load up your genset

Topic: load up your genset (Read 1633 times) previous topic - next topic

load up your genset

January 06, 2018, 11:01:04 am

I recently installed oil pressure and water temperature gauges for my genset. I've only run it a few times, so this isn't a very scientific study at this point. I noticed that it's not possible to warm up the genset in cold weather unless you load it up fully. Even with both rooftop units running on electric heat, the oil pan heater, electric water heater, refrigerator on electric, and the charger all running it still won't get to 180 degree water temperature. It can run for hours without ever warming up, even under a fairly heavy load. This concerns me because the oil has to get warm enough to boil off contaminants and moisture so acid won't form in the crankcase. It's possible that other gensets have a fan clutch or an electric fan controlled by thermostat, which should make it easier to warm up. I have the Onan (Cummins) 7500 three cylinder liquid cooled diesel. I think a smaller genset would warm up more under the same load. I think if you run your genset in cold weather you should load it up as much as possible and be sure to let it run long enough to warm up as much as it can under the circumstances. I wasn't even aware of this issue until I installed the gauges... Thought you'd wanna know about this.

Re: load up your genset

Reply #1 – January 06, 2018, 11:05:13 am

Sounds like a thermostat issue my generator will over heat and shut down when the fan isn't working.

Re: load up your genset

Reply #2 – January 06, 2018, 11:16:20 am

Quote from: craneman – January 06, 2018, 11:05:13 am

Sounds like a thermostat issue my generator will over heat and shut down when the fan isn't working.

Agree, on my 10 kw, radiator blower runs anytime generator is running , only thing that controls water temp is thermostat. Engine will warm up to 180 f in 30 min with one heat pump on.

Re: load up your genset

Reply #3 – January 06, 2018, 11:17:12 am

Temporary solution: put a big piece of cardboard over the opening where cooling air is sucked in. Old truck driving trick...

Re: load up your genset

Reply #4 – January 06, 2018, 11:28:55 am

No question, start by replacing the thermostat. They wear metal to metal. Probably original and getting cranky in its old age.

Re: load up your genset

Reply #5 – January 06, 2018, 03:27:50 pm

There isn't any thermostat problem, or any other problem. This thread was intended as a warning to anyone running their genset in cold weather to be sure it warms up completely, by fully loading it. If your genset doesn't have a temperature gauge you'd have no way of knowing that it wasn't warming up. People who seldom use their coach and start up the genset once a month to run it unloaded for a half an hour are especially susceptible.

Re: load up your genset

Reply #6 – January 06, 2018, 03:36:20 pm

Scott,

I am very familiar with these small diesels (in both RV generators and sail boat auxiliary engines).

Agree, they warm up slower than larger engines and certainly slower than gasoline engines, but it DOES sound like yours is taking way longer than normal.

So, while we all agree that exercising your generator requires at least 50% load, it should still reach operating temperature quicker than you experienced.

Re: load up your genset

Reply #7 – January 06, 2018, 04:06:22 pm

I, and many others, have an ir gun. You can point this at your water pump or thermostat housing before it warms up.
After warming up, {in my case about 30 min with a 20-25 amp load], thermostat will open and you can shoot the radiator hose intake area and get a reading. My generator is in a box so heat of combustion stays in the box and heats generator engine and electrical end quickly, until thermostat opens and sends coolant outside box to radiator. It may take a little longer in freezing conditions, but generator and your main engine are designed to reach optimum operating temps without fully loading them, which is probably not a good thing to do anyway, until they are warmed up.

Re: load up your genset

Reply #8 – January 06, 2018, 06:17:56 pm

I believe you DO have a thermostat problem because my Kubota reaches 175 within 10 minutes of starting no matter what the load is or what the weather is. It also stays within 180-190 no matter what, and based on the oil analysis I did on my last change interval, it is healthy and will last a long time. I was boondocking for over a month and racked up nearly 250 hours, and the other hours were after sitting in the sump nearly a year occasionally running for exercise but the analysis proves this is nowhere close to requiring an oil change yet.

