Glow Plug Time and Glow Plug Life

[Sweden-Art]

Smalljobs: If you are looking for a heater I can recommend as Nuno did a tank style coolant heater with a built in circulation pump.

 

[Transit]

I disagree with your disagreement Greg. When I use glow plugs to start my 254, I keep the heat on until I see the current stabilize at 15 amps or 5 amps per plug, that is the hottest attainable from battery power. Which indicates that as the plugs heat their resistance increases, hence drawing less current.

One day, out of curiosity, I operated the plugs as a pyrometer with the engine running and the current draw was about 3 amps or 1 amp per plug. Although not very accurate without calibration nor a quality ammeter and outside its intended use. It dose demonstrate that the plugs are glowing at a higher temperature than expected. Now I cant say that is the case for every engine.

Back in school, power lab, we used pyrometers and other instruments to measure the combustion temperature and gas pressure as the piston moved within the cylinder, drew graphs and calculated the hp developed. Compared the thermal hp to the hp measured by a pony brake, than calculated the efficiency. That was way long ago.

 

[Bob Rooks]

Back in school, power lab, we used pyrometers and other instruments to measure the combustion temperature and gas pressure as the piston moved within the cylinder, drew graphs and calculated the hp developed. Compared the thermal hp to the hp measured by a pony brake, than calculated the efficiency. That was way long ago.

Here ya go Mike. I actually used to use one of these.
Marine engineers' handbook - Google Books

And that's PRONY brake.

 

[Diamondpilot]

Greg, I have a 6.0 qt system so maybe I was a bit undersized. My Kats is 5 years old or and I must have gotten a good one.

As for the high failure rate one thing I feel contributes to this is once folks install them they should run the tractor till it comes up to temp, about 80C, then top off the fluid. You must purge the air. Just like a hot water heater. I have seen many of them with failed elements when folks just install and fill with water. You should really run the water at all fixtures for 2-3 minutes to purge.

Chris

 

[Transit]

Yes Bob, thats the toy. We took a somewhat different approach more from the thermodynamic point of view, comparing the ideal power cycle graph to what was recorded from the instruments. Each leg of the graph corresponds to a different thermodynamic process, isobaric = constant pressure, isothermal = constant temperature, isovolumic = constant volume. As I remember the graph represented a 3-D picture of the power cycle. Lots of calculus, Gf/dx, partial derivatives.

Another principle that one may not be aware of is that the act of measuring effects what you are measuring. Huh?
Measure the current in a circuit with an inline ammeter, the ammeter has resistance, hence a voltage drop added to the circuit or measure the voltage across a resistor. The volt meter probes across the resistor are a parallel current path adding to the total current flow. Of course this equipment is designed to have minimal effects.

 

[Transit]

Good point Chris, I would think one would be running the engine under load to cycle the T-stat to open and close purging more air. Maybe not a fast enough flow rate causing the Kat to overheat?

 

[Bob Rooks]

Measure the current in a circuit with an inline ammeter, the ammeter has resistance, hence a voltage drop added to the circuit or measure the voltage across a resistor.

I use a high end shunt. Works great for my purposes.

 

[Smalljobs]

Kats lower hose heater: After installing my first one last year at this time, bleeding entire system, running tractor, topping off coolant etc........the Kats failed immediately. I'd bought it from Amazon months earlier and had no time that cold day to return it so I had to buy another one immediately. It worked last winter but I've not yet plugged it in again. As long as there's an alternative such as a properly sized Wolverine, I' won't buy another Kats product of any kind.

 

[Smalljobs]

Autozone relay is done and working. When I crimped a new eyelet connector on the original power to the bus strip I was amazed at how small the original wire was. Now, I have ten gage from the starter/battery lug right to the relay which is screwed to some angle iron framing on the tractor "fire wall". Another 10 gage goes to the newly cleaned bus strip. A small ground goes from the relay to one of the screws holding it to the firewall frame. When I turn on the key to glow, the relay reacts with a nice loud click and full battery power goes right to the bus strip. Since I have only one or none glow plugs working now, I still cannot start the tractor unless I run the Kats radiator hose heater.

I took a look at the oil pan and it has a raised diamond shaped foundry mark right in the middle. Since the driveshaft passes right under the pan, it's not easy to grind flush the foundry mark. The mark is raised around 1/32". There's enough space for two 3" X 3-1/2" Wolverine heaters but they don't come in that size. Their Model 9.0 is 125W and is a 3" diameter round design. Two of them would fit nicely and deliver 250 watts.

For now, my new glow plugs will come next week and that's the next step. Hopefully a pair of the Wolverine's will follow. I just don't trust that Kats heater quality and I don't want to have to replace it again on a cold winter day outside.

 

[greg_g]

My oil pans have a north/south tunnel to accommodate the front driveshaft housing. No place at all to install the 250w 3.75"x4.25" pad. So I went with a pair of 125w 1.5"x6" strips, one on either side of the tunnel. Didn't want two plugs, so I cut both off - and paralleled both strips into a single plug

//greg//