: Loss of oil pressure @ high rpm


Peace
23-09-2012, 11:10 PM
I have put this thread in here as i feel the performance guys might be able to help more...

I have had this underlying problem since i built the engine (http://www.volkszone.com/VZi/showthread.php?t=776893) but has become more obvious now im 'ragging' it a bit more.

It first occurred on the motor way when i had given it a bit of high rpm cruising for a while. The oil pressure gauge went from full pressure to nothing and the oil light came one... foot on the clutch and started to pull over when it all came back to life... thought it was a bit strange but took it steady from there on in...

Now im noticing it when i accelerate hard... i take the revs up high and as soon as i go to change gear the pressure drops, if i change gear quick enough the pressure stays ok, it i take my time changing gear i loose it all together.

I have also experienced it a second time with cruising at high rpm on the motorway. only this time it stayed off for longer.

The fact that it happens at high rpm would indicate that im dropping oil level in the sump (i have a thin line sump and longer pickup tube fitted). Perhaps i should look at either a deeper sump or run a thinner oil to allow it to flow back quicker? have have heard of people (http://www.cal-look.com/forum/cal-look-high-performance/loss-of-oil-pressure-*after*-a-high-rpm-blast/) removing or making holes in the 'hood' on the standard pickup tube to allow the oil to flow back to sump quicker.

The fact that it also happens during gear change could suggest that i have a sticking pressure relief valve. the piston might be getting stuck when the pressure/flow drops during gear change. But you would expect the pressure to return when the rpm increases - but it doesnt...

I faintly remember having a conversation with someone at VW Action about this and he said that his motor often does the same thing when crossing the line during drag racing...

I have not yet looked at the pick up tube to make sure it is still in position but i would be very surprised if it isnt.

I am running a CB Maxi 30 full flow pump, external filter and oil cooler and a 1L thin line sump. I have plugged the case where the 'standard' outlet from the pump goes.

I have tried running at various levels of oil (upper and lower level) and appears to get worse when the oil is lower.

Anyone got any other ideas before i start the investigating?

Cheers,
Peace!

alex1916v
23-09-2012, 11:26 PM
1st thing id check would be the extenstion pipe going into the deep sump...

how did you attach it? mines welded, as i dont fancy that jubille going loose!

also, with the deep sump what quantity of oil are you putting it?

after that id be pulling the pump and the CB maxi thing and going 'propper' full flow

Rich Jones
24-09-2012, 12:04 AM
Put a bigger deep sump on it

lukej
24-09-2012, 09:43 AM
I think that at high revs you are draining the sump. A combination of a 26mm oil pump, a deeper sump and/or drain lines from 3/4 side rocker box should sort you out.

Peace
24-09-2012, 05:52 PM
I just used the jubilee clip that came with it... I don't think that's helping the situation tbh... I wish I knew about these things before I built the engine and I would have welded it

As for the quantity, I have tried it at various levels (both upper and lower limits on the dipstick)



1st thing id check would be the extenstion pipe going into the deep sump...

how did you attach it? mines welded, as i dont fancy that jubille going loose!

also, with the deep sump what quantity of oil are you putting it?

after that id be pulling the pump and the CB maxi thing and going 'propper' full flow

Peace
24-09-2012, 05:54 PM
Put a bigger deep sump on it


Might be an option but I don't think the deep sumps come with the return fitting/threaded bit for the turbo oil return... Not the end of the world but I'm would like to try other options before splashing out more cash

Peace
24-09-2012, 05:59 PM
I think that at high revs you are draining the sump. A combination of a 26mm oil pump, a deeper sump and/or drain lines from 3/4 side rocker box should sort you out.

I have heard that it can be due to the larger pumps... If I got a 26mm pump, would it be ok on lower rpm? And what would be the point in selling 30mm pumps if they just drain the dump dry? I would have thought, if anyone would need the biggest pump, it would be the likes of me running 2332cc's??

What do you mean on the drain lines from 3/4 side rocker box?

Peace
24-09-2012, 06:34 PM
I think that at high revs you are draining the sump. A combination of a 26mm oil pump, a deeper sump and/or drain lines from 3/4 side rocker box should sort you out.

