Blown head gasket?

2004 FORD F-450
294,000 MILES • 6.8L • V10 • 4WD • AUTOMATIC
Avatar
SAM422026
  • MEMBER
  • 4 POSTS
I recently had a lot of engine overheating due to a failing water pump, a dirty radiator and a sticking thermostat. I had a mechanic flush out the radiator then replace the water pump and the thermostat. They only added about 3 1/2 gallons of antifreeze it’s I’m assuming the other 3 1/2 gallons, my truck holds about 7 gallons, was left in the engine block. They also added a new overflow bottle and then fill up the vehicle with new coolant, 3 1/2 gallons. My vehicle was overheating a little bit after that because the thermostat was sticking but now it has been running fine and I have drove it about 1000 miles since then and I’ve only had the thermostat stick just a few few times but it seems to be working normally if you let idle at a cold start up to operating temperature then the thermostat works like it should. My problem is, there is still garbage in the overflow and wondering if it was that old dirty antifreeze that was left in the block that’s mixed with the new. I did have gone under my overflow cap, but it wasn’t like a milkshake. It was a little wet but mostly dry. There is nothing in the oil as the oil is clean and underneath the oil cap there is no gunk either. Do you think I have a blown head gasket or do you think oil is mixing in somehow causing the coolant to be dirty even though there is no coolant in the oil, possibly a bad oil cooler, or do you think that the garbage that was left in the engine block mixed with the new coolant and that is why the overflow has gunk in it? do you think it’s a blown head gasket even though the bucket truck is driving fine?
Mar 25, 2026 at 4:42 PM
Advertisement
Avatar
CANNON1349
  • CERTIFIED EXPERT
  • 861 POSTS
Hello, if you take the cap off the radiator/reservoir, whichever is pressurized, and then start the truck, you can watch for bubbles in the coolant. If you immediately get bubbles it can be a bad head gasket. If not, you should be fine. It sounds like you have corrosion in the block/head passages and I would recommend an appropriate cooling system flush with a machine under pressure. The new thermostat should not stick, however the corrosion will cause problems that act like a bad thermostat.

William
Mar 25, 2026 at 7:22 PM
Avatar
SAM422026
  • MEMBER
  • 4 POSTS
Thanks for the information
Mar 25, 2026 at 7:32 PM
Advertisement
Avatar
CANNON1349
  • CERTIFIED EXPERT
  • 861 POSTS
No problem, please let us know how it turns out. If we can help any further just reply here.

William
Mar 25, 2026 at 7:33 PM
Avatar
SAM422026
  • MEMBER
  • 4 POSTS
I do have one more question, regarding engine temperature and the thermostat. It seems for some reason that the engine temperature will climb, Whether it is at idle or I’m driving, It will climb till about 3/4 Of the entire gauge, Between normal and hot, And then it seems the thermostat will open and then the temperature goes back to normal. The thermostat was replaced by a mobile mechanic a few weeks ago And the thermostat was from Napa and I think it was a cheap thermostat. Once I get driving though after its at normal operating temperature , I have no more issues, it’s only on a cold startup when this happens. Should I go ahead and replace the thermostat for a gates brand or Motorcraft? Do you guys have one brand in particular that has a high temperature rating since I’m driving a bucket truck?
Mar 31, 2026 at 2:06 PM
Avatar
CANNON1349
  • CERTIFIED EXPERT
  • 861 POSTS
Gates is good and of course OEM is better. However I am still thinking corrosion is still an issue or some kind of flow issue.

William
Mar 31, 2026 at 2:27 PM
Avatar
SAM422026
  • MEMBER
  • 4 POSTS
I’m going to take the truck to my main mechanic in about three or four weeks as I am out of town at the moment. I’m going to get him to do a complete flush and a new radiator install. Hopefully with a new thermostat change and a clean engine that should correct the issue
Mar 31, 2026 at 3:11 PM
Avatar
CANNON1349
  • CERTIFIED EXPERT
  • 861 POSTS
Sounds like a good plan. Please let us know how it turns out.

William
Mar 31, 2026 at 7:48 PM