How add oil pressure gauge?

[massnspace]

Would like to add an oil pressure gauge to my Westerbeke W-40.

There is an oil pressure switch (sounds the alarm) already installed. I do not want to remove that (want to keep the buzzer sound). So where does the oil pressure gauge screw in?

David
Seattle

[Jim Cate]

In the past I h ave used a short nipple screwed into the port that the switch used, leading to a tee with the switch on one side and the connection to the gge on the other. Has worked as expected.

Jim

[massnspace]

Thanks. Where does one buy this tee fitting?

[Bowdrie]

Originally Posted by massnspace

Thanks. Where does one buy this tee fitting?

These people will have virtually any fitting you can imagine, and ones you've never heard of in all kinds of threads.
https://www.mfcp.com/locations/wa-seattle

What you don't want is a bunch of devices hanging off the engine on a little 1/8 to 1/4 pipe nipple, (a Christmas tree).
Better to run a short hose from the engine to a little manifold mounted to a bulkhead.
The said manifold can have sending units/gages/buzzers/switches, et all on it.

[Khaos13]

Most oil pressure gauge senders are MALE 1/8" NPT. (1/8" MNPT to be exact). The engine block fitting is often 1/4" FEMALE NPT. (1/4" FNPT).
These are simply abbreviations for male or female national pipe thread.

To keep it short and sweet, you'll need a 1/4" Male NPT to 1/8" Male NPT adapter. (Male at both ends). You'll also need a 1/8" Female NPT Tee. Screw the center tap on the tee to the adapter from the block. Screw the alarm sender in one end of the tee and the gauge sender in the other end of the tee. This shortens the "lever" produced by the weight of the senders.

I prefer stainless or mild steel to brass or copper due to the extra strength.

Do NOT use teflon tape as it could interfere with the ground which comes from the engine block.

Oil pressure gauges are often 0-100 PSI or 0-80 PSI. You should use the sender specified for the gauge's range.

[capt jgw]

Originally Posted by massnspace

Thanks. Where does one buy this tee fitting?

They're standard pipe fittings, any hardware store will have them. If you go to a real hardware store, not Menards etc, where the workers actually know what they're doing, they'll get you set up.

[tkeithlu]

Here go. The nipples you need will be on a nearby page. M-C's online catalog is a tree; work your way down from the general to the specific part you need.

https://www.mcmaster.com/products/th...=pipe+thread+t

[massnspace]

Thanks to all who helped. I will get a tee fitting and off we go!

David
Seattle

[NorthCoastJoe]

VDO makes a sender for gauge and alarm in one unit. No need for a "T" or extra plumbing.

https://www.amazon.com/VDO-360-006-P...a-571009045429

[massnspace]

North Coast Joe wins the prize. That seems like the way to go, a 2 for 1 sender.

Questions:
1. Are the threads on such a sender going to fit into my Universal M40 diesel?
2. The ones I see online sound an alarm when the pressure goes below 16 psi. I thought I read somewhere an idling marine diesel may be as low as 10. So, I don’t want the alarm sounding when just at idle. Will it, if it trips at 16?

[Wotname]

The VDO unit reference above has M10x1.0 thread i.e a standard metric 10mm thread. I don't know what M40 engine has but it easy enough to check if it a M10 thread by trying a M10 bolt in the existing sender port.

Additionally the unit has a trip point of 7psi which is IMO, ideal for a small marine diesel.

[Wotname]

Be aware that there are (at least) 2 different standards of ohmic range for oil pressure gauges. This VDO sender is a 10 to 180 ohm sender.

However VDO makes about a zillion senders so it is very likely they will have one with the same thread as your engine and with a suitable ohmic range for whatever gauge you intend to use.

[massnspace]

“Ohmic range”….

Love it!

I got it. Seems like most are 10-180, but I see others. I need a dash gauge as well, so I’ll match the ohms.

[stormalong]

Originally Posted by Bowdrie

What you don't want is a bunch of devices hanging off the engine on a little 1/8 to 1/4 pipe nipple, (a Christmas tree).
Better to run a short hose from the engine to a little manifold mounted to a bulkhead.
The said manifold can have sending units/gages/buzzers/switches, et all on it.

I have to disagree with this suggestion. A flexible hose is a potential failure point. If a connection fails or the hose bursts the engine oil will be pumped into the bilge. A metal nipple with a T on it is much more durable.

I had a leak from an oil cooler dump quarts of oil into the bilge. Not pretty. Especially when the automatic bilge pump dumps it overboard. Took months and a lot of washing to remove every trace of oil.

[skipperpete]

Originally Posted by stormalong

I have to disagree with this suggestion. A flexible hose is a potential failure point. If a connection fails or the hose bursts the engine oil will be pumped into the bilge. A metal nipple with a T on it is much more durable.

I had a leak from an oil cooler dump quarts of oil into the bilge. Not pretty. Especially when the automatic bilge pump dumps it overboard. Took months and a lot of washing to remove every trace of oil.

You are entitled to disagree but in practice the flex hose works perfectly, I use this manifold and hose hookup fairly often, mostly using non wire braid hose to isolate the senders rather than buy the above ground senders for insulated earth modifications but often to remove the “christmas tree” (as it was so eloquently described a few posts ago) to a safer location. Some engines use multiple gauge senders as well as hobbs switches to excite the additional alternators and its nice to have em in a neat row on the engine room wall rather than a cluster hangin off a shaky old Perkins, caterpillar or Ford. In ancient times, capillary tubes ran from the engine to the mechanical gauges and you’re right, they did leak, with messy results if you’re lucky and disastrous results if you’re not. I use either skinny steel reinforced hydraulic hose or high pressure synthetic tubing (2,000psi working pressure), never had or expect to have a problem. What IS a problem is for one of those crappy oil pressure switches to blow out, hidden, unseen and ….. because it blew out the contacts…. unheard down there, low on the engine block. At least with remote mounting you get a visual warning when that sucker goes down.