New Solution For Mi16 Oil Surge

[welshpug 1,622]

now thats the kind of investigation work that needs to be done!

[jacobs53 0]

I think the peugeots boys had the head oil capacity at 3.5 litres, when the lifters are full and the head cavity filled.

 

lee

[nick 3]

are you sure thats right Lee?

 

There has got to be at least another 1/2 litre floating around as mist and filling the galleries and oil pump, that leaves 1 litre in the sump!!

 

Just by looking at the sump I don't think one litre would be enough to cover the pickup.

 

Who are "the Peugeot boys"??

 

Nick

[jacobs53 0]

Peugeot boys are the Ryton employee race team, They used the xu9j4 engine until peugeot brought out the xu10 and then they still preferred the xu9j4. Even when the gti-6 came out, they hated the iron block, because of the extra weight penalty. Luckely enough they aquired over 200 mi16 engines before hand to use. They lasted until 1999 aparenetly, when the had no alternative but to use the gti-6 engine. When the 180 engine was released they quickly used this engine removed the vvc operation and used two exhaust cams to produce good power.

 

Im sure its 2.5 litres, but I was told over a year ago. I could of got it wrong. But someone could quickly confirm by filling the head cavity's while blocking the return holes.

 

lee

[Gentrix 2 1 Cars]

One question comes to my mind. If the Head is full of Oil, and the Oil has to return through the Oildrains, is there enough Vacuum in the Sump, to ensure it gets sucked out quick enough?

As an Example, if you fill a bottle of water and hold it upsidedown, it will last a while, until everything is out, cause the exiting water leaves a vacuum. So there has to be air entering the bottle via a snorkel or a hole in the bottle or you create a turbulence (twister?)

 

And if someone says, the pump delivers 16 liter per min. and you take a look at the size of the Oilways there is no way, that 16 liters of Oil will flow back through them, without beeing forced to flow, somehow.

Could it be, that the engines suffering from surge have blocked or rerouted Vapourhoses? Maybe Carbs or TBs and just a breather filter on the block instead of the complete and oringinal hoses?

Edited October 9, 2006 by Gentrix

[Sandy 189]

16 litres might be a free flow figure, in which case it would be nothing like that against pressure.

[niklas 1]

Interresting point though.. Would a semi-blocked breather system increase the risks of surge??

[Emmy Seize 8]

Interresting point though.. Would a semi-blocked breather system increase the risks of surge??

 

At least it leads to an over-pressurized crank-case which could keep the oil from draining back into the sump.

[Dazza 4]

I think what you getting to fella's is ;

1 Pumped oil at 16 litre's ? north bound .(is this 16 litres at maxmum rev's or tickover ,7000 rpm's or 1000 rpm's ?)

2 Gravity /unpumped return to sump at a slower rate .

3 Worn engine,s and substandard engine case breather system allowing pressure build up and vaccuming slowing the oil gallery gravity return

4 frothing or bubbles being created by Velocity of crank action revolution

5 Engine back pressure to catch tanks ?

6 These suggestion's and clollaboration's are all responsible for your issue and all take there toll eventually .

7 Oil pump location on the pulley side and chain driven from a sprocket .

8 low oil level's ?ie not on max level 4.5 ltr's

The XU9JA 8v engine has no Hydraulic followers,no Oil spray bars on the Gudeon pin's ,half the oil volume required to supply the singular spray bar although the pump's the same iirc so the 16 LPS still applies ,iirc the oil returns similar to although i am to look at this asap ?

basically the 8v doesnt need as much lubrication as the 16v unit and by over filling it with oil your not really in practice going to solve this one imo although it looks a good suggestion.

Correct me if iam wrong this Oil surge issue ONLY OCCURS WHEN GOING AROUND A LONG RIGHT HAND BEND ? and the oil pump has little or no oil supply to draw from .HAS this ever occured throughout acceleration-decelleration -braking hard or left hand cornering .

 

To conclude my thought's the 16v does need more VOLUME of oil to feed its design over the 8v unit ,however there is a debate on the oil level in the sump whilst on full revs and cornering looks insufficient ? The frothing to me does look as if it could be a slight problem as we all know bubbles only sit on top of the oil level and the pump cant such these up so it says the oil level-pickup are one such issue of many here .

