Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-04-2015, 18:21   #1
Registered User
 
brownoarsman's Avatar

Join Date: Nov 2008
Location: Round Bay, Severn River
Boat: Formerly Pearson 28-1, now just a sailing dinghy
Posts: 1,320
How big of a deal is hydrolock?

I recently had my exhaust system off looking for back pressure that might have been the reason for my lack of a firing engine. As a result, I read the internet guides on manifolds, elbows, exhaust anti-siphon loops, etc. and wanted to curl up into a bar and sob about hydrolock. Articles from boat us and other sources basically say if you get hydrolock you might as well throw away your engine.
However, calder is fairly benign on the subject. My experience was that I spun out the water by engaging decompression and flooded the cylinders in wd40 and she was running strong a few days later after I fixed all the other crap on the engine. A fellow cruiser had hydrolocked his brand new yanmar and had her running again after an hour with a mechanic.
So what's the deal: disaster or inconvenience? What determines which? For damage, I could see anything from some slight corrosion on the cylinder walls, to blown cylinders and bent arms from the inability to achieve compression.
As to what determines the damage, I guess hydrolocking from spinning your starter a few too many times may be less severe as the cylinder probably isn't full of water, just a bit on the bottom that keeps it from firing. An exhaust system leak on a boat that sits for weeks at a time may have time to fill the cylinder entirely, causing the catastrophic damage. Does size of the engine matter too, with bigger engines blowing themselves up?
What's your take?


Sent from my iPhone using Cruisers Sailing Forum
__________________

__________________
brownoarsman is offline   Reply With Quote
Old 18-04-2015, 18:37   #2
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: How big of a deal is hydrolock?

A little water in the cylinders is one thing, hydrolock is when there is enough water to keep the engine from turning over. Unlike air, water cannot be compressed so if the piston tries to rise and can't because of water in the cylinder(s), something has to break. And it won't be something cheap.
__________________

__________________
rwidman is offline   Reply With Quote
Old 18-04-2015, 18:41   #3
Registered User
 
brownoarsman's Avatar

Join Date: Nov 2008
Location: Round Bay, Severn River
Boat: Formerly Pearson 28-1, now just a sailing dinghy
Posts: 1,320
Re: How big of a deal is hydrolock?

So it's really the degree of water in the cylinder? I had that distinct hydrolock thud three times before I figured out I had made a big oops. But, no significant lasting damage apparently. I guess a little or a lot of water will both keep the engine from turning over, but a lot of water is more likely to blow the engine up?


Sent from my iPhone using Cruisers Sailing Forum
__________________
brownoarsman is offline   Reply With Quote
Old 18-04-2015, 18:44   #4
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,331
Re: How big of a deal is hydrolock?

Quote:
Originally Posted by brownoarsman View Post
I recently had my exhaust system off looking for back pressure that might have been the reason for my lack of a firing engine. As a result, I read the internet guides on manifolds, elbows, exhaust anti-siphon loops, etc. and wanted to curl up into a bar and sob about hydrolock. Articles from boat us and other sources basically say if you get hydrolock you might as well throw away your engine. ………..


What's your take?


Sent from my iPhone using Cruisers Sailing Forum
My take is:
Avoid hydrolock in all cases!

OK for the damage, it really depends on the amount of power that is applied to the non compressible water and the ratio of water to the given volume.

So applying a small amount of force cause only a small problem but a big amount of force cause big problem and a low ratio of water to the given problem is a small issue etc.

Worst case is applying a big force to a high ratio of water in the said cylinder.

So in your instance of spinning out the water with the decompression levers operated shouldn't cause any problem presuming the water has only been in the cylinders for a few minutes or an hour or so at the most. No great force as been applied as there as been no compression force applied and what force has been applied is limited by the power of the starter motor.

Again lets say there is only a teaspoon of water in a largeish cylinder, this will raise the compression ratio maybe by 1 or 2 percent, no big deal but a cup full might increase the compression ratio by say 50% and if another cylinder is firing OK, you are going to get a large amount of force applied to the water filled cylinder with the now compression ratio of 30:1 or even 100:1.

Something is going to break!!!!! A bent rod or a shattered piston will only be the start of the woes!
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 18-04-2015, 18:57   #5
Registered User

Join Date: Jan 2010
Location: Ma
Boat: Sabre 28
Posts: 190
Re: How big of a deal is hydrolock?

"As to what determines the damage, I guess hydrolocking from spinning your starter a few too many times may be less severe as the cylinder probably isn't full of water, just a bit on the bottom that keeps it from firing. "

A little water in the cylinder that doesn't stop the piston on the compression stroke is not hydrolocked. Hydrolock is when you have more water in the cylinder than the size of the combustion chamber. On the compression stroke this stops the piston dead in its tracks and if the engine is running very likely bends/breaks the con rod or piston from the forces generated by that immediate stop and the inertia in the rest of the system trying to keep the piston moving.