I'm struggling to find a 26mm oil pump for 3 bolt performance cams

Anyone know/advise on which on I need? :)

lukej
24-09-2012, 08:05 PM
Schadek do one. Lap the body and the cover to ensure minimal clearance between the two.
The fact you're running big cc's has nothing to do with needing a bigger pump, if you're brg tolerances are all good (you plastigaged when building didn't you ;)) and the rest of the system is in good shape a 26 is ample.
If you're running big external coolers then a 30 may be necessary but even still I doubt it.

Due to the cranks rotation, you end up filling the 3/4 side head with oil at high rpm. And I mean full!
You can weld an AN fitting into the rocker box and the same onto the sump and drain it, otherwise it's just got the pushrods tubes to rely on.

Peace
24-09-2012, 08:17 PM
Schadek do one. Lap the body and the cover to ensure minimal clearance between the two.
The fact you're running big cc's has nothing to do with needing a bigger pump, if you're brg tolerances are all good (you plastigaged when building didn't you ;)) and the rest of the system is in good shape a 26 is ample.
If you're running big external coolers then a 30 may be necessary but even still I doubt it.

Due to the cranks rotation, you end up filling the 3/4 side head with oil at high rpm. And I mean full!
You can weld an AN fitting into the rocker box and the same onto the sump and drain it, otherwise it's just got the pushrods tubes to rely on.

ahh :) that makes sense :)

if i increase my breathing on the heads (i dont have any yet) would it allow oil to flow from the heads back to sump quicker?

I suffer with my oil temp starting to increase when cruising at 70+ so i was tempted to add another oil cooler. The addition of a second cooler may mean i need the 30 pump... bit of trail and error i suppose until i find the right combination :)

Peace
24-09-2012, 08:21 PM
http://www.vwheritage.com/vw_spares_Oil-pump-Schadek-26mm-70-not-inc-cover-AC115145_act_shop.product_pID_96211_lang_EN_countr y_GB.htm

this looks like the one :) not a bad price either

beetleragtop
24-09-2012, 08:33 PM
Is it a maxi 30 pump from cb you have?

If so I'd pull it and open it out a bit, some of the castings are a bit tight and unless you know to look that will be restricting flow at high revs;)

I've told cb and they are addressing it but there are some out there when you pull them apart they have restrictive castings, they flow great when sorted:D

Cheers James

lukej
24-09-2012, 08:38 PM
That's the one Peace.
I'm not convinced adding oil coolers is the best solution just yet. Whether cruising at 70mph with a 1600 or a 2332 the actual work done by the engine should remain the same so if your thermostat is in place and working along with the rest of the tinware and doghouse oil cooler there shouldn't be a problem.

Maybe you're jetted a little lean or advance out a touch could explain running warm.

As for the breathing-if you have oil pouring out of the crank snout behind the front pulley then yes you have breathing issues. I don't think adding a breather will alleviate the head full of oil. The only solution here is the drain lines back to the sump (and maybe windage PR tubes to minimize the oil slosh around corners.)

There are good videos online showing the oil levels in the heads using a plexiglass window bonded into the rocker covers. I'll have a route round.

Peace
24-09-2012, 08:47 PM
Is it a maxi 30 pump from cb you have?

If so I'd pull it and open it out a bit, some of the castings are a bit tight and unless you know to look that will be restricting flow at high revs;)

I've told cb and they are addressing it but there are some out there when you pull them apart they have restrictive castings, they flow great when sorted:D

Cheers James

it is a CB maxi 30... you should know, i bought it from you :P and i would have thought you could have checked it for me before you posted it ;) lol only jokin...

i dont think im suffering from poor flow as i have good solid pressure the rest of the time... if anything, im suffering from excessive flow.

