Lessons in Hydrolock

[SMWS6TA]

Today’s lesson is Hydrolock – what is it and how bad is it? (this is a long read but worth the time)

Hydrolock (a shorthand notation for either hydraulic lock or hydrostatic lock) is an abnormal condition of a reciprocating engine in which an incompressible liquid, commonly water, has been introduced into one or more cylinders, causing immobilization or damage.

Hydrolock can occur because an internal combustion engine must compress a volume of gas in order to operate, while most common liquids that could enter a cylinder do not compress. If liquid is introduced at a volume greater than the volume of the cylinder at its minimum (end of the piston's stroke), the piston cannot complete its travel. Either the engine must stop rotating or a mechanical failure will occur.

Hydrolock was first associated with steam engines. When the cylinders are cold, steam condenses allowing a build up of water. The engine driver would normally open the cylinder drain cocks when starting from cold to allow the condensed steam to escape and not build up to dangerous levels.

Hydrolock can also occur when a steam engine's boiler is too full, allowing water to be carried to the cylinders along with steam.

Hydrolock is relatively common when driving through floods, either where the water is above the level of the air intake or the vehicle's speed is excessive, creating a tall bow wave. A vehicle fitted with a cold air intake mounted low on the vehicle will be especially vulnerable to hydrolocking when being driven through standing water or heavy precipitation.

Another cause can include a head gasket failure, which may allow the radiator coolant to leak into the combustion chamber. Fuel entering one or more cylinders in liquid form due to carburetor flooding or other abnormal operating conditions can cause an engine to hydrolock, although this is relatively rare.

EFI engines can also succumb to Hydrolock when the Fuel Injectors are stuck in the open position. This will flood the cylinder.

Symptoms and damage

If an engine hydrolocks while at speed, a mechanical failure may occur. Common damage modes include bent or broken connecting rods, a fractured head, a fractured block, crankcase damage, damaged rod bearings, damaged seals, or any combination of these. Forces absorbed by other interconnected components may cause additional damage. Physical damage to metal parts will manifest in a "crashing" or "screeching" sound and usually requires replacement of the engine or a substantial rebuild of its major components.

If an internal combustion engine hydrolocks while idling or under low power conditions, the engine may stop suddenly with no immediate damage. In this case the engine can be purged by unscrewing the spark plugs or injectors and spinning the engine to expel the liquid from the combustion chambers. Depending on how the liquid was introduced to the engine, it possibly can be restarted and dried out with normal combustion heat, or it may require more work, such as flushing out corrupted operating fluids and replacing damaged gaskets.

If a cylinder fills with liquid while the engine is turned off, the engine will refuse to turn when a starting cycle is attempted. Since the starter mechanism's torque is normally much lower than the engine's operating torque, this will usually not produce damage as long as the operator does not continue with the attempt. The engine can be drained as above and restarted. If a corrosive substance such as water has been in the engine long enough to cause rusting, more extensive repairs will be required.



How this above effected me -


Now that we got all the technical stuff out of the way…. My niece (sorry guys no pics will be posted of her) has a Chevy Cavalier. I know a giant POS that is a cursed object. It’s her first car what can I say? This thread does apply to any vehicle so it is worth reading. Anyways this car has tested my mechanical knowledge every time I work on it. Well this weekend was no different.

She starts off finding a leaky fuel injector while changing her plugs. She sent me a pic of it via cell phone asking “Is this suppose to leak?” After scrambling to call her back telling her not to start the car and wait till I get home. I pulled the injector and found the O rings have gone bad (what’s with GM vehicles and O-rings?!?)(CLUE Number 1) So I get a new O-ring and replace it. At this point later I find that I should have started looking into a possible Hydrolock situation. We go to start the car to see if it was fixed. It turned once, twice then a loud “thunk”. Crap the starter just went. (Clue Number 2) We go get a new one, while I’m there we’ll test the alternator and battery, no need for a second trip right? Alt passes but battery may need replaced, oh well it can wait. Get the starter on, try again. This time it needs shims. Drop and repeat installing starter. This time it engages by doesn’t turn the motor and then starts to smoke…a lot? WTH?!? (CLUE Number 3) Ok, now because the parts guy said the battery seems weak I try jumping it, made it worse. Crap, did I just broke the starter?, Damn it the battery is toast to. Take it back, get a replacement (ALWAYS TAKE THE WARRENTY IN CASES LIKE THESE) and a new battery. This time we had new results – still bad. As I go to hook up the negative cable to the battery the car try starting itself without a key and nobody in it? Honestly scared the crap out of me because I was standing in front of the car. Oh great now what? Ignition switch bad?!? We get new one. Self starting issue fixed, but still won’t turn over. (INSERT MASSIVE CUSSING and CLUE Number 4) F it I’m going to bed.

We start fresh by taking the starter back and having it tested. Passed - Oh’ come on is it? Never had a starter give me such a ass pounding !!!. I surrender, called a buddy, tell him what’s up. He calls back in 5 mins, asked me to pull all the plugs. I did so, shined a light into each. Guess what I found. Same cylinder that had the bad fuel injector was flooded. I pulled over a pint of fuel out of it. So, I’m kinda back at square 1. Bad injector. I get a new injector, replaced it, get everything back together.

