Engine gurus, thoughts please

[Golfball]

Back in Oct of last year I had an issue with the tired 302 in my 75 when we were down at Cruisin the Coast. The engine would run at 170 degrees until I shut it off, then would jump to 190+ and start spitting coolant out the overflow. It did leave us stranded in traffic a couple of times where it would just shut down and refuse to start up for 20 minutes or so. I pulled it out of the garage for the first time yesterday and again, it ran at 170 even idling for 15-20 minutes in the driveway. It never overheated and only puked when I shut it off. It does seem to be loosing some coolant besides what its puking.

I am suspecting a head gasket issue but wanted to get some opinions here before I pull the heads or just grab a 351W.

Thoughts??

 

[Blue Bastard]

How's the radiator cap? What is your cap rated for as for pressure? Seems odd that it is after you shut it off. I would think the bad gaskets should show up while the engine is running?
FYI..... I'm not a engine guru.

 

[Rustytruck]

When my 1974 Bronco did that it was a head gasket failure. Upon removing the head and inspecting the gasket the steel firering in the head gasket had rusted through allowing compression into the water jacket port. Motor ran fine, no coolant out the exhaust or into the oil. Just when you turned the motor off it acted like the engine was overheating popping the radiator cap and bubbling out the overflow bottle. Ford didn't use stainless steel in their head gasket composition back then. On mine it was obvious when you looked at the rust tracks under the gasket.

Just be very careful with installing the intake manifold. there have been allot of failures of the intake gaskets supplied these days.

http://classicbroncos.com/forums/showthread.php?t=135536

 

[jckkys]

Before you pull the heads, you should know that all engines get higher temperature readings, when they are shut down. Without the water pump to circulate the coolant, heat in the heads continues to transfer into the coolant until the temperature is equalized. Any vehicle with a temperature gauge will show a much higher reading within seconds after the engine is shut off. Are you over filling the radiator? The owners manual recommends filling no more than 2 1/2" below the opening. If filled to the top there is no room for expansion and some coolant will be forced out at the cap. My thermostat is 192 degrees so if you your going to 190, that should be no problem. In fact Ford specs call for 190 degree thermostats on all EBs.

 

[Golfball]

I am running an older Howe radiator that was a little over half full, so not over full for sure. If I fill it just below the top, it pukes pretty quick.

My big question is why did it keep dying on me in traffic. It took 15-20 minutes before it would crank and run again. When it stalled, it would almost start up and give me hope, then die again. Once it sat for a while, it would fire up and run fine.

I think it would be just as easy to drop in a 351W as it would be to pull the heads ;D

 

[Jdgephar]

I had a similar issue with my '94. When I shut it off, it would start to puke coolant. What fixed it for me was a new radiator cap. The old one had wore out and wasn't holding pressure on the system anymore. Without the pressure, volume went up and overflowed the tank. Combined Gas Law...Pressure x Volume = constant x Temperature. When the temperature goes up when you shut it off, the cap has to hold the pressure, else the volume goes up.

 

[Blue Bastard]

So it won't even crank over? Like locked up? That's not good.

 

[bigdaddyof4]

I have a newly rebuilt 302 in mine and it did the same so I just didn't top it off. It doesn't puke any coolant now nor does it over heat. But just in case your significant other reads this thread, JUST PUT A 351 IN IT AND ALL WILL BE FINE!! Allow her to read the caps only

 

[jim3326]

If your radiator was only half full, the 170 reading is air temperature, when you shut it off the water starts to boil up and gives the water reading. You said when you fill it up, it starts to puke pretty quick, as in a minute or after 5-10 minutes? If a minute then deffinatley a head gasket, 5-10 would be after the thermostat opened and would indicate a bad cap, it should hold pressure better than that. I would consider putting an overflow bottle on if I were you. I made a quick and dirty one from a gear oil bottle. Get a smaller tube that fits inside the overflow tube, cut the other end at an angle, clip the bottle cap so the tube is a snug fit and run the tube almost to the bottom of the bottle, poke a small hole in the cap to relieve pressure, secure and have a beer;D

Jim W.

 

[OkieAggie]

Doesn't sound like a head gasket or the like. Blue Bastard spotted it with the cap, jckkys on temps rising after shutting it down, and jim3226 that its not reading the correct temp. of the water.

A half full radiator is not sufficient to cool properly. You have to have the full circulated amount of liquid to keep it cool. Think of it as boiling water on your cook top. Half a pot of water will boil faster than a full one. Same thing on your half full radiator. It's getting hot quicker. The more liquid going through the radiator, better cooling properties than less liquid.

If it were me, I'd run down to my favorite parts place that sells quality parts and grab a new 15-20 lb radiator cap, likely the big part of the prob, a new thermostat and gasket, (Gates or BWD brand is tough to beat) new temp sending unit (if yours is boiling and puking, you're not at 170-190° Water boils at 212°, water/antifreeze mix about 230°) and some good ol green antifreeze. Fill it to just below the filler neck at running operating temp and throw the cap on! Grab an overflow bottle if you want. When they first came out, they were as handy as a shirt pocket and kept the garage floor dry if you had a weak cap! ;D. Can't go wrong there! Then go enjoy a nice cruise in it!

As for it dying and not wanting to start for 15-20 mins, I'd put my best guess that with it getting hot under your hood, you've got a weak ignition module that needs to cool down after the temps rise from the engine getting hot. I'm guessing you have a Duraspark if it's a stockish 75? Or a weak coil or one that the oil is getting cooked that's mounted on a hotter than normal engine.

Just my 2¢. In any case I hope it's nothing major!