Theres a point... what about if i just restrict the flow coming out of the pump. perhaps put a reducing bush from 3/8" down to 1/4" and use a 1/4" NPT to 1/2" hose tail... the smaller internal diameter should reduce flow and not suck the sump dry...

does that sound like a risky idea?

lukej
24-09-2012, 08:51 PM
http://www.shoptalkforums.com/viewtopic.php?f=15&t=136101

Peace
24-09-2012, 09:13 PM
http://www.shoptalkforums.com/viewtopic.php?f=15&t=136101

nice find... people have far too much time on their hands ;)

I dont have the 'slosh' issues from cornering... i only go fast in a straight line... i might be a loony, but cornering hard in a split is suicide lol

and i like my adjustable push rod tubes far to much ;) lol

I would have expected my head temp to go up tho if i was running lean/timing issue... plus, im injected and the AFR is all set right :)

perhaps i will just get some ram air over the cooler to cure that mystery :)

as for the oil pressure... im thinking i might just chuck a 26mm on and see how it behaves. I think that will sort out most of my issues.

I need to do an oil change anyway now so i will get a good look at my pickup tube and see if there is anything obviously wrong there.

lukej
24-09-2012, 10:20 PM
Good luck!

Rich Jones
24-09-2012, 10:40 PM
A 26mm schadeck pump should be plenty for most people.
If you have a one litre sump you need a bigger one. the oil will either stay in the rocker covers or cavitate in the sump at high revs causing the pump to suck air and then you lose pressure.

Mellis
24-09-2012, 10:43 PM
James,

Could you give us some details on what to look out for with the Maxi 30 pumps, I also have one from you that will be going in my engine build. Be better for me if I could check it out first time round :)

Cheers,

Mike

Peace
25-09-2012, 12:29 AM
James,

Could you give us some details on what to look out for with the Maxi 30 pumps, I also have one from you that will be going in my engine build. Be better for me if I could check it out first time round :)

Cheers,

Mike

Hijacking my thread are you? ;)

I will be at stonehouse tomorrow morning... I will come and have a chat with you :)

judgie
25-09-2012, 09:46 AM
I have seen the extension tube for the deep sumps pulling air as they have not been fitted correctly. the slits in the tube have not been covered by the og pick up tube. when your at low revs its fine as the oil level is above them but once you get the motor spinning it uncovers the slots and the pump pulls air.
As you are turbo i would stick with the bigger pump, your asking the pump to do a hell of a lot of work over a stock motor. coolers , filters and a turbo all take there toll on flow and pressure.
If your having too high a pressure you can always get a adjustable relief valve to bring it back down.
Flow and pressure are two different things even if they are connected.

beetleragtop
25-09-2012, 11:28 AM
it is a CB maxi 30... you should know, i bought it from you :P and i would have thought you could have checked it for me before you posted it ;) lol only jokin...

i dont think im suffering from poor flow as i have good solid pressure the rest of the time... if anything, im suffering from excessive flow.

Theres a point... what about if i just restrict the flow coming out of the pump. perhaps put a reducing bush from 3/8" down to 1/4" and use a 1/4" NPT to 1/2" hose tail... the smaller internal diameter should reduce flow and not suck the sump dry...

does that sound like a risky idea?


Only just found out about the quality issues;)

I've sent the ones I had back

Just a thought, but if you have good static pressure it's not the issue

Cheers James

beetleragtop
25-09-2012, 11:34 AM
James,

Could you give us some details on what to look out for with the Maxi 30 pumps, I also have one from you that will be going in my engine build. Be better for me if I could check it out first time round :)

Cheers,

Mike

Yours is pre casting issue;)

Basically though open the pump up, if the gallery holes line up it's all good, if the casting restricts flow use a needle file to correct

It's a 5 min job

Cheers James

Mellis
25-09-2012, 01:45 PM
Cheers James,

I'll take a look before I install mine, just nice to know what to look out for :)

Mike

Peace
25-09-2012, 08:17 PM
I have seen the extension tube for the deep sumps pulling air as they have not been fitted correctly. the slits in the tube have not been covered by the og pick up tube. when your at low revs its fine as the oil level is above them but once you get the motor spinning it uncovers the slots and the pump pulls air.
As you are turbo i would stick with the bigger pump, your asking the pump to do a hell of a lot of work over a stock motor. coolers , filters and a turbo all take there toll on flow and pressure.
If your having too high a pressure you can always get a adjustable relief valve to bring it back down.
Flow and pressure are two different things even if they are connected.

Thanks Judgie, Im pretty sure i made sure the extension tube was fully on when i assembled the engine... but the more i think, the more i doubt myself, so i will be checking this.

