DX Sportline Low Low Oil Pressure. Some investigation done.

Hi all,

I have a problem with my new car…  a 91 Sportline GTI Cabriolet

Problem: Low Low oil pressure, causing the oil buzzer/lamp to come on.

History

Bought my car last week with 114k miles for £2500…

Ran 30 miles en route home before Oil light/buzzer came on…

Rang the seller, he said he had not heard that before on his 6 mile journey to and from work.

Checked oil, engine for leaks etc., all looked OK, so carried on…
 
No more problems till I hit slow moving traffic in London near the end of my journey from collection in Devon.

Rang the guy that rebuilt the engine in Sept 2010 (from receipt given) the very next morning, he said we'd have never made it home if there was a 'big end' problem…  
He suggested a faulty oil pressure switch.

Testing

Took the car ASAP, the '6 or so miles', to my VW trained/specialist mechanic who ran an oil pressure test.

He recorded 8psi at hot idle, he reckoned that it should have been 40 psi. I then changed the oil & filter (even though oil looked clean) for genuine VW articles to try raising the pressure. The oil pressure instead reduced even further, down to 5psi at hot idle. My mechanic reckons a 'Oil Fortifier' was used before purchase to thicken up the oil thus 'quietening down' the problem…?

He then removed the sump and oil pump. Upon checking the pump, my mechanic said it looked tired, scored and warn, even though the pump gears had 'apparently' been replaced during engine rebuild…

He then checked the crankshafts big ends and main bearing clearances (using 'Plastiguage'). Which were 1 - 2 thou (thousands of an inch). Which he thought was fine.

New parts fitted - not holding my breath…

-New German built oil pump (inc. new pick up tube, gasket/o ring & oil pressure release valve).
-Baffles (original snapped during reassembly)
-Sump gasket (sump cleaned thoroughly)

Tested and only a slight improvement to 10+ psi at hot idle.

Conclusion

I bought this car for £2500 with the ad reading 'Get ready for summer'.

Now did this mean pay a fair price for the car, and then spend a week in and out of the garage, ruining your weeks holiday off work 'enjoying the sunshine' whilst running it back and forth to the garage, trying to do bits yourself to keep the spiralling £50/hour garage bills + parts down…

My mechanic says whilst he can do the 'investigation' work, its the labour charges that are going to mount up, and we may not get anywhere in finding the cause… He has spoken to the 'Engine rebulider', and to other people in the trade for clues.

He says he cant remember any 'oil ways' in the 'DX' engine that have 'blanking' plates in that may have come adrift, causing a leak and thus this crazy crazy low pressure.

My mechanic reckons it could be the head. He thinks it could be cracked, OR maybe has worn out bearings/casings, possibly due to the 'big end' fault and therefore possible 'head' oil starvation due to the the original 'bottom end' complaint. OR that the head was replaced for a higher mileage unit, during this period, thus more worn out, therefore lower oil pressure…

Please please if anyone has any knowledge to help, this would be very gratefully received…

Regards Ed

(ps. It is unfair right, to sell a car, for good money (£2500) and have a 'Major' engine fault just 30 miles after collection… Ok, the car is 20 yrs old, I can deal with the leaking cooling system, the syncromesh on 2nd gear is gone,  the knackered door handle, worn ignition switch, rattling tappets (pinking, needs a tune up), the dizzy cap on 180 degrees out, causing poor running, the hood knocking, the previous 'poor' alarm removal, leaving holes under scuttle panel causing wet carpets/electrics and the brake lights not working).

Sorry to hear about your car it sounds a right pain. Don't be put of though as I have the exact same car as a weekend motor and it is brilliant and a real head turner.

I unfortunately can't help you with the pressure problem but all the wee things will be easily fixable, just annoying when you want to enjoy it!

How are you measuring oil pressure ?

lhasadreams said

How are you measuring oil pressure ?

That was going to be my question.

If you had low oil pressure like that the engine would be rattling about like mad.  In fact id guess that it would of maybe seized up on that drive home.

Cheers all for your replys,

The car runs sweet, 'sometimes' a little 'tappity' from immediate cold start, but no smoke or anything, so not seized up… Yet..?!!

It has been measured by removing the 'top' (24mm??) oil pressure sensor, on the RHS of the head, and screwing a 'Smiths' oil pressure gauge in there using the same size thread as the pressure switch.

