Generator Fan Blower

[Jon Wehrenberg]

Tuga,

Why would you be concerned? Is the engine overheating?

If the engine is overheating I would make sure the belt to both the pump and radiator fan is intact. Assuming everything you check visually is OK I would run the engine and feel hoses for heat. The top radiator hose would be the heated water. If the engine starts showing an over temp and no heated coolant is flowing into the radiator my next step would be to verify the thermostat is opening. Removing it and placing it in water being heated and observing its temp at which is opens is all that is necessary.

If all else checks out then I would focus on the water pump. In my experience they leak but do not fail to pump unless the impellor has broken or separated from the shaft.

Before I sent my money to Kohler, I would take the pump to a local tractor dealer to see if they could match it. Yanmar engines are used on a lot of smaller diesel tractors and mowers.

[phorner]

Tuga,

I agree with Jon. You should be able by feeling the inlet and outlet hoses whether coolant is flowing through the radiator.

Although I've never tried it, I'm not sure you can "see" coolant "flowing". In my experience, when the coolant is heated and you open the cap, it just pours out under pressure from being hot.

What has "changed" that makes you want to explore your generator cooling system?

[merle&louise]

Jon & Paul,

The generator overheats (runs at 220 degrees) with 95 degree ambient temps. I tested the thermostat in a pot of boiling water - it opened. I installed a new one (after I tested it in a pot of boiling water) just to make sure. I removed the radiator and had it rodded and cleaned (twice). I flushed the system with Prestone Flush and rinsed it out thoroughly with water and filled with fresh 50/50 mixed.

I then brought it to Gulf South Armature (a generator repair shop) they removed the thermostat and ran the gen and watched for water flow - the water flowed strong. This was in May of this year.

I did the same test they did yesterday because I noticed higher operating temps. This is why I believe the water pump impella is shot.

I will check the hose temperatures with a IR thermometer today.

I will add one more observation: the operating temps increase steadily as the day goes on. As ambient temps rise so does the operating temp of the generator until it hits 225 and I shut it down. I NEVER see the temp gauge drop from the thermostat opening. This is why I feel that the water pump is not moving the water thru the system. Also, I can not see strong water flow in the neck of the radiator: only bubbles and still water.

[phorner]

Tuga,

I can only think of three reasons why coolant would fail to flow through your system: a stuck thermostat, a blockage of some sort (collapsed hose, air pocket, or such) or a water pump that has failed.

Was your generator running hot before you took it to the shop where they saw the coolant flowing freely? If they demonstrated that your coolant was flowing, and it still was running hot, there may be something else going on.

[Jon Wehrenberg]

An air bubble will stop a pump from working. Unless the system has been opened and drained since the time it worked properly that is likely not the issue, but don't rule it out. Our generators are notoriously hard to burp.

If you feel it is the water pump the easiest way, based on what you have done so far is to pull the pump and examine it. If the impeller is damaged or is slipping on the shaft it will be readily apparent. But if the impeller is OK and not slipping on the shaft then the system has blockage. The generator should cycle at the opening and closing temperatures of the thermostat and I seriously doubt that temp is 220.

If there is blockage, possibly due to a hose that has its inner plies separated and blocking flow it is possibly on the suction side. Hoses are cheap and unless they are brand new it might be good to just replace them before you pull the water pump. In that way you won't have to try to get a new gasket or face possible leakage around the pump, and you will have ruled out blockage.

[RussWhite]

Tuga,

This is NOT a recommendation, just a mention of what I do. As Jon says, air in the coolant system is a very bad thing. I have a couple cars with radiators in the front and engines in the middle - now that is a challenge to do a coolant fill and get all the air out. There are bleed screws all over the place and the directions for bleeding runs many steps long. I got frustrated with it and especially the first few trips after a fill as I was on pins and needles wondering if I got all the air out. Well, I bit the bullet and purchased a vacuum fill system and LOVE it. As you might guess, you just hook up to the fill opening with a modified cap, and after draining, start the vacuum pump. I vacuum down to about minus 26 inches of water, I think. I then let it sit there for a while as a leak check of the system and any hoses and clamps that I might have replaced or disturbed. If all is well, just slowly open the valve to the fill container and watch the coolant rush into the engine without spilling a drop! And no more worries about there being any air in there. Has worked like a charm for me. Russ

[Jon Wehrenberg]

Like Russ I also have a vacuum fill device. I have used on all sorts of vehicles that are diffiult to fill and it works like a charm.

On a recent generator coolant change I used it and never had to burp the system. The first time you use it it is kind of unsettling to watch all the coolant hoses get sucked flat.

[merle&louise]

I ran the generator this afternoon for 2 hours. Outdoor temperature was 95 degrees. Drawing 40 amps on Leg 1 and 35 amps on Leg 2. After the first hour a little antifreeze overflowed thru the tube that runs down from the neck of the radiator cap.

Using my trusty IR thermometer I shot some readings on the radiator hoses. I don't know which hose is the suction hose and which one is the return hose. Keep in mind the VDO gauge on the dash showed 200 degrees and did not move. There is no thermostat in the system; I removed it to see if the water was flowing.

The top hose - leads from thermostat to the top of the radiator - 170 degrees

The bottom hose - leads from the water pump to the bottom of the radiator - 160 degrees

I spoke to a mechanic with Gulf South Armature and he said it sounds like a bad water pump. I asked him about burping the generator and he said all he ever does is let it run with the cap loose adding water/antifreeze as needed.

Why does the VDO gauge read 200 degrees if the hoses are showing 170 - 160 ???

[Jon Wehrenberg]

It may be an error in calibration. I presume the generator system has an automatic shutdown i the event of an over temperature condition. The fact your gauge read 220 plus degrees but the generator did not shut down suggests the gauge is wrong. It would be interesting to take the temps at the temperature sensor that is a part of the automatic shut down.

However, if there is no thermostat I would expect lower temperatures. That is solely a guess so take the comment with a grain of salt. You did not have a big load on it. Assuming there is a correlation between the VDO gauge and the temp at the radiator it does seem when it waqs reading 220 at the VDO the outlet from the engine (top hose) was at 190, and that sure is not a concern, and the bottom likely was 180, something I think is too high. I would expect a greater than 10 degree temperature differential from inlet to outlet on the radiator. I also shooting from the lip on that comment and now my curiosity is going to get me to shoot some temps on mine to see just how much a radiator drops the temps.

[phorner]

I tend to agree that there should be more than a 10 degree drop in temperature through the radiator.

On mine, with the generator up to operating temperature (180), my top radiator hose is too hot to hold onto, while the bottom hose is almost cool... you can easily hold your hand on the copper pipe comfortably. In fact, mine was cooling so well I suspected a problem at first.