Oil light flashing up

[Rich Tea]

Hello Aidan It's a shame we won't be there on the same day. I'll give you call tomorrow afternoon though. I've no problem with posting it back to you at all, I'll even make sure it's insured just in case.

Thanks also Kev for your offer of assistance.

Rich

[Rich Tea]

Back home after a great Saturday at Vanfest.

It was good to meet up with both Patrick and Kev for a quick chat and some advice. Thanks to Patrick for passing on the oil pressure gauge and thanks of course to Aidan for the loan.

I fetched the van back from storage today and checked the oil pressure.

I don't have built in gauges for any of the important things so I used the following : -

Oil pressure = Aidans wet gauge
Revs = function on my multimeter
oil temp = infrared pyrometer (aimed at the oil pressure gauge fitting and at the thermostat housing which were surprising similar).

I started with a temp of 75°C after my drive back from the yard.

75°C
tick over = ~900rpm = 25psi, 2000rpm = 50psi, 2800rpm = 60psi

85°C
tick over = ~900rpm = 18psi, 2000rpm = 30psi, 2800rpm = 48psi

95°C
tick over = ~1000rpm = 15psi, 2000rpm = 30psi, 2800rpm = 35psi

103°C
tick over = ~1000rpm = 15psi, 2000rpm = 25psi, 2800rpm = 32psi

107°C
tick over = ~1000rpm = 14psi, 2000rpm = 25psi, 2800rpm = 35psi

I started with an engine temp of 75°C and ran the engine on the drive for over an hour, with the fan coming in and out many times, hopefully this was enough to get a true feel for the condition of the engine.

The low pressure sensor is marked 0.3bar +/- 0.15bar (2.2 - 6.5 psi) At no point did the gauge give a reading which should trigger the low rpm/ low pressure sensor.

Is there any chance it might be tripping the high rpm / low pressure sensor? I'm not sure what's fitted (very hard to see) the wiki suggests there are two types Grey = 0.9 bar (13psi) and white 1.8 bar (24psi) . I'm not sure which one would be fitted to my 1.9 DG

The question is, what could be causing the oil light to come on after long journeys (e.g. coming off the motorway, and stopping at traffic lights, junctions etc)? Once it comes on, everytime the the engine is at idle it comes on again, (with a small bit of gas it goes off).

By the way, there's no buzzer. I check the wires in the engine bay, and there's no sign of the either of the sensors being earthed, I did notice that in the electrical box that both the wires from the sensors had been pierced, although someone has spiked them with a multi meter probe at some time.

Any further advice would be greatly appreciated.

Cheers

Rich

[Aidan]

well the figures say that op is fine so it must be faulty sender or wrong one fitted
high pressure sender should be 0.9bar
bod goes off if op is less than 13psi at 2000 rpm

basic system test is
engine off/ignition on oil light must flash
engine on below 2000rpm, ie idle, disconnect wire from lop sender and earth - oil light must flash
engine on above 2000rpm - disconnect wire from highp sender but do not earth - oil light must flash and bod goes off


if these checks are all ok and the bod is going off then it's the high p sender under reporting the op

if it's just a flashing light thing then the low p sender is faulty or there's a poor connection that improves with engine vibes (ie revving it)

[ewenmaclean]

Hello,

just to add my experience to this in case it helps. In my bod circuitry, someone had scored through the solder to the buzzer itself - which is on the circuit board within the speedo. Worth looking and testing that and the multipin connector - pin 12 is the 0.9 bar switch - it should earth at above 2000 rpm, if not then the buzzer will go off.

I've got a tdi, but the op principles are the same - whenever I'm low on oil and brake I lose oil pressure, or when I turn left. This is to do with where the oil pick up pipe for the pump is. Because I am an idiot I was reading the wrong markers for a bit on my dipstick, so was running low, so this was happening when the oil was hot. There is a baffle in the sump to keep the oil in place when you brake hard so that the pick-up pipe can still get to it. As stupid as it sounds, you've got to check you're not running low! I'm sure you're not an idiot like me, but best to mention it.

