AFM mixture screw.......!

[937carrera]

Could it be a faulty "relay 43" ??

Oil pressure test is the way to go, but I would still test the operation of the BOD circuitry by earthing / isolating the wire to the rear pressure switch when the engine is above 2000 rpm as a test of the BOD circuit logic

Earthed = silence, isolated = very annoying buzzer

and of course with this test it doesn't matter what the oil temperature is so can be done with a cold engine

[spanishfly]

Thanks as always... tested the BOD circuit and appears good albeit the light doesn't flash when buzzer sounds though does flash at ignition on.

Update... the detective work continues.... fitted a remote oil sender kit from BW also a s/h sender and NOS VAG cockpit VDO gauge 1-5 calibrated in kp/cm2 (exotic!) which I believe equates pretty much to bar?

Pressure cold reads at 1/2/3 at tick over/ 2000/ 3000 rpm
Ran it up to temp at a constant 3000rpm and pressure gradually dropped to 1 @ 3000rpm which I take to be alarming...?
Buzzer went off as temp needle hit the middle of the temp gauge @ 3000 rpm. This atleast has been consistent.

Just to repeat the limited back story, engine 76000 miles and van RHD Syncro panel van were recommissioned by PO about 3 years ago after a 14 yr hiatus in a dry barn (full of rats!). He had replaced rear Brakes, Radiator, fuel pump and heads, belts, filters then drove it about 2000 miles a year on bi-weekly trips to a fishing spot for the following 2 years before sadly passing away, whereupon all spares and history, invoices etc disappeared probably skipped.

Judging by the brands used (good quality) and the oil marks on the Haynes manual that came with the vehicle the PO was probably not aware of atleast didn't buy from BW or any of the usual suspects preferring to use a local supplier.

He replaced heads and radiator as evidenced by the shiny bits and the remains of what appears to be a full gasket set. Elring. Before being confused/ defeated? by the effects of the rats eating the loom behind the rear lights which had led to random and confusing running faults.....all this evidenced by finger prints in the newish Haynes manual. These have now been largely rectified, starts on the button at an energetic tick over before dropping back once warm. Sounds happy enough apart from the BOD and now the OP..

My guess is that having gone to the trouble of doing the heads and everything else he may well have replaced the oil pump but not known about the thick gasket issue? This maybe wishful thinking.

Having spent 2 solid months replacing all the worn parts I could find, fashioning a respectable Rock and Roll bed and roof tent and making all kinds of wild promises to the rest of the family about wild camping / surf trips to the Pyrennes this summer I'm tearing what remains of my matted oil and dirt encrusted hair out!

So.... what next?
Please....

[937carrera]

Pressure cold reads at 1/2/3 at tick over/ 2000/ 3000 rpm
Ran it up to temp at a constant 3000rpm and pressure gradually dropped to 1 @ 3000rpm which I take to be alarming...?
Buzzer went off as temp needle hit the middle of the temp gauge @ 3000 rpm. This atleast has been consistent.

So.... what next?
Please....

Hmmm, I think you have a feeling what the bad news coming is.

Based on those readings you have very low oil pressure.

I suspect you may have referred to my oil pressure testing thread http://forum.club8090.co.uk/viewtopic.p ... 6&start=60, there are some good comparison points for you, but essentially you are only getting at cold what I was getting at 87 degrees oil temp. Those readings are from a used, and "ok" engine, not a fresh rebuild. Itchyfeet did some measurements as well so they are worth a read too.

The buzzer goes off when the engine is over 2000 rpm and the pressure at the rear switch is below the set point. Rear switches come in 0.9, 1.4 and 2.0 bar varieties, so I suspect you have a 0.9 bar one.

There's every reason to pull the oil pump and check the condition / gasket arrangement, but it does look more like the bearings are worn.

What oil are you running, how fresh is it, could it possibly be diluted with petrol ?

[spanishfly]

Hmmmm trying not to let myself think that..

I had referred to or atleast read your post but if it includes other members pressure readings then couldn't find it again!

Swapped after market switch for a s/h vw grey one, the front was blue before I fitted the remote and sender/ gauge.

Interesting what you say about petrol as AJSIMMO referred to a possible hosing injector when I was battling with the rich running problem and discovered no.3 injector was very wet. Now replaced all of them with rebuilt ones.

Would it be worth a new filter and oil change? Had only changed the oil for 10w40 as I had some from my JX. Didn't change the filter as van had done so little mileage and didn't have one handy. Would a refresh with 20/50 or 10/50 help perhaps?

May not help but van hasn't been driven throughout these complicated getting to know each other rituals not on the road anyway. May not be enough to save my bacon I guess?

[937carrera]

This is the reference for the oil pressure switches

https://www.brickwerks.co.uk/brickwerks ... -switches/

Grey is 0.9 bar, as suspected

Definitely change the oil, petrol in oil makes it thin and is a poor lubricant meaning more heat.

10W40 is too thin for me.

15W40 is what most people use

I use 20W50, mainly because I am used to using that in type 4 engines

Ajsimmo has previously recommended a 15W50 product, which has gone down well with itchyfeet

For now, on the assumption you are likely to be stripping the engine, just get some basic 20W50 mineral and see how it behaves. Remove / refill the filter, but as it's fairly new I wouldn't bother replacing it with a new one.

