New Engine Replacement - Engine Died and Hydro locked after 5 hrs!?

[CaptnO]

When it hydrolocks is it random or is it only when decelerating?
In addition to checking for other signs of water intrusion (cooling system air pressure test) there are are a few other things:
One thing I’m wondering about the cam grind used on that engine, is it definitely a marine grind or a high performance grind? Because if by chance you were sold an automotive version the cam grind could be causing reversion which can cause a hydro lock.
Did the survey find signs of trapped moisture to account for what was felt to be excessive weight?
Other things I’m wondering about are that swim platform adding too much weight and the lack of any kind of flappers. I have seen one Volvo SX equipped boat that had a similar problem, this was a small boat with a big engine (Four Winns 180 with a 5.7 V8)
He wound up trying this with success: removed the VP exhaust bellows and fitted an inboard style flapper to that flange. You’d have to measure the exhaust flange diameter to get the right size.
PS: is that swim platform OE or was it added on as an aftermarket accessory?

Hey Lou, thanks for your continued input and following the thread,

The hydro lock is a few minutes after slowing down never when at full throttle or on plane. It happens intermittent once I slow down and cruise for a bit. The only difference from two weeks ago when it didn't happen versus yesterday was that i was cruising between 3-4k for a bit longer before slowing down and cruising at 1k rpms. But I not sure why this issue didn't arise two weeks ago when I was out vs yesterday that's what doesn't make sense either.

The cams should be working okay the whole block came from that Eagle Marine Sales company and they said I should be fully compatible. Even though my original Volvo Penta did come with differ rockers and cam setup. However if there was an issue there I believe that the reversion would be happening more often and more consistent.

Swim platform was OEM from Chaparral and came with the boat when it was constructed in 2004 from what I can gather.

 

[Scott06]

I've been looking into more doing some pressure testing however not sure how to do that. I've seen some videos that show to to pressure test the exhaust manifold and risers so I think i will try that today. The only place it would leak from would be the riser gaskets but both are brand new from installing the taller risers and they were new before with the shorter risers and the issue now is happening before and after so the chances of have bad gaskets twice i think is unlikely. But again I don't know what else to check.

The intake manifold and cylinder heads haven't been ruled out as this was a new motor put in so there was no need to check that but i guess again at this point it wouldn't hurt to look and see. I rather test it with the engine put together rather then start taking everything apart but not sure if there is a way to test it like that?

I don't think the hydro locm has done any damage yet however not sure how to check that.

Not the best video but might help, bascially you have to block the water inlet and outlet hoses with pipe plugs/fittings and rig up a way to supply compressed air, see if it holds 15 psi.

You have to either remove the elbows of the exhaust manifolds and block off the manifold opening with a blank plate or take the hose off the manifold and plug it and test manifolds separately.

If you remove the elbows you should be able to see inside if the manifold to elbow joint is leaking back into a cylinder

 

[CaptnO]

Not the best video but might help, bascially you have to block the water inlet and outlet hoses with pipe plugs/fittings and rig up a way to supply compressed air, see if it holds 15 psi.

You have to either remove the elbows of the exhaust manifolds and block off the manifold opening with a blank plate or take the hose off the manifold and plug it and test manifolds separately.

If you remove the elbows you should be able to see inside if the manifold to elbow joint is leaking back into a cylinder

Which video?

 

[alldodge]

Still think it goes to deep when slowing down. Water over the swim deck. Suggest when slowing to idle, slow until you see the water just starting to reach the swim deck. Then increase throttle enough so your pulling away from the wave and slow down again

 

[Lou C]

Don't know what video that was, but...here are a few other things that V/P has done to combat exhaust reversion after the Vortec engines came out. Due to the changes made in them they were in certain installations more prone to reversion, which is when a vacuum develops in the exhaust system and actually pulls water up and into the exhaust elbow. The 4.3 V6 was more prone to this than the V8s (but this depends on installation factors)
What they did on the 4.3s:
changed the shape of the aluminum exhaust pipe that joins the rubber hoses coming off of the elbows to the Y pipe, they made this have a sharper angle, instead of a gradual slope, not sure if these will fit V8 exhausts though. I have them on my old pre-Vortec 4.3.
added a vacuum break valve that allows air into the exhaust system to reduce vacuum and the risk of that pulling water back up the exhaust. I think for sure you could at least add the vacuum break valves to your exhaust elbows.

All Products | iBoats

Since 1998, iboats is the most trusted water lifestyle online store for boat parts and accessories, boats for sale, and forums. Enjoy great priced products with fast shipping.

www.volvopentastore.com

later model exhaust on the V6 showing the vacuum break valves and alu exhaust pipes....

