I have had a 92 F-150 I-6 since Nov.95. I can't keep the coolant reservoir full and sometimes I'll find the coolant about 2 inches low when I look into the filler neck. This baby has a slow leak in the engine and I have looked for hose and radiator leaks and everything is tight. No antifreeze on my driveway either.No coolant from the heater core. What should I look for when making the case for a new head gasket? Also I have always had terrible gas mileage, 12 to 13 miles per gal. I drive like grandpa.I wonder if a bad head gasket could be causing coolant to be retarding my combustion and MPG. It isn't a critical problem, the system only takes a quart every 2 months. My truck always has run well, good pick-up, power, etc. Is it worth fixing her?

 

I might be having the same problem, a friend of mine told me that Snap-on makes a tester kit! I don't know the name or part #, but if you call them they more than likely could tell you what exactly it is, I know it does not cost all that much, I think arround $10 my friend said (not completely sure). It would be something I would suggest looking in to!


Bru

 

I have a 91 Cougar 3.8 V6 that was thirsty also. Then it started to run a just little hot. Then boom steam from the tail pipe. I had a very very small failure of the right head gasket. You can use a tester to pressurize your cooling system and check it out. I was also told in Tech School you can put compressed air in thru the spark plug hole then check for bubbles at the radiator. Also the spark plug of the affected cylinder will be very clean.

Gasman
Propane:Smells Funny Burns Great

 

I like the compressor in the spark plug hole. It sounds easy enuf. I have a compressor and a compression testor. If I could set up my air into the compression tester hose with a tee I might be able to see what cylinder can hold some air the longest or shortest.My wife had a 89 cougar V-6 3.8L, hers also blew a head gasket. POOF one day it just opened up. Steam out of the exhaust. Luckily, it was covered by warranty.THX

 

You might want to try the following... when the engine is cold, take the cap off the radiator and make sure it's full. Start the motor, and with the cap still off, rev it up slightly. If water surges out the radiator as you rev the motor, you may have a blown head gasket.

 

Marragtop, sounds easy,I will rev her up tommorrow, check for the surge and report back.

 

Well, its alot later than I thought... Started up the truck cold, pulled the radiator cap off and rev'ed the engine. What I observed was a nice little whirlpool of coolant in my filler neck, no bubbles,
no, no splashing.

 

I'm not too sure that test is going to rule out a minorly cracked head gasket compared to a fully blown one. If the crack doesn't present itself until the engine and gasket are fully warmed up, you may not be able to see an effect by revving it up & looking in the radiator.

But I seem to have the same problem, too. Mine is just a tad thirsty over long periods of time - moreso than most other vehicles I've owned.

Best,

 

This seems like a small leak. It could be hard to determine some of these test results. I think it best to compare spark plugs. Remember 3.8's are notorious for blown head gaskets. If you do this job yourself remember to use new head bolts & dowls.

 

IME this is a common problem on 302s and 351s, not sure on the 4.9. My bet is that it's on the back of the motor, it won't always leak while parked and evaporates pretty quick.

I'd get a pressure tester for the cooling system. I just used one for the first time and they're the coolest thing since sliced bread! Stant makes a nice unit, you can even search on Ebay for something like "stant pressure" etc, I bet you'll find several. Seriously, get the right tool for the job, it takes all the guesswork out of it and it's really easy to hear leaks if the motor's not running.

 

I have this problem too...its annoying ain't it. My 302 loses coolant, but i've never found from where. Oh well, when i build a new motor hopefully it won't than.

Ryan