There you go, 15 pages of oil thread in one post

[spanishfly]

Fast forward a couple of months, my syncro is finally on the road and completed its first trip to a nearby beach. New oil, new pressure spring, new filter, reassuring oil pressure gauge in the dash and my best guess at AFM and mixture settings seemed really happy pulled well, no squeaks or clonking a joy like on rails and 60 at 3200rpm or their abouts and plenty to spare... sun shining, happy kids sitting on the roof rack reading (once we'd got there obviously) Life is good?

Until on the way home, in convoy with a friend in an Aircooled gave it some beans up a long hill, not racing just stretching its legs a bit. At the top a familiar flashing closely followed by the BOD. Pressure below 1 at 2000 rpm buzzer went out if revs blipped but I guess this confirms the original worn bottom end prognosis...?

I realise this has been done to death but given the newish (2000 mile) shiny AMC heads and relatively low mileage 78k I want to make a plan that will enable me to make the engine as good (reliable) as it can be with a view to eventually in a couple of years taking it on a long heroic trip so I'm assuming rebuilding sooner rather than later will be a better investment in its longevity?

Is it still worth trying to plot wet gauge pressures on the road, presumably a compression test would be useful?

Is it possible a Marco oil pump would be all that's required or should I look for somewhere dry to store it, remove the engine and start saving for bits and machining/ measuring work. Those are the things I can't or atleast don't have the tools or expertise to tackle.

I'm happy to take the engine out and heads and ancillaries off with help from the build threads on here but haven't found a knowledgeable machine shop engine builder in the southwest? They don't have to be in the southwest.

There is a company down the road who build pinto race engines but they don't want to touch a DJ. I've seen ads for companies in the Netherlands that look good but seem very expensive and am not really interested in a recon exchange. I'm hoping to build on the work I and the PO have already done.

Would the newish AMC heads mean a rebuild now would be cheaper than running it until something more serious happens...? Or am I being soft?
There does seem to be some conflicting advice from people who seem to have ploughed on for years with the BOD going off, maybe I misunderstood?

[937carrera]

Running it until it goes bang is the most expensive way.

The buzzer went off because more work was being done, so more heat, so thinner oil, so lower pressure.

It sounds very much as though you need to split the cases and put new mains and big end bearings in.

You could try replacing the pump and making sure the clearances are as tight as possible - worth considering as it can be done without removing the engine.

What oil did you put in ?

[spanishfly]

Thanks The bang option doesn't sound good and it was 15/50 superma as per recommendations. So sadly not likely to be the oil.

I'm up for doing it myself,but not sure how practical it really is without engine stands specialist tools but guess If I read enough build threads........ just don't want to end up with a box of bits!

It's frustrating the way all the US ones say things like 'dropped it off at my local machine shop to be.... line bored or whatever' I haven't found the same to be true here and presumably I would need the measuring (machining if necessary) bits done prior to collecting together new shells, shims, over sized or not, seals etc.

It may not be allowed but if anyone has any recommendations they would be much appreciated. I'm clearly not the first DJ owner with low oil pressure, needing to rebuild a bottom end..... and trying to work out the best plan of attack.

[937carrera]

Post number 2 has lots of links

http://forum.club8090.co.uk/viewtopic.php?f=37&t=162895

There's not much in the way of specialist tools needed, an engine stand makes it easier, but is not necessary. Line boring is not generally needed, but if you let it go bang the chances of spun bearings increase that chance.

A £15 pair of vernier calipers from Aldi can go a long way on the measurement front, micrometer and bore gauges are optional add ons. Machining probably isn't necessary if you replace the bearings before they completely wear out and contaminate other parts of the engine

[spanishfly]

Thanks Carrera, an hour just slipped by reading your rebuild thread. This could become quite addictive!

It does seem to make sense to replace the bearings before the big bang and despite the daunting factor of splitting the case these links do provide a lot of reassurance.

Time will tell....

[T25Convert]

Thanks Carrera, an hour just slipped by reading your rebuild thread. This could become quite addictive!

It does seem to make sense to replace the bearings before the big bang and despite the daunting factor of splitting the case these links do provide a lot of reassurance.

Time will tell....

Don't be daunted, there isn't much inside the case.

To get a 'perfect' engine you need top quality measuring gear. However, you'll note that a large number of people have made perfectly serviceable engines using cheap vernier calipers and end float tools from scrap iron and feeler gauges.

When I did mine I figured if I got it apart and the inside was really trashed, then it would be a good time to put it back together and use it as a core exchange - i.e. there was nothing really to loose by opening it up and having a look!

[spanishfly]

Thanks Carrera, if I can find somewhere dry for it in North Cornwall could be a good over the winter project.

In the meantime I got my hands on a decent 2nd hand SP pressure tester kit, plugged it in and sure enough 4.0 at cold idle falls to 0.6 at hot idle so attention needed.

What is interesting is that the pulley and pulley nut are painted silver and pretty much spotless which implies they've been off recently. Probably when the AMC heads were fitted < 3000 miles ago. so perhaps a new oil pump and an overly fat gasket were fitted then....?

Will check that next.

[spanishfly]

Fast forward 2 years and all is good.
Rebuilt the engine timed to 5 degrees, screwed throttle body screw in a turn and a half nice even tickover at 900rpm. which now shows a little over 3 at idle where before it was 0.6!

Very happy. Now need to find out about the running in routine.....?