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

[Lou C]

Depending on how much tolerance you have for more hydro locks you could just change one thing at a time to answer the question what was the cause. So if the flapper solves it totally you know it was back wash/stern of boat too low if not then it’s solved with adding the vacuum break valves you’ll know it was exhaust reversion. There was a vid someone put up on you tube with clear plastic hoses so you could see what reversion actually looks like. This is why marine inboards cannot have radical cams with lots of valve overlap.

 

[CaptnO]

Yea i think that's the plan. I ordered ordered the flapper it's coming in on Tuesday. I need to call the Volvo Penta dealer and see about those valves to see how long it would take to get those parts just so I have them ready to go incase i need them. I rather have them and return them if I don't use them versus waiting another week or two for parts.

 

[CaptnO]

Installed flapper and it started over heating. We rev'ed it past 1k rpms and the engine started to cool down a little bit but didn't want to risk it over heating out in the water. Took the flapper back off and put the exhuast tube back on. I went out with a new mechanic that I hired and couldn't get it do die out. They did find some ground cables which were loose as well as my distributor cap. They also recommended that I replace my ignition coil as it looked old and rusted out. We cleaned up some of the ground cables to get the corrosion off and retighten them. For now I'll wait till Friday til I get my new ignition coil and some other parts then do more water trails.



They also definitely thought that my boat was sitting low as some of the drain holes were covered when I put my boat in at the boat ramp and they think that extra weigh could be from wet stringers or a wet transom but don't believe the issue of my engine just shutting off is part of that. They believe it's electrical.

 

[alldodge]

but don't believe the issue of my engine just shutting off is part of that. They believe it's electrical.

When it shuts down after coming off plane it has water in the cylinders and "they don't think that's the problem and its electrical"?

I'm scratching my head real hard right now

 

[Lou C]

I am surprised that it started overheating when you installed the flapper. VPs from '98-98 had the OMC designed flappers in the Y pipe and all Cobras had them till the end of production (1986-1998) and overheating was never a problem unless one actually dislodged & blocked the exhaust.
When the engine dies does it gradually lose rpm & start running rougher or just it just stop as if you turned off the key? If the former that definitely could be reversion/water rushing up the exhaust, but if the latter, might be something else. Mercruiser had a very good service bulletin on how to troubleshoot water in the engine, depending on the presentation...

 

[CaptnO]

When it shuts down after coming off plane it has water in the cylinders and "they don't think that's the problem and its electrical"?

I'm scratching my head real hard right now

The engine doesn't shut down right after coming off plane if that was the case then water coming in from the exhaust makes sense. This happens a few mins after coming off from plane NOT immediately. Sometimes it's a minute after, sometimes 5 mins after sometimes nothing happens.

 

[CaptnO]

I am surprised that it started overheating when you installed the flapper. VPs from '98-98 had the OMC designed flappers in the Y pipe and all Cobras had them till the end of production (1986-1998) and overheating was never a problem unless one actually dislodged & blocked the exhaust.
When the engine dies does it gradually lose rpm & start running rougher or just it just stop as if you turned off the key? If the former that definitely could be reversion/water rushing up the exhaust, but if the latter, might be something else. Mercruiser had a very good service bulletin on how to troubleshoot water in the engine, depending on the presentation...

Remember those flappers were at the top of the y pipe by the risers. This flapper that i installed replaced the exhuast tube where the outdrive is. Pics here https://photos.app.goo.gl/woZRc8XnfDJxJnBi6

I think maybe when putting the boat into the water from the boat ramp water pushed up against the flapper and kept it shut. Then while the boat was idling there wasn't enough pressure at low rpms to open it? We reved it to 1500-2k rpms quick and we think that got it flowing correctly. It went back to normal operating temp but we just cruised we barely only left the boat ramp and we decided to put the stock exhaust tube back on to make sure we don't add any additional issues to how the boat runs. I cruised for about 15mins on plane then slowed down to about 1k Rpms for like 5 mins and nothing happened . They were wiggling wires and everything and noticed the boat was running fine only thing was the few ground wires behind the engine block on port side which were loose and the distributor cap which they tighten everything down. I did a few more runs from plane to slow speed and couldn't replicate the problem today. We were out for about 1.5 hours.

