Generator Motor Shuts Off On It’s Own

[GarryH]

Any suggestions as to why Next Gen system shut off after about 20 minutes under load? 2021 R-29 vessel and Generator has 16 hours on it. Tried to restart without success. Turned over, but not sustainable. Checked: water exiting exhaust when motor was running, oil within dipstick range, diesel fuel available and both fuel filter canisters full and no apparent water visible. The motor and compartment was extremely hot, but no alarms. After about an hour with the generator motor off, it started immediately, but I shut it off after 15 seconds to prevent damage. Any thoughts or suggestions? Thank you in advance.

 

[dbsea]

Sounds like an overtemp shutdown to me, and the first thing I’d do is check the impeller. I’m sure others will have better advice than I though…

 

[gwishon]

I agree, overheating. Check the impeller. It’s not a difficult job.

Gordon

 

[BB marine]

Over temp shut down can be caused by 2 issues when talking about the NexGen. Yes it uses raw water cooling to cool the heat exchanger and the exhaust. This cooling system is a simple convection cooling. There is no circulation pump associated with the closed cooling system. The hot antifreeze in the block heat syncs to the exchanger where the raw water is cooling it. Theses engines run hot normally above 200 F and will not shut down until about 230F. There are two elements to this cooling system working properly. A good raw water pump and good fresh air flow in and out of the generator sound proofing. If one or both of theses components are marginal the generator engine will shut down from an over heat.

The fact that you get 20 minutes before a shut down under load and you are in Florida (based on your user information) I would inspect both issues. Replace the impeller, based on the trouble shoot description you do have water flow coming out of the exhaust port, so the pump is pumping but it may be reduced flow because of a worn impeller. The air flow issue is a common problem with many Ranger Tugs. The R29 has had issues with elevated generator temperatures which reduces the breaker capacity and will trip the breaker below its rating. The temporary fix for many R29 owners has been to install larger breaker. This works but eventually the elevated temperatures will destroy the Capacitor. Many Ranger Tug owners carry a spare. The poor air flow also effects the engine operating temperature. Remember the cooling system is a convection cooling system. This cooling system relies on good water flow from the raw water cooling side and good air flow in and out of the sound box. The Air circulation should come from the bottom of the sound box and be exhausted out the top with a mechanical blower moving a minimum of 125 to 150 CFM of air. The Tug manufacture did not follow through with these requirements. I have seen many R29 Tugs with the exhaust coming out of the bottom and the hose exhausting out of the compartment kinked and smashed. This is restricting the needed air flow for cooling. These generator installations are always operating on the edge of over heat. A raise in ambient temperature added to a impeller that is pumping at 70% along with restricted air flow coming out of the sound box equals an over heat. Install a new impeller and all is good ! Not really only one element of the issue has been addressed. Install a larger breaker and all is good! Not really only one element of the issue has been addressed. Install a capacitor all is good! Not really only one element as been fixed. Confirm Good water flow and good air cooling flow and the unit will operate flawlessly.

The bottom line If you install a impeller it may solve your problem for now. If you inspect the ventilation system and confirm that it is installed to NexGen specifications I believe this will fix the issue too. It will also allow the generator and motor to run cooler all the time. This will take the load off the electric generator and reduce the chance of tripping the breaker and destroying the capacitor.

I believe that boating in warmer southern waters this issue is seen more than boating in the PNW. The over heat issues are not noticed as much there. If Fluid Motion had most of their customers based in Florida they would probably be making changes to the install.

I mention all of this because we tend to fix the issues in the box and never look outside the box to address whole problem.

 

[it4llc]

I was/am having the same issue on our NextGen generator. Based on some other postings, I checked the anode and found it was somewhat eaten up - it hadn't broken off but there may have been some little bits that came off which might be clogging up the heat exchanger some. I also planned to replace the impeller based on prior posts. I started trying to figure out how to replace the impeller in advance of actually receiving the replacement part, but couldn't figure out how to get the flywheel/front of the pump off, so I called NextGen. They answered the phone right away and the guy on the phone was very helpful and knowledgeable. To replace the impeller, you need to access the backside of the pump by removing the water hoses. I also asked about flushing the generator, and he said that was probably also a good idea. His instructions for this were to run water into the raw water inlet at the top of the generator, and it would flow out of the hole where the anode bolts in (obviously assuming the anode is removed). However, he strongly cautioned that I should also remove the exhaust first to prevent any water from getting into the exhaust/muffler which could then come back into the generator and hydrolock it. Because we were boating in relatively warm water for us, I also asked if that could cause a problem by itself. He said that the only time they ever heard of water temp being too hot and causing the generator to shut down was from a boat in Bahrain, and that no water temps you would normally encounter would cause this. (Hopefully I'm relaying all of this correctly.)

