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  1. #1

    Default Blown head gasket/cracked head symptoms?

    In another thread we have scratched our collective heads and come up empty. So let me try it this way. Can a blown head gasket or cracked head only leak some of the time?

    I have driven 1200 miles with no problem. I can accelerate heavy with no problem. I can't make it happen like you think it would. But at cruising speeds my 1995 V6 gets air in the cooling system, at the top of the motor. No water circulates through the heater core and the temp gauge reads the air temp, which is hotter than the water actually is. The radiator will overflow into the overflow bottle. After 5 - 10 minutes the air bubble goes away and everything returns to normal and I can not make it do it again, like hard acceleration would if the head gasket were blown (right?)

    The first time this happened was the first time the outside temp hit 16 degrees. I did not drive it the previous two days. I had driven in 20 degree weather before. I was cruising at 35-40 miles an hour on my way to work. I had been driving about 15 minutes when it happened. After about 10-15 minutes everything returned to normal and I was able to drive back home.

    After replacing the radiator and thermostat I drove the car 770 miles to Florida. 400 miles into the return trip, after stopping about 25 minutes, it happened again as I pulled out of a rest area. It was 50 degrees and I had been driving continuously for about 300 miles before I stopped for gas. I made another 20 minutes stop maybe an hour later and after the 20 minute stop about an hour later the problem happened again.

    Repair History:
    In July the water pump developed a leak and I replaced that and the thermostat. In August the radiator cooling fan died and I replaced that. Nothing happened until that 16 degree morning in December. I replaced the radiator and the upper and lower hoses and the serpentine belt. I still got the air bubble problem. The local Ford dealer told me some mechanics in town prefer Ford thermostats over aftermarket parts so I tried that but I still get the problem.

    I am getting air in the upper part of the cooling system, causing nothing to flow through the heater core - the heater blows cold - and the radiator still overflows. The problem goes away in about 10 minutes and I never know when it will happen again. Before this happened the heater always blew good and hot. The heater core can't be blocked, because in the summertime, the A/C cuts off flow to the heater core and this doesn't cause the radiator to over-flow.

    I know there's air in the system because I open that air bleed thing on the intake and air escapes, not water. When everything is operating normally, water escapes from the valve when I open it. The Ford dealer says he doubts that bleed valve could be bad because he has never sold any replacements. But the air isn't there when I first start the motor - the heater blows warm. After a few minutes - if it is going to happen - the heater starts to blow cold and the radiator will over-flow.

    If I can get anybody to buy this car what motors should I avoid (like the '94-'96 V6s)?

    Tracy
    Tracy M&M #245
    Mac OS X/ Earthlink DSL
    2004 GT 5-speed
    1956 F-100 Panel w/429 (3.50 9")
    1966 F-100 SWB w/351C (3.25 9" - 3.70 posi for Saturday nights)
    Music City F-100's,
    1965 Holman Moody B/P "What if?"(2.78 1st & 3.70 TracLok 9")
    Music City Mustang Club
    1969 Schwinn StingRay
    Don't focus on the destination....make the JOURNEY the adventure
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  2. #2
    Join Date
    Nov 1999
    Location
    Parkersburg WV M&M #277
    Posts
    397

    Default

    Pressure test the cooling system. This will tell you if you have a leak in the system. Pressurize system 3 lbs. above rated cap pressure. Look for signs of coolant leaks and watch the pressure gauge. If it drops, there's definately a leak somewhere. While the pressure tester is still on the radiator, start the car and watch the gauge. If the gauge goes up this indicates a blown head gasket, allowing compression to enter the cooling system.

    As for the a/c, it does not cut off flow to the heater core. This only closes a blend door that blocks air from flowing across the heater core.
    Andy

    M&M # 277
    64' Falcon Futura
    95' Mustang GT

  3. #3

    Default

    The big question is Can a bad head gasket be good some of the time? While testing the car I have done acceleration tests that do not cause the problem. The pressure buildup seems to occur while cruising, not accelerating.

    As for leaks, I don't really see a loss of coolant, either. The level in the overflow bottle does not drop as it would to compensate for a leak. It would do that, right?

    The weather and my time to work on the car aren't going to cooperate this week. It looks like next Monday, 2/7, will be my next opportunity, if the temp under my shade tree isn't too cold.

    So if/when I replace this car, what are the engines to stay away from?

    Some A/C systems shut off the water flow to the heater core. My 1978 F-150 has such a valve.

