Hydrolocked... now what?

[mklearl]

I had a Volvo penta 5.0gi which I got a new long block 2 years ago. Went with a Holley carb and swapped all my Volvo parts over. So for all intents and purposes I have a 5.7 gl now. Winterizing last year I had milky engine oil. I thought I narrowed it down to the manifolds and risers. I put new ones on this spring and went with the tall risers as I removed the flappers. I followed the directions to a t and harrassed many people looking for advice since I know the Volvo risers can be a bit finicky. I had the surfaces shiny, tapped the holes as recommended, torqued, retorqued all in a crossing pattern. I have no signs of water leakage on the outside and the risers are cool enough to touch and leave my hand on them.
I went for a cruise on Friday afternoon and it ran fine. On Sunday morning I went to start it and all i got was a clunk. I pulled the number one plug and water dumped out. I pulled the rest and there was water in all cylinders. The worst being one and 8. I turned it over by hand to get all the water out. Squirted some oil down the plug holes. Turned it over by hand again until nothing came out. Put the plugs back in and fired it up. I let it run for less than a minute and shut it down. Took the plugs back out and no water. Started it again and let it get to temperature. Shut it down and pulled the plugs... dry again. Went for a cruise and checked the plugs again... still dry.
The engine is fresh water cooled (half system) which I believe Volvo only makes the half kit. That being said, where is the water coming from? I tasted it and it was definitely salt water. With the half kit cooling system the only place salt water goes through the engine would be through the manifolds, risers, and out the exhaust, correct? Therefore salt water can only get into the cylinders through the manifold/risers or in through the exhaust. I thought maybe I backed up too hard on Friday, but I would think it would hydro lock immediately, but the next day. So I'm leaning toward the manifold/risers. But I had water in both sides... I know I could have not installed either side correctly but its 4 bolts to the riser.... and I followed the directions very carefully... it cant be that hard can it? Also, why would it leak intermittently? Any other things I should be looking for?
I should also mention that when I'm idling around temp.is around 170. When I give it some juice to get up on plane it will creep up to just under 180 and then drop back down to 170. I've never noticed it doing this before.
Also, the oil was clean... no water in the oil.
Thanks for any ideas on what to.do next. I appreciate all the help I can get..

 

[Lou C]

OK I went back and read some of your previous posts and it looks like before you replaced the original exhaust you had water in the motor oil, but now you feel you don't, you are getting water in the cyls and its hydrolocking, correct?
For one thing are you sure there is no water in the oil, it doesn't show up on the dipstick till it gets bad. With the engine cool, put you finger (carefully!) inside the valve cover, thru the oil fill hole. See what's on your finger? Brown engine oil or mayo looking? After that what I might do is this:
get some help because they are heavy...remove both exhaust manifolds with the elbows and risers still attached. Then rig up a way to prop them up, and run water from a hose to the inlet ports. Do it in a way so water is not spraying all around. Then watch the ports that match up with the exhaust ports, let it sit a while with the water off. See if you see any leaks, this about the only way you can test if the elbows+riser gaskets are sealing correctly. These were new Barr manifolds correct? Did you use the Barr gaskets or the Volvo ones? I used the Barr ones coated on both sides with Permatex Aviation and have not had leaks. Same design just the V6 manifold, same style elbow but no riser. My OMC still has the flappers though but that might not be relevant to your problem.

Absolutely sure its not water in the oil?? make certain of that first...because that leads you in different directions....

 

[Scott Danforth]

after you get it running on the muffs and dried out

and after you see what is in the valve covers as Lou mentioned

acetone test the manifolds AND elbows as you have them bolted together

 

[mklearl]

Ok. Boat's on the mooring still. I was hoping to not have to haul it out but I honestly can't see any other place the water is coming from. I went with OEM tall risers and the metal Volvo gasket. I do have the barr gasket (green) which i may switch to... nothing to lose at this point. I'll check the oil fill tomorrow and let you know what i find. Thanks for your help.
lastly, am i right in assuming on the cooling system salt water only goes through the exhaust?

 

[Lou C]

yes raw water cooled exhaust only salt water goes from the exits for raw water from the heat exchanger...

 

[QBhoy]

Hi
im no where near as good as these guys on the GM engine but after 25 years of owning most of them I’ve had a few issues with water in the cylinders and similar. But...never have I heard or experienced water in both sides of the V engine from a rotten exhaust or riser. It’s almost always on one side of the V first. Same if it was a cylinder head issue. You maybe need to look towards something that’s common to both sides like an inlet manifold or a slug of water up both exhausts

 

[mklearl]

yes raw water cooled exhaust only salt water goes from the exits for raw water from the heat exchanger...

Yes. I know salt water and exhaust only go out the exhaust. I was more curious as to where else salt water goes in this type of cooling system? I was under the impression that salt water goes from the pump to the heat exchanger to the manifolds and out the exhaust. If that is true I could also rule out the intake manifold.
I will also mention that I was having a hard time starting it when this happened. It was turning over but I couldn't get it to fire. It then sputtered once so I thought I was almost there. Then when I tried to start it again just a clang. I'm not sure if this helps anything... just trying to figure out where the water came from.... and also, why it didnt do it again.

