Overheat related to blown head gasket?

My 2003 Honda Civic EX overheated (boiled - indicator past the red) and shut down while driving on interstate at 44K miles on engine. This is the only time my car has overheated. Now at 103K miles, I have a blown head gasket (coolant leaking into 2nd cylinder). Is it probable that the overheat weakened the head gasket, or are the two events most likely unrelated?

It did not help.

However 60k latter there is no definitive answer. Why do ask?

Quite possible they are related, consider yourself lucky that the overheating only resulted in a head gasket. A good mechanic should pressure test is to see where the leaks are. The head has to come off of course and the head and block checked for straightness and cracks before the new gasket is installed. Budget $400 or so at least.

Again, I have had several friends who completely wrecked their engines through overheating and just driving on until the car stopped.

I asked because the overheat was caused by radiator cap not being put on properly in service at Honda dealer 30 miles prior to overheat/shutdown. They admitted that they caused the problem, towed the car in, flushed radiator and said there was no blown head gasket at that time. I have no problem with that, but I believe that event may have weakened the head gasket and I want them to share costs in repairs.

The dealer says the leak is only in the gasket for 2nd cylinder, if I am understanding properly. Cost estimated at $1400.

It is extremely highly likely, almost guaranteed, that the blown headgasket was a result of your overheating. When you overheat an engine until it shuts down, the head can warp. The spot where the head warps away from the top of the block can leave that spot on the headgasket less compressed, allowing it to weaken. Even if the head returns to normal after the engine cools (many do not), the headgasket can be fatally weakened at that spot. Failure is inevitable.

The $1400 quote assumes that the head will be flat enough that it won’t have to be disassembled and machined. If it does, the price will go up.


Why didn’t you stop before the gauge passed the red line?

Thank you very much.

It’s the dealers fault if they left the cap loose and overheating can definitely weaken a head gasket. At some point afterwards it may decide to let go.

Your culpability in this is not stopping when the car overheated. When the gauge rises towards the red you MUST pull over then and there.

That being said, it’s likely this engine has far more serious problems than a head gasket fault.
Severe overheating like this can cook cylinder walls, score pistons, and ruin piston rings by either seizing them on the pistons or removing the ring temper. (temper meaning springiness)
If coolant diluted the engine oil then this can damage crankshaft bearings. Either of the above means a complete engine overhaul.

There is no way I would consider replacing a head gasket on this car without performing a compression test to determine if ring damage exists (and even that is not 100% definitive) on the cylinders not affected by a head gasket breach.

Failing to do this may mean that you end up with a smoking, oil burning engine with a new head gasket.
Just my opinion, but this problem was caused by the dealer and they should pony up at least halfway on the repair as their failure to tighten the cap initially caused this problem and your failure to stop the car when overheating also contributed.

I started from home (completely cool car) and was about 15 minutes up the road when the car started making a roaring noise, so I looked at the heat gauge and it was already in the red part. I immediately put on my flashers, began to decelerate and the car completely died. By that time, it had gone past the red. It was probably less than 30 seconds time total from when I noticed the sound to when it died. The odometer showed a total of 30 miles driven since the dealer’s service, which was 13 miles from dealership to my home the day before and then the second trip where it died.

Okay, I can understand that.

UPDATE: After reviewing my service records that showed their mistake at 50K miles, the dealership agreed to absorb 50% of the cost of head gasket repairs, so my total bill was $744 (taxes included). The car has more get-up-and-go that it has had in a long time, and I am very happy with its performance. Thanks to everyone for your feedback.