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During the winter, I'm gonna be pulling the engine (Briggs 24HP twin) due to the oil sump gasket leaking badly. I'm gonna inspect and reseal the engine as well as take care of maintenance it needs as the tractor has +/- 600 hours on it and I know not all of the required maintenance has been done on it.

Although the engine is air cooled, I've been thinking I'd like to add a temperature gauge because I'd like to keep an eye on it. It hasn't been acting as if it's running hot at all, but since I'm gonna have the engine out and disassembled, I figured it's as good a time as any to add one. I was wondering if anyone has added a gauge to one of these engines, where you installed the sensor, and what brand sensor/gauge did you use? I've found plenty of sensor/gauge kits for water cooled models but they include sensors intended to be mounted in a cooling passage. I did find a head temp sensor that would be very easy to install (https://www.amazon.com/Cylinder-Hea...instruments+temp+sensor&qid=1604018011&sr=8-5) but it doesn't include a gauge and I'm not totally sure what it would need. My experience is with negative temp coefficient sensors but I haven't yet found time to determine if that's what this sensor is.

I was also curious if there's any other suggestions for what I should do while the engine is out. I'm planning to replace the steering shaft gear as it's stripped and the front spindles as they are worn. The tractor is in overall good condition, it just needs a little TLC.

I'm a professional auto mechanic and we also do plenty of small engine work at my shop so I'm not at all intimidated by anything on this mower - just need some tips and suggestions.

Thanks.

I'd recommend replacing the PTO seal also.
I've personally never heard of anyone adding a temperature gauge to an Air cooled engine, doesn't mean it can't be done. as long as the cylinder head cooling fins are clean of mouse nests and grass clippings, and you don't run the engine slow when mowing, the flywheel fan will keep it cool.
Might also want to put some anti-seize on the crankshaft PTO, so that way if you ever need to remove the pulley again you won't find it Rusted to the crank.

I've put a gauge on engines before by making a metal bracket for the sensor bolted close or against the block. Get the oil temp with this, heat will conduct through the bracket to the sensor with very little loss. Also did this for the hydro transmission to see actually how hot it runs, sensor down in the fins, around 120 degrees on a hot summer day. Kind of surprised me, thought it would be much higher.

Go cart racers have used this type of head temp guage for many years.
The most important temp is cylinder head temp.
You can also get temp guage kits that have an L shaped bracket that mounts a temp sensor and then is attached by a cylinder head bolt.

The last sump gaskets I changed, turned out to be the darn oil quick change plug. Lesson learned. I check them all now.

PTmowerMech said:

The last sump gaskets I changed, turned out to be the darn oil quick change plug. Lesson learned. I check them all now.

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The yellow EZ Drain ones? there's one on my cub, i'm going to replace it this spring with pipe and a cap.

I try to get customers to replace those yellow quick drains because they are always loose and leaking.

Thanks to all who’ve responded. This forum is a bit different from some of the others I’ve been on, so I’m not sure how to quote multiple posts at once (maybe not an option because I’m on the mobile site?) so here’s the next best I can do...

I meant to elaborate a little more on why I wanted a temp gauge - besides just being the kind of person that likes to monitor basic engine operating conditions (such as temp and oil pressure), part of my reasoning here is that I’d be able to see a potential problem before it causes damage. A temp gauge is an easy way to do that, because although I don’t know what temp it should be running at, I’ll be able to get an average temp as a baseline, then watch for it to be exceeding that temp as a warning sign.

Scrubcadet10 - I bought what should be a complete gasket and seal kit online a few months ago when I originally planned this project. After deciding to wait until winter, I put it in a place that I’m sure to have forgotten about by now and will eventually give up looking and buy another one , so I’ll make sure to have a PTO seal ready if my kit doesn’t already have one.

The only air cooled engine I can think of that had a temp sensor on it was my 1972 Honda 350 motorcycle. But I never needed to mess with that engine beyond a few minor repairs, so I’m not sure what type of sensor it was or where it was mounted.