 

[Bt Doctur]

what is the water line to the exaust elbow measurement see page 44 http://www.boatfix.com/merc/Install/gas/86017211.pdf

Now if you had a few lovely babes on the rear deck that would lower your stern

 

[mklearl]

what is the water line to the exaust elbow measurement see page 44 http://www.boatfix.com/merc/Install/gas/86017211.pdf

Now if you had a few lovely babes on the rear deck that would lower your stern

I'll have to check but I want to say 14 inches. I replaced the short risers with the tall risers this spring.

 

[Lou C]

Yes. I know salt water and exhaust only go out the exhaust. I was more curious as to where else salt water goes in this type of cooling system? I was under the impression that salt water goes from the pump to the heat exchanger to the manifolds and out the exhaust. If that is true I could also rule out the intake manifold.
I will also mention that I was having a hard time starting it when this happened. It was turning over but I couldn't get it to fire. It then sputtered once so I thought I was almost there. Then when I tried to start it again just a clang. I'm not sure if this helps anything... just trying to figure out where the water came from.... and also, why it didnt do it again.

You are right, the impeller draws in salt water, this cools the antifreeze in the heat exchanger, and then that salt water is exhausted out the manifolds and elbows. The engine cooling system has the circulating pump draw AF in the block and then pumps it up to the heads, next it flows up to the front of the cyl heads and then out the passage in the front of the intake manifold (via the thermostat housing). So the block, heads and intake all have AF in them in your case.

Even though its a pain due to the weight of the parts, I'd want to see for myself how those manifolds+tall elbows test out off the boat. You can fill em with Acetone and let it sit (BE CAREFUL VERY FLAMMABLE) or just use water make sure there is no liquid in the ports that match up to the cyl head. If not then you have to make sure the moisture in your oil, is not really from AF.

When the head gaskets blew in my engine, I had water in 2 cyls but it did not hydrolock, it would get enough that it would run rough but not enough to hydrolock. When I took it apart, I could clearly see the fire rings were slit. I really doubt that this is the problem with yours though, unless there was an assembly issue of some kind.

I was able to get mine up and running with reman cyl heads since the old ones were cracked in the center cyl exhaust seats and 15+ years of raw water cooling in the salt eroded the cooling passages to the point that they would not have sealed against the new HGs.

 

[Lou C]

PS if you had your motor oil analyzed, like by Blackstone labs or similar, that would for sure tell you if it was salt water or antifreeze.

 

[mklearl]

PS if you had your motor oil analyzed, like by Blackstone labs or similar, that would for sure tell you if it was salt water or antifreeze.

Engine oil is clean on the stick as well as under the fill cap. I can assure you that the water that came out of the cylinders was crystal clear salt water and not orange antifreeze. Ran it for an hour today and rechecked.... no water in the cylinders. I'm thinking that somehow when I had trouble starting it I sucked water into the exhaust. I have 14 inches to the from the top of the riser to the static waterline. The engine turned over fine... just wouldn't start. I tried for several minutes to get it started and luckily didnt fry my brand new starter from trying.... it was hot to the touch. Only after all this did it get hydrolocked... it wasnt running when water entered the cylinders. Cylinder 1 was the first one I took the plug out of and water dumped out. 8 was probably the second worse dumping on my new starter. Not as much on the remaining, but the amount of water seemed to be relative to the firing order of the cylinders.
lastly, if the risers were leaking I would think they would just leak... especially when sitting for a couple of days... the water would drip down the leak on the cool risers. That didnt happen. I dont feel as though the risers would leak intermittently.

 

[Scott Danforth]

so now move on to testing the exhaust manifold and elbows (acetone test)

 

[ChrisinPHX]

"I thought maybe I backed up too hard on Friday". This comment jumps out at me. If it was the joint between a manifold and elbow, that would typically be on one side or the other. You would have to be pretty damn unlucky to have it happen on both. And to get water in all 8, that has to be a decent amount of water. Again, on both sides. So highly unlikely. I'd probably drain and refill the oil and take it for another spin. Don't back up!! LOL If it doesn't come back, assume you did back up too hard.

"Went with the tall risers as I removed the flappers" ...And get yourself some new exhaust flappers.

 

[Lou C]

Volvo said to remove the (OMC designed) flappers, but I think they might have been wrong. I never ever had water come up the exhaust in 15+ years of boating with the exact same design flappers. The only time they will cause trouble is if you have an overheat bad enough to melt them and then you'd have the same issue with a Mercruiser.

I would think about doing this....remove the exhaust bellows...and then find an inboard style exhaust flapper that will fit over the exhaust opening in the transom mount (not sure of the diameter but measure the flange that the bellows fits on to. This way it would slam shut when water tried to back up the exhaust, but can't fall down and block the exhaust like the original design.

You may be right about the cause, its unlikely to get water on both sides from defective exhaust and once they leak they should leak consistently. The lack of flappers and a quick stop, or hard backing up...esp if the boat is low in the stern...could be for sure....