Hydrolock after towing

[acdfpic]

Due to the loss of my transmission on my RT 25SC with the D3 150 hp, I had to get towed in. I’m on the Great Loop in Michigan, and my first tow was by the Coast Guard in 3 to 5 ft seas. I have detailed this on the Facebook Tugnuts page, so I won’t go into all the details now. They towed me into a port without any repair facilities, and so it took a further tow to get me to the repair facility. We had to wait almost a week for good weather conditions, but finally had a 50 NM, 9-hour tow to get to Cheboygan, MI where I could get the transmission replaced. I’ve detailed the transmission issue in another thread.

After replacing the transmission, we went to start and it was immediately apparent that there was something wrong…wouldn’t turn over and just clicking. We suspected hydrolock right away. The injectors were pulled and sure enough there was water in one cylinder. It took a fair amount of time to get all the water cleared out of the exhaust system, but afterwards the engine started and ran fine. Stopping as soon as there was a problem was probably the key to not having any other damage. We also did an oil change before running the engine. If we find any evidence of water in the oil, we will do another change in a few hours.

So what caused the hydrolock? During the entire tow, the thru hull was closed. There was just about no wave action the day we towed her, so there probably wasn’t pressure enough to force water up through the exhaust. The only other water source was the cooling line to the prop shaft packing. It looks like with the prop slowly turning as it was being towed, that water might have been pumped up into the exhaust system. Looking at some old Tugnuts pages, it appears that some with the Yanmars have had this problem in the past. It may have been a function of the length of the tow as well. Just a little bit of water, over a 9-hour time frame can add up.

I hope that I never have to be towed again, but if I do, I will clamp the cooling line closed and tie the prop shaft off so that it can’t rotate.

Chris Boyd
2014 RT 25SC
Destined Nomad
Facebook Group: Destined Nomad

 

[BB marine]

The D3 sits low in the boat and I found the exhaust hose elevation to be marginal going across the transom. I measured it to the Volvo Specs and found it slightly below what was recommended. I Emailed Fluid Motion and they said it was ok. I still raised the hose 2 inches higher. This probably was not the reason for the water injection but may have contributed. The water cooled packing line may also be a contributing factor. When there are marginal installations recommendations followed it is not one factor that causes the issue it is several. The holes in the cheese line up and the result was water ingestion in the engine. It sounds like you were aware of the through hull needing to be closed so the issue was not has bad. One cylinder with water is bad but still an issue if not found. Good luck I hope you have smooth sailing from now on.

 

[Cutwater28GG]

There are a few posts on this in the past. If I recall, if you tow, shut the seacock

 

[dclagett]

Chris,

Looks like I got hit with the same problem resulting from my transmission failure. With all SEACOCKS CLOSED I was towed 10 miles last September to the repair facility that installed the new transmission. While preparing for launch last week in the process of replacing the timing belt it was found that the crankshaft was hard to move. Further investigation found water in the engine and exhaust system full of water. I wish I had seen your post prior to having the boat towed. It doesn't make logical sense to me that water will backup the shaft log while being towed forward, but that is the only explanation I have also. The yard will be pulling the engine to determine the extent of the damage.

Dick

 

[BB marine]

Dick, sorry to hear about the additional issue that you are experiencing. I have followed all the issues that you have had with your Tug. I hope that the damage is minimal but I would expect that if Salt water has been sitting inside the pan and cylinders since last fall a rebuild at the least will be required.

The Tugs and Cuts with inboard engines are very susceptible to water intrusion while being towed. The hull design allows for a low engine installation. There are Volvo and Yanmar engine installation specifications that are required to help eliminate this issue. Unfortunately even with the specifications marginally met there is still a chance for water to enter the exhaust if there is a water path open. Exhaust outlet, water inlets and packing glands all have raw water entries to the engine. Under the proper conditions the engine can have water intrusion while not running and being towed.

I found my exhaust hose mounted 2" lower than Volvo's specification. This hose comes out of the muffler and then ran across the transom. Cable ties were used to hold it in position. There is a specification of bottom of the hose 4" above the water line when the boat is fully loaded floating in the water. The photo below puts it right at 4". The original installation had the top of the hose even with the top of the transom cross support which is 4" above the water line. This never presented an issue but it could have under the right conditions. I cut the Tie and lifted the hose to have the bottom of the hose even with the cross support. I wanted to make it higher but this would have required installing a longer hose. The boat was only in service for a year when I found this so the hose was new and hard to justify replacement at my cost. I spoke with Fluid Motion and they said it was fine the way I had it adjusted. Once I got the hose in place I did install more cable ties to make sure the hose did not fall to a lower location as I believe it did before.

gallery2.php?g2_itemId=68972

After you get the engine back together. I would suggest acquiring a Volvo D3 engine installation manual and confirming all Volvo specifications were met. I would assume they were but it doesn't hurt to check.

This issue has been posted before on TugNuts. Unfortunately it is not something that is looked for until it happens. I know several Tug owners that have experienced the same as you. Many required new engines others were able to pickle the engine in time and save it. Some lucky to get the Tow Boat US company to reimburse for damages others did not.

I hope all works and you are on the water enjoying your boat this summer.

 

[knotflying]

Speak to your insurance company. If there is engine damage you may have a legitimate claim.

 

[DBBRanger]

There's been posts about this in the past. One point that was brought up is that pulling the plug/cap on the muffler will drain it in the event that water does get into the exhaust system. Are there any issues with doing that prior to towing? I would also expect to close the seacock, clamp the hose to the cutlass bearing and stop the prop from turning. But it seems draining the muffler during a tow is the ultimate protection against hydrolock. Is that right? For some that may not be easy and I do agree with others that the threads can be cross threaded if not careful.

 

[dclagett]

Thanks, Brian, for the information on possible exhaust component to my problem. I will look at the installation very closely and correct before putting the boat back in service.

DBBRanger, I knew about closing the thru hull to stop water ingestion and tie the shaft to keep from turning so you don't damage the transmission, however pinching off the cooling line to the packing material and the exhaust component is new to me.

I have not done a lot of research on other manufactures in relation to this problem, but when I talk to mechanics and read recommendations from marine groups on in water towing, it seems like pinching off cooling lines and draining mufflers are unique to Ranger/Cutwater boats. I would think that a responsible boat manufacture would put out a service bulletin once they found out their boats require special attention prior to towing.

Dick

 

[GaylesFaerie]

I wonder if another piece to an overall solution might be an exhaust plug at the water line where the exhaust exists the boat. During winter I see a number of inboards with round foam plugs in their exhaust outlets to keep critters and salt air out. Seems like putting one of those (small enough and light enough to carry onboard) in the exhaust behind the flap before towing would keep water out of the exhaust system. In concert with opening the muffler drain (in case water does make its way past the plug), crimping the cutlass bearing water feed hose and shutting the seacocks, maybe that will do the trick? Gary

 

[dclagett]

Gary, I think plugging the exhaust port prior to towing is a good idea. It should be easy kneeling on the swim platform one could stuff even a towel in and keeping a small portion visible for verification it is still in place. However, I still want to verify the exhaust system meets engine manufacturing specifications as Brian suggests. What else could go wrong with a marginal exhaust other than towing?

Dick

 

[GaylesFaerie]

However, I still want to verify the exhaust system meets engine manufacturing specifications as Brian suggests.

Oh, absolutely. I wasn't suggesting you not. Just like thinking about the challenge from various angles. G