If you have the decompression lever ON (and it does all cylinders) I don't think you really can hydrolock as you are keeping the valves open which would allow the water to escape preventing the stoppage of the piston.

In a car this happens when someone drives into a deep puddle of water and the car has an air intake that is fairly low in the engine compartment, it sucks up water into the intake.

Having said that, having water sitting in a cylinder for a period of time is of course not good either. You can corrode the rings or cylinder bore or have the rings rust in place seizing the engine. That isn't the same as a hydrolock though.

Shawn
__________________
Shawn67 is offline   Reply With Quote
Old 18-04-2015, 19:20   #6
Registered User
 
psneeld's Avatar

Join Date: Oct 2010
Location: Avalon, NJ
Boat: Albin 40 double cabin Trawler
Posts: 1,831
Re: How big of a deal is hydrolock?

I had 2 cylinders hydrolocked on my Ford Lehman 3 years ago and have put over 7000 miles and 1200 hours on my engine with no noticeable issues. Oil analysis has been perfect every oil change.

Only thing I did was pull the injectors, run the engine for an hour (no noticeable water in the oil at first), then change the oil after that hour run. After that ....ran it 800 miles back to Jersey and have had no issue as I said.

I knew it was hydrolocked the first second I hit the starter...so after that all movement was by breaker bar till the injectors were out.
__________________
psneeld is offline   Reply With Quote
Old 18-04-2015, 19:34   #7
Registered User

Join Date: Apr 2012
Posts: 570
Re: How big of a deal is hydrolock?

If you have hydro locked your engine, you have an engine problem or an operator problem, and need to correct whichever it is.
__________________
fryewe is offline   Reply With Quote
Old 18-04-2015, 19:41   #8
Registered User
 
brownoarsman's Avatar

Join Date: Nov 2008
Location: Round Bay, Severn River
Boat: Formerly Pearson 28-1, now just a sailing dinghy
Posts: 1,320
Re: How big of a deal is hydrolock?

Thanks for the clarifications! To sum up, in no particular order the damage from hydrolock is determined by the following:

How much water was in the cylinder
How much force was applied to the cylinder (corollary, worst if the engine is running at the time)
How long the water is in the cylinder for (more a corrosion issue than a sudden catastrophe)

This has been interesting, thanks!




Sent from my iPhone using Cruisers Sailing Forum
__________________
brownoarsman is offline   Reply With Quote
Old 18-04-2015, 19:51   #9
Registered User

Join Date: May 2012
Posts: 466
Re: How big of a deal is hydrolock?

well this is a bit hard to explain but if you have a lot of water the piston will stop well before it reaches the top of the stroke and most likely no damage but if there is just enough that the piston is very near the top the leverage of the crankshaft will bend rods valves ect, and water setting in a cylinder is never good
__________________
sartorst is offline   Reply With Quote
Old 18-04-2015, 21:20   #10
Sponsoring Vendor
 
Tellie's Avatar

Community Sponsor

Join Date: Oct 2007
Location: Hollywood, Fl.
Boat: FP Athena 38' Poerava
Posts: 3,046
Re: How big of a deal is hydrolock?

Fixed several diesels that had been hydro locked with no mechanical damage. One of the real dangers of a hydro locked engine besides apparent mechanical damage is the possibility of burning the electrical circuits feeding the starting system. Usually before one realizes that their engine is actually hydro locked they have the tendency to push the starter button and hold it down waiting for the engine to turn over. Fire is a real possibility trying to turn over a hydro locked engine.


Halden Marine Services | Marine Watermakers, Solar Panels, Wind Generators
Tellie is offline   Reply With Quote
Old 18-04-2015, 21:37   #11
Registered User

Join Date: May 2011
Location: Pensacola, FL
Boat: 1969 Roamer ChrisCraft, Riveria, 46'
Posts: 126
Re: How big of a deal is hydrolock?

I hydrolocked one of my lehmans with a faulty gasket install between the riser and exhaust manifold. When I hit the starter the engine cranked ever so briefly before abruptly halting.

I fixed the gasket, pulled the injectors, cranked the motor by hand to clear the cylinder, did an oil change, reassembled and have been running on it for 7 yrs and counting.


Sent from my iPhone using Cruisers Sailing Forum
__________________
neptunesjester is online now   Reply With Quote
Old 18-04-2015, 22:32   #12
Senior Cruiser
 
roverhi's Avatar

Cruisers Forum Supporter

Join Date: Aug 2005
Location: Kona, Hawaii, Carlsbad, CA
Boat: 1969 Pearson 35 #108 & 1976 Sabre 28
Posts: 6,003
Send a message via Yahoo to roverhi
Re: How big of a deal is hydrolock?