We try bumping the starter. It engages and starts turning the engine. Thank you Car Gods, however Mr. Murphy hasn’t finished with me yet. Now I need to drain all of the oil and change the filter. When you get that much gas into the cylinder and try starting it will seep passed the rings and mix with the oil. You will know because the oil dip stick usually comes flying out and spraying oil everywhere when the car starts up and runs (trust me, it will happen, took another 15 mins cleaning the mess up). Also another clue that this has happen is the giant cloud of thick smoke you coming from the tail pipe.


Now, some Q&A:

1) How did you get the fuel out of the cylinder?
You have a couple of ways to do this. The most common is to turn the crank bolt till the exhaust valve opens. Fuel drains and goes out to the back end. You may have a pop or two till it all burns off.

Choice 2 is to keep the plug off, pulled the fuel pump fuse (Important to do this because you don’t want to add more fuel to the cylinder), and bump start the engine. Now I did try this but you need to be aware that all that fuel is going to be coming out that hole at about 100 psi or greater. It will fly everywhere. Now to see if you are paying attention, what happens when gas is vaporized into the air and a spark plug wire that you have disconnected is sparking away? In the great words of Sir Beavus – “FIRE, FIRE!!!” I personnel do not recommend this step but it is a process that is used by some mechanics. If you do, make sure your Life and Medical insurance are paid in full.

Choice 3 (I did this) is to get one of those pumps that screws on the bottles of ATF you use on to fill your trany with or a very thin turkey baser. You need to be able to fit the tubing into the spark plug hole. Use this to suck out the fluid. You won’t get it all but you will get enough.

2) Does this only apply to fuel? No, same above method is used for water or coolant. Maybe that’s why mechanics use choice 2.

Now I do not claim to be an expert on this subject, just thought I would share and hope others will learn from it. Ask away and I’ll see if I can answer.

[Firebirdjones]

Choice 2 is the easiest/quickest way. You don't have to worry about fire if you just kill the spark too along with the fuel pump

[blackSS01]

Usually when a engine is flooded with gas it will reek like gas. Thats how it has been in every engine I've dealt with

[SMWS6TA]

I believe I discredited the smell because I had pulled the fuel injector first trying to replaced it and assumed the smell was from this in the process. Only other time I smelt gas was after the plug was pulled.

I should add that the head gasket is fine because it has less then 300 miles on it. I had to fix that too 3 months ago.

[blackSS01]

I believe I discredited the smell because I had pulled the fuel injector first trying to replaced it and assumed the smell was from this in the process. Only other time I smelt gas was after the plug was pulled.

I should add that the head gasket is fine because it has less then 300 miles on it. I had to fix that too 3 months ago.

I can see that happening, once you smell gas you tend to smell gas

One thing to note though is just because the head gasket was installed 300 miles ago doesn't mean its good still. Head could be cracked or block deck might not be true (from overheating) I'm not saying that this is the case, just sayin

[SMWS6TA]

I can see that happening, once you smell gas you tend to smell gas

One thing to note though is just because the head gasket was installed 300 miles ago doesn't mean its good still. Head could be cracked or block deck might not be true (from overheating) I'm not saying that this is the case, just sayin

I also had the head decked and the blocked checked too. Didn't want to invest in that much work if it wasn't going to work.

[blackSS01]

I also had the head decked and the blocked checked too. Didn't want to invest in that much work if it wasn't going to work.

Then you my fine sir did it 100% correctly

[Mike Holmes]

Hello all
Well 1st time poster and I have an issue with this I would suspect, today I was heading out and went thru flooded road at first the water wasn't that deep as I went around the corner the road dips down and water was very deep at this point I tried to make it through it, but the car just shut off no noises it just stopped after pushing car out I tried to start and it did nothing, I brought back home and started searching net, found some articles on what to do 1 take off air filter and it was soaking wet and box had water in it so next I removed the tube going to motor and a lot of water came out, then I removed the plastic box on top of the manifold and throttle body had water in it so removed it and dried, then removed the manifold and it had water in it also cleaned and dried it, next took out plugs only cylinder 3 was wet thought that was odd, after i removed the plug look through the hole in the head and saw cylinder 3 was filled with water where the lifters where I used a spray bottle and lengthened the tube by attaching another spray tube to top one and proceeded to suck out the water in there after some time it was gone I then dried all the areas and reassembled all the parts, then with plugs out still I tried to crank it nothing Still had a neighbor try and jump me still nothing, I have been reading I should turn the harmonic balancer and eject the water out thru spark plugs how long should I do this and is there anything special like direction I turn it ? also I am going to change oil, I hope I gave enough info of issue and someone has a solution or at least a path to follow, I am unemployed and need my car to find work
car is a 2003 Chevy Cavalier with Ecotec engine only has little over 75K hate to have to get a new motor, not like I could afford too
well thanks for any help that may be given
and take care
Mike