Problem with 8kva NL Generator

[Chotu]

I forgot to add... When I fixed this same problem this summer, I ran soapy water through the freshwater part as well, with (I think) a vinegar base. Did this a few times to help clean out the head, as the last poster mentioned.

Trying to recall, but I believe I used straight gallons of vinegar and dish soap. Ran that through until overheat 2-3 times, then cleaned out the heat exchanger. Incredible amounts of gross brown stuff came out, so it must have done something.

The actual radiator flush stuff probably works even better.

[Chotu]

Not sure if we have the same heat exchanger, but my northern lights looks like this. See the little bronze looking thing sticking out on the right? That slides out quite easily and allows you to clean it and all the little holes. I'd imagine that all have a similar design.


This is what the heat exchanger core looks like after you slide it out. This is where all the action takes place so it's got to be very clean.

The black thing at the end is the rubber boot over the heat exchanger. Held on by hose clamps.

It's really REALLY simple to slide this core out and clean it. The most annoying part of the entire operation is draining and refilling the coolant. Lol

Worth cleaning this when you get a chance.

[Symphony]

agree with Chotu - I've done this and the worst part was draining the coolant without spilling.

be very careful around the sensors (like on the exhaust elbow), their wires are both touchy and expensive. I got lucky on my exhaust elbow and the sensor is good.

[Palarran]

I drained and refilled the coolant system 5 times today, once with vinegar. We ran the generator between fillings and it would get up to 205 then drop down to 200. The flushes came out looking like piss. Finally I was like, this is enough, refilled with coolant, and the system immediately started to run 5 degrees hotter. Started the water maker and under a 20 amp load (out of 30), it shut down within 10 minutes. Tomorrow I guess I'll take apart the coolant pump and remove the thermostat. It is very erratic, like up and down, constantly.

[a64pilot]

Best coolant is water, any dilution with anti freeze actually isn’t as good a coolant. Of course we can’t run pure water cause everything would corrode.
Removal of the thermostat may help, but I’m afraid you really do need if possible get that tube stack out and with it out try flushing though the passages of the heat ex. And of course clean the stack too, but ai’d suspicion your blockage may be getting into or out of the heat ex.
Of course raw water runs through the inside of the tubes and coolant on the outside.
It really really sounds like your heat ex is blocked.
Other than mechanical cleaning I don’t know what to tell you.

[Chotu]

Originally Posted by Palarran

I drained and refilled the coolant system 5 times today, once with vinegar. We ran the generator between fillings and it would get up to 205 then drop down to 200. The flushes came out looking like piss. Finally I was like, this is enough, refilled with coolant, and the system immediately started to run 5 degrees hotter. Started the water maker and under a 20 amp load (out of 30), it shut down within 10 minutes. Tomorrow I guess I'll take apart the coolant pump and remove the thermostat. It is very erratic, like up and down, constantly.

Don’t lose hope. It’s an annoying project. I know. Mine was doing the exact same thing. Same numbers. Same overheating. Same automatic thermal shut off.

It’s one of those things where you just have to do all of the things Possible and eventually one of them hits on it.

I think mine took two days. Two pretty long days.

I started at the seacock and went all the way to the exhaust mix elbow. And all of the fresh water cooling system as well. It was pretty maddening actually. I restarted it many times and had it overheat just like what is happening with you. Eventually, you’ll hit on one thing or do a combination of things that will make it work again..

After doing everything possible, mine now runs at 190° no matter what load I put on it. It does not overheat anymore.

The things I did were as follows.

make sure I had adequate row water coming in from the seacock,
make sure the impeller was working. Make sure the belt on the water pump was nice and tight. The water pump pulley should not be able to turn when you try to spin it by hand. The belt should prevent it from turning at all. If it does not, tighten that up.

I ran the vinegar through several times. As in, put fresh vinegar in with dish soap and Ranett I ran the vinegar through several times.. Then I drained all of the brown gunk out and ran it again. And then I did it again and again with fresh vinegar each time.