A 'home made' contraption, made by my mechanic, (incidentally who I found out the other day, started his training with VW in 1968)..!!

When  at 'cold' idle the pressure reaches 80 psi, and I thought all was ok, but as soon as it warms up, reduces down to 5-10psi at idle, and up to 30-40 psi at 'hot' higher revs, he says it should be nearer 30-40 at 'hot' idle….?

I hope my ramble makes sense…?!!

Thanks a heap for your help.

Best Regards Ed

better to measure the pressure at the filter housing, it will always read a bit lower at the head. you should see at least 0.4bar at the head though.

if the pressure is much better at filter housing then that suggests cam cap bearings are worn

Thanks a heap John…

A few further questions if you please…

- AT what RPM should the engine be at, for the head reading to be 0.4 bar (5.8 psi) (I guess engine should be warm for all results)..??

-What pressure should I expect to see at the filter housing..? & @ what RPM..??

Many thanks
Regards Ed

ps if head bearings are worn, what would your advice be for rectification please..?

you want to see 0.3bar at the very,very least at idle rpm so around 800ish. at the head it will always be a bit lower than a reading at the filter housing, but you still want to see around 0.4 bar really, 0.3bar is the warning threshold for the lamp on the dash see.

at the filter housing i would expect to see around 0.7-1bar warm with a healthy oil pump. worth an oil change if its not been done or you are unsure on the spec of the oil, 10w40 is what these cars like i use synta silver or fuchs titan from gsf/avs/vw

if you have lower than 0.3bar at the head but fine at the filter housing it could be the cam caps, if so you need a new head
if its low in both places then the oil pump may need changing, or the oil pickup is clogged

Cheers again John,
Oil, filter, oil pump/pickup have all been renewed for genuine articles or the pump/pickup was a German made unit. The sump pan was cleaned out by my fair hands so I know it's clean nothing to block up pick up tube…

Will check the pressures at filter and head for the values you advise.
Where abouts do you test at filter..? Oil pressure switch..? Same as head..?

Cheers again
Regards Ed

Ps know of anyone selling a head..?!

either hole in the filter housing will be fine

I had this exact problem on my mk2 after fitting a supposed 'rebuilt and flowed' head. all the cam caps were buggered and it was leaking oil thru the zaust vale stem seal into #3

in the short term i moved the low pressure switch to the filter housing just to stop the light reminding me i had been ripped off whenever it got warm

good excuse to go 16v, thats what i did

Thanks again John..!

Have been advised as a short term measure to just put a thicker oil in it 20/50 (possibly with an additional fortifier), to get more pressure, and when/if i find a good top end, I could replace it then..?

Or…

How long would a 16 valve conversion take to do..? Is there anyone that you could recommend to carry this out…?

Best Regards Ed

if you keep your box its a direct bolt in fit, except you need a conversion manifold of some kind. wiring wise a kr is pretty simple to do. i would think about getting an abf and running it on the proper managment though, they're brilliant engines. you'll have to take more care choosing the right conversion manifold to get it in though as they're a bit taller.  wiring more tricky on the abf managment, but i can make you a conversion loom no bother.

also since you're local i could help you out if need be>? depends how handy you are with the spanners

Thanks John,

I'm usually game for all of this, but, I work in the middle east, & only get back periodically, so this is why I thought I'd buy a car for more than my usual 'project/fixer upper' Mk2 GTI money, and hopefully have a good reliable runner with only minor problems, how wrong was I..!!

I will asses the pressure issue as you describe in your previous post and go from there…

Thanks for your help…

Regards
Ed

ps - as a quick fix, if you hear of a good condition DX head going pls pm me

FIXED..!!

Cheers everyone for their help…

Measured the oil pressure at the lower/'Oil Filter' pressure switch location, instead of the upper/'Head' oil pressure switch…

VW recommend 2 bar, mine was 4 bar..!  

I replaced the 2 pressure switches as mine were old… Spoke to Steve Creswell @ C&R, who was extremely helpful, & said the oil pressure switch at the 'Head' was changed from a Brown colour to a Blue colour 15 or so years ago. Mine was still the old Brown coloured one. The oil pressure switch at the 'Oil Filter Housing' was and still is white in colour.

Now no more buzzing..!

Hope this can help someone else out…

Regards Ed

me thinks you need to thank RJ he was bang on the money............again