As far as an op gauge goes, I got one from autogauge, which is fine, but in order to get the low pressure switch in (all 1/8 NPT thread and tappings I believe) as well as a gauge, I bought one of these:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0666497627" onclick="window.open(this.href);return false;

and fitted it to the low pressure gauge tapping on the cylinder head. This works fine, but you'll need to provide an earth for the threading to the low pressure warning sensor as that stuff doesn't conduct earth from the engine block!

Wiring it up is a doddle once you've got a wire from the front to the back nice and discretely!

Hope this helps a bit anyway

Ewen

[Rich Tea]

Thanks for the advice guys.

The van's back at storage so it might be a few days before I can do these checks or maybe even the weekend.

If my memory serves me well I think someone has cut a hole through a track on the PCB. Maybe this is why there's no buzzer when the light comes on.

I'll let you know what I find when I've had a look.

Thanks again

Rich

[HarryMann]

Rich, Nobody seem yet to have pointed you at the two 8090 Wikipdeia threads that run through a lot of the basics and feel you would benefit, from reading this all in one place (or two)... it is far from uncommon that it's the tracks broken or contacts corroded, or even the whole DOPWS circuitboard is u/s

https://club8090.co.uk/wiki/Pe ... DOPWS_Info

https://club8090.co.uk/wiki/Al ... and_causes

At least you have eliminated low pressure itself. A multimeter on resistance at the ribbon contacts, with the engine running above /below 2250 rpm might be the next step

[Rich Tea]

Harry,
Thanks for your reply.

I'd previously read the wiki articles and they were really helpful in getting me started, I'm also really grateful for all the advice from those more experienced than myself.

Because I keep the van in storage, unfortunately I have more time to read, talk and worry about it than I have to do work on it, but I've got a big list of items to check. Unfortunately my weekend appears to be filled with non van related activities but fingers crossed, if I get out of work early tomorrow I can spend a little time on her down at the yard (not ideal, but better than nothing).

Cheers

Rich

[Rich Tea]

Well I did manage to finish work early and have a play this afternoon.

The below 2000 rpm check worked just fine.
The above 2000 rpm check did not.

Investigations moved to the dash. I knew the dash illumination had been replaced (hacked about) with apparently random cables and some bulbs which had melted the shrouds. I'd already tidied this up and fitted LEDS, but I hadn't removed the dash pod and checked the 14 pin connector previously. This is where I started.

On pin one the terminal in the socket appears to be bent out of place such that it may not make contact.

The PCB was very corroded on pin 5 as was the terminal in the socket but as I've no clock this does not appear to be a problem.

All the rest of the terminals looked ok and I just gave them a light clean.

The big problem lies with the wiring to the 14 pin socket.

Pin 1 = Gray- blue cable has another cable soldered to it which runs to the LHS of the dash where it joins another Gray - blue cable. Back at the pin the gray-blue cable runs off and joint 4 other gray-blue cables.

Pin 4 = missing (I assume this is originally the case).

Pin 11 = blue cable which is cut and soldered to a yellow cable which terminates (not connected) under the drivers seat.

Pin 12 = Yellow cable, cut and soldered to another yellow cable (I didn't have time to check where this terminated)

Pin 13 = Blue-Black cable cut from the socket joins directly to lampholder fitted into the Oil Pressure bay on the dash (by cutting a hole through the pcb). The power supply has been run from the live terminal on the heated rear screen switch via a 7.5amp fuse.

All the other pins didn't appear to have been tampered with.

Additionally I discovered that the screw holding the Voltage regulator was loose. the plastic socket having fractured on the back plate of the gauge.

So I guess that explains the following : -

1. why the alternator light doesn't come on.
2. why the greater than 2000 rpm test didn't work (only the low rpm/low pressure sensor controls the light)
3. why there is no bod.
4. why the dash lighting was rewired???

So it's quite a mess under that dash. I need to decide what to do now, should I rewire the bod in and hope that goes ok?
What do I do with the cable to pin 11 to get the alternator light working again?

