84 bronco running hot/ vapor lock

[Taylormadebronco2]

Hey guys. Newbie here. First post. I’ve got an 84 bronco 2 with 2.8 and C5 automatic. As long as it’s cool outside, say 70 degrees or below, she runs great. When it’s warmer outside temps will climb all the way to 230 degrees on my manual gauge. Around 200, the truck will begin to vapor lock. I have installed new water pump, three flue radiator, electric cooling fan, removed the thermostat completely, and installed electric fuel pump and have flushed the cooling system even though I don’t think it needed it. Still vapor locks at warm outside temps especially if you idle for long at all say like in a line at the bank teller. Have purchased the stuff to install fuel filter with a fuel return line back to tank. Was just wondering if any of you have run into this or have any ideas. Truck never actually runs hot, ie doesn’t boil over but it will vapor lock to the point of not cranking until it cools off considerably.

 

[duffy]

You deleted the thermostat? I'd put it back in there, and use a 190 or 195. You will have the problem you describe without a thermostat.

 

[JerryC]

What do you mean when you say it vapor locks?

A vapor lock won't keep the starter from cranking the engine over. If the starter won't crank, you need a new starter and/or you need to shield the starter from heat sources such as the exhaust.

A good radiator and fan should keep the engine from ever getting to operating temp without a thermostat. The job of a thermostat is bring the engine up to temperature and keep it there. Contrary to what people might think it has nothing to do with cooling the engine. The radiator, fan, and water pump do the cooling and are designed to over cool the engine in every situation. You can get an air bubble in the cooling system and that can make it run it hot as it prevents or slows coolant flow through the system.

If you mean you are getting fuel system vapor lock, the fix is keep the heat away (insulation and shielding) from the fuel system components and get water out that may have been mixed in with the fuel that in turn boils in the lines. Low fuel pressure might be a contributing factor so make sure you have the factory specified fuel pressure. The e-fan may not be moving air over and around the engine the same way as the stock fan and shroud and not cooling the fuel system components.

I hope that helps.

 

[Nelson and Hudson]

so maybe just a can of seafoam (or two) to flush the water out?

Does it matter how full your gas tank is? Does it happen when the tank is full and when the tank is near empty?