Club 80-90 Forums

Hi all

I have a reconditioned engine (DG 1.9 watercooled) in my bus, supplied by Elite VW 11,000 miles ago. All has been well, until last Friday. Quick trip along the motorway (60-65mph) and then into stationery traffic - at which point the oil pressure light started flashing I blipped the accelerator and the light went off, until the idle speed dropped down again

I checked the oil level and it was pretty much right up to the top, so no problems with amount of oil. Plus, once the engine had cooled down a little, the light stopped flashing.

Got the bus home and did an oil and filter change on it (it was almost due anyway). I took the bus out again last night and it's still doing the same thing - as soon as the engine gets to motorway temperatures, it won't idle without the pressure light coming on.

I've spoken with Elite VW and they say that they can't look at the bus for two weeks and I'm unlikely to get it back before VanFest - which would be a bloody nightmare. So, can anyone give any advice on things to check/replace in the meantime?

For reference, both pressure switches were replaced when I fitted the engine 6 months ago and the Buzzer of Doom is currently shorted out.

Thanks in advance

Richard

My 10p worth

Could be at worst the oil pump has worn out.

what oil grade did you use?

The low oil pressure senders have been known to fail, but not often esp if only 6 months old.

Usual cause of such behaviour is slack main and/or big end bearings or a duff oil pump

I don't wish to sound pessimistic, but is it still under guarantee ?

Oil grade was just your basic old 15W40 so, in theory, shouldn't be an issue

The weird thing is that, otherwise, the engine sounds sweet - no rumblings, no tappettings (new word I just invented - like it? ) no nuffin

On a more positive note though, I've got an electric oil pressure gauge in my bay which I could wire into the T25 to actually check the pressures. This in mind, is the general concensus to fit it instead of the low pressure switch (between the cylinders) or the high pressure one (by the water pump)?

Thanks as always for the guidance!

Richard

Oh, and yes, it's under warranty. Elite VW are happy to sort things out, but they're not going to be able to do it before VanFest, so I'm trying to answer as many questions as I can beforehand

Globbits wrote:Oil grade was just your basic old 15W40 so, in theory, shouldn't be an issue

No it shouldn't, but it usually is, with old high mileage engines.

I would try a good branded 20/50 mineral (duckhams, Morris)

As these old engines wear the gaps get bigger and a thicker oil helps, especially in the warmer months.

no harm in trying

This may not be of much help but the only gauge I would/do trust is a capillary, failing that temporary connect your electro unit, if this says the pressure is ok then it will be,

Just cos it was a new sender 6 months ago means nothing, I have had brand new HP hoses from demand valves on BA sets go faulty ,3 in a row in fact and manufacturers had had a prob with a batch, plus p**s poor quality control.


Mike

might this be of use? from bens site? -


Oil pressure senders on 2.1L engine
(The 1.9 use only one sender, between pusrods, left side, same location of 2.1L but not the same BAR, it's the blue one)


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(Click on image for a bigger view and more information.)



View of the .9 BAR location and wiring & information



View of the .3 (.25) BAR location & information



This is another picture sent to me by Ken Lewis, you can see it in the red circle.

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This one is from William Polowniak from the The Vanagon Mailing List Server, you will see that the sender angle looks different but the location is the same.


Color code for the sender

Brown (i have seen a blue one) .3 bar 081 C (side of case / low pressure)

Grey or Black .9 bar 081 A (back of case / high pressure)

Blue .25 Bar ? (new spec from VW) (side of case / low pressure), the blue one is also use on the 1.9

Oil pressure sander/switch anatomy. (explanation) (and the "Idiot oil light pressure problem)
There's also a good writeup on how oil pressure work, why they go ON and gauge installation on van-cafe's site:
http://volkscafe.com/vanagonparts.jsp?p ... 1401786957

Why does the light go out at 2000 RPM?

While there is a "high" pressure switch and a "low" pressure switch, they both cause warnings when the oil pressure drops too LOW. Since "too low" is a bit of a subjective thing in an engine, VW decided to implement two standards. The higher the engine RPM, the higher the oil pressure should be. If you have just one oil pressure switch with a set point low enough (say 4.4PSI, 0.3 bar) to not engage at idle, that leaves way too much slack for when the engine is at high RPMs when the engine should have at least 13.2 PSI (0.9 bar / replacement part by VW is 0.75-1.05 BAR, see picture at left) . The "low" pressure switch is used to alert the driver if the oils pressure dips too LOW while the engine is running at less than 2000 RPM and the "high" pressure switch is used to alert the driver if the oils pressure dips too LOW while the engine is running at more than 2000 RPM.