Got the old MD2 started with the compression relief levers when it was brand new. Don't ever trust an anti syphon valve.. Dropped first one and that lever and the engine fired right up. Apparently the second cylinder was the one with water in it as the engine stopped dead when I dropped the 2nd cylnder's compression lever.
fortunately it was under warranty so called Westasil and they got a factory mechanic down to look at it right quick. The mechanic checked compression and determined the rod was shortened trying to compress the water in the offending cylinder. He pulled that head and cylinder, installed a new rod and piston and put it back together with the engine in the boat. Love the modular design of those old Volvos. It ran for years and 2 1/2 trips to SoPac. Finally died after more than 20 years in the tropics.
__________________
Peter O.
'Ae'a Pearson 35
roverhi is offline   Reply With Quote
Old 19-04-2015, 05:53   #13
Registered User
 
brownoarsman's Avatar

Join Date: Nov 2008
Location: Round Bay, Severn River
Boat: Formerly Pearson 28-1, now just a sailing dinghy
Posts: 1,320
Re: How big of a deal is hydrolock?

I'm loving these stories about hydrolocked engines running forever after the initial event; gives me hope!


Sent from my iPhone using Cruisers Sailing Forum
__________________
brownoarsman is offline   Reply With Quote
Old 19-04-2015, 06:14   #14
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: How big of a deal is hydrolock?

I've seen it go both ways and it really boils down to how it hydrolocked.

Excess Cranking - Not seen internal damage and the engines were revived with multiple oil changes and a good long hot run after. (On one boat the engine was badly damaged, not due to the hydrolock resistance but because the owner did not realize it hydrolocked and he let it sit there, full of salt water for two weeks, before he showed up again with a new battery)

Failed Siphon Break - Same as above minus letting it fester in salt water

Forward Facing Scoop Strainer - Same as above (burned out starter trying though)

In-Out Bucket Located Above The Siphon Break - Same as above but again a burned out starter and some melted battery cable.....

Connected Garden Hose To Intake - Snapped rod. This one was amusing because they guy approached me in the yard with what appeared to be a 3/4" intake hose and asked me if I had any garden hose fittings he could adapt to it. I suggested that if this was for his engine he was welcome to use my in-out bucket to which he declined. I then politely reinforced to him that under no circumstances should he connect pressurized water to his raw water intake........ 30 minutes later all I could hear was swearing and "oh $hit, oh $hit, oh $hit".....

He thought he could beat the system by not turning the hose on until the engine fired, which was the worst possible thing he could have done. Hose pumped water in faster than the engine could expel it and it went from 2000 RPM to 0 RPM in about 0.01 seconds. The Yanmar engine was a total loss....

It usually depends upon how you hydrolock it and how quickly you get the water out of it, change oil and give it a good hot long run...
__________________
Marine How To Articles
Maine Sail is online now   Reply With Quote
Old 19-04-2015, 06:27   #15
Registered User
 
brownoarsman's Avatar

Join Date: Nov 2008
Location: Round Bay, Severn River
Boat: Formerly Pearson 28-1, now just a sailing dinghy
Posts: 1,320
Re: How big of a deal is hydrolock?

I still need to give it a good long hard run. I spun the water out right away, and started her up until the overheating issue caught up with me, then couldn't start it again. After spending a couple days trying to fix the starting issue, I flooded the cylinders with wd40 and spun that out. Starts up like a dream now with no audible damage. Hope it's not just the oil coating! However, still putting the engine back together and waiting for parts after taking everything off before I run it for more than a couple seconds.

Here's another question on the subject. When you spin the water out of the cylinder, where does it go and how does the rest of the water get out? I assume the excess starting water enters through the mixing elbow, fills the lift pump and works its way back up the riser (though shouldn't this not happen if the riser is above the level of the exhaust hose)? Don't you need exhaust to force water out of the lift pump? So when turning the engine over by hand without firing, wouldn't you just be putting water into water? Where does all the excess go?



Sent from my iPhone using Cruisers Sailing Forum
__________________

__________________
brownoarsman is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Centerboards- A maintenance nightmare, or no big deal? JulieMac Monohull Sailboats 44 07-06-2014 19:58
Deal or no deal captainbri Monohull Sailboats 4 03-04-2014 23:40
Make a Deal-Get a Deal- Used Boat Gear lynnrgardner Commercial Posts 0 09-12-2013 11:42
Yeah, no big deal. Im just gonna install these port gaskets real quick Moonpie Deck hardware: Rigging, Sails & Hoisting 3 23-02-2013 07:18



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 17:36.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.