Im not suffering with high pressure at all. Its only appears to be flow related. From what i understand so far, the pump is delivering far too much oil to the engine so a large % of that delivered oil is going straight to sump via the pressure relief system. For arguments sake, im using 30% of the oil and dumping 70% of the oil. And so the oil must be being pumped at a quicker rate than the oil returning to sump.

If i was to fit a smaller oil pump, then i should end up using 90% of the oil and dumping 10%. The general flow is less, the pressure is still the same and im not sucking the sump dry :) simples :)

It makes sense that this is the problem but it could quite simply be, i dont have enough oil. The oil is being thrown around, up the heads, round the oil system and at high rpm i just dont have enough oil. But unless i have a glass engine case and heads, there is no way of telling this. I would rather fit a 36 pump and trial it carefully, than waste 160 on a deeper sump and loose even more ground clearance.

Trial and error i think at the moment. Anyway, im going to order a pump :)

lukej
25-09-2012, 09:09 PM
I think that's a good idea :)

lids_2001
26-09-2012, 07:29 AM
Does this just occur when the engine is hot, or can you get the same symptoms from start up?

Peace
26-09-2012, 08:17 AM
Does this just occur when the engine is hot, or can you get the same symptoms from start up?

Happens hot and when it's warm.

I havnt really started it up and instantly ragged it up to 6000rpm yet :p

judgie
26-09-2012, 11:53 AM
as i said flow and pressure are different things but are related.
you can flow 50 ltrs/hour but at 5psi or 100psi at 10.trs hour it all depends on what your pushing the liquid through and how big the pump is.
if its dropping pressure at constant revs then i would have thought its pulling air as the oil is not getting back to the sump, even if it is dumping the oil back to sump via the relief valve. there is somthing stopping the amount of oil the pump needs getting to the pick up tube.
one thing to check is how close to the sump plate the pick up tube is, I had a motor in that had the wrong sump bolt in the deep sump. this bolt was almost going up inside the pick up tube, made for some interesting pressure problems that took a while to find.

Rich Jones
26-09-2012, 02:20 PM
Some oil pressure problems can be a pig to find. I don't think it's a relief valve problem, I do agree it's sucking air.
Checking the tube is an easy enough job. That's your first step.
I still reckon it needs a bigger sump - the CB slimline 1 litre is TINY.

spannermanager
26-09-2012, 05:07 PM
its bound to have pressure problems if it sucks air, as soon as the oil becomes emulsified, the pressure will go away, but all you need to do to check yay or nay is to stop the engine soon as the pressure fades, then quickly pull of the oil filter and pour the oil into a glass jar, if the oils emulsified in the filter, you've got your answer, if not, its not pumping air, on the other hand, covering the pick up extension with the addition of more oil in the sump will stop it sucking air, try adding more oil first , do it motor running and watch the gauge, if it still happens its because the pump is losing prime, the reasons for that are many, but start with checking the gears are not losing their pressed on interference, and thereby spinning on the shaft when hot, if they check out ok, try getting more oil onto the pump gears on the priming side by blue printing the pump, if it definitely has emulsified oil in the filter, its likely the pick up tube is lose in the case.

Mellis
26-09-2012, 10:09 PM
Just a thought.....no expert but I was discussing this with the Kernel earlier.....

Is the return/drain on the Turbo big enough?? If not could tht be slowing the return I oil back to the sump??

Peace
26-09-2012, 10:11 PM
Just a thought.....no expert but I was discussing this with the Kernel earlier.....

Is the return/drain on the Turbo big enough?? If not could tht be slowing the return I oil back to the sump??

It has a large pipe (about 1/2-3/4") return and is installed as CB supplied.

It only has a small feed, so i dont think it uses that much oil...??

Peace
26-09-2012, 10:22 PM
its bound to have pressure problems if it sucks air, as soon as the oil becomes emulsified, the pressure will go away, but all you need to do to check yay or nay is to stop the engine soon as the pressure fades, then quickly pull of the oil filter and pour the oil into a glass jar, if the oils emulsified in the filter, you've got your answer, if not, its not pumping air, on the other hand, covering the pick up extension with the addition of more oil in the sump will stop it sucking air, try adding more oil first , do it motor running and watch the gauge, if it still happens its because the pump is losing prime, the reasons for that are many, but start with checking the gears are not losing their pressed on interference, and thereby spinning on the shaft when hot, if they check out ok, try getting more oil onto the pump gears on the priming side by blue printing the pump, if it definitely has emulsified oil in the filter, its likely the pick up tube is lose in the case.

