Water in Cylinders

Triple502

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Oct 22, 2016
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Okay, I have been a reader of topics for years, and always seemed to find my answers to my boating questions. I know the topic of hydrolock has been addressed here many times, but I can't quite find the answer to a question. The other day I took the boat out to pump the head and enjoy the mid 80s day here in Southern MD. After pumping the head, the starboard motor wouldn't turn over. Like many people I assumed the starter went bad and putted back on the port motor. Upon research, I discovered the motor had hydrolocked. I removed the spark plugs, manifolds and risers. I was able to get the motor free with a breaker bar and used fogging oil into the cylinders (it was all I had at the time). The next day I put Marvel's Mystery oil in the cylinders. As I bumped the starter, water shot out of the 2 middle cylinders on the starboard side. I continued the process and water continued to come out. I sprayed the cylinders and left for the day. Came back down and started the process over and water continues to come out only those 2 cylinders. I did a compression check and all cylinders are in the mid to upper 140s. There is no water in the oil. My question is if the exhaust valve is stuck or if there is a problem with the head, would the raw water pump still be pumping water to the problem areas even by just bumping the starter? It seems like the water is never ending. Is there really that much water sitting on top of that piston? Is there an easier/better way of getting it out? I really would prefer not to tear the motor down. I am running 1995 Mercruiser 5.7, 4bbl, Bravo II drives, unknown hours. I should note that the riser and manifolds looked pretty good when I took them off. I am no expert but it appears that the riser gasket may have failed based on the small amount of corrosion where it mates up to the exhaust manifold. There was water sitting in the bottom of that exhaust manifold when I pulled it off, which leads me to believe it was a riser/manifold issue. Also, there appears to be surface rust on the exhaust ports on the starboard side only. Any thoughts would be appreciated.
 

alldodge

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Howdy

As I read your saying you removed the manifold and as you continue to crank the motor water keeps coming out. So the exhaust manifold is off and water continues to come out. If this is the case, you have a blown head gasket or cracked in the water jacket of the head or cylinder wall.

Without the engine running you won't see milk or water in the oil. The water will fall to the bottom of the oil pan and the oil will rise. If there is enough going in the oil volume will appear to rise and be to full. The dip stick will not show any water, only the level is rising.
 

tpenfield

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+1 , agreed . . . water is probably coming from another source that still has a supply of water. Intake manifold, cylinder head/gasket, etc.
 

Bt Doctur

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Aug 29, 2004
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Remove the belt from the raw water pump, remove the hoses from the bottom of the manifolds and drain. remove the plugs and dry them , spin the motor to remove any water. Wait 5 minutes, spin the motor again to check for water. If there is , remove the block drain at this time and drain the block.

Install the plugs and try to start the motor without water to dry everything. you can safely run for 10 - 20 seconds.
Remove spark plugs, reconnect raw water belt , attach muffs/hose and crank engine DO NOT CONNECT MANIFOLD HOSES, direct then into the bilge.
Water from the cylinders is block, head, head gasket issue. no water comes out , possable manifold/riser issue.
 

Triple502

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Oct 22, 2016
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Thanks for the quick reply guys. I will give it a shot and get back to you on the results. I am fearful that I see major surgery in my future.:grumpy:
 

shaw520

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Aug 27, 2009
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634
I see you're running bravo's, so while cranking the impeller is continuing to introduce more water into the system. Remove outdrive first...then I would check manifold and riser on that side. A failed gasket could multi-port water into cyl.
 

Triple502

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Oct 22, 2016
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I went back and reread my original post. When I said water was coming out of the cylinders, I meant to say it was coming from exhaust ports (midnight shifts are brutal). When I originally removed the spark plugs on the starboard side, water poured out of the holes. Now when I crank the motor over, water shoots out of the 2 middle exhaust ports. Does that change anything? Sorry for the confusion. Again, midnight shifts are not my friend.
 

Bt Doctur

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Remove the exaust manifold hoses from the bottom of the manifolds and drain,'
crank engine, if water still present suspect head cracked, head gasket blown, block cracked.
 

Triple502

Seaman
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Oct 22, 2016
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There is still water present when the motor is cranked over. I will be removing the heads this week. I will keep my fingers crossed that its a gasket. Thanks for the advice and I will let you know how it turns out.
 

Triple502

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Oct 22, 2016
Messages
66
Another question. While pulling the risers from the exhaust Y pipe, I noticed there were no flappers. Is this correct, or should there be some there? There doesn't appear to be a place in the connection where they would go. Just curious if Merc stopped using them at some point.
 

Bondo

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There is still water present when the motor is cranked over. I will be removing the heads this week. I will keep my fingers crossed that its a gasket.

Ayuh,.... Welcome Aboard,.... Pressure test the block's coolin' passages 1st to pin-point the problem, as once ya pull the heads, that option disappears,....

Just curious if Merc stopped using them at some point.

Nope, you should have shutters in there,....
 

Triple502

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Oct 22, 2016
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I already pulled exhaust manifolds and risers. Can that be done with them off, or do I need to reinstall them? It is raw water cooled so I am assuming I will have to rig something homemade to make it work.
 

Bondo

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I already pulled exhaust manifolds and risers. Can that be done with them off, or do I need to reinstall them? It is raw water cooled so I am assuming I will have to rig something homemade to make it work.

Ayuh,..... Yer testin' the Block, not the exhaust,....

At the t-stat housin', block off the in-comin' waterline, 'n the lines to the exhaust,...
Rig a low pressure gauge, yer lookin' for 'bout 15 psi,...
'n a way to blow the air in, a shrader valve, like on a tire,...

Pressurize to 15 psi, 'n Listen,....
If there's a leak, you'll probably hear it,....
Follow the sound to the leak,....

Rig it right, 'n a good block will hold 15 psi pretty much forever,....
 

Triple502

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Oct 22, 2016
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I watched a video on youtube where someone did just this. Now what the video didn't tell me was what air leaking tells you. 1. If coming from carb, what does that mean? 2. If from exhaust? etc. Also, if no air escapes from anywhere, am I to assume it was the risers/manifolds all along? Or does this just eliminate one step? Sorry for the questions but I am trying to save some $$ before I ask a professional. Thanks for the help.
 

alldodge

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If it leaks air anywhere something is cracked. If it doesn't leak then your good.

Try the pressure test and tell us what you found which will make it easier then trying to explain all variables
 

Triple502

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Oct 22, 2016
Messages
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Air leaked out of front cylinder. Going to pull heads once I get boat on the hard. Looking at just going ahead and replacing the motor with a new long block. Those motors are over 20 years old and who knows what kind of abuse they have had. Thanks for all the advice.
 

camalot

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Once the heads are removed take the valves out of the offending cylinders, my guess is you will find a hole behind the valve. They just corrode through over time.
 

harleyman1975

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May 12, 2003
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The cyl heads will rust through around the valve seats. the intake can also rust through. I am suspecting that this is a problem that has been ongoing but un-noticed.
 

shaw520

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Those motors are over 20 years old and who knows what kind of abuse they have had. .


Can you guess aprox how many of those 20yrs was she in saltwater ? Once ya get the heads off you'll get a better idea of the condition.
 
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