YACT: Got my Z back - sucked up some water - but it lives!

[flot]

The Nissan fans will like this one.

I drove my Z (91 twin turbo) into a "puddle" the other day. (puddle: 10" of standing water) Engine sucked up a bunch of water, went sputter sputter sputter BLAM and then locked up. (locked up as in, the starter couldn't turn the engine over = water inside a cylinder)

Towed it to the local Z shop. They dismissed it as a total loss, said if the engine was locked, not much they could do, just sit tight for my insurance co.

Well this morning, they took off the throttle bodies, and said about a gallon of water poured out of the intake manifold. Then they took out the spark plugs, cranked it, and said water shot all over the garage.

Just for fun, they put the spark plugs back in and cranked it again...

Runs fine.

So, car gurus, now what? They changed all the fluids, and yes, amazingly enough, it appears to be running 100%. Well actually about 95%, I'm down a little on boost pressure but will give it a couple days and see how it does. I figure I'll go back in a week or two and get another oil change just to be on the safe side, but damn I'm amazed. So were the guys at the shop - they said they'd never seen an engine with that much water in it start back up again... Obviously I'm glad to have my car back (since if it needed an engine + 2 turbos it's possible it would have been totalled) but I'm a little worried too...

 

[GoodRevrnd]

Soooo.... why did you drive it into 10' of water?

 

[BCYL]

Why did you go drive your car into the puddle again?

 

[notfred]

You're lucky you didn't bend a rod. But, since it survived, it'll probably be fine.

 

[Anubis]

thats more of a small lake then a puddle

 

[BatmanNate]

Originally posted by: BCYL
Why did you go drive your car into the puddle again?

Poor genetic material.

 

[Rainsford]

I'm pretty sure most cars would survive this. I mean, the Z is a nice car that I'd like to have, but the same thing happened when my brother drove my old-ass toyota wagon into a big puddle. Just drain the water out of everything and you're good to go.

 

[flot]

Obviously I didn't know I was driving into 10" of water. We had absurd rains and flooding here in Ft. Lauderdale on tuesday. It was insane, the # I heard was that we got 9" of rain from 2:00-3:00... and then it continued to rain until 11pm.

The "puddle" was a dip in our work parking lot just before the exit. 150 other cars made it out, but it was past my vantage point so I couldn't see them actually crossing THAT area. It was raining like hell and I pretty much had to leave sometime, so I went on my merry way and then bam that was the end of it.

I dunno, I'm pretty damn astounded. Water in the intake is one thing, water in the engine block is definitely another. I was sure that at the very least, I would have snapped a valve. The other 2 Zs they had in (from the same storm) both had broken rods.

 

[Wintermute76]

How do you drown a car in 10 inches of water? Is the intake that low?

I submerged my old Suzuki 125 ATV once, got the water drained and it fired up again, had to change the oil about 5 times to get it where it wouldn't turn gray or white anymore. Put another 2000 miles on it no problems.

 

[NogginBoink]

Originally posted by: Rainsford
I'm pretty sure most cars would survive this. I mean, the Z is a nice car that I'd like to have, but the same thing happened when my brother drove my old-ass toyota wagon into a big puddle. Just drain the water out of everything and you're good to go.

Most cars would not survive this.

When the piston travels down, it sucks in an air/gas mixture. Then the piston goes on the upstroke, compressing the air/gas mixture.

Water is not compressible. If a piston ingests water and tries to compress it, you get a bent rod. It's called hydro-locking an engine, and it's a Very Bad Thing.

Flot, do you have really really worn valves, perhaps?

 

[ndee]

Why is water bad in an engine? If you let it run again, doesn't it vaporise? Sorry, I'm no motorhead.

 

[Toasthead]

congrats man... looks like you squeaked by this time.

 

[flot]

Noggin, as far as I know the engine is in pretty good shape. It still pulls off 15 psi of boost and will vaporize the 275 series rear tires on a cool day... However, I *was* at idle when it sucked up the water, and since the car runs such high boost, it's a pretty low compression engine to begin with.

But yes, to answer "in general" why it is bad to put water into your engine: Imagine your cylinder as a tennis ball container, and the piston as a tennis ball that fits exactly inside it:

Now, in a normal situation, the cylinder is full of 90% air and 10% fuel. The piston goes down, compresses the air, and when the fuel explodes, bam, the piston flys back up. Now, imagine that same scenario where the cylinder is filled with 90% water and 10% air. As the piston goes down, it will compress what air is in there - but NOT the water, as liquids cannot be compressed. So the 3 pistons on the other side of the engine are all putting force on it, and it is pushing down on the water. So two things can happen - either the water finds a way to escape (bent/broken valve, cracked head, etc) or the piston stops pushing down (broken/bent rod, hole in piston, etc).

Or, in my case, apparently the piston just stopped moving.

 

[Marshallj]

Originally posted by: flot
The Nissan fans will like this one.

I drove my Z (91 twin turbo) into a "puddle" the other day. (puddle: 10" of standing water) Engine sucked up a bunch of water, went sputter sputter sputter BLAM and then locked up. (locked up as in, the starter couldn't turn the engine over = water inside a cylinder)

Towed it to the local Z shop. They dismissed it as a total loss, said if the engine was locked, not much they could do, just sit tight for my insurance co.

Well this morning, they took off the throttle bodies, and said about a gallon of water poured out of the intake manifold. Then they took out the spark plugs, cranked it, and said water shot all over the garage.

Just for fun, they put the spark plugs back in and cranked it again...

Runs fine.

So, car gurus, now what? They changed all the fluids, and yes, amazingly enough, it appears to be running 100%. Well actually about 95%, I'm down a little on boost pressure but will give it a couple days and see how it does. I figure I'll go back in a week or two and get another oil change just to be on the safe side, but damn I'm amazed. So were the guys at the shop - they said they'd never seen an engine with that much water in it start back up again... Obviously I'm glad to have my car back (since if it needed an engine + 2 turbos it's possible it would have been totalled) but I'm a little worried too...

Keep a close eye on your temperature gauge and the exhaust. I can imagine that your headgaskets did not like the pressure of the pistons trying to compress the water too much.

 

[Marshallj]

Originally posted by: Rainsford
I'm pretty sure most cars would survive this. I mean, the Z is a nice car that I'd like to have, but the same thing happened when my brother drove my old-ass toyota wagon into a big puddle. Just drain the water out of everything and you're good to go.

No, most cars would not survive this. If they did, then hydrolocking an engine would not be considered such a bad thing.

 

[Marshallj]

Originally posted by: ndee
Why is water bad in an engine? If you let it run again, doesn't it vaporise? Sorry, I'm no motorhead.

Because your pistons compress the fuel/air mixture. On his car, the compression ratio is 8.5:1 meaning that the space inside the cylinder is compressed by a factor of 8.5 to 1 when the piston moves all the way up. Water does not compress at all. The piston is going to slam up, try to compress the water and fail. The engine will stop instantly, and usually something will give... and it won't be the water.

 

[OS]

Might be a good idea to change the oil right away.

 

[ndee]

Originally posted by: Marshallj

Originally posted by: ndee
Why is water bad in an engine? If you let it run again, doesn't it vaporise? Sorry, I'm no motorhead.

Because your pistons compress the fuel/air mixture. On his car, the compression ratio is 8.5:1 meaning that the space inside the cylinder is compressed by a factor of 8.5 to 1 when the piston moves all the way up. Water does not compress at all. The piston is going to slam up, try to compress the water and fail. The engine will stop instantly, and usually something will give... and it won't be the water.

Thanks