<html class="apple-mail-supports-explicit-dark-mode"><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">I’ve had a few oil pressure sending units fail. Granted, they typically were full failures and didn’t work at idle either, but I could see how the failure mode might be vibration induced.<div><br></div><div>I’d get a super cheapie oil pressure gauge at the auto parts store, or this:</div><div><br></div><div style="display: block;" class=""><div style="-webkit-user-select: all; -webkit-user-drag: element; display: inline-block;" class="apple-rich-link" draggable="true" role="link" data-url="https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html?hftm_sc=&hftm_source=google&utm_source=google&utm_medium=cpc&utm_campaign=21901271210&campaignid=21901271210&utm_content=171677806502&adsetid=171677806502&product=62621&gad_source=1&gad_campaignid=21901271210&gbraid=0AAAAADAHb4eil-ADMAET3vLnfQyDpklM-"><a style="border-radius:10px;font-family:-apple-system, Helvetica, Arial, sans-serif;display:block;-webkit-user-select:none;width:228px;user-select:none;-webkit-user-modify:read-only;user-modify:read-only;overflow:hidden;text-decoration:none;" class="lp-rich-link" rel="nofollow" href="https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html?hftm_sc=&hftm_source=google&utm_source=google&utm_medium=cpc&utm_campaign=21901271210&campaignid=21901271210&utm_content=171677806502&adsetid=171677806502&product=62621&gad_source=1&gad_campaignid=21901271210&gbraid=0AAAAADAHb4eil-ADMAET3vLnfQyDpklM-" dir="ltr" role="button" draggable="false" width="228"><table style="table-layout:fixed;border-collapse:collapse;width:228px;background-color:#5C5B66;font-family:-apple-system, Helvetica, Arial, sans-serif;" class="lp-rich-link-emailBaseTable" cellpadding="0" cellspacing="0" border="0" width="228"><tbody><tr><td vertical-align="center" align="center"><img style="width:228px;filter:brightness(0.97);height:228px;" width="228" height="228" draggable="false" class="lp-rich-link-mediaImage" alt="62621_I.jpg" src="cid:1DF74614-F4CD-4998-A5EB-F6B22C77B139"></td></tr><tr><td vertical-align="center"><table bgcolor="#5C5B66" cellpadding="0" cellspacing="0" width="228" style="table-layout:fixed;font-family:-apple-system, Helvetica, Arial, sans-serif;background-color:rgba(92, 91, 102, 1);-apple-color-filter:initial;" class="lp-rich-link-captionBar"><tbody><tr><td style="padding:8px 0px 8px 0px;" class="lp-rich-link-captionBar-textStackItem"><div style="max-width:100%;margin:0px 16px 0px 16px;overflow:hidden;" class="lp-rich-link-captionBar-textStack"><div style="word-wrap:break-word;font-weight:500;font-size:12px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-topCaption-leading"><a rel="nofollow" href="https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html?hftm_sc=&hftm_source=google&utm_source=google&utm_medium=cpc&utm_campaign=21901271210&campaignid=21901271210&utm_content=171677806502&adsetid=171677806502&product=62621&gad_source=1&gad_campaignid=21901271210&gbraid=0AAAAADAHb4eil-ADMAET3vLnfQyDpklM-" style="text-decoration: none" draggable="false"><font color="#FFFFFF" style="color: rgba(255, 255, 255, 1);">Engine Oil Pressure Test Kit</font></a></div><div style="word-wrap:break-word;font-weight:400;font-size:11px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-bottomCaption-leading"><a rel="nofollow" href="https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html?hftm_sc=&hftm_source=google&utm_source=google&utm_medium=cpc&utm_campaign=21901271210&campaignid=21901271210&utm_content=171677806502&adsetid=171677806502&product=62621&gad_source=1&gad_campaignid=21901271210&gbraid=0AAAAADAHb4eil-ADMAET3vLnfQyDpklM-" style="text-decoration: none" draggable="false"><font color="#FFFFFF" style="color: rgba(235, 235, 245, 0.6);">harborfreight.com</font></a></div></div></td></tr></tbody></table></td></tr></tbody></table></a></div></div><div><br></div><div><br></div><div>remove the sensor, and then hook it up to confirm if you have a real problem.</div><div><br></div><div>Spencer Yost</div><div><div dir="ltr"><br><blockquote type="cite">On Jan 22, 2026, at 10:44 PM, Dean VP <deanvp@att.net> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div class="ydpe2f2d0b6yahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:13px;"><div><div dir="ltr" data-setdir="false">Dean,</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">My guess would be a faulty sensor or a loose wire shorting out somewhere due to the vibration of the running engine. I sincerely doubt you have an oil pressure issue. Check everything around areas where your shop may have worked. I think they damaged or disturbed something while working on the other stuff. Is there any wiring that they could have disturbed? </div><div><br></div><div class="ydpe2f2d0b6signature">Dean VP</div></div>
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On Thursday, January 22, 2026 at 08:19:55 PM MST, Dean Vinson <dean@vinsonfarm.net> wrote:
