I am completing a 302 ford re-build. The bolck is just back from the machine shop. All new pistons. rods, crank, bolts bearings. Cam. In other words everything is new. Aftermarket heads Trick flow Twisted wedge 2.02 in 1.60 ex. New lifters, puchrods, roller tip pedestal mount rockers, Edelbrock performer intake, summit 550 cfm (Holley clone) carb (new). Running old points distrib. New torque converter to match the cam with a 2000 stall. Running thermostat 160, Fairly new 2 months old with heater core bypass. problem is that after 10-15 minutes at idle car is running above 220 farenheight and begins to boil over the radiator, checked the impellers of the water pump and they visually seem ok and the not binding, checked all of the hoses can't seem to figure out why the engine is overheating. Thought it might be an airbubble in the block, attempted to run it and flush it out, but still gets hot. For now running stright water until I get the problem solved then I will drain and fill with coolant. Not sure what else I need to look at. thinking to just removing the thermostat, to elimiante the restriction. Any ideas on how to solve this?
Country: United StatesMake: FordModel: MustangYear: 1968Engine: 302
Running it though to try to burb the air bubble. ran by-pass hoses and disconnected the heater core, Before it was plugged at the water pump. by-pass hoses went from the pump to the intake to allow circulation.
Welcome to Just Answers, The by-pass hose from the water pump to intake needs to be hooked up.the heater core being by-passed should not be a problem. Has the radiator been professionally cleaned and rodded out? Is it a 2,3 or 4 row radiator?The engine you rebuilt,is it the original engine in the car or a newer late model engine?Are you running v-belts or did you convert to a serpentine belt set up?
Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice so we may have to fine tune the answer. Feel free to add any additional info you feel is needed as we go on. Always keep in mind that I am here to help you with any questions.
I would take the thermostat out and put it in a pan of water on the stove, turn the burner on high. You should be able to watch it open at about 160, so a thermometer would be good to have for the test. If the thermostat hasn’t opened by the time it starts to boil, it is bad. I have seen even new thermostats be bad, so don’t assume it is good if it is new.
On the water pump, be sure you have the correct style for your engine. The water pumps for the 5.0 HO engines with the serpentine belt turned the opposite direction of the older type 302 water pumps, it will cause a lot of problems if you get these mixed up. If you have the correct water pump, the only way a water pump can fail is for the bearing to go out, or the shaft to break. Water pumps are basic components, as long as it is the correct application, and it turns it will pump water.
From there you need to evaluate the radiator fan and make sure the radiator has sufficient air flow, otherwise it will overheat. The condition of the radiator is another factor to consider. I would also check the cooling system for combustion gas, it takes a special tool, you can get one at the link HERE. If there is a micro leak in the head gasket, it can cause overheating. If this is the problem many times the ONLY symptom will be unexplained overheating. No matter what else you do it will still overheat if you have this problem, so it is a good thing to check. As far as an air pocket, it wont happen on a ford 302. Many engines like the reverse flow cooling system on the 350 LT1 chevy from the 90's this can happen on, but the 302 is immune to this problem because of the cooling system design. The basic things to look at are Thermostat, combustion gas, airflow, and radiator. The problem will most likely be one of these items. All in all it sounds like a great combination of parts, how did you decide on the carburetor size. If you have any more questions, as always, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.I hope this helps, 100% satisfaction is my goal. Myself personally, and Just Answer are here to serve you. If the answer is not clear, let me know what additional help you need, and I will assist you further. A bonus and positive feedback are always appreciated, good luck and Thanks.
Thank you for your reply but that was not the problem, so I will not be accepting your answer. I contacted Trick Flow the manufacture of the heads and they informed me that I needed to use a special intake manifold gasket between the alum heads and the cast block. A fiber based OEM gasket will occasionaly create overheating conditions as to the design of their twisted wedge head and the relocation of the combustion chamber in relation to the new valve positioning. I purchased their special head gasket and the problem no longer exist. Thank you, in any event.
Glad you were able to resolve your issue,I never heard back from you with info on the questions I asked so I didn't research the issue any further. Good Luck with your mustang