Re: load up your genset

Reply #9 – January 06, 2018, 08:58:59 pm

I have installed gen set gauges, temp and oil press. I have never noticed the temp below 170 (after a 10 minute warm up) even when the temps were in the mid 20's last November while dry camping in the Pisgah National Forest. Only load at the time was the gas furnace and battery charge. Usually runs 180 - 200 no matter what the load is.

I have heard this mentioned on the forum before and wondered why? Isn't it the job of the thermostat to keep the engine at operating temp? I can understand an overheating problem, the thermostat can only open so far to increase coolant flow, but underheating?

Re: load up your genset

Reply #10 – January 06, 2018, 10:08:23 pm

Quote from: RvTrvlr – January 06, 2018, 06:17:56 pm

I believe you DO have a thermostat problem because my Kubota reaches 175 within 10 minutes of starting no matter what the load is or what the weather is. It also stays within 180-190 no matter what, and based on the oil analysis I did on my last change interval, it is healthy and will last a long time. I was boondocking for over a month and racked up nearly 250 hours, and the other hours were after sitting in the sump nearly a year occasionally running for exercise but the analysis proves this is nowhere close to requiring an oil change yet.

Have worked for companies that ignore the "manufacturers recommended oil change intervals" and gone exclusively with oil analysis results. When changing 75 or 100 gal of oil, an extra 500 hours between oil changes is a sizeable decrease in maintenance costs. They also use the results to schedule future repairs, as a rise or change in certain metals can indicate wear or problems in different parts of the engine.

Re: load up your genset

Reply #11 – January 06, 2018, 10:50:10 pm

Sounds like your genset is very well designed and all the components are very well matched. From there manufacturers will upsize or downsize capacity to keep the same components. Many thermostats have a bypass hole to keep enough flow to prevent the water pump from cavitation which destroys the pump impeller. This can lead to over cooling at low temps. I agree with Chuck cardboard over the radiator can help keep everything running at proper temps at low temps.

Re: load up your genset

Reply #12 – January 08, 2018, 12:35:38 am

The fan is pulling 25 degree air over the engine, and the bypass around the thermostat won't allow the water to shut off completely no matter how cold it is. It's the same thing when driving a commercial truck in cold weather. This is why truck drivers up North install a winter front over their radiator when it gets cold. For a real challenge ride an air cooled motorcycle in cold weather and try to get it to warm up properly. There's nothing wrong with the thermostat or anything else. This is normal for cold weather. I just wasn't aware of it until I installed the temperature gauge. I thought others would want to know about it so I wrote this thread. I'm not asking for advice about fixing a non-problem. When the weather warms up I won't need to fully load the genset anymore.

Re: load up your genset

Reply #13 – January 08, 2018, 01:40:51 am

Quote from: RRadio – January 06, 2018, 11:01:04 am

It can run for hours without ever warming up, even under a fairly heavy load.

I will venture to say something is definitely out of whack at only 25 degrees ambient. It's your machine care for it as you wish.

Re: load up your genset

Reply #14 – January 08, 2018, 02:00:00 am

Wonder what the cost of a new thermostat, gasket and some antifreeze is compared to a new genset?
Just saying.

Re: load up your genset

Reply #15 – January 08, 2018, 07:08:59 am

Well let's talk the ism and what I noticed driving in cold weather. I would normally be at 180-190 on my coach in the summer just driving along. I went south and the temps were 10 degrees and the coach was running 175-185. This is on both my coaches. I would see 190 on steep grades but after a while back to 175-185. So I was running ten degrees cooler. The transmission was 160 mist if the time. I believe the cold weather was responsible. I had new thermostat and radiator in the coach as well. Now that said my newer pickup runs just over 200 in the same temps. Go figure.

Re: load up your genset

Reply #16 – January 08, 2018, 09:46:15 am

if it's not obvious, you are speaking of Diesel Gensets, not gas. It is common for diesels to not get to temps unless under load. From my experience , I agree with you and don't necessarily think you have a thermostat issue. Load'em up !