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<div><div id="ydpe2f2d0b6yiv5888147905"><div><div class="ydpe2f2d0b6yiv5888147905WordSection1"><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;">Dean, ah, I see now how my sale of the 620 is coming back to haunt me. :) </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;">On the plus side for green tractors, my 3020 runs like a top and is standing by in the barn with the rear blade attached, ready for the snowplow duty that per the weather forecast looks mighty likely in the coming few days. Moving 8 or 10 inches of snow with a rear blade is not ideal but it beats relying on my scoop shovel.</span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoPlainText">(Speaking of not ideal, the high temperature for the day after the snowstorm is currently forecasted to be 7°F and of course the 3020 is an open-station tractor. “Cab by Carhartt,” as the saying goes.) </p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;">The oil pressure warning light issue on the Ford 3600 does concern me a little. The idiot light comes on when the key is turned on but prior to starting the engine, exactly as it should to demonstrate that the circuit is intact and the bulb works, then goes off once the tractor starts and oil pressure builds enough to open the pressure sensor switch. The only surprising part is that the light comes back *<b>on</b>* when I throttle up. One possibility is that there is a glitch causing a “false positive” warning light even though oil pressure is fine. The other is that the sensor and wiring are functioning exactly as intended and oil pressure is for some reason dropping.</span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;">Today I added about a third of a quart of oil to bring it up to the “Full” line on the dipstick, and I removed, inspected, reconnected, and fiddled with the idiot light wire where it clips onto the oil pressure sensor just to make sure it felt secure. Neither of those actions stopped the warning light from coming on as soon as I throttle up past idle, but it seemed worthwhile to try them just in case.</span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;">The repair shop hasn’t called me back yet, so I’ll follow up with them tomorrow. The timing of this issue—literally popping up in the first few seconds after they brought the tractor back to me after working on it—makes me wonder if something they did somehow caused this, maybe by aggravating an existing problem enough to push it from “this is going to fail soon” to “this has failed.” But maybe it’s just a coincidence. Either way, I can’t use the tractor with the oil pressure warning light on.</span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;">Dean Vinson</span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;">Saint Paris, Ohio</span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span></p><div id="ydpe2f2d0b6yiv5888147905yqt62570" class="ydpe2f2d0b6yiv5888147905yqt1145589489"><div><div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in;"><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><b><span style="font-size:11.0pt;font-family:sans-serif;">From:</span></b><span style="font-size:11.0pt;font-family:sans-serif;"> AT <at-bounces@lists.antique-tractor.com> <b>On Behalf Of </b>Dean VP<br clear="none"><b>Sent:</b> Thursday, January 22, 2026 2:36 AM<br clear="none"><b>To:</b> Antique Tractor Email Discussion Group <at@lists.antique-tractor.com><br clear="none"><b>Subject:</b> Re: [AT] One of those days</span></p></div></div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"> </p><div><div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">Dean,</span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">I've had all too many days like that. it can be exasperating. As I get older, they seem to come more often. Lost items can usually be better described as misplaced items. Absent minded excellence. I'm really good at that. But in your case, it is all because you sold the JD 620. If you had sold the M you would only have had 5 nuts to contend with rather than three, but the advantage is missing one out of 5 is not nearly as serious as one out of three. But eventually you will see the light! :-) </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">But I will admit I have never had the light sequence you are experiencing. Probably because JD did not use idiot lights on the two-cylinder tractors. But it is exactly opposite of what one might expect. Is it possible that with your multiple tractors you have forgotten how this one is supposed to work? I don't recall any piece of machinery that that has worked like that except my JD 750 Compact Tractor. It has a light on the dash that turns on when the key is turned on and stays that way and is not dependent on RPMs. Since I too have multiple tractors and this is the only tractor that works this way, it has more than once caused me to stop and question what is wrong. Then I realize this is the way this one works. </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">I cannot think of an oil pressure sensor could possibly fail backwards. This will be interesting when you find out what is going on.</span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">The other Dean in AZ</span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">Dean VP</span></p></div></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div id="ydpe2f2d0b6yiv5888147905ydpcd80734fyahoo_quoted_9638964519"><div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">On Wednesday, January 21, 2026 at 04:53:43 PM MST, Dean Vinson <<a shape="rect" href="mailto:dean@vinsonfarm.net" rel="nofollow" target="_blank">dean@vinsonfarm.net</a>> wrote: </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;"> </span></p></div><div><div id="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656"><div><div><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;">Minor tinkering today with my Farmall Super M, chainsaws, and Ford 3600. Nothing quite went as expected.