CBRF3
Full Access Member
I've seen that. Certain engines can have localized hot spots that would cause the flash boiling scenario. I don't think our IDI's are one of them though.
In my experience, most engines that appear to be flash boiling actually have cracked heads/blocks or a failing head gasket. All of those will all put air in a cooling system, and since air doesn't transmit heat as well as water, the thermostat closes, vapor locking the cooling system, causing an overheat. Or it causes the radiator cap to open, lowering system pressure, causing more boiling.
You can plug it, I don't really care, but drill a small hole in the plug to vent the air trapped behind it when you do so.
when you crank up the fuel on our motors and go into mountains under hard load aka low air density our EGT's spike fast causing coolant to boil ( because alot of coolant in the head is used to cool the exhaust ports ) very often risking the thermal runaway. I have had this happen to 10 motors of mine and these were studded and built properly motors that pretty much no cost was spared AKA done right and built to the hilt and overkill. So saying a faulty head gasket was issue when it was built overkill running a stock 7.3 turbo injection pump turned up and a HX40 turbo with intercooler power stroke rods the 10thousandths raised wrist pin pistons and no more than 18psi boost and these were decompressed motors mind you so 18psi was not the issue and these motors could hold around 25psi+ literally all day long but I dialed them back and I didn't have the fuel to push above around 18psi.
I believe i need to help explain this I had a fleet of farm trucks and logging trucks built around these 6.9 / 7.3 IDI's for simplicity and reliability over the first gen powerstroke and Dmax's of the day I wanted to keep it analog with as little electronics as a issue considering the ones of that time that were electronic were a nightmare to keep going the cummins 12 valve was a option but the parts availability at that time was slim yet our old IDI's we could go into pretty much any autoparts store and get anything we needed anywhere in the country and not have to find a rare cummins dealer of that time we could be in the back woods find a napa or oriely's / IKT and such and get our parts literally same day or over nighted not so much with the cummins 12 valve at that time.
Last edited: