Buzzer of doom

[Gary.]

Hi All, I'm new here so please be nice! Problems with oil light / buzzer of doom. I've look through other posts but I'm still a little lost.

Just picked up a nice T25 Syncro Doka with 1.6TD.

Buzzer comes on when warmed up, but goes off when revs above 3000.

Any pointers much appreciated.

Thanks,
Gary.

[marlinowner]

Hi, it reads like genuine low oil pressure, you could change the oil and filter, maybe worth going to 20w50 oil. If buzzer still sounds then you need to get the oil pressure checked.

[MGP]

It sounds like a genuine low pressure warning rather than an electrical problem.
The first thing you need to do is get a pressure test done.

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[Gary.]

What does an oil pressure test involve? Can I do it myself?

Thanks

[MGP]

It just involves fitting a mechanical pressure gauge to an oil gallery on the engine, running the engine and reading the gauge.
You can easily do this yourself you just need an oil pressure tester with an m10x1 thread.
Depending on what garage you use it can cheaper to buy a gauge than to get a garage to test it for you.

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[chapperss]

Hello and welcome Bruv. you might want to post this in the mechanical section too. I hardly ever look in the electrical section as I haven't a clue about electrics!

[Gary.]

Thanks for the feedback & hi Bro! . Not being a mechanic or electrician etc, I'm somewhat unfamiliar with terms such as 'Oil Gallery' (I presume that's a term for threaded hole for oil pressure switch).

I've found a great diagnostics guide from Brickwerks, which I'm trying to follow: https://www.brickwerks.co.uk/brickwerks ... -switches/

Unfortunately I'm stuck at step one - I can't find the pressure switch! The image on this website is great, but no pressure switch listed...



Here's a pic of my engine bay. All I could find was a yellow wire connected to something facing the cab.



I would appreciate help please, thanks.

[Gary.]

Ah ha, just discovered this doc in the wiki and found the switches: https://club8090.co.uk/wiki/Al ... and_causes

[Gary.]

I'm in need of more help please. I've plugged in a pressure gauge to the port on the oil pump bit and it reads just above 1 bar cold. When hot this drops to pretty much zero. Though with blue switch disconnected, I still get buzzer & light.

Do I need to connect the pressure gauge to the port on the front of the head too and take readings, or will that tell me the same?

Basically, I don't know what to do next, what does this mean? Gut feeling is this truck has done way more than 40k miles!

[marlinowner]

The buzzer uses the other pressure switch, with the blue switch disconnected then the light will be off before engine started, and stay off until the engine is at approx 2000rpm, when the buzzer circuit is activated. At this point low oil pressure will sound the buzzer and flash the light. Can't see testing pressure at other switch will make much difference, probably need new main and big end bearings, best case would be oil pump.
Just to add - what is the pressure at 2000rpm hot and cold?

[Gary.]

Oh, that sounds simple. Can I do that with an adjustable spanner and a hammer ?

[Gary.]

I've done some hot cold pressure testing:

Cold:
1000 rpm - 1.6 bar
2000 rpm - 2.4 bar

Hot:
1000 rpm - ~0 bar
2000 rpm - 0.6-0.9 bar.

Interestingly, it is really hard to hold the throttle at 2000rpm when hot, it increases revs without any further depression of pedal?

I'm also guessing this is not an electrical fault as I've checked the earths, though not sure how to remove the dash pod to check the PCB?

Thanks again.
Gary

[Gary.]

I've done some hot cold pressure testing:

Cold:
1000 rpm - 1.6 bar
2000 rpm - 2.4 bar

Hot:
1000 rpm - ~0 bar
2000 rpm - 0.6-0.9 bar.

Interestingly, it is really hard to hold the throttle at 2000rpm when hot, it increases revs without any further depression of pedal?

I'm also guessing this is not an electrical fault as I've checked the earths, though not sure how to remove the dash pod to check the PCB?

Thanks again.
Gary

[MGP]

It's not electrical your oil pressure is low, the minimum on the jx engine is 1.1 bar at 2000 rpm at 80 degrees oil temperature.
Your cold pressures look very low as well I'm wondering if someone has put an very thin oil in it.
Do you know what oil is in there? If not I would be tempted to replace the oil and try again.

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[marlinowner]

Whs^^^
Try oil change to 20w50 oil, suitable for turbo diesel engines.
eg https://www.amazon.co.uk/gp/aw/d/B00D8Z ... ref=plSrch" onclick="window.open(this.href);return false;