I'm definitely going to fit that oil pressure gauge I keep talking about anyway.

Rich

[Aidan]

Rich
you need Bentley manual which has all the detail for the wiring
5 is the clock is permenantly live and always corrodes
on the flip side of the 14 pin connector tracks on the pcb is the ident detail in german
blue grey is instrument lights (inc radio)
1985 MY on
1 instrument lights
2 high beam warning
3 ground - earth
4 open
5 clock
6 coolant temp gauge
7 fuel gauge
8 positive
9 tacho if fitted
10 indicator warning
11 alternator warning
12 op 0.9 bar
13 op 0.3 bar
14 glow plug warning diesel only

looks like someone has butchered the high p wire and tried to wire it to earth permanently

[ewenmaclean]

Hello again Rich,

you'll probably find that the wire from pin 11 to under the passenger seat once controlled the split-charge of a leisure battery. This only provides an earth when the engine is not running, so won't charge the leisure battery unless the alternator is doing its job. The blue gray wire soldered from pin 1 probably went to an illuminated display of some sort.

Aidan's probably right about the high pressure wire being earthed, but another possibility is that someone's already put in an oil pressure gauge at some stage (now removed), with a sender unit in where the high pressure sensor should be, and has wired an external oil pressure gauge (with illumination from pin one) using the yellow wire from the high pressure sensor as the sender input. I would be tempted to do the same if you want an oil pressure gauge and the bod circuitry isn't working already.

Ewen

[Rich Tea]

Cheers for the additional comments, it all helps.

I'll look into getting a Bentley Manual, the wiring diagrams in Haynes just confuse me.

Non of the instrument, switchs or even the cigar lighter, light up as they should. The Brake warning light doesn't work nor the high beam light. So plenty of head scratching to be done.

I think you're right Ewen regarding the alternator cable, it just sits under the drivers seat by where the split charge relay is. Although I guess it's redundant now as a smart relay was fitted at some point.

An interesting point regarding using the yellow cable, I think I'll look in to it.

Best regards

Richard

[Rich Tea]

It's been a while, but I've been busy on the van, at least some of the time.

I collected up the necessary bits (TIM electric pressure gauge, remote T-piece, Gauge Pod etc.) and wired in a permanent oil pressure gauge.

I also spent some time fiddling with the dash wiring : -

I've got the brake warning light working (disconnected at the hand brake, broken loom plug and fractured PCB in the light assembly)
The battery light and Main beam light works sometimes (dodgy 14 pin connector).
During all of this I've started getting constantly flashing coolant LED (damn my tinkering)

My major concern at the moment is the oil gauge readings, they don't tie up with what I got using Aidans wet gauge (although there's been a fair bit of elapsed time, theres's not been many miles done).

Once warm, after a short drive the drive the gauge is dropping to 0 psi on tickover (but no low/low warning light ). Yet with the wet gauge the lowest figure I got was 14 psi (on tickover) after running for over an hour on the drive with an engine temp of 107°C. It also doesn't seem to be hitting the higher pressures previously observed, even when still cold.

A quick inspection shows oil weeping through the core of the 0.3 bar pressure switch (now fitted to the remote T-piece) next to the sender. Could this be the cause of the unusual readings?

I'm using a TIM sender that came with the gauge, could this be out of calibration?

Off to visit Brickwerks now for a pressure switch.

I'll keep updating, as and when. I'm determined to get the bottom of this oil presure business and my pain may help someone else along the way.

[Aidan]

weeping switch won't hold pressure

[Rich Tea]

The Brickwerks Febi switch is installed and the weeping has ceased.

The only problem is ,the gauge is still dropping to zero on tickover (when warn). What I don't understand is how it can drop so low without the Low pressure light coming on. Can I really trust the gauge?

I'll play some more tomorrow and see If I can get to the bottom of it.

Rich

[kevtherev]

Maybe it is the gauge

I fitted a Mechanical (wet) gauge for accuracy (and cheapness) purposes, my readings are similar to your "wet" readings ie no lower than 15 psi (WBX)