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Oil Pressure Sender

Posted by Colin Becker 
Oil Pressure Sender
29 August, 2017 12:19

I'm having trouble with the oil-pressure gauge on Chang Sha.

Gave me quite a fright coming through Begnagh Bridge on Sunday. Suddenly realised the gauge was reading zero. Nothing, Nada.
(As a complete aside, I don't know who designed that bridge but they should be given a severe talking to! It's got to be one of the trickiest manoeuvers on the system to get through there with a big boat).

Stopped engine and investigated down in the dungeon but no obvious major oil leak or water in oil or anything else unsavoury. Turned on ignition again and realised the gauge wasn't even moving of the pin up to zero like it usually does so concluded that the problem was electrical.

Started the engine and let it idle for a bit and it seemed happy enough so we proceeded to Richmond Harbour.

Now I need to solve the problem.

I need to do a thorough check of the wiring to make sure I don't have a loose connection someplace but that will take a little time to achieve and I want to get ahead of the posse and at least have identified a source of spares.

The gauge seems to be a standard Vetus 8 Bar unit (24V) but the sender is somewhat of an unknown beast.

It has the legend 0-8 Bar on the hex-nut and 02.07 on the other side and the number 38029725001 on the main part of the body. Perkins/Edina in Dublin deny all knowledge of it's existence as do Massey Ferguson (the engine came out of a MF combine originally). Anyone any ideas where it came from ?

When I put an ohm meter across the terminal and body on the sender it reads 240ohm which I think is correct. I haven't yet tried that with the engine running but I think it should drop down to 100 or less.

My fall-back position is to replace the sender and the guage completely but that leads me to my second problem. I don't know what the thread is on the sender. I think it's either a 1/8 tapered NPT or an M10x1 tapered thread. Both seem to be possible on these types of units. Anyone any idea about the size used on the 6354 ? Or an easy way to tell them apart ? When I read the tables they are very close dimensionally.

Best Wishes,

GMY Chang Sha

Re: Oil Pressure Sender
29 August, 2017 22:52
Hi Colin
If you remove the wire from the sender and short it to earth it should result in a full scale deflection of the pressure gauge. The sender is a resistance that varies with pressure. That will test the gauge.

I can lend you a 1/8 ntpf sender (american range and 12v ) to help verify thread size if still needed
Re: Oil Pressure Sender
29 August, 2017 23:10
Hi Colin
Try on here if you need are placement sender, the oil pressure alarm looks interesting too.

Andy Jordan
Re: Oil Pressure Sender
04 September, 2017 10:35
Hi Colin
Did you get sorted as I might be able to help and not that far away from you (Longford) also McHughs do a fantastic range of Engine bits and pieces and they are 3/4 miles from Richmond Harbour
I have a sender from my Ford engine which was put on Incorrectly as I have 2 steering positions and the one fitted is for a single position ie single sender and is a 1/8 ntpf sender 24 Volt,

Edited 1 time(s). Last edit at 04/09/2017 12:25 by Robbie.
Re: Oil Pressure Sender
04 September, 2017 10:40
Hi Colin
The thread on the Perkins 6345 is usually 1/8 NPTF follow this link

This one I have used but working
Re: Oil Pressure Sender
04 September, 2017 11:13

The problem is solved. Thinking through the symptoms and talking to some knowledgeable people and taking counsel from this forum I concluded that the problem was more likely to be an open circuit in the system someplace. I removed the engine instrument panel from the console yesterday and did a bit of investigating and discovered it was as simple as a wire off the back of gauge. The original wire was just a smidgen too short and obviously had worked loose over the years. When I had peered at the back of the panel last weekend from underneath the console, I wasn't able to see the offending wire hiding in the loom but once I lifted the panel itself it was obvious. Les Saunders on 41M came to the rescue with a couple of spade connectors and a crimping tool and I made up a short extension to the wire and plugged it in.
Turned on the isolator and the ignition and the gauge came to life. Cranked the engine and voila, full oil pressure.
Then discovered I had no cooling water and spent an unpleasant half hour clearing a blocked intake pipe which involved getting soaked from the waist down when the offending clump of weeds suddenly ejected into the engine room followed by closely by a goodly bucketful of the fetid waters of the Royal Canal.

As an aside talking to the nice people in Union Chandlery in Cork I concluded that the sender I have is most likely a Vetus unit even though there's no indication on the unit to that effect.

But that's canal boating for you.

Thanks to all who offered advice and help.

Best Wishes,

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