So, I have the replacement impeller and am ready to do that this week. I had ordered replacement anodes but discovered they were the wrong thread size so need to try to figure out where to order them. As best as I can tell they are 24 threads/in but I can only find ones with 20 count online. If anyone has insight on where to get a replacement it would be appreciated.

 

[it4llc]

Further update on this:

- to replace the impeller, there are 2 bolts holding the water pump on. Loosening both of those bolts let's you take the water pump off, although still attached to the hoses. There is enough play in the hoses to twist the pump enough to be able to take the 3 screws off to open it up and change the impeller.
- I've got about 15 hours on our generator, and 3 splines were broken off. Replacing the impeller will be an annual maintenance item going forward.

 

[CaptT]

Thanks for posting this, I am in the process of replacing my NextGen impeller as well. Just received the new impeller and your posting will help a lot!
Regarding the anode, my boat came with 3 extras the PO had on board. They were packaged in a Fluid Motions envelope so you might want to check with them. Although they recently sent out a notice saying that they are getting out of the parts business but they still have a lot of parts to get rid of and may have the anodes available. If they don't have the part the people that work there are great in steering you in the right direction.
Terry

 

[it4llc]

When I talked to the guy at NextGen to ask what part/size it was to replace the zinc, he was surprised that I was just trying to replace the zinc portion - he said it usually doesn't come off so easily and most people just replace the zinc and bolt together. Mine did come apart w/o too much problem, but I couldn't find the right zinc alone and ordered the whole assembly to replace. I'm planning to do that tomorrow so we'll see if I have the right now...

 

[Pattystug]

We recently had a similar problem where our generator would quit after 5 to 10 minutes with no load. We checked all our systems filters, etc and after speaking to a NextGen rep we checked our impeller and it needed to be replaced. Gen is working ok now. You might want to check your impeller.

 

[Jfrano]

Also check that the air blower is venting, the generator properly. When the generator starts the blower starts automatically. Mine was not vented properly and I had symptoms as described.
Typically the starboard side rear white louver is the intake and the port side louver you should feel the warm generator exhaust .
These were typically installed by the dealers, so proper installation was hit or miss.

 

[Florida_Cruiser]

The impeller is easy to get to, and the change out is quick. You can purchase the anode directly from NexGen.

 

[GarryH]

Thank you for all of the responses. I am very sorry for the lengthy delay in an update. The authorized NexGen repair technician visited and replaced the impeller, anode and exhaust elbow. Also tested other various components. He said the impeller was “tired” but not damaged. Anode showed signs of pitting, but not bad. Replaced anyway. Elbow showed some buildup, but not severe. Replaced. Generator started fine, and sounded good per the technician. He asked me to run the generator with a load for about an hour after he left. I did as asked and it ran for 40 minutes and then shut down on its own. I called him and He said he was not sure what the issue is, but would return at some point. At that time, he wants the generator to be running and expects a failure. Hopefully he will be able to diagnose the issue at the point of failure. I am also going to pass on the comments provided in the postings. Thank you and I will keep you posted.

 

[Someday*]

Find out what the problem was?

My generator just started, ran for about 10 minutes and now won’t start.(nexgen) 2021 r29
Turns over but won’t start.

 

[Gypsy]

My Next Gen was shutting down after running 20 minutes. I replaced the impeller which was badly damaged. The generator would then run longer, but would eventually shut down. When I changed the impeller, I checked to make sure that there was no blockage from the pump to outside the boat. I also checked that there was no blockage between the intake strainer and the pump. In frustration, I pulled the pump and examined it on the table. What I found was that the intake side of the pump was clogged with bits of impeller. The clog was out of sight, so if you changed the impeller like you would normally do, you would not see the clog. My thinking at the time, was that if pieces of the impeller broke off, they would get caught exiting the pump. I didn't think to examine the intake side. Lesson learned.