When able to replicate the issue it is a sudden shut off like the key was turned off. No Sutter no hesitation nothing like that.

 

[CaptnO]

Put another 2 hours on it yesterday with no issues and plan on going out for 5 hours or so today. Here are some pics of the Old Ignition Coil that I replaced.
Pics here https://photos.app.goo.gl/Hk2cAa7DyRo3vur87

Only Thing I noticed was that my Starboard Side riser was warmer then my Port side. Supposedly my raw water pump has a small water leak and I don't think that was replaced during all prior work so I am going to throw a new one on there on Monday. That should keep the risers cool on both sides. My temps are always good though usually around 160-170

There is also some water coming in from the Transom so looking to get this fixed as well. I believe it just a seal which needs to be replaced. Video of water coming in.

New video by Orlando C Karpf (OCKarpf)

photos.app.goo.gl

 

[Lou C]

Well that’s good to hear because if the engine was losing ignition that alone could allow water to rush up the exhaust without the pressure of the exhaust to push it out.
That leak, well I’m not sure could be a few things like the steering arm seal etc

 

[CaptnO]

Yea so 4 days of back to back testing and it has been running solid no engine dying out. So I guess it was an electrical issue. Combination of lose distributor cap and ground wires. Replacing that old ignition coil definitely helped as well I believe.

I just didn't think that just cruising at 1k rpm 4-5 mph and engine dying out would allow water to come into the engine. I guess those dual props are moving a good amount of water even at that low rpms. Lucky my ignition problem was only happening while going slow as well.

So now hopefully I can enjoy the boat this season and work one the other small minors things and upgrades I want to do now with some peace of mind.

 

[Lou C]

I think you got it, there is a wall of water that comes up against the stern when you slow down, so it can happen that way. Combine that with no exhaust pressure pushing out the water and there you have it.
Still hard for me to accept that Volvo thinks no flappers is OK though.

 

[Scott06]

Yea so 4 days of back to back testing and it has been running solid no engine dying out. So I guess it was an electrical issue. Combination of lose distributor cap and ground wires. Replacing that old ignition coil definitely helped as well I believe.

I just didn't think that just cruising at 1k rpm 4-5 mph and engine dying out would allow water to come into the engine. I guess those dual props are moving a good amount of water even at that low rpms. Lucky my ignition problem was only happening while going slow as well.

So now hopefully I can enjoy the boat this season and work one the other small minors things and upgrades I want to do now with some peace of mind.

I understand pulling the kill switch at rpm will create hydrolock potential… both are killing the ignition…and i think engine can spin backwards when it sputters .

 

[alldodge]

Glad there are no issues but I don't believe killing the ignition will hydrolock a motor.

 

[CaptnO]

I understand pulling the kill switch at rpm will create hydrolock potential… both are killing the ignition…and i think engine can spin backwards when it sputters .

Wasn't the kill switch we checked this serval times. The ignition would just shut off randomly while cruising slowly. Never would die when moving fast 3k-4.5krpms and taking sharp turns etc.

Glad there are no issues but I don't believe killing the ignition will hydrolock a motor.

Yea I didn't think so either but I think my boat is still sitting low which would make it much easier for water to get inside even if the engine were just to shut off at low RPMs. But as long as the motor doesn't shut off any more I am happy. It just weird that it only happened a few minutes after getting off plane.

 

[CaptnO]

I think you got it, there is a wall of water that comes up against the stern when you slow down, so it can happen that way. Combine that with no exhaust pressure pushing out the water and there you have it.
Still hard for me to accept that Volvo thinks no flappers is OK though.

Yea I agree. I might try that flapper again just wanted to make sure we got the issue resolved. Ill do some testing with a hose and see what happens with the temps outside the water. Then do some runs in the water and see if it starts to overheat again. Might have just been an initial thing when I put the boat in the water from the boat ramp?