At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.
1985 chevy runs rough when hot outside and runs hot,took thermostat out and has new radiator , new timing chain new oil pump , can't figure out why it's running rough , it's a 350 engine ran great for about 200 miles also had heater hose leaking and replaced it also
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
The unlikely one is the head gasket. Do you have water in your oil, do you have mayonnaise on the oil filler cap?
If the area under the thermostat is dry, the most likely issue is water pump failure. Empty the system, backflush the radiator and heater hoses with a garden hose. Replace the water pump and thermostat. Fill the system with coolant, turn the engine on, heater to maximum temperature and keep topping up the radiator until the coolant is hot and the thermostat opens. Squeezing the top and bottom radiator hoses also helps to get air out. Turn off the engine and top up the radiator one last time. Put the cap on and then top up the expansion reservoir.
One thing often overlooked with overheating issues, make sure the radiator fan is working properly.
The most common cause other than what you have replaced is a leaking head gasket.
Could also be a coolant flow problem inside the engine, or air flow thru the radiator.
Check the dipstick and underside of oil filler cap for signs of oil/coolant mixture(chocolate milk).If so, bad news, you have signs of a blown head gasket. Also make sure your radiator isn't plugged. You can check this by running your hand along the surface of the radiator when warm, with the engine off of course. You should not feel any cold spots. I'm assuming your cooling fan(s) are working.
A rough check of the water pump is to pinch off the upper radiator hose with your hand while the engine is running, squeeze it as tight as you can, then release. If pump is working you should feel a surge of coolant as you release the hose. So the fans do come on by themselves? If the coolant got hot enough when stopped, they should have come on. You may want to have the cooling system pressure checked to see if it holds pressure.
It sounds like you have the wrong thermostat installed in your car. You need to get the water to the block quicker then what it's doing now. Always check oil every time before driving. This is a must on older cars. Some Mechanics differ, but in the long run it will pay off. An oil spot beneith the car might be bolts that need to be tighten on the oil pan, of you may have a bad oil sending unit. Also ehck power steering pump fluid level and make sure there is not a leak there.
Flushing the radiator, replacing the radiator cap, adding new coolant, replacing the sensors and a new thermostat solved the problem. Probably didn't need to do all of these things - but since we just purchased the truck, and given the fact that is probably hadn't been done in a while, we chose to do all of these things (which really didn't cost a whole lot), it's running like a charm now.
Was the thermostat put in backwards? I know this is a silly question, but I've seen it happen. The water pump will fight it if it is. Another thing are the coolant passages, are they flushed out? Also, if that fan clutch is the original one, I would go ahead and replace that as insurance against the water pump breaking.
×