My 03 Sonoma 4.6 will roast you out of the cab with the heat on high. That is as long as the vehicle is moving. At idle it blows cold. Rev it up and it turns hot again. I just found out that the gallon of duracool i put in my radiator and overflow tank is gone. There is no visible coolant leaks inside the cab and out. There is no coolant smell. Exhaust doesnt smell of coolant nor steam from the exhaust past your normal warm up. Someone said it was an intake leak. Is this a common problem?
Heat, no heat
- Thread starter rodgtard
- Start date
IMO -
Common or not if the coolant is leaking into the block
you need to get it repaired ASAP , like - park it until you can - ASAP .
Pull your dipstick , you should see signs of it there - discolored oil and
a gallon past the full mark .
And - if the oil is OK , double check that the heater core isn't leaking.
Also - By chance , did you notice what the temp gauge was doing ?
Common or not if the coolant is leaking into the block
you need to get it repaired ASAP , like - park it until you can - ASAP .
Pull your dipstick , you should see signs of it there - discolored oil and
a gallon past the full mark .
And - if the oil is OK , double check that the heater core isn't leaking.
Also - By chance , did you notice what the temp gauge was doing ?
No milkshake in the oil. And i cannot find a drop under the hood. The interior is dry. Is it possibly being leaked thru a head but not enough to contaminate the oil? And the heat stays at 190, even when it starts blowing cool. Like the heater hose is at a higher elevation than the temp sensor
Cant find a leak under the hood . With it hot or cold. although something made a strange noise on start up. That slowly went away
The 4.3L engine have had a bad reputation for having a leaking intake manifold gasket. On mine it was leaking from the back of the intake manifold and running down the bell housing. It would never leak enough to cause the truck to drip on the ground, but enough to cause no heat and then a gurgling sound in the htr core.
The cause of this is a plastic intake manifold gasket plate that deteriorates over time with the heat from the engine.
The cause of this is a plastic intake manifold gasket plate that deteriorates over time with the heat from the engine.
radiator cap
had the same problem in my 2001 jimmy.thought it was an air lock.was hearing gurgling under the hood as well.took my radiator cap off to fill with coolant and accidentally dropped it somewhere in the fender.couldnt find it so whent and bought a new cap.that seems to be what the problem was.put coolant in and new rad cap on and everything has been fine ever since.pretty sure the cap was faulty.good luck
had the same problem in my 2001 jimmy.thought it was an air lock.was hearing gurgling under the hood as well.took my radiator cap off to fill with coolant and accidentally dropped it somewhere in the fender.couldnt find it so whent and bought a new cap.that seems to be what the problem was.put coolant in and new rad cap on and everything has been fine ever since.pretty sure the cap was faulty.good luck
Mine also goes through coolant. I fill the overflow reservoir twice a year. No leak or drip is evident. But by chance, I was crawling around underneath it one day, and noticed that the oil pan was covered with coolant. Must have been 100 drops ready to fall. With the exception of fuel and brake fluid, every other fluid in the engine compartment was leaking. My point is, you won't always see a drip.
Molson02536
New member
Start with the simple and replace your thermostat. The thermostat could be stuck in the the open position or may not be closed 100% and your coolant is constantly cycling throughout your radiator all the time which can also cause your coolant to run low from evaporation through your radiator cap.
Be on the safe side and check your engine oil and transmission oil for contamination of coolant. What ever you do, never add radiator leak in to your system. If you want to add anything to stop a slow leak, just add 2 table spoon of kitchen black pepper in to your system, it cleans up with a simple flush and will not hurt your cooling system.
Good luck and keep us posted. At worst, it's your water pump getting weak.
Molson02536
A GM service bulletin said to check for leaks into the engine or trans fluid. Neither had antifreeze in them. It then said with truck cold, to fill reservoir to the hot mark. I did and it did not drop for two weeks. Then i went to start it one morning and there was a clacking noise like a lifter and it missed out . I shut it off and checked antifreeze. It was fine. Checked the oil and it was barely touching the stick. Added oil. It took 2 1/2 quarts to fill. I started it and the clack went away and the miss. Until it set's over night. Then the clack returns and the miss and both go away within 2 minutes. I changed the oil and filter today along with the spark plugs. Previous owner had installed 4 electrode bosh plugs. i replaced with ac. When i started the truck the clack was there for just a moment and went away. After it warmed up i went and drove it. Now the oil pressure moves like an rpm gauge. the more gas you give it the higher the oil pressure goes. Im ready to burn this thing as i believe it to be a lemon. ANY THOUGHTS AS TO WHAT'S GOING ON?
update, alternator bearings were about to seize. Actually made the engine slow down at idle and hard to turn over when starting. Still have clacking and slight miss on start up. Both go away within two minutes. Oil pressure guage reads fine after alt swap. Strangest damn thing ive seen in awhile
After installing alt i took truck out and ran it hard trying to get problem to expose itself. ran great. no leaks, no smoke.
After installing alt i took truck out and ran it hard trying to get problem to expose itself. ran great. no leaks, no smoke.
The first two times i started it cold it clacked for just a second and hasnt made a peep since. No miss, no clack, oil gauge reads normal, and hasnt used oil or coolant. I still feel like im waiting for a bomb to go off.
Try Stop leak
Sounds like you are losing a lot of fluid, But if you want to try a quick fix. Add one or two helpings of stop leak and let it run to try and seal the leak. It's cheaper than getting to a whole head gasket job.
Sounds like you are losing a lot of fluid, But if you want to try a quick fix. Add one or two helpings of stop leak and let it run to try and seal the leak. It's cheaper than getting to a whole head gasket job.