Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Blown gasket after slipping into a pond

I’m wondering if the head gasket blowing could have anything to do with slipping into a muddy, half frozen pond (april 1st snow storm in maine was no joke). The engine was submerged but it was determined that no water entered the engine and given a clean bill of health. However a week later the car started to overheat. We discovered that there was no coolant in the car. AFter filling the coolant we drove it to the mechanic. But just as we pulled in, the car started to smoke. It was only then that it was determined that we had blown the head gasket.

Could the cold water dip have cracked the radiator? Or caused some sort of seal to break? Or is this totally unrelated?

4 cylinder Subaru Outbacks in the 1996-2004 vintage blow headgaskets at an alarming rate.


The Cold Pond Water Probably Drowned The Termites Who Were Joining Hands Trying To Hold That Subaru Head Gasket In One Piece. Although Very Determined, Termites Are Very Susceptible To Hypothermia And Some Just Can’t Swim Worth A Darn.


The blown head gasket is not related to the car being in the water.

The problems you will start having in the not-too-distant future, however, will definitely be related to the car having been in the water.

Insurance Companies Don’t Hesitate To Total Out Cars That Have Had Engine Fires Or Have Been Involved In Flooding. Too Many Problems Down The Road Rear Their Ugly Heads.


Some possibilities could be:
Typical Subaru head gasket failure and it was a fluke that it gave up at that time.

Cooling system was damaged, coolant ran low, and overheating caused it to give up.

Thermal shock when the hot engine hit the icy water and this is not unheard of, especially with aircraft.

Engine inhaled water, there was some hydrolock during starter motor operation, and it may have weakened an already weak head gasket which then caused it to fail a week later.

Yes, it’s possible this could have been caused by the accident but it would be interesting to know just how submerged this engine was and if there was any water in the engine oil or intake tract. (Latter leading to hydrolock of course.)

Something doesn’t add up here. It’s stated that “the engine was submerged but it was determined that no water entered the engine and given a clean bill of health”. Who gave it a clean bill of health and what exactly was done to determine everything with the engine was fine ?? Although it’s possible that it’s a coincidence that the car overheated and head gasket failed a week after submerging the car, I think it’s more likely something happenned to it at the accident that caused it.

Like OK4450, I’d guess that thermal shock was a major contributing factor. The fact that headgasket failures are not uncommon in these engines suggests that even under normal operating condition there may be differences in expansion coefficients anyway. Heat the notor up and dunk it in freezing water and the effects of these differences will be magnified exponentially. The block and the head probably did to the headgasket what twisting the cookies does to the center of an Oreo cookie.

Hee, hee. Good one, CSA

When the car slipped into the pond was it still hot from running? If it was warm and/or heated up to normal operating temp a dip in a pond cold cause sudden cooling in a very unnatural way and caused damage. There are different metals in the heads and block and sudden temperature changes cause the metals to contract at different rates and that can create damage.

I guess Subaru’s should carry warnings not to drive through puddles (or standing water, pretty lame for an AWD vehicle,don’t get the engine wet or it may thermal crack,lions and tigers and bears OH NO), “thermal shock”? I think there are a few that need electro-shock.

You cannot thermal shock an engine by splashing it. But you absolutely will by heating it up and dunking it in icewater. Engines aren’t designed to withstand this type of thing.

There’s a world of difference in the definition of the words wet and submerged.

My gut feeling is that if the deceased crew and passengers in the cut and paste below could be returned back to the form they had before impact they would probably go along with the thermal shock theory.

The causes of three aircraft incidents in the 1990s (United Airlines Flight 585, USAir Flight 427 and Eastwind Airlines Flight 517). Thermal shock caused their power control unit in the tail to jam and cause rudder hardover.

We have all agreed to avoid race car and aircraft comparisons,worse that apples and oranges. But if you must pull out the airplane comparisons, do what you have to do.

Lets get some poor slob of a Subaru owner to drive his car in a icy lake and see. I really like the “partial hydrolock” theory, is that like “a litle bit pregnant”?

PBS has a documentary out showing liquid water at something like -19F, as soon as the first bit of dirt entered the water it was solid in an instant. No race car or airplane analogies please.

We have??? Where was I???

From an engineering standpoint, when discussing subjects like thermal shock, there really isn’t any difference between automobiles and aircraft. Components and assemblies that can readily withstand gradual changes in temperature cannot necessarily survive sudden and dramatic changes. In qualification testing, thermal shocking is an entirely different test than temperature testing. It subjects the device to very different stresses.

The OP asked for opinions on whether or not this accident could have led to the head gasket problem and my response was to give them 4 options as to why the head gasket let go, with thermal shock being one of them.

Thermal shock may be laughed off but if one was aware of the tendency of those stubby Subaru cylinder heads to warp out of spec even when they’re not overheated even a blind man could see that instantly submerging a hot engine into ice water can tip things over the edge. Aluminum can move drastically with temperature extremes, especially if those extremes are instantaneous.

For non-believers in thermal shock, long about the first week in August after the windshield in your car has been sitting all day in 110 degree heat try throwing a large bucket of ice water over it. The result will be your thermal shock.

As to full or partial hydrolock there is such a thing and I’ve seen it a number of times. (Mostly Subaru of course) Maybe one’s mechanical horizons need to be expanded to be aware of this phenomenom.