All very well and good... but i dont think the neighbors would be too happy if i sat on the drive, running at 6K with no silencer ;) lol

Ive tried running the engine with a little excess oil in with no difference.

I believe the gear is keyed on the CB pumps??

Im going to try a 26mm pump and inspect my pick up tube first. im going to refit the pickup tube with some loctite to help seal it so that should rule that out.

Prob wont get round to doing that until next week now but i post the outcome :)

lids_2001
27-09-2012, 07:11 AM
The pickup tube needs to be at the correct height. Too long and its too close to the sump plate causing loss of low and the same if its to high.

Peace
08-10-2012, 07:26 PM
sooo.... i havnt yet tried the smaller pump or even looked at the pick up tube.

Ive sorted out all my breathing issues as i was suffering with large amounts of oil being chucked out the pulley due to excessive crankcase pressure.

Ive fitted a vw speed shop tube fed from the breather tower and fuel block off plate and also taken a feed from the tube to a catch tank linked to the air filter as well to pull some vacuum through. Works great!! Im getting nothing coming out the pulley now and i dont have to clean my engine bay every time i go for a drive ;) Im also going to be fitting a sand seal so i dont pull anything in through the pulley now she's pulling vacuum.
http://i557.photobucket.com/albums/ss18/russellpeace/8DE15CF5-6A7B-45D5-ACC5-69B2A512662D-1265-00000152AF03DA85.jpg

linked into this issue however, since i have resolved the breathing problem, i havnt experienced loss of oil pressure.

is it possible that the whole issue was linked to poor breathing? perhaps there was so much oil in the tower, heads etc that it was draining the sump dry... now there is better air flow its allowing the oil to flow back to sump quicker???

what are your thoughts?

Peace
17-06-2013, 10:02 PM
Well... It's been a long time since I started looking into this problem.

It turns out my breathing issue was due to a cracked piston.

Stripped the engine right down again and checked the pick-up tube and sure enough... The little bugger was leaking. So I welded on a better one :)

Put the engine back together and thought everything was ok but as I've finished running in, I'm beginning to push it more and I've experienced a drop in pressure again :( I thought it was definitely the pick up tube!!

I even had the issue going up a steep hill and at 3000rpm. I wonder if it is still the loosing oil in the sump issue due to the pump being to big.

Going to take it steady to EBi and play sound with it a bit more after... Shame I really wanted to race at EBi :( but I can't afford to do any damage due to low oil pressure :(

Maybe I will fit it this weekend and trail :S lol

tufty
18-06-2013, 11:11 AM
Well... It's been a long time since I started looking into this problem.

It turns out my breathing issue was due to a cracked piston.

Stripped the engine right down again and checked the pick-up tube and sure enough... The little bugger was leaking. So I welded on a better one :)

Put the engine back together and thought everything was ok but as I've finished running in, I'm beginning to push it more and I've experienced a drop in pressure again :( I thought it was definitely the pick up tube!!

I even had the issue going up a steep hill and at 3000rpm. I wonder if it is still the loosing oil in the sump issue due to the pump being to big.

Going to take it steady to EBi and play sound with it a bit more after... Shame I really wanted to race at EBi :( but I can't afford to do any damage due to low oil pressure :(

Maybe I will fit it this weekend and trail :S lol

have you tried a 26mm pump yet?

Peace
22-07-2013, 07:41 PM
Fitted a 26mm pump and the problem has disappeared :) pushed it to its limits with no oil pressure loss :)

I also fitted standard relief valves instead of the grooved one. And also swapped to a slightly thinner oil.

If I cruise along the motorway at fast speeds for long periods of time and the oil temp reaches 100 then I get the oil pressure light flickering on idle. Some thicker oil should sort that out :)

All in all I think the problem has been solved :D

VW action here we come :)