All Products | iBoats

Since 1998, iboats is the most trusted water lifestyle online store for boat parts and accessories, boats for sale, and forums. Enjoy great priced products with fast shipping.

www.volvopentastore.com

older V6 exhaust showing no vacuum break valves and original style alu pipe with the more gradual angle
note that the Y pipe on this still has flappers, which were a hold over from the original OMC design.

If I was going to repower my boat with a Vortec V6 for sure I'd add the vacuum break valves.

 

[DS_G]

Update as of today. Took the boat out last 2 weekends ago and it ran fine. I had 8 people total and did a few slow downs and the engine never hydro locked. So I thought the taller risers did the trick. Turns out I was wrong. Today took the boat out with 6 people and went for a 15 mins cruise at around 3-4k rpms then entered a no wake zone. Dropped it gradually to 1k RPMS and in about 3-4 mins the engine just shut off. Tried to turn it back on and nothing. Hydro locked again! I removed all the spark plugs and them looked okay. No water came out of the cylinders expect for cylinder 3 when I pulled out the plug water came gushing out. I then disconnected the fuel pump and the ignition coil and cranked the engine. Water did come out in all 8 cylinders. So again I have no idea what is causing my engine to hydro lock. Any other input would greatly appreciated.

As previously posted, a rapid Deceleration regardless of the cause, can pressurize the exhaust ports in a stern drive, causing backflow up to the level of the water pressure. Even with higher risers, a high-pressure water pulse is probably washing back into the engine. This is why you mainly see water in one cylinder, because as soon as this occurs in any cylinder, the engine will stop. If the engine is under any type of load then you can easily destroy a connecting rod piston or even crankshaft When subject to Hydro lock. Blowing a head gasket will also cause water in multiple cylinders.

From your description, it doesn’t sound like the engine cut out causing the deceleration but regardless of the cause, this phenomenon can occur. Is it not possible to install water shutters in your Y pipe? That is a near fool proof way to prevent backwash into the engine.

 

[Lou C]

As previously posted, a rapid Deceleration regardless of the cause, can pressurize the exhaust ports in a stern drive, causing backflow up to the level of the water pressure. Even with higher risers, a high-pressure water pulse is probably washing back into the engine. This is why you mainly see water in one cylinder, because as soon as this occurs in any cylinder, the engine will stop. If the engine is under any type of load then you can easily destroy a connecting rod piston or even crankshaft When subject to Hydro lock. Blowing a head gasket will also cause water in multiple cylinders.

From your description, it doesn’t sound like the engine cut out causing the deceleration but regardless of the cause, this phenomenon can occur. Is it not possible to install water shutters in your Y pipe? That is a near fool proof way to prevent backwash into the engine.

V/P decided to remove them in '99. There was a service bulletin, saying they were not effective in preventing hydro lock and can melt and block the exhaust if you overheat the engine. The latter statement is true not sure about the former, I have the same flappers in my '88 4.3 and never ever had a hydrolock from the exhaust. In this case the easiest thing to do would be to remove the exhaust bellows and fit an inboard style flapper over the exhaust housing flange.

 

[Scott06]

Which video?

The one I forgot to include the link to

 

[CaptnO]

As previously posted, a rapid Deceleration regardless of the cause, can pressurize the exhaust ports in a stern drive, causing backflow up to the level of the water pressure. Even with higher risers, a high-pressure water pulse is probably washing back into the engine. This is why you mainly see water in one cylinder, because as soon as this occurs in any cylinder, the engine will stop. If the engine is under any type of load then you can easily destroy a connecting rod piston or even crankshaft When subject to Hydro lock. Blowing a head gasket will also cause water in multiple cylinders.

From your description, it doesn’t sound like the engine cut out causing the deceleration but regardless of the cause, this phenomenon can occur. Is it not possible to install water shutters in your Y pipe? That is a near fool proof way to prevent backwash into the engine.

Yea I think shutters on the Y pipe would be a good idea or flapper somewhere, I speak to some techs if this can be done. I know Volvo got rid of them back in the 90's however Merc has always used them and I don't believe they had any issues. Maybe there is a kit I can find somewhere for the Volvo applications

V/P decided to remove them in '99. There was a service bulletin, saying they were not effective in preventing hydro lock and can melt and block the exhaust if you overheat the engine. The latter statement is true not sure about the former, I have the same flappers in my '88 4.3 and never ever had a hydrolock from the exhaust. In this case the easiest thing to do would be to remove the exhaust bellows and fit an inboard style flapper over the exhaust housing flange.

what do you by an inboard style flapper over the exhaust housing flange? I know where the Exhaust bellow is on my boat I believe I posted a pic of it earlier in this thread but what else would go there?

