1991 WLSP 12VDC 120VAC Build Sheets

[KenS]

Ned,

the color of the wire for the previous incident was blue with black stripe. It has a label of 21.

But, eureka!, I took your advice and started from the 12v box. Saw some splices and manipulated them and tried the start switch. Found one that responded. Reworked that 3-way connection and now all 4 gen start switches work as well as after-market tank monitor. I think the tank monitor power 12v+ comes from the gen start circuit so that would explain the correlation.

But, now that it runs, it overheats but this time doesn't trigger the hi-temp cut-off switch. Using an infrared/laser thing see weird things. Not sure which way coolant goes around? Driver side is cool like 100 degrees; top of head is 300+.

Have a new thermostat in there. Could be an air trap? Thinking I'll pull tstat and gauge sender and temp-cutoff and test in hot water. Other ideas appreciated.

Ken

[nbedinger]

The automatic high temp shutdown doesn't kick in until the sensor hits 265F. But the sensor is designed to be in contact with coolant, if coolant is low it will be slow to reach trip point.

And I'd say yes, it is wicked easy to get air locked coolant flow when you drain and refill it. Bleed all air out while you top off the coolant. Look for a petcock on the thermostat housing to bleed air or top up with the thermostat out.

Also any tiny slow leak of gen coolant will eventually catch you with low coolant! Safest practice to avoid overheats and low coolant is always keep a inch or two of coolant in the surge tank when cool. Check it when you run.

Now you can test that high temp shutdown breaker

Easiest test is run a wire from a ground to the overtemp sensor while the gennie runs. Hold it for a few seconds, it seemed to take a little time to kick the breaker on the DC control box. My original breaker didn't pass this test, but the replacement from Onan works.

Testing the overtemp sensor itself will be harder, stick the wet end of it in a shallow oil bath and bring it up to temp, checking it for open or closed circuit through the mid-200F range. You can find a replacement high/overtemp Onan sensor on the web if you think you need one. I bought one this year, not the exact one, but a cross-referenced or superceding model. All it has to do is close the circuit when it gets too hot.

For obvious reasons, the overtemp shutdown test won't work if you run the test lead from ground to the temp gauge sensor instead. They're both one-wire sensors threaded into the coolant stream, they look a lot alike, and they are just inches apart on the cyl head. Good luck

[Rick]

Ken, Since you had to work on the wiring I'd see if a wire is disconnected on the cooling fan. Remember our talk about our changing to the automotive type fan on our Alaska trip? Start the generator and check that the fan is running. If it's not, one of the wires has been disconnected. Call if it's not running and I'll explain how it's wired.

By the way, that temp sensor and the over temp sensor where new in May.

[KenS]

Rick, I think the fan is running but I'll check again. So my fan is 12v, not 120?

I think my heat problem is air and just have to work through it. Can anyone confirm that cooled water comes from the rad via the hose on the left/drivers side and hot water is pumped out the top and along the right side?

The temp gauge always reads high or is pegged. I put a new sensor in (not the cut off switch) which didn't help, so new gauge time for me?
Ken

[Rick]

your fan is 12 volt flat automotive rather than a AC fan. Many have changed over to this type cooling fan.

You have the flow of coolant right. Cool from the rad on the dvrs side. Hot down the pass side.

[Randy Dupree]

Ken,this is going to be a simple fix.
Unless you have lost coolant or "worked" on the cooling system,i doubt its an air pocket.
I would be checking the fan or checking the rad for dirt etc in the fins.

[KenS]

Sorry for time lag. Gen status as follows. I'm confused on temps:
starts and runs well with 2 AC unit load.
Temps seem high but no cut off. Readings are with infrared gun.
Top of engine/t-stat/temp cut off switch = 300 degrees
coolant down pipe to rad before Y up to expansion tank (cap off) = 157
expansion tank (cap off) 137
coolant down to Rad from Y above: 90 degrees (cool to touch)
left hose out from Rad to left side Pump 160 degrees
Tail pipe Exhaust is white; much output from breather tube.

[brhodes]

Tail pipe Exhaust is white; much output from breather tube.[/QUOTE]

One of the main causes of white exhaust smoke and coolant loss is a cracked or warped cylinder head, a cracked engine block, or head gasket failure caused by overheating. A cracked head may allow coolant to leak into one or more cylinders or into the combustion chamber of the engine.

There is a bleed valve on the bottom of the remote radiator which can be used to bleed off any air which may have entered the coolant system. Open this while the engine is running and bleed until there is coolant running out.

Ensure you are adding coolant while doing this and may need to do multiple times.

Also, once the coolant level is full and the radiator cap is off, do you see bubbling in the filler neck? If so, you could have an issue as described above.

Much output from the breather tube is more than likely blow by and another sign of an issue above.

Good luck

[KenS]

So, took it into my shop and they said the wiring to the fan was abraided as it was just run in there with no protection, although I thought the fan was working when I checked. Plus, wiring in the DC box for the breaker was missing or broken which means the over-heat sensor was non-op. The over-heat was working before; don't know how it went awry.

Anyway, the head is cracked. $1,500 plus labor. Could have been worse.

Water over the bridge, just wanted to ask if this sounds legit?

Also, should I consider a whole new, modern, gen-set and what's a ball-park on that?

Onward, Ken