugs and to look for evidence of coolant fouling. Can anyone point me toward other ways to figure out where the coolant is going? Or maybe suggest chronic weak points that deserve special scrutiny? Thanks!