 

[Lou C]

Exhaust Flap 3"/3.5"/4"

Exhaust Flap 4" . Free shipping on all orders over $99 from WaterSkis.com

waterskis.com

something like that, to prevent water from washing up the Y pipe.
Does your engine have the vacuum break valves in the exhaust elbows? If not you can add them.

AFAIK there is no add on kit for flappers in the Y pipe, not that you couldn't adapt a set of OMC Cobra ones but you have to drill those holes in exactly the right spot. I have another idea but have to think on it for a while....

 

[CaptnO]

Exhaust Flap 3"/3.5"/4"

Exhaust Flap 4" . Free shipping on all orders over $99 from WaterSkis.com

waterskis.com

something like that, to prevent water from washing up the Y pipe.
Does your engine have the vacuum break valves in the exhaust elbows? If not you can add them.

AFAIK there is no add on kit for flappers in the Y pipe, not that you couldn't adapt a set of OMC Cobra ones but you have to drill those holes in exactly the right spot. I have another idea but have to think on it for a while....

So that flapper I could just install on top of the exhaust bellow or to replace the exhaust bellow?

I don't think the engine has a vacuum break valve in the elbows what would that look like?

 

[Lou C]

All Products | iBoats

Since 1998, iboats is the most trusted water lifestyle online store for boat parts and accessories, boats for sale, and forums. Enjoy great priced products with fast shipping.

www.volvopentastore.com

part #5, same for v6 & v8 as are the elbows.
you don't have an exhaust bellow that's an exhaust tube. remove the tube & replace with a flapper, if it fits ok over the tube & won't come off you could do that as well...

 

[CaptnO]

you mean that Tube is the only way water is going up the exhaust? that is the only area?

 

[Lou C]

you mean that Tube is the only way water is going up the exhaust? that is the only area?

yes, there are also idle relief ports in the bottom of the transom mount where water exits at idle but at sped most comes out that tube

 

[CaptnO]

how the hell is all that water then getting up into my engine from such a small diameter hole. that is crazy. I think a flapper there would definitely help.

Something like this would be perfect. Link here. It can go inside the tube so I won't have to remove that and it would add additional protection? Any negative about using something like this? maybe higher manifold temps? or it could restrict the exhaust a little?

 

[CaptnO]

Also these are my risers that I got - https://www.cecilmarineonline.com/3...er-elbow-11-3-3862627-in-stock-ready-to-ship/

Where would you add that purge valve to? There is a plug on the top and side I believe and where would the other side of the purge valve connect too?

 

[Lou C]

that looks like it might work. As far as how water gets into the engine, keep in mind there are really several sources....the engine while running has to have a steady flow of cool water pumped in by the impeller, naturally this gets exhausted 100% out the elbows, BUT, if reversion is happening, some of it gets sucked back up into the cyls. THEN, there's back flow that hits the transom of the boat when you slow down, and can run up the Y pipe. So there are actually TWO different sources of water that can wind up in a cylinder. Reversion, and back flow.
The other sources are blown head gaskets, or a cracked cyl head, but they will also cause other observable problems.

 

[Lou C]

Also these are my risers that I got - https://www.cecilmarineonline.com/3...er-elbow-11-3-3862627-in-stock-ready-to-ship/

Where would you add that purge valve to? There is a plug on the top and side I believe and where would the other side of the purge valve connect too?

Well given the problems you've had I probably would. See the thing is we don't know if it is mostly reversion, mostly back flow or a combination of the 2. So if you add that vacuum break valve (I can't believe VP charges $95 each for them!) and the exhaust flapper you have both possible causes covered. Just my opinion but others here may have good ideas in addition to this.

 

[CaptnO]

This is making sense now. So the back flow when slowing down is filling up the Y pipe with water pretty high and I could be having some reversion at lower RPMS which could be sucking some of that water from the Y pipe into the engine which is why it's happening a few minutes after getting off from plane and also why it has been so intermittent. I wonder if maybe I also need to pay attention to my trim level as well. If My trim is too high then that Exhaust elbow won't sit flush with the back of the outdrive and maybe allow more water to enter?

Also Scratch that one I sent you I took measurements and that one I sent fits into a 4in Exhaust tube. The ID of the exhaust Tube is 3" and the exhaust tube after the risers are 3.5"ID so I think my only option for that is the flapper you suggested and to remove the OEM Exhaust tube and swap it for the flapper however if I do this then there will be no tubing lined up to the back of the outdrive but I guess in theory that won't matter since the back pressure of the exhaust at higher rpms will keep the water out of there.

I can start with this flapper for now and test that out - 3" Flapper

 

[Lou C]

Sounds like a good plan…