Club 80-90 Forums

itchyfeet wrote:Looks like I spoke too soon about oil pressure.
It's much lower than my DG, it's only just 2 bar hot 2000 rpm and I'd bet thats not even 80 deg oil temp on a day like today.
Hot idle is 0.8 bar.

Disapointing.

I wonder if thats due to crank being reground under size on big ends, it was about 0.02 under
or is it's down to standard crank bearings being used and not blue colour code, the main bearing journals were spot on blue but they are NLA

I measured tye difference between new main bearings and DG crank and it was about 0.1mm which I was surprised at, all the WBX I have stripped have had quite a lot of play in main bearings
Why are main bearing clearances so much more than big ends?
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Have you thought about asking Marco?

Does that involve facebook?

itchyfeet wrote:Does that involve facebook?

For me yes but then I'm not a member of the wbx rebuilding club like you - don't you have a direct line to him?

Is your pressure relief valve working correctly?

Be careful as you could be following my footsteps.......


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Wilber wrote:Is your pressure relief valve working correctly?

Be careful as you could be following my footsteps.......

I have no reason to think it's faulty but no harm in checking it.
New con rods and stretch bolts so unlikely those more likely clearances out of spec.

if I didn't check pressure I would probably be blissfully ignorant.

Can you check the actual oil temp? Assumptions can be the mother of all f.. ups?

tobydog wrote:Can you check the actual oil temp? Assumptions can be the mother of all f.. ups?

Yes I can with a thermocoupke but in summer it will get much hotter than this, it's just not good enough, it's why this engine was removed, I find it hard to believe it could be a problem with the case.

I am going to split and measure up mayo engine but I think this one has to come out again

I assume tha lack of knoledge on crank acceptability is that most people take them to a machinist for advice, even sarran did that on ooops when he gad the same problem.
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I don't think 0.8 bar / 11.6psi is anything to worry about on tick over when the engine is hot.

The low pressure warning light kicks in at 0.3 bar / 4.3psi.

Does the pressure rise up to 2-3bar / 30-40 psi around 2K rpm when the engine is hot? If so that's what it should be.

sorry to hear your oil pressure woes after such a detailed rebuild. Have you checked the accuracy of your oil pressure gauge I'm assuming its's not the same one as in the DG. My MV is also low on pressure at hot idle (gauge checked against tyre pressure with Easibleed)10-12psi and 25-30 at 2000 rpm after an hours drive and I have installed a remote oil cooler to try and help, my next thing was to remove the interwarmer as these are supposed to reduce available pressure to see if that makes a difference,hoping so as the thrashed DG in the buggy has around 10psi more with no interwarmer.
Having said that without the gauge I would be in ignorance and happy with the way it sounds and drives, maybe it's normal.

It's a wet gauge that I previously checked against the electric gauge, I will check it again in the DG but I see no reason for it to suddenly read low.

the DG has loads of healty pressure, far more than this.

The great thing about having two vans is I can still go on holiday this year even if I don't get this reliable in time

Thanks for all the comments and encouragement.

Tonight I did some tests, I connected an electric pump to the gauge and at 2 bar they matched.

P1060859 by Paul_Barr, on Flickr

Next I ran the engine for 20 minutesat about 1500 rpm until the thermostat opened then stuck a thermocouple down the oil filler tube, I was surprised to see 95 degC oil temp.
I guess the hard work of dragging those rings up and down the honed barrels makes a lot of heat.

So I let it cool to 80 degC ( test temperature) removed the probe and started it, I got 2.5 bar at approx 2000 RPM ( no rev counter but I compared to the DG and so I can approximate 2000rpm) so I'm happier with that, still less than I'd like but hey ho.

P1060864 by Paul_Barr, on Flickr

P1060866 by Paul_Barr, on Flickr

Some better news are the compressions 13.5 to 14.5 bar that's 195 to 210 psi after 2 hours of running.
( tested hot 10 turns plugs all out throttle open)

P1060871 by Paul_Barr, on Flickr

I have decided to give the engine a chance, it's no more work to fix the mayo engine ( broken head stud) rather than strip and rebuild this so that's what I'm going to do.

My DJ produces approx 20 PSI at HOT idle with 20/40 semi in. Thats with oil temp about 90 degrees. As soon as I rev up and cruising at 2000rpm its about 50PSI . At 3500 rpm and hot it is around 65/70 PSI. I have just rebuilt it using a crank with no measurable wear and a standard set of bearings. Yours is giving 2.5 Bar at tickover at 80 degrees which is more than mine but what does it do when revved up a bit?

My old DG which was also rebuilt after 125000 miles again with a standard pump produced 25/30PSI at hot idle with no real difference in clearances from the DJ after rebuild. (excellent crank standard shells and mains.)

I reckon that's what you call good.

It would be interesting to know what the factory engines produced in new spec with everything brand new?

PS my compressions took 500 miles to get up to 195, they started between 160 and 180. Probably those grants rings I used!!!

Sorry I read it wrong you say 2.5 bar at 2000rpm? I guess you used a nice thin gasket on the oil pump cover and that the pressure relief is free in its bore. So 30PSI at 2000 rpm. When my oil temp shows 105 degrees after a motorway sprint mine is around about that. My pressure gauge is on the main gallery at the front is that where you are testing? Mine shows lower in the tappet gallery.

A bit out of my league this Paul but I reckon your right to give the old girl a chance and see how she's gets on. Out of curiosity, what type of oil are you using, usual 15/40 mineral? Could/would a different type make a difference (I use 20/50 Valvoline VR1 mineral).

123-jn wrote:My pressure gauge is on the main gallery at the front is that where you are testing? Mine shows lower in the tappet gallery.

Yes Tappet gallery at 80 degc and 2000 rpm, its the only test VW spectify and must be 2 bar min.
Ideally everybody who can should test theirs and post results

I have read the high pressure switch location give much higher readings, my logic is the difference is readings for a given pump flow will depend on how leaky your oil system is so there is no set relation between the two.

Leaks can be from excessive crank main clearances, standard bearings are bigger than blue, excessive big end clearances, this crank was reground under size, or wear in tappet bores.

I'm going to compare my DG with the same test tonight.

300CE wrote:A bit out of my league this Paul but I reckon your right to give the old girl a chance and see how she's gets on. Out of curiosity, what type of oil are you using, usual 15/40 mineral? Could/would a different type make a difference (I use 20/50 Valvoline VR1 mineral).

15W40 mineral, yes I used to use 20W50 in my old DG, it helps very hot oil pressure, I will if I have to.
yet to get it stinking hot to see what happens, probably won't do that for a couple of weeks until it's run it better.