BOD - your thoughts please

[Ads1987]

Hi everyone,

Just hoping I could get your opinions please;

Got a 1.7d ky engine in my camper, brought it a year ago and it's always had the occasional buzzer of doom, this normally occurs slowly down from a high speed up to certain roundabouts and in the odd really steep hill. The guy that sold it to me said he had it pressure tested and the oil pressure was fine, but obviously this light and buzzer is still coming on - it seems to be low revs and low pressure as it normally stops when I drop a gear and increase the revs, however now that the weather is warmer I've noticed it's coming on a little more frequently, I only serviced it a few weeks ago and put 4.5 litres of 15w40 mineral oil in it.

I'm going to spend some time looking into the wiring this weekend of both the switches and also behind the dash, my main question is has anyone actually found it to be wiring faults or am I just in a state of denial and clutching at the hope it might be a cheaper fix?

Also I'm thinking about installing an aftermarket oil gauge kit that has a dual connection sensor to keep the bod, or I could get the oil pressure tested by a garage for the same price.

What do you think is more useful, a decent oil pressure test once or an assumably less accurate constant check via the gauge?

Thanks guys.

[marlinowner]

I think if the buzzer only sounds in circumstances when you would expect the oil pressure to be at its lowest, then it probably is genuine. Personally I would prefer a gauge in the van, my preference would be for a mechanical gauge rather than electric. In my kitcar with 1960s Triumph bits I have mechanical temp and oil pressure gauges, which seem pretty accurate.

[Hacksawbob]

[Ads1987]

So I'm assuming these are circumstances you would expect low oil pressure because of the fast change from high to low revs then?

[marlinowner]

Its because the oil is at highest temp when engine has been working hard, then the engine rpm and hence oil pressure drop before the oil cools down. The hotter the oil, the lower the oil pressure, for a given rpm.

[Ads1987]

Doubt the previous owner did a proper oil pressure test then by the sounds of it

[kevtherev]

Most garages can do a wet gauge test.
I also fitted a mechanical gauge... very comforting.!

[Ads1987]

Are the electronic gauges not very reliable then ?

[kevtherev]

I couldn't comment but having a physical link to your engine is nice.
My pal has an electric one and he isn't 100% with it... wiggling wires doesn't instil confidence in me either.

Simple and effective relief of engine death worry

I would get it properly checked though first, you really need to know where you stand with this before any purchases are made

[Ads1987]

I'm still a little confused about what's worse, the buzzer and light go off as I slow down from speed, they both stop when I increase the revs - this indicates a low pressure and low rpm fault doesn't it?

I would imagine if it was a genuine oil pressure fault that this warning would continue to sound for a lot longer after the revs increase?

[Plasticman]

No it wouldn't,re read what was said,low rpm = lower oil pressure as soon as revs rise then so does pressure,so you do have a problem but it may also be the senders ,so take to garage and get wet test cold and hot and go from there
mm

[Ads1987]

Thanks mm, are there different tests available or will they all be a wet test? I've never done much work with engines so it's all a bit new to me

[ghost123uk]

It's all the same test. They take out one of oil pressure sensors (doesn't matter which) and they screw in a proper oil pressure gauge. Then they test pressures at tickover and then at about 3000 rpm, then they let the engine warm up to operating temp and do it again. You then compare the readings with the correct spec (wiki ?) and if yours are well down then you have a "real" oil pressure problem (worn shell bearings and/or pump). If the readings indicate your pressure is within acceptable range, then you have a sensor or wiring problem.

[Ads1987]

That makes more sense, thanks ghost

[AdrianC]

Are the electronic gauges not very reliable then ?

An electronic gauge has a sender at the engine end to convert the pressure to resistance, which is then converted back to movement at the gauge.
A mechanical gauge has a bit of pipe between the engine and the gauge, which then mechanically moves the needle.

Both use beically the same basic mechanism - the pressure expands a little vessel against a spring. The only difference is that the mechanical has a physical link to the needle, the electronic doesn't. (Some electronic gauges may use a piezo-type sender) They're both as "accurate" or reliable as they're calibrated - and you don't really want an absolute figure. What you're after is an indication of what happens when the oil's cold versus hot, especially at idle.

The other major factor is whether you're running a pipe of hot oil the length of the van or a single bit of wire. I know which I'd rather have a problem with in use...