More specifically it works like this:


The dynamic oil pressure monitoring system gets inputs from two pressure switches. One switch is closed with no oil pressure and opens when oil pressure rises to about 0.3 bar, called the .3 bar switch. The .3 bar switch is located between the left (driver's side) two cylinders (pushrods). The other switch is open with no oil pressure and closes when oil pressure rises to about 0.9 bar, thus called the .9 bar switch. The .9 bar switch is located below the water pump & crank pulley, near the oil pump.
(I just found this one location today with the help of William Polowniak photo's & other good member of the list)

The monitoring system seems to only "look at" the .3 (.25) bar switch below 2000 RPM and ignore the .9 bar switch. Above 2000 RPM the active switch is the .9 bar switch while the .3 bar switch is ignored. Below I've described a properly operating monitoring system. Note that I say "monitoring system" because some of the conditions describe an abnormally low oil pressure condition.

A. Ignition ON, engine NOT running -- or -- engine running at LESS than 2000RPM (.9 bar switch is ignored)


1. Low oil pressure exists (below .3 bar), keeping .3 bar switch closed


--Oil light: Flashes


--Buzzer: Silent



2. Normal oil pressure exists (above .3 bar), opening .3 bar switch


--Oil light: Off


--Buzzer: Silent



B. Engine running at MORE than 2000RPM (.3 bar switch is ignored)



1. Low oil pressure exists (below .9 bar), keeping .9 bar switch open


--Oil light: Flashes


--Buzzer: Sounds



2. Normal oil pressure exists (above .9 bar), closing .9 bar switch


--Oil light: Off


--Buzzer: Silent

WARNING ---WARNING ---WARNING ---WARNING

CHANGE BOTH SENDERS / SWITCH IF YOU DON'T KNOW THEIR HISTORY, READ THE FOLLOWING...(Scary!!!)



The .3 (now a .25 BAR is sold to replace the .3 to solve the "Idiot oil light warning problem") bar oil pressure switch located between the 2 left cylinder pushrod should be change if your not sure about her history, it is located at the lower part of the engine so if it start leaking like mine did, your in deep trouble, I almost blown a engine because of that switch. I have lost more than half of the oil (in a 10 minute drive). The switch give no warning at all as she still had pressure!!!. I was lucky (it could have been a blown engine) that I work close to my home. (Major spill in my garage)


Be aware that this is a very serious problem, (oil is a must) and this part should be CHANGE before any major trip. It is a easy job to do, it take a 24mm socket head and an hour to change.

The .9 BAR is a lot more difficult to reach (take note that it seem that there is different location / angle for this one, probably years/generation related - see picture). It also takes a 24mm socket but the lack of space is the problem, the water pump pulley as to be removed. I use a mix of 24mm key/vice grip/24mm socket to remove this one.

Globbits wrote:
On a more positive note though, I've got an electric oil pressure gauge in my bay which I could wire into the T25 to actually check the pressures. This in mind, is the general concensus to fit it instead of the low pressure switch (between the cylinders) or the high pressure one (by the water pump)?


Richard

I would stick it in the low pressure hole and keep the high pressure one working the light ( and buzzer ! ) as a sudden loss of pressure at driving speeds is much more likely to cause damage than low pressure at low revs ( imho )

E D I T = Did you mean just for a quick test ? ( in which case I don't think it makes any difference ( standing by to be corrected ! ) which hole you use and the one by the pump is a s0d to get at !! )

Just to clarify, the engine is a 6-month old recon unit from Elite VW and, in theory, should therefore be trustworthy and all tolerances far better than acceptable. Both pressure switches were replaced with new ones when I fitted the recon engine and, at least at the time, both were behaving properly.

To be honest, I've no desire to leave an oil gauge in place for any length of time (if nothing else, the one I've got is a cheapy and would simply be used for guidance). I'm just looking for ideas really

Richard

Low oil pressure due to a knackered pump or bottom ends will result in a very rattly engine as the tappets drain and then can't/don't reprime. Try the thicker oil but consult your warranty holder ... it's their resposibility after all.

Ian.

more ideas?

http://volkscafe.com/vanagonparts.jsp?p ... 1401786957