</span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;">This morning I went into town to pick up the Super M’s right front wheel, which a local tire shop had finished pulling thorns out of and putting a new tube into. When I got home I went to put it back on the tractor, which is sitting by itself on the (relatively) clean concrete floor in the far corner of my enclosed shop. Got the rim in place and went to bolt it back on, only to discover I was short by one nut. Neat little pile of hardware on the floor right where I’d left it, three bolts, three lock washers, but for some reason only two nuts. Couple of wrenches nearby but nothing else, no junk, no random stacks of supplies or half-full jugs of engine oil, nothing to camouflage the presence of the missing nut. (My shop is not exactly short of any of those things, but they’re all over on the other side near the workbench where I spent most of my time, not here where the tractor’s been sitting.) I got down low and looked, picked up the wrenches and put them back down, checked under the other front wheel, checked the area, nothing. Big dang nut for a 5/8” bolt just disappeared. Scratched my head for a minute but soon enough gave up and went back into town to visit the local hardware store for another nut. Problem solved, tractor is now all back together.</span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;">Next task was to clean up my two chainsaws and figure out why one of them wouldn’t start last time I tried to use it. I take both with me when I’m clearing osage orange and honeysuckle from the old overgrown pasture. The newer saw cuts clean wood, and the older saw with a no-longer-fresh-but-still-halfway-okay chain cuts stumps down low and serves as the backup in case I get the other one pinched. Last time I went out I absolutely could not get the #2 saw to start, but it’s been an egregiously long time since I cleaned (much less replaced) the air filter. So today I got the saw all cleaned up, and also cleaned up the other one while I was at it, but didn’t see anything that looked bad enough to keep the saw from running. Scratched my head for a while and then finally thought to check the fuel tank, which of course turned out to be bone dry. Last time I went out I must have somehow forgotten to fuel that one up. This was mildly funny to me today, but it had not seemed so last week when I was out there in the woods yanking endlessly on that starter rope and scaring away wildlife with a loud string of curses.</span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;">Last task was to take delivery of my Ford 3600, which for several weeks had been at a local shop for an overheating problem. The shop’s diagnosis, as written on the completed service order, was that the “coolant was nasty and radiator was almost plugged.” They removed the radiator, sent it out to get cleaned, then put it all back together, function checked it, and brought it back to me late this afternoon. After their driver started it up and idled it backwards down off his tilt-bed truck, I went to put it in the barn…and as soon as I throttled it up past idle, the oil pressure light came on. I tried throttling down again and then back up, and shutting the tractor off then restarting, but same thing every time: Charging system and oil pressure lights come on when key is turned to the “run” position, then both go off when the tractor starts, but the oil pressure light comes back on at anything above a moderate idle and goes back off upon returning to idle speed. I checked the oil level and it’s about halfway between “Full” and “Add” on the dipstick, so I wouldn’t expect it to just be an oil level issue. Their driver hadn’t left yet so he called his service manager and gave him the rundown, but by then it was nearly five o’clock so the plan is they’ll call me in the morning and figure out the next step. I won’t need the tractor for anything until springtime, but still, dagnabbit it I was looking forward to having them all back home and in one piece today. :)</span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;">Oh, and of course, as I walked back through the shop to close up the doors and turn the lights off, I stumbled across that missing nut about 15 or 20 feet from where the Super M is parked. Maybe I somehow kicked it over there without realizing I’d done so, or maybe a cat had been entertaining itself, who knows. But now I have an extra 5/8” 11-pitch nut in a shop drawer, in case I ever need one.</span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;"> </span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;">Dean Vinson</span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p><p class="ydpe2f2d0b6yiv5888147905ydpcd80734fyiv8063073656msonormal"><span style="font-size:11.0pt;font-family:sans-serif;">Saint Paris, Ohio</span><span style="font-size:10.0pt;font-family:sans-serif;"></span></p></div></div></div><p class="ydpe2f2d0b6yiv5888147905MsoNormal"><span style="font-size:10.0pt;font-family:sans-serif;">_______________________________________________<br clear="none">AT mailing list<br clear="none"><a shape="rect" href="mailto:AT@lists.antique-tractor.com" rel="nofollow" target="_blank">AT@lists.antique-tractor.com</a><br clear="none"><a shape="rect" href="http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com" rel="nofollow" target="_blank">http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com</a></span></p></div></div></div></div></div></div></div></div><div class="ydpe2f2d0b6yqt1145589489" id="ydpe2f2d0b6yqt58149">_______________________________________________<br clear="none">AT mailing list<br clear="none"><a shape="rect" href="mailto:AT@lists.antique-tractor.com" rel="nofollow" target="_blank">AT@lists.antique-tractor.com</a><br clear="none"><a shape="rect" href="http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com" rel="nofollow" target="_blank">http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com</a><br clear="none"></div></div>
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