Tom3 - thanks for the idea. Did you mount the bracket using existing studs or bolts, or some kind of epoxy (jb weld/other)? Was the bracket open ended (such as an L shape) or enclosed somehow?

Hammermechanicman - thanks for the suggestion to look at racing applications - wasn’t even on my radar.

PTmowerMech - I’m certain it’s the sump gasket that’s leaking. When I first got this mower, I could tell it had a bad leak but there was so much grime and dirt on the engine I couldn’t tell where from. I thoroughly cleaned it using hot water, then watched for the leak with the engine running - oil was definitely coming from the sump gasket. That said, I don’t care for the quick drain valves either - I’m considering replacing it with a ball valve or something similar that doesn’t rely on spring tension.

if you want to quote multiple posts, hit the 'Reply' button in the bottom right corner of each post

Scrubcadet10 said:

The yellow EZ Drain ones? there's one on my cub, i'm going to replace it this spring with pipe and a cap.

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I need to find or make a tool to fit those things. I can never seem to get the monkey wrench in some of those to get a good grip with enough room to turn them. I believe they're 15/16ths. But a socket doesn't fit over then, even when the plastic removed, because of those little nipples that slide into the plastic parts grooves.

Usually get to them with a crowsfoot wrench.

Gumby83 said:

During the winter, I'm gonna be pulling the engine (Briggs 24HP twin) due to the oil sump gasket leaking badly. I'm gonna inspect and reseal the engine as well as take care of maintenance it needs as the tractor has +/- 600 hours on it and I know not all of the required maintenance has been done on it.

Although the engine is air cooled, I've been thinking I'd like to add a temperature gauge because I'd like to keep an eye on it. It hasn't been acting as if it's running hot at all, but since I'm gonna have the engine out and disassembled, I figured it's as good a time as any to add one. I was wondering if anyone has added a gauge to one of these engines, where you installed the sensor, and what brand sensor/gauge did you use? I've found plenty of sensor/gauge kits for water cooled models but they include sensors intended to be mounted in a cooling passage. I did find a head temp sensor that would be very easy to install (https://www.amazon.com/Cylinder-Hea...instruments+temp+sensor&qid=1604018011&sr=8-5) but it doesn't include a gauge and I'm not totally sure what it would need. My experience is with negative temp coefficient sensors but I haven't yet found time to determine if that's what this sensor is.

I was also curious if there's any other suggestions for what I should do while the engine is out. I'm planning to replace the steering shaft gear as it's stripped and the front spindles as they are worn. The tractor is in overall good condition, it just needs a little TLC.

I'm a professional auto mechanic and we also do plenty of small engine work at my shop so I'm not at all intimidated by anything on this mower - just need some tips and suggestions.

Thanks.

Click to expand...

For your reader search for "K type thermocouple reader" Amazon.com has one for $10.49

Needed clarification on this since I’ve narrowed down one of 2 ways I want to set up the temp gauge.

The preferred option is the CHT sensor. Since the engine has 2 cylinder heads, do I have to have 2 separate gauges, or can I wire 2 sensors into one gauge? I realize that may only provide an average reading of both heads, which I’m fine with, but if it won’t work, I’m not interested in setting up 2 separate gauges.

The second option is to monitor oil temp - location for the sensor TBD.

Thanks.

So I put my search engine skills to the test and finally figured out that wiring 2 CHT sensors (type K thermocouples) in parallel will work on one gauge, but for the most accurate measurement, it’s important that the circuit resistance for each thermocouple is the same, as well as the materials used to make the thermocouple and wire. I also learned that a resistor can be added to each branch of the circuit to compensate for minor variations in circuit resistance due to different lengths of wire where the splices are made.

During my research, I found these 2 websites to be the most useful.

Thermocouple operation, types, and temperature to voltage correlation charts -https://www.thermocoupleinfo.com/

How circuit configuration affects thermocouple performance (this site is full of technical info - I plan to do more reading here when I have the time) -https://www.allaboutcircuits.com/textbook/direct-current/chpt-9/thermocouples/

Thanks again to all who contributed to this discussion.