Oil pressure senders Perkins 4.236M

[mtompson]

Hi all
I have a single oil pressure sender under my injection pump. It’s an old one that does gauge & alarm (three terminals)
I want new senders and they all seem to be either just for the gauge or just for alarms. So I guess I now need both? Looking at the attached pic, I notice a second nut to the left of my sender. Is this a location for a second sender?
Many thanks for your time.

[Bill O]

We have a 4.236 and have never seen an oil sender like that one.

From this listing for the oil sender and alarm combo, it appears you use the new style sender and hook up the alarm to it w/a single terminal.


Different subject. Did you recently purchase your boat and was that the one for sale in Oban??(nice boat)

[Bill O]

Was curious and looked around. This looks like your 3 terminal switch
https://shop.perkins.com/parts/elect...ensors/2846071


It appears the other one I previously linked does need to go to another separate oil port as you suspected.

[mtompson]

Many thanks, yes I think it was advertised in Oban, we got it about 3.5 years ago, it’s a great sea boat.

[a64pilot]

There are almost always other plugs into the oil galley so you can separate the switch from the sender, however if I could source the OEM part unless It was crazy expensive that is what I would do, switches come either normally open or normally closed, odds are yours is normally closed, senders however can have different resistance values, so you need to know the correct value to order one.

If its working I’d leave it alone, but order a spare, it may be hard to source off the beaten path. You may also measure the resistance of the sending unit and determine for certain that the switch is a normally closed one, and write both down in your engine log in the event that you had order another one, and your senders may be BSP thread too and not NPT, BSP can also be harder to find.

On edit, it’s also common for switches and sending units to have a very small hole that senses oil pressure, this is so that if the housing ever gets busted there won’t be a major oil leak, but a slow one. However a lot of “bad” switches and senders aren’t bad, just the hole is plugged and carb cleaner will often clean that hole out, just don’t get any in your eyes.
Years ago we had a Ford truck diesel that the hole would plug and set the low pressure alarm off, and that was a combo unit too, so you got got a low light and the pressure gauge reading zero, which scared me the first time it happened and stranded me, cause of course you always back up the light with the gauge and if both are low, that validates you really have no oil pressure.


However is it possible that sending unit is meant to drive two pressure gauges as in a separate helm? Pratt & Whitney Turbine’s do that if you have a dual cockpit aircraft and two gauges. Just wondering.

[barnakiel]

I remember buying decent aftermarket senders from VDO / Vetus.


They were sorted by pressures and then by the thread/size.


Look up aftermarket engine parts. I think you will find replacements.


b.

[Lancerbye]

On my Perkins 4 236 s a tee is used so both switch and sender can be used off the same oil port. they are 1/ 8 pipe fittings. This allows two separate devices and some redundancy.

[motretu]

when using more than one sender/switch unit on an engine port, engine vibration may cause a long nipple to fail. best to use a tube from the engine port to a sender/switch tree mounted somewhere on the engine.

[Gjoa14]

I think we got the same oil pressure sender on our Perkins 4.236, 3 Pins, reading gauge and alarm, made by VDO. As it is not working anymore we just ordered last week the sender from a Perkins distributor in Germany for 26€.
The german seller couldn’t explain me why on the US Perkins website the price is 144$ ?! But we are happy to have found it so much cheaper. Unfortunately right now waiting that the sender arrives, so can’t tell yet if it’s gonna work.

But just recommend checking for the sender at your local Perkins distributor.

[BruceS]

I had trouble fitting two on my old engine so used a grease gun flexible hose to remote fit a 't' piece & two senders.

[mtompson]

Thanks everyone! Some kind of tee, or a replacement, getting there. I’d appreciate a link to that German website if pos? Cheers guys

[Bill O]

Looked on our rebuilt 1988 4.236 and there was another bolt hole adjacent and same height as the other hole currently being used for the oil sender (port side under the injector pump). As A64 discussed this is an alternate port for another oil sender unit. Not certain if it is on all of the motors.

The reason I know it goes to the crank case is when we originally moved the boat, we had an oil leak/noticed a slow drop in oil pressure. There was no bolt in that hole and it was slowly leaking oil into the engine bilge. This could have been a big problem, but once we found a bolt to fit, no more oil leak.

[slug]

Originally Posted by mtompson

Hi all
I have a single oil pressure sender under my injection pump. It’s an old one that does gauge & alarm (three terminals)
I want new senders and they all seem to be either just for the gauge or just for alarms. So I guess I now need both? Looking at the attached pic, I notice a second nut to the left of my sender. Is this a location for a second sender?
Many thanks for your time.

Consult the VDO catalogue for replacement
https://www.vdo-gauges.com/sensors/pressure-sensors-switches.html

[mtompson]

Cheers Bill O, so maybe that’s the nut I mention in my original post, the image is rotated 90 degrees anti-clockwise.