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Kabunza · 30-11-2020, 21:13

I have a Pearson 36-2 with a Yanmar 3HM35F w/ type B panel. Recently the oil pressure buzzer and light have been behaving intermittently.

They only seem to come on once the engine is warm. Not while the engine is running of course, but just prior to starting the engine or when I shut it down. I've checked the buzzer and each input seems to trigger a sound. I'm not sure if the same happens with the temp. When it works, it works great. Nice bright light and loud buzzer.

Anyone have any idea on why things may be working correctly with the engine warm and not with the engine cold?

Compass790 · 30-11-2020, 21:23

My guess ( I'm no electrical expert ) is that you have a connection problem. When we have issues like that it usually come down to a plug or spade connector but someone with engine specific knowledge may be able to help you better. We have a yammer but not your breed.

**Wotname** · 01-12-2020, 02:33

My guess is that is not heat related but vibration related. Of course the vibration occurs while the engine is heating up (ie running).
The vibration shakes up a corroded connector somewhere in the wiring loom and it continues to work for a short time after.

Sherpa17 · 01-12-2020, 04:47

Have you had a recent oil change?

**GordMay** · 01-12-2020, 05:30

I think Compass and Wotname have probably identified the general cause of your problem(s).
An older thread,“Basic Engine Gauge Theory and Testing”, might help you track down your specific issue(s)
➥ https://www.cruisersforum.com/forums....html#post2597

Kabunza · 01-12-2020, 08:54

Thanks for the replies.

This is definitely electrical, but I don't think it's vibration related otherwise the buzzer and light would come on occasionally while the engine is cold. everything works fine only after engine is warmed up.

I was going to post this under electrical, but I figure since it's Yanmar system related, I'd post here.

My guess is that it's near the engine and that thermal expansion from the heat is closing the gap at a loose connection. I just don't know where else to look.

Kabunza · 01-12-2020, 09:11

Just noticed a couple of the other replies.
Yes, on the oil change.
GordMay, thanks for the link. I'll be reviewing that today. Looks very informative.
Thanks again all!

Kabunza · 01-12-2020, 09:13

By the way, does anyone know how to remove the connector wire from the oil pressure sensor? I can't tell if it snaps on or screws on, and the rubber boot cover is hard to pry off. I'm afraid of breaking something by trying to remove it the wrong way.

ilanortho · 01-12-2020, 09:58

I had this problem; turned out to be a simple connector corrosion problem at the oil pressure sender which resolved when I cleaned it

SeaBreeze-1 · 01-12-2020, 10:11

Quote:

Originally Posted by Kabunza

By the way, does anyone know how to remove the connector wire from the oil pressure sensor? I can't tell if it snaps on or screws on, and the rubber boot cover is hard to pry off. I'm afraid of breaking something by trying to remove it the wrong way.

I just replaced one recently on my 30QM30H and had the same issue. The sensor wire is held on by a small Philips screw once you get the rubber boot off. You can try and preheat the boot with a heat gun and pry it back down the wire a little or cut it off and add a new boot. You will need to slide a new boot onto the wire before you crimp a new ring connector on. I suppose you could also slit the boot off with a utility knife but will have to ensure that the now exposed connection is in a safe enough place that it won't be contacted by anything else electrical.

Cadence · 01-12-2020, 10:35

My first suspect would be a sending unit (sensor) they can be erratic.

Kabunza · 01-12-2020, 10:44

Thanks again. I like all the suggestions. Good idea on heating up the sensor contact boot.
I'll try that and report my findings, since it's nice having closure on these posts.

Cheechako · 01-12-2020, 11:04

I had a sender fail on another model Yanmar, drove me nuts thinking I was overheating. Sender fixed it.

Lazy Jack 32 · 01-12-2020, 11:36

My 4 cylinder Yanmar had a dim light and faint buzzer for water temp and oil pressure. Those didn't inspire confidence in an old guy with dim ears and dimmer eyes, so I had a mechanic friend install gauges for both. The trick turned out to be converting the US-made gauges to Yanmar's metric sizes, which required adapters obtained from a Catalina specialist parts supplier. But I'm a whole lot happier now, not only knowing if the water is too hot, but how hot, etc.