Jimna 254 / Siromer 304 Oil Pressure Gauge

aesmith · Sep 2, 2018

Hi,

The oil pressure gauge isn't reading, absolutely no movement of the needle. As a quick check I confirmed power to the gauge, and continuity along the wire sensing wire to the sender. Second check I measured the resistance of the sender to ground. Engine off that reads 1400 or so ohms, dropping to 24 when the engine starts, and 17 when revved up a bit. Can anyone confirm what the readings at the sender should be? I'd like to whip the gauge out and test on the bench with suitable resistance simulated, and also if the gauge is dud I need to know what sort to replace it with.

Thanks, Tony S

aesmith · Sep 5, 2018

Alternatively does anyone know the thread where the sender installs to the engine? The most sensible way might be to replace both sender and gauge, assuming a "normal" sender can be made to fit. Thanks, Tony S

aesmith · Feb 21, 2019

Bump, just wondered if anyone had any info on this.

Wassa · Feb 26, 2019

Usually the sender is the issue. I've not seen a gauge fail, but have twice replaced a sender (two different tractors) and fixed the problem. Contact the UK Siromer distributor for a new sender.

aesmith · Feb 27, 2019

Thanks all. I haven't tried shorting the lead from the gauge but I'm going to whip the gauge out and test on the bench. I was thinking the gauge was more suspect as it doesn't move at all, whereas the sender shows variable resistance between engine off, idle or revved up. Local importer has both in stock so I might replace both anyway.

Does anyone know if the thread is standard 1/8" NPT?

Wassa · Feb 27, 2019

Sender thread is 1/4" BSP. I suggest you replace both gauge and sender with original parts, they are inexpensive and rarely fail.

aesmith · Mar 3, 2019

Thanks. I've just whipped mine off for a check, and mine is actually 1/4" NPT. A bit annoying because none of the parts offered for Chinese tractors look the same as mine, and none give the thread size/type in their descriptions. My preference would be to fit an industry standard gauge and matching sender, but they almost exclusively seem to be 1/8" NPT. (Edit the gauge is stone dead, completely open circuit when tested on the bench)

Trains1938 · Mar 7, 2019

HI, I have a Jinma 254 and none of the electric instrument gauges work except for amp meter. The amp meter shows a discharge when the glow plugs are turned on but never shows a charge when the engine is running. However, the battery seems to stay charged. Why don't any of the other gauges work? I know that the instrument panel gets it power through the head light fuse but I checked that fuse and it is good. What else could it be except the panel its self.

aesmith · Mar 7, 2019

Hi, realistically you are going to have to test as it could be any number of things, even could be a big coincidence and all gauges are dead. Does the rev counter work? What I'd suggest is picking one of the non-working gauges, probably which ever is easiest to reach, then first check it's receiving 12V when the ignition is switched on. On mine it's a red lead in each case and it chains from gauge to gauge. If it doesn't, then trace back where the lead comes from until you find the break. If the gauges are receiving power but not working then it's time to look in the other direction, is the connection to the sensor OK, does the sensor work etc.

By the way when I was messing around with the oil pressure gauge I found the fuel gauge started only working intermittently. The fault in that case was a bad crimp on the red wire that connected to the +ve post on the oil pressure gauge. Fitting a new crimp fixed that (although I'll have to change it again because the new oil pressure gauge has smaller posts.

Good luck and let us know what you find.

aesmith · Mar 9, 2019

I ended up replacing both gauge and sender with standard off the shelf parts. I think it's better having industry standard bits where possible, and in actual fact this gauge and sender together cost less than just the sender from the UK importer. The only modifications needed were an adapter from 1/8 to 1/4 NPT for the sender, and some new crimps to suit the terminals on the gauge. Will replace the temperature gauge as well in the same way when I get around to it.