I pulled the core of the heat exchanger out and used pipe cleaner type things to clean the inside. I also clean the outside.

I replaced the thermostat.

I didn’t have a gasket so I use that crappy high temperature gasket stuff from the hardware store. It held. It held for hundreds of hours after.

I can’t tell you which thing I did made it work again. But after all of that, 190° all day long every day. Nevery an overheat.

Just keep hanging in there and keep at it. You will get it. Just keep in mind it is a system from one end to the other. There are only so many things that can go wrong. And you pretty much have to fix them all. LOL

[Symphony]

Once I cleaned out the tube bundle and replace the mixer I still had the problem. I finally found the Raw water intake hose had a slight crack just before the water pump, and that was pulling in enough air randomly to cause an overheat and the sensor to shut the unit down. Check the easy stuff first.

[Palarran]

Here is an update on my situation. I left Hope Town yesterday and am in Spanish Wells now so the internet is much better.

I ran vinegar through the system, took the thermostat out, still overheated, put the thermostat back in, still overheated, so quit working on it for about a week. Then I thought I'd give it one more shot and was going to drain the radiator but thought to check the level before doing so. It was low on water as this is what I've been refilling it with. Filled it up and the unit ran for quite a long time at 195 degrees before creeping up to 210. Shut it down and found after it had cooled that the water level was low again. This scenario has been repeated about 4 times now where it runs for 3 or 4 hours and eventually the temp increases, we shut it down, and it will be about 16 to 20 ounces low on water. I've looked everywhere for a wet spot on the block and under it and found nothing. Could it be evaporation? I'm getting some radiator flush in a few days and after using that will refill with cooling fluid.

Any ideas?

[tanglewood]

The hose clamps on the rubber boots on either end of the heat exchanger need to be tightened in the right order. Check the repair manual, but my recollection is that you tighten the inner clamp first, then the outer one. It's not obvious, but the boot serves double duty. It keeps the water inside the whole unit, but it also keeps the coolant side isolated from the raw water side.


Also, I apologize if this has been covered as I only skimmed the thread, but have you done a careful check of the exhaust elbow? They cake up with soot, rust, and other nasties over time, especially if the gen is run lightly loaded. They can look pristine from the outside, but be upper shirt on the inside. If it's choked up then water flow can be restricted.

[a64pilot]

It’s not evaporation, hopefully it is fresh water going out the heat exchanger, that would be better than a blown head gasket.

You did remove and clean the heat ex?

While you are there in Spanish Wells go by R&B boat yard and talk to Robert Roberts, he is a good guy, and what amounts to the town Mayor, I believe the name is conciliator or similar. He may not be a generator expert but I bet he may know someone who is, and he can get parts faster then most places, not sure how he gets them, but he does.
Don’t not go by and talk with him.

Is Spanish Wells OK? I assume they weathered the storm? Fuel available etc?

Seriously there are few people I trust, but Robert Roberts is one. Tell him I said Hi, he may remember me as the guy who changed out his black water thru hull and three way valve last year.

[GordMay]

Robert Roberts
Cell: (242) 557-7632
E-mail: Robert@RBboatyard.com
R & B Boatyard Office: (242) 333-4462

[Chotu]

Originally Posted by tanglewood

The hose clamps on the rubber boots on either end of the heat exchanger need to be tightened in the right order. Check the repair manual, but my recollection is that you tighten the inner clamp first, then the outer one. It's not obvious, but the boot serves double duty. It keeps the water inside the whole unit, but it also keeps the coolant side isolated from the raw water side.


Also, I apologize if this has been covered as I only skimmed the thread, but have you done a careful check of the exhaust elbow? They cake up with soot, rust, and other nasties over time, especially if the gen is run lightly loaded. They can look pristine from the outside, but be upper shirt on the inside. If it's choked up then water flow can be restricted.

In light of the current findings and given there are absolutely no other leaks, this is a good thing to look at.

Also as mentioned head gasket. Let's hope not.