Aircooled Engine, Diesel Instruments. DOPS.

[Andyroo]

I have a 2ltr air cooled engine on my 1982 van and at sometime in it's life it's been fitted with an instrument cluster from a diesel.
No idea when or why.
There was an electrical fault which I had to look into (temp lamp flashing when main beam used) which I sorted, but along the way I discovered the DOPS (Dynamic Oil Pressure System) which was fitted to water cooled vans, post 1985.
After reading about how air cooled engines only put the oil warning lamp on when all oil pressure has been lost, which is probably too late, I want to try and use the DOPS seeing as it is there.
I haven't stripped an engine before and I haven't started on mine yet either, it's still in the van, but I was thinking along the lines of making some kind of manifold/splitter to take three sensors off the point at which the current oil pressure switch fits. One port for the existing N/C blue switch (0.25 bar), the second port for an extra N/O white switch (1.8 bar) and the third port for an oil temperature sensor.
My question is, what kind of pressure can be achieved from the existing port on the engine? On water cooled engines the second (white) sensor is fitted at a different point.
I'm hoping someone out there has done this before.

Andy.

[AngeloEvs]

Diesel DOPS board is different to the petrol version due to the type of rpm signal, diesel from the alternator, petrol from the ignition coil. The DOPs monitors the rpm which is essential for the DOPs oil warning system to function correctly. On later vans with DOPs, the rpm signal is included in the wiring to the dashboard, earlier vans will need this added as a separate wire from back to front of van.

The other major problem is lack of the second oil pressure location.

[Andyroo]

I'll be wiring a green cable from the ignition coil (t1) to pin 9 on the cluster connector. Will this work with a DOPS for a diesel? I'm assuming that the DOPS is the one that came with the diesel cluster, but if there are different types it might not be. Some of the parts are original Aircooled/petrol, some aren't. Is there any way to check the DOPS circuit board for an indication? The marker on the cluster 14 way connector on the circuit 'board' for pin 9 is showing KL.1 (I think that's what it is). But the DOPS board could be off a petrol. It's partially wired.

Also, it's the oil pressure I'm concerned about. Will the normal take off point on the air cooled engine get up to 1.8 bar at 2000 rpm +?


Andy. (from my phone)

[Andyroo]

And, I can't find an electrical circuit drawing for a diesel from 1985+ to check against. Only 82 or 83.


Andy. (from my phone)

[AngeloEvs]

You need a petrol DOPs. If your dashboard has the Glow Plug Led symbol on the LED display then it will most likely be a Diesel DOPs.

A popular mod is to fit a Oil Pressure gauge sender in place of the oil pressure switch (or an adaptor to fit both) so I see no reason why a 1.8 Bar switch could be used but wether your method of using two oil pressure switches will work I cannot say.

Regards the schematic, there are a few here at club 80-90 in the Wiki and various posts but the only difference between post 1986 Diesel and Petrol is pin 14 on Diesel models conects to a LED for the gLow Plug (LED and Resistor missing on petrol versions as not needed). I will find a link and update this reply

http://forum.club8090.co.uk/viewtopic.php?f=39&t=125921&start=75

It has been a long time since I compared a Diesel v Petrol DOPs PCB and the posts regarding the differences have probably disappeared over time. Apart from the part number I am sure there is a physical difference that can be seen, it may have been the Integrated Circuit (type 4001) or a component etc. I have a petrol one (just listed it on EBAY strangely enough). I will see if I can upload a picture but you can see it on EBAY. Easy to remove/fit as it just clips into place.

Quite frankly (others may disagree), there are better alternatives to the DOPs system which can be problematic and unreliable as these vehicles get older due to wiring issues, etc. You are better off having an oil pressure gauge if you are going to all the trouble of adding wiring from front to back (the type that uses a sensor to output a voltage not a capillary tube type).

I removed the DOPs from my dashboard a long time ago and have a green Led connected to the 1.8 Bar switch and a flashing Red Led to the 0.3 Bar.

At start up the Red Led goes out and the green Led comes on and stays on. Even after a long run at 850 RPM Idling the Green Led flickers, at 1000 RPM it is back On. It behaves differently after a fresh oil change and even at idle stays on - simple to do and my preffered choice over the DOPs.

If that Green Led went out whilst driving I have a problem.