Wantabe

Re: load up your genset

Reply #17 – January 08, 2018, 03:35:59 pm

I installed a generator temp gauge as well as a fuel pressure gauge. Ours is the same model as yours and has an engine driven fan. It will come up to thermostat temp fairly quickly with a moderate load, a little longer with no load. Sounds like your thermostat has a lower temp rating, perhaps missing or has lost it's way. A good way to tell is to remove it and stick it in a pan filled with water on the stove. With a candy thermometer, you should see it open at the temp stamped on the body of the thermostat.

Pierce

Re: load up your genset

Reply #18 – January 08, 2018, 10:17:04 pm

Quote from: Pierce & Gaylie Stewart – January 08, 2018, 03:35:59 pm

A good way to tell is to remove it and stick it in a pan filled with water on the stove. With a candy thermometer, you should see it open at the temp stamped on the body of the thermostat.

Pierce

Yep, that's what I did too..... wanted to see when it opened and how much it opened. Compared the old with the new.
Here's a photo of the one for the Cummins:

both opened close to the 180 set point, but the new one on the right opened a bit more.

Re: load up your genset

Reply #19 – January 08, 2018, 10:28:16 pm

Quote from: FourTravelers – January 08, 2018, 10:17:04 pm

Yep, that's what I did too..... wanted to see when it opened and how much it opened. Compared the old with the new.
Here's a photo of the one for the Cummins:

both opened close to the 180 set point, but the new one on the right opened a bit more.

Good pics, I can see if stuck on the open position, most of the cooling water would go through radiator and it would be difficult to get engine up to operating temps, no matter what the load is in cold weather.

Re: load up your genset

Reply #20 – January 09, 2018, 12:18:24 am

Quote from: jcus – January 08, 2018, 10:28:16 pm

Good pics, I can see if stuck on the open position, most of the cooling water would go through radiator and it would be difficult to get engine up to operating temps, no matter what the load is in cold weather.

Don't forget, thermostats are designed to fail open also, resulting in max. coolant flow.

Re: load up your genset

Reply #21 – January 09, 2018, 01:07:13 am

That's a very good point Moby, some things are made to fail open some things are made to fail closed. Depends on the device.

Re: load up your genset

Reply #22 – January 10, 2018, 11:55:25 am

Again, there's nothing wrong with the thermostat or anything else. This is normal behavior. The temperature gets up to about 175 degrees under a fairly heavy load even with 25 degree air blowing across the engine and the bypass allowing water to go around the fully closed thermostat. I wrote all about boiling the thermostat on the stove the other day on this forum. I have many years of experience as a mechanic and I even do my own engine overhauls. I've dealt with many bad thermostats over the decades. This is not a bad thermostat. I can't get my Detroit Diesel to warm up in cold weather without loading it either. Do I need to change both thermostats in it too? What about all the commercial truck drivers up north who put a winter front on their radiator to get their diesel engine to warm up, do they need to change their thermostats too? Do I need a thermostat on my air cooled motorcycle because it certainly won't warm up at 25 degrees even with a load on it. Most of you have missed the whole point. I guarantee if I replace the thermostat with a solid disc the engine still won't warm up at 25 degrees unless I load it up. I'm not gonna do that because the thermostat actually works and I learned years ago not to disturb a working thermostat because it's difficult to find one that works well... Just the other day someone on this forum told me the engine will overheat if I REMOVE the thermostat... no really!

Edited to meet TOS

Re: load up your genset

Reply #23 – January 10, 2018, 12:56:42 pm

Wow.

Re: load up your genset

Reply #24 – January 10, 2018, 02:31:44 pm

" I can write something important that's proven true only to get a bunch of foolishness from armchair RV owners who use their coach so infrequently that they have algae in their fuel and other "lack of use" problems. I'd kinda like to start a whole new RV forum restricted to full timers who have actual experience and know what they're talking about."

Well, that leaves me out, I'm full time but still learning.

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