• Hello there guest and Welcome to The #1 Classic Mustang forum!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Tampered at a car show?

RagTop

RagTop

Old Grumpy
I was at a mixed breeds car show yesterday with my 69 vert. It was a typical 95* day here in lovely Sacramento and I ran out of tolerance for the heat around 2pm and headed home. It was a 21 mile drive with mixed country roads, surface boulevards and a little freeway. When I pulled into the garage I noticed the distinct smell of a radiator. The car had not been overheating on the drive home. I opened the hood and checked the top tank hose. No pressure in the system. There was also some coolant dripping on the garage floor from the overflow tube. I checked the oil and it was clean. No milkshake. I didn't notice if the cap was tight or not, but I did wonder if the cap had failed. I checked the coolant level and it was about 1" below the neck of the radiator and covering the tubes. I drove the car today and purposely went to a drive thru fast food place because the Mustang really hates that. No radiator smell. When I returned home I checked the top hose and it was tight as a drum. All pressured up. The only thing I can think of is that someone might have rotated the cap just enough to catch the second set of detents while it was on display. Does anyone else have any suggestions about what could have caused this peculiar problem other than fan interference? I've never had my car screwed with at a show before, but I've heard some incredible stories from friends, like a guy caught removing the red caps from an Autolite battery. Said he was just checking the acid levels but he did have three of the caps in his pocket already.
 
Put the cap partway on and take it for a drive. If it does the same thing, mystery solved.

Never had anyone mess with the car, but I do worry about someone scarfing my removable steering wheel. I either lock the car or put the wheel in the trunk.
 
"Put the cap partway on and take it for a drive. If it does the same thing, mystery solved."

I'm not quite sure what mystery that would solve. Our radiator caps have two detent positions. The first is like the safety latch on our hoods. It prevents the cap from leaving the car if some gas station attendant (remember those?) didn't fully tighten the cap. It compresses the spring on the cap sufficiently to prevent it from passing the first set of tabs on the radiator neck but it does not pressurize the system. The second detent position compresses the spring on the cap to press the rubber gasket against the base of the neck and, if the spring and the rubber gasket are in spec, create a pressure seal to allow the cooling system to operate at normal pressure. If the pressure becomes too great, the spring will permit some of it to pass into the neck and the overflow tube. If I set the cap on the first detent and drove the car, I can assure you that it would puke coolant out of the overflow and smell like radiator. I was asking if anyone had another possible scenario that would result in the radiator puking on the garage floor. BTW, let's save the possibility of a weak spring or a worn or cracked gasket on the cap. It wouldn't have behaved normally yesterday if that were a problem. The coolant in the system is clean and normal. No obvious scale floating around in there and no scale on the top of the core. Somebody suggested a stuck thermostat, but I don't think that would cause the system to overflow.
 
Without an overflow tank, the radiator should not be filled to the top. Leaving the fluid about 1" below the neck but covering the core gives the coolant room to expand without overflowing. If it was filled a bit high and not driven far enough for it to really warm up, parked and then driven again on a longer ride, it could show some overflow. I normally fill them up and drive them and if it overflows, I check it when cool again and as long as it is above the core, I leave it.
 
I learned the hard way that the radiator needs about 1" of room at the top of the tank to allow for expansion. I don't have an overflow tank to keep the car looking as stock as possible under the hood (if you ignore the tri-Ys and the 4V). I do have an Odwalla bottle that I tape to the washer reservoir for days at the drag strip, however.:) They hate antifreeze overflow on the track. It's passed inspection every time.
 
OK. The folks in Rio Linda are off the hook. I had a second experience with the flaccid hose syndrome (no wise a$$ comments Mike) and the car was puking antifreeze out the overflow. I have a spare radiator cap that is a little higher pressure than stock (16# vs 13#) so I swapped caps and just drove the car about 20 miles in moderate ambient temperature. Same thing. Flaccid upper radiator hose, temp gauge was about 1/4 gauge higher than usual and my oil pressure is dropping off from it's normal level. I thought that the only way pressure can be released by the cooling system is if there is a breach somewhere in the system. If it's not the radiator cap seal, then it would have to be a hose, a gasket or a freeze plug that would be allowing the pressure, and the coolant, to escape. Actually, the coolant level is not low and there is no sign of steam or other leakage anywhere that I've seen. My water pump does not show any weeping. Someone suggested that it could be a stuck thermostat. If the thermostat were stuck either open or partially open, wouldn't that still permit the cooling system to build normal pressure? I obviously don't get this. Can anyone suggest a possible cause for my cooling system problem?
 
I would think that if there is a breach in the head gasket between a cylinder and water jacket that the cylinder could be pumping air into the cooling system and perhaps create some air pockets in the system causing the rise in temperature. When the engine is cool, start it up with the radiator cap off and watch for air bubbles in the coolant... that could be a sign of the above.
 
If the head gasket were breached between a cylinder and a water jacket, wouldn't the cylinder be drawing coolant into the cylinder on the down stroke as well as pumping air into the cooling system on the upstroke? I would think that I would have some steam showing at the exhaust pipe as well as some traces of water in the oil pan since water/glycol is a lot less viscous than motor oil and would probably pass the rings. Neither of these conditions exist. Besides, even if it didn't produce either of the two conditions above, I would be seeing a loss of coolant as the stuff was burned off in the combustion process and I would probably be experiencing a major miss because the plug in that cylinder would be fouled.

Does anyone have a comment on the stuck thermostat theory? I think I probably need to find a radiator shop that can perform a pressure test on my cooling system.
 
You must log in or register to reply here.
Back
Top