[Andyroo]

Thanks for your replies AngeloEvs,

The DOPS wasn't working at all over the past year that I've had the van so I've not been in a position to get an opinion about it, but from what you've mentioned I'll have a rethink about how to get an 'early warning system' wired up. I was going for an oil temperature gauge so I might just get a pressure gauge too.
Do you know the kind of pressure that I should get at the point where the current switch is when at idle or 2000 rpm+ ?
I can't check now as the oil has been drained and half the van's electrics removed ready to remove the engine in the spring.

Thanks,


Andy. (from my phone)

[dave friday]

Go to www.syncrosport.com and look for manuals
Good luck.

[AngeloEvs]

Isn't the oil pressure led working (should be flashing with ignition on)?

It should be working even without the second oil pressure switch and RPM signal, they have no effect on the low oil pressure led function . If your van is pre 86 with a later dash then, for it to work, someone must have repositioned the cables in the edge connector to suit the later dash. Quite simple to do if you have the relevant info regards which cable goes where in the connector. I have the details somewhere.

It is simple to have the early oil pressure system in later vans and I have details/ pics on how to do it assuming the edge connector is correctly wired for the later dash.

[Andyroo]

The oil lamp didn't flash. It would just be on steady until the engine was started. I stripped down the cluster and made a drawing of the circuit to trace the wiring as the temperature lamp would flash whenever the high beam was turned off. I sorted that (pins 2 and 3 needing swapping), plus I'm going to blank off the temperature gauge eventually as I obviously don't need it. That's when I discovered the DOPS circuit board inside. I'm going to pull the PCB out tonight and take a look at it. If I can swap it for a petrol one I might do that, otherwise I'll probably go down the pressure gauge route. It would be nice to have a warning rather than watching gauges that aren't in the cluster. Not sure where I'd put them actually.


Andy. (from my phone)

[Andyroo]

Here is the quick drawing I made. The layout represents the path of the tracks on the instrument cluster's plastic circuit board. Everything up to the DOPS connections should be ok, and as long as the DOPS circuit board connected to it is for a petrol.

Circuit Pic.JPG

Diesel Instruments Circuit.

(107.01 KiB) Downloaded 51 times

[Andyroo]

Here are the cable colours and connections to the 14 pin connector.
The first colour shown is the main cable colour and the second colour is the stripe. e.g. connection 1 is a grey cable with a blue stripe.

Cable Colours and Connections.

Colours Pic.JPG (69.26 KiB) Viewed 812 times

[Andyroo]

Go to http://www.syncrosport.com and look for manuals
Good luck.

Perfect. Thanks.


Andy. (from my phone)

[Andyroo]

Hi AngeloEvs, ok, so I've taken the DOP circuit out of the speedo case and compared it against the image of the petrol one you have for sale on ebay and they look exactly the same to me. I've tried to zoom in on your picture and compare the resistor colours and I obviously can't look at the tracks on the reverse side as there is no image of that.
From what I have read, they should be the same apart from the input signal for the tachometer. This signal charges the green capacitor, the one underneath the IC chip. The higher the revs, the more pulses, until the capacitor charge is enough to trigger the circuit to start looking at the higher pressure sensor.
As there are more pulses from the petrol engine compared to the diesel (2-1) they need to control the amount of charge going into the capacitor via a resistor. It's the difference in the value of this resistor that determines whether the DOP will work will petrol or diesel, apparently.
On the circuit that I have that resistor is 100K. I can't see what it is on your board as the resistor looks dark.

My board is here. It's the dark brown resistor roughly inline with the sixth connector pin along the top edge.

100K

IMG_9319.JPG (97.25 KiB) Viewed 757 times

Would you be able to upload a few images so I can see if I require your circuit board, or do I already have the same one? As I mentioned the other day, the cluster is from a diesel, but some parts are not. Hopefully we can get the information together for anyone with the same issue in the future. It would be nice to think that we could swap DOP circuit boards between vans and just change one resistor if required.
Your help would be greatly appreciated.
I've also taken a picture of the reverse to view the track routing.

Reverse

IMG_9320.JPG (99.07 KiB) Viewed 757 times

I hope this helps.

Thanks,

[dave friday]

Hi Andy,I hadn't realised how simple the DOPWS circuit board is...one cosmos chip and 3 transistors!
But you/we still need a circuit diagram ...
Just a thought ,fit a diesel alternator,or modify yours so you have a W terminal ( for the DOPWS )?
Kr,Baz.

[AngeloEvs]

That looks pretty much identical to mine. I will take a pic and upload later, just wondering if its possible to track the VAG Part number and see if they are different for Diesel but, based on your image, if yours is a Diesel one they appear the same unless there is a difference in some component values. I might just have to read the values and post later......