1989 F250 4x4 reg cab 7.3l Truck has 149k , overheated yesterday on the way home from work, I'd driven appx 25 miles @ 55mph. I saw bubbles in the overflow, didn't see any evidence of coolant in the crankcase, don't see any white smoke out the tailpipe. Pulled to the side of the road, it appeared to be a hole in the radiator, right about the middle. I added a gallon of distilled, and a gallon of coolant and it was still leaking but I couldn't see where because of the steam/smoke from under the hood, but not overheating. By the time i got home, it didn't seem to be leaking at all. Drained radiator because i thought i would be replacing, but because i couldnt get the new radiator til 2:30, I refilled with water from the hose and started truck, looking for leaks. I didn't see any leaks, no wet spot on the front of the radiator where i thought i saw it last night. drove the truck around, let it run/idle for 3-4 hours and it was fine. i logged maybe 20 around town miles, avg speed 35-45mph. Bubbles in the overflow tank were consistant, presumably when the stat opened, bubbles stopped when closed or so i suppose. Infared thermometer on the temp sender maintained a consistant 195 temp +or- 5 degrees.
Based on what i've read here, I gather I have a blown head gasket ? Looking for confirmation or any other suggestion. Just for grins i did buy a new radiator cap, put that on and had the same result, bubbles in the overflow.

Sorry for the long winded post and thank you ahead of time for any suggestions/conformation/comment

 

Pull the radiator cap off and let it idle. You should see a constant stream of bubbles coming out if you have a blown head gasket.

 

remove the heads and inspect gaskets for damage. and heads for a cracks.

 

my bet is the bubbles you saw were simply the engine "burping" trapped air out of the block from running it low on coolant.
i would fill it and keep an eye on it for a few days. if the bubbles slow down then stop, i would call it trapped air.

 

I would agree that since you had radiator damage that one would lean toward trapped air. Was the overflow tube purged of air prior to observing the bubbles in the overflow? When I replaced my coolant my reserve dropped considerably for two days of local use. So trapped air was being sent to the overflow and coolant was being drawn into the radiator from the overflow.

 

I pulled the radiator cap and watched for bubbles in the radiator, saw none. When the stat opened the coolant level dropped to where i could see the core, when it closed coolant was purged through the top of the radiator.

 

In that situation, if you could add fluid when the radiator is down, then replace the cap, you would be ahead of the air game. I use to have a helper raise the rpms and the fluid would drop, then I would fill and cap, then let the closed system cap and reservoir do its job.

 

I'm going to do just that, let you know how I make out after a few days.

 

sounds like you just had trapped air. fill it up and keep an eye on it.
mine likes to sit about 1 inch below the cap.
i also do not have an overflow tank, that started leaking and went in the garbage at least 15 years ago.

 

Correct! You now have an open system and should have the open system cap. A system with an overflow is considered a closed system and should have the fluid up to the cap when cold. The closed system needs a closed system cap to operate properly.

 

i still run the 13 lb cap. from the day i got my truck it would always run around 1 inch low, no matter if the overflow was full empty, or not on it. same with the old radiator, or the new radiator.
fill it all the way up, and the next day it was 1 inch low.
the 89 worked properly, the 90 and 91 are the same as the 88, no matter what you do they run 1 inch low.

 

3.5 years later i had time to take it apart... I was never able to purge the coolant system of the bubbles
I know this is old but here's the result
I'm bringing the heads to a machine shop today to have them checked for cracks.
I bought the gasket set and new bolts. gasket set is good but bolts bag had a hole in it so some surface rust on bolts.
Clean bolts up and use the or buy another set ?
Sludge around bottom of injectors...new o-rings needed ?
While I'm into the engine this far what else should I look at or replace ?
Before the head gasket truck was running great. Of course its sat in my back yard 3.5 years now so all suggestions welcome.

 

Thanx for the follow up .. Reps given for that move
what I have learned is any time there is an over heat issue there is generally damage to the head gaskets... it may not show up immediately but will eventually manifest itself.

Coolant system Pressure testing tools are right handy.. you can pressurize the system and check for leak down and you can also detect an increase in pressure from combustion leaks.
there are also combustion leak detectors that work very well.

of course these are not items that the general backyard mechanic has. BUT they are not expensive.