    Tracy
    Last edited by DidgeyTrucker; 01-30-2011 at 10:39 PM.
    Tracy M&M #245
    Mac OS X/ Earthlink DSL
    2004 GT 5-speed
    1956 F-100 Panel w/429 (3.50 9")
    1966 F-100 SWB w/351C (3.25 9" - 3.70 posi for Saturday nights)
    Music City F-100's,
    1965 Holman Moody B/P "What if?"(2.78 1st & 3.70 TracLok 9")
    Music City Mustang Club
    1969 Schwinn StingRay
    Don't focus on the destination....make the JOURNEY the adventure
    Visit my Web sites:
    DidgeyTrucker's Website
    The Hot Rod Johnny Travelling Rock And Roll Show

  4. #4
    Join Date
    Nov 1999
    Location
    Parkersburg WV M&M #277
    Posts
    397

    Default

    I've never seen a blown head gasket come and go, but that don't mean it can't. When you filled the radiator, did you bring the car up to temp., then top it off after?
    Andy

    M&M # 277
    64' Falcon Futura
    95' Mustang GT

  5. #5

    Default

    I check the level several times and keep it full. I even crack open the "air bleed" deal on top of the intake to make sure water was up in it. I have been wondering if that air bleed could be bad and allowing air in as the coolant cools and contracts. The Ford parts guy said he has never sold any so he doubts it has gone bad.

    Sometimes after letting the car sit overnight or even a few days, when I check the level in the radiator, the coolant is down to the top of the core. It takes less than a pint to fill it. Sometimes the coolant is all up in the cap like it should be.

    I put in a Ford thermostat that has a little "pop-off/air-bleed" in the outer ring that would slowly allow pressure equalization on both sides of the thermostat. On the first test I could not make anything happen. Heavy acceleration would not make it go berserk. I drove around for about 30 minutes. After cooling overnight I went on another test drive. After about seven minutes the heater started to blow cold and continued for about 5 minutes, then warmed up to normal. The temp didn't get as hot as it had in the past, though. I believe the temp gauge is measuring hot air, not coolant, because when the heater starts to blow hot the temp drops to normal. As the temp needle moves down it matches the rising air temperature coming out of the heater.

    There is NOTHING consistent about the conditions (outside temperature, length of parking or driving) that bring on this problem.

    Tracy
    Tracy M&M #245
    Mac OS X/ Earthlink DSL
    2004 GT 5-speed
    1956 F-100 Panel w/429 (3.50 9")
    1966 F-100 SWB w/351C (3.25 9" - 3.70 posi for Saturday nights)
    Music City F-100's,
    1965 Holman Moody B/P "What if?"(2.78 1st & 3.70 TracLok 9")
    Music City Mustang Club
    1969 Schwinn StingRay
    Don't focus on the destination....make the JOURNEY the adventure
    Visit my Web sites:
    DidgeyTrucker's Website
    The Hot Rod Johnny Travelling Rock And Roll Show

  6. #6
    Join Date
    Jun 1999
    Location
    Kansas City, MO.
    Posts
    4,077

    Default

    My posts from your previous thread:

    Quote Originally Posted by submariner mustanger
    You made no mention if you checked for exhaust gases in the coolant. Those 3.8 liter motors.....1988-1996 were NOTORIOUS for head gasket problems. Ford gave extended warranty coverage up to 100k miles. Doesn't explain why your issue is so intermittent, but I'd check out a head gasket problem also.

    http://www.autosafety.org/ford-38l-head-gasket-trouble
    Quote Originally Posted by submariner mustanger
    Based on what you've said about the car....the mileage....prior replacement of the radiator.....water pump.....weird cooling system problems.....if it was my car, I would definitely rule out the head gaskets BEFORE doing anything else. I didn't say that the head gaskets are definately your problem, but based on what I've seen (8 years Ford tech), I really recommend you have it checked out.


    Head gaskets!!!
    Last edited by submariner mustanger; 03-04-2011 at 03:53 PM.
    M&M Member #91
    Ford Dealership Engine/Chassis Master Certified Technician
    Operation Iraqi Freedom Vet...x 2...USAF Reserve. U.S. Navy submariner Vet x 12 years.

    Current Stang-1993 LX 5.0 'vert. All My Past Mustangs:'84 GT-5 spd, my first; '91 GT-auto; '70 M-code Mach 1-grabber yellow; '95 GTS-5 spd, Pro-Charged, totaled; '95 GTS 5 spd, replacement; '89 LX 5.0 'vert-5 spd; '90 LX 5.0 hatch-5 spd; '69 M-code Mach 1-4 spd; '90 5.0 LX 'vert; '03 Mach 1-5 spd.

  7. #7

    Default

    $2.75.

    Tracy
    Tracy M&M #245
    Mac OS X/ Earthlink DSL
    2004 GT 5-speed
    1956 F-100 Panel w/429 (3.50 9")
    1966 F-100 SWB w/351C (3.25 9" - 3.70 posi for Saturday nights)
    Music City F-100's,
    1965 Holman Moody B/P "What if?"(2.78 1st & 3.70 TracLok 9")
    Music City Mustang Club
    1969 Schwinn StingRay
    Don't focus on the destination....make the JOURNEY the adventure
    Visit my Web sites:
    DidgeyTrucker's Website
    The Hot Rod Johnny Travelling Rock And Roll Show

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