Buzzer of Doom!! Oil pressure buzzer keeps going off!!

[swillicott]

Hi,

Been reading for a bit about other buzzer of doom problems on here and wondered if anyone could help with mine.

I have just had my 1.9 waterboxer dropped out of the van to fix the dreaded snapped stud nut issue (which occured bang on 130,000 miles!!)! Anyway, after a lot of time, money and a lot of new parts I have had the engine completely overhauled and rebuilt after replacing any parts that needed doing (new big ends etc).

Anyway, got the van back and it was (and still is) running sweet as a nut. I used the van for a couple of short trips and on its 20th mile or so I got the dreaded oil pressure light and buzzer come on. I stopped immediately and topped up the oil. It then drove OK for a few miles with no buzzer where I parked up for an hour or two. Then, half way home the buzzer and light came on again. I once again pulled over immediately and checked for any leaks etc and then checked the oil which was fine. Started it up once again and got another 100 yards and the buzzer went off again.

So, not wanting to knacker the engine I have just spent a lot of money rebuilding, I called the AA who came and had a look. He could not see any problems and as the engine sounded and ran alright he offered to follow me home.

The van drove perfectly all the way home (about 3 miles) but the buzzer went all the way. He thought it must be a faulty switch.

So... took the van back to the garage that had completed the rebuild and they have checked the oil pressure and all is fine. The replaced one of the switches and the buzzer still came on so they decided to disconnect both the oil pressure switches but the buzzer still comes on. They then tried earthing the connection but the buzzer once again still stayed on!

They are at a loss as to how to fix it (they are not a specialist VW Garage and do not know the in's and outs of T25's) so I thought I would do some digging around online.

To me, this sounds like the normal buzzer of doom problem (although I am worse than useless with the technical stuff) as if started up and left on idle the buzzer does not come on, but when you rev the engine it comes on and stays on!

Does anyone have any idea what we hit next to try and stop the buzzer coming on? Is it a case of taking out the dash to check all the connections behind there?

Any help to get my van back on the road would be greatly appreciated!

Thanks!!

Steve

[AngeloEvs]

First, disconnecting both oil pressure switches will not provide a temporary solution and the buzzer will sound if you do this. Your mechs need to leave the low oil pressure switch connected as normal and disconnect the high pressure oil switch wire and connect it to ground/chassis.

The BOD needs a signal from the coil and it needs to see that the low oil pressure switch opens (no connection to chassis) and the high oil pressure switch closes (makes connection to chassis) when the engine is switched on and running from cold. The BOD responds and activates above 2000 RPM if the high oil pressure switch is 'open'.

A few people have had this problem with recon engines and various reasons were given why it can happen, i.e. type of oil used for running in, rings and shells bedding in, etc. ( have to say I'm sceptical but could be right!)

If it worked before and you haven't disturbed the dash then I doubt its the cause but check that the horizontal multi connector is fully home.

Have the switches been replaced with the correct ones? There are various available with different operating pressures and its vital that the one under the pushrod tubes 'opens' and the other 'closes'. If you can't get it working and the oil pressure is definitely OK then read the link below concerning modifying the BOD to the pre 86 spec (which do not have BOD) until you can isolate the problem. Alternatively, fit an oil pressure guage and dispense with the BOD altogether..........bettar than a BOD IMO.

https://club8090.co.uk/forum/viewtopic.php?f=2&t=59635

[pocolow]

I ha d a similar problem with my engine although in this case a 1.6td.. It would be worth checking what grade of oil was put in as when it gets hot 15-20 miles it thins and could trip the BoD..Also as Angeloevs says check the right pressure switches are fitted(They are colour coded,blue and grey or blue and black usually) Mine had the wrong one put on after an engine swap and when I changed them..problem solved. Mark

[ghost123uk]

If the oil pressure has been properly checked and all is ok, and if the "earthing" trick did not shut it up, then it is most likely a break in the wiring between the sensor switches and the the multi connector on the instrument binnacle (most likely in the engine bay, so easy enough to trace each wire back from both the senders).

After that, the 2000rpm sensor wiring part of the system might be the cause, somewhere between the coil and the multi connector on the instrument binnacle. (not sure what colour the rpm sensor wire is from the coil, the Haynes will tell you if you can figure it out !)

~~~~~~~~~~~~~~~

If you don't mind telling us...
How much was your rebuild ?
Who did it (and are you happy with them) ?
What provoked the stub to snap ?

[swillicott]

Thanks for all the replies.

I passed what you all said to the Garage and they found it very useful. It turns out they replaced the high pressure switch with the wrong switch. They then found a loose connection in the wiring (probably knocked out of place when the engine was dropped out) which they fixed but the buzzer still came on (due to the wrong switch being fitted). Then, when I gave them the info in this thread they realized that the wrong switch had been put in, so they put the original one back in and all worked fine! So I guess it was just the loose connection.

Anyway, once again, thanks for your help - much appreciated and I am back on the road!

Steve

[swillicott]

Oh...

and as for the rebuild - here is the info:

How much was your rebuild ?

With all parts and labour, about £1800.

Who did it (and are you happy with them) ?

Brixham Garage in Paignton - and yes, very happy with them . They went out of their way to take on my project when they were busy and have been very helpful and patient with parts (took my ages to get a stat housing and all in all the van was with them for over four months).

They were also very helpful with this latest problem and came up straight away and towed the van back to the garage.

What provoked the stub to snap ?

Not sure really? The engine has just hit 130,000 miles and I have read that this is quite a common fault of engines around this age. The stud snapped in half where it had rusted and it then dumped the water out about 200 yards from my house (luckily!!) so I managed just to get it on the drive before it was too knackered! After looking at recon engines the garage suggested dropping our my engine (as we would have to anyway) and had a look at the engine and they said it looked in good condition. I have heard horror stories about recon engines blowing after only a few thousand miles so I was keen to keep my engine. I have run it for 5 years and know the history of the van and therefore the engine.

The hard bit was getting the snapped stud out of the engine, but once that was done it was just a case of getting the parts. I have had all parts the garage thought were looking worn replaced (new big ends / Push rod tubes / Push rod tube seals / con rod bearing set / Full engine gasket set / Piston ring set / etc ). Also, in dropping our the engine a lot of other parts were damages (due to corrosion etc). I therefore have also got a brand new thermostat with housing (a nightmare to get hold of!) as the old one fell to bits when touched! New engine mounts, new Cylinder Head Studs (obviously) as two had snapped but some of the rest were looking rusty, new stud nuts (again, very hard to find) and all new exhaust brackets.

Anyway, let me know if you have any more questions.

Thanks

Steve

So, a lot of work and a lot of money but the engine is running perfectly (for the moment anyway) and so far I am really pleased.

[ghost123uk]

Always good to find a garage that you like, they are quite rare, esp in the world of the T25 !!

I have put a link to them in the T25 recommended garages in our wiki.
See => https://club8090.co.uk/wiki/Ga ... 5_Specific" onclick="window.open(this.href);return false; under "West Country"

If you feel you would like the wording different, just let me know and I can change it.

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