If you can return the maximum amout of oil to the sump, youve sorted it as ime ive not met an mi owner whom has suffered loss in oil pressure in brutal forlward acceleration ,thats one thing we can be sure of (providing his-her oil level was regularly checked)

Dazza

Edited October 10, 2006 by Dazza

[petert 550]

Correct me if iam wrong this Oil surge issue ONLY OCCURS WHEN GOING AROUND A LONG RIGHT HAND BEND ? and the oil pump has little or no oil supply to draw from .HAS this ever occured throughout acceleration-decelleration -braking hard or left hand cornering .

 

and short left handers if you're pedalling fast enough.

[Dazza 4]

and short left handers if you're pedalling fast enough.

Thanks Peter ,can we assume then it is undoubtably the oil is washing away from the pick-up then ,Full stop.Due to the depth of pump extension in comparrison to the sump depth ? If so how much clearance is there from the sump and base of the pick up on the oil pump ( in mm)

[nick 3]

Dazza,

 

Points 1 and 2 can't really be true.

 

If you are pumping oil to the top end quicker than it can drain back down the sump will empty and you will have a gallon of oil in the head.

 

Nick

[C_W 3 1 Cars]

Only ever happens on left handers for me (or chicanes); is fine going round right handers all day.

[Dazza 4]

Dazza,

 

Points 1 and 2 can't really be true.

 

If you are pumping oil to the top end quicker than it can drain back down the sump will empty and you will have a gallon of oil in the head.

 

Nick

Hi Nick ,i was trying to explain and eliminate the train of thought with the point's rather than imply there factual bud .

Ive stripped one of my collection of mi 16 engines down over the last couple of hours and there a brilliant piece of engineering over the 8 v unit ,the sump design and pump do look the part even if were no convinced there any good !

keep the debate continuing with feed back of the Mi surge's and IAM SURE i /we have an answer coming !

Dazza

[jacobs53 0]

As C_W has already identified the mi16 manily suffers on left hand corners. So the oil return problem must be on the camshaft side of the engine, as the oil will be pushed over due to the inertia. The oil pump is also located on this side of the engine, but im not sure how centralised the oil pump pick-up is located inside the sump.

 

So fine in a straight line, and right handers.

 

I'd personally be looking into the oil return on the camshaft side of the cylinder head and block to see if there any obstructions. And compare both sides for flow rate, when the head is filled with oil.

 

Cheers lee

[petert 550]

So fine in a straight line, and right handers.

 

No, it surges on right handers as well. It does it both ways. READ MY LIPS. It does it both ways. Why do you think XU10 sumps have the trap door where it is?

[mos 1]

interesting reading guys

 

simple thinking here and i can't check aginst my head as its away at the moment.

but if oil is being trapped in the head and oil starvation is an issue when cornering in both directions then would it not be a good idea to have a couple of external drains to the sump located at either end/side of the head so that when all the oil that is trapped in the head on a long corner has a method of returning to the sump regardless of the direction of travel.

like i said my engines are away at the moment so i cant check if this is even feasible but seems to make sense to me.

also using a trap door sump and a longer pickup cant hurt and must give a better chance of avoiding oil starvation

 

thanks

 

mark

[veloce200 3]

someone said this "The 8v never surges or should i say the guage never budges even on slick's ."

 

that's simply not true. The XU series have crap pickup design and suffer from surge on cornering - mainly right handers (why do we think the pickup is right side biased- 'cause they drive round roundabouts the wrong way !) but also under braking. The XU Mi has additional problems with the head too. IMO I would fit an electric scavenge pump (as mentioned b4 M5 has 4 of these!) to pump oil from head to the sump.

[Dazza 4]

Just to assist one or two fellow mi fan's .

The Mi head and block drain on BOTH SIDE'S ,CAM BELT AND DIZZY SIDE.

The oil on the cam belt side drains onto the oil driven chain-sprocket and like wise on the dizzy side it spill's onto the main's end cap from the head.

They are located to the rear end of the engine and looking at it out of the car it looks like it would hold a small amount of oil but imo not enough to be totally resonsible alone to cause starvation.

The oil pump-up is some 15-16mm up from the base of the sump ,the actual face plate-filter of the pump is 5-6 mm from the base of the sump .

The oil is pumped up the front side of the engine and into the head through a in-line gauze filter some thing like 7-8mm dia.

The oil surge usually imo gets the second conrod shell's first (3 rd in from the pully side)as this is the furthest one from the pump ,the reason it doesnt do the first con-rod shell's (closest to the gear box) is the oil drains directly on to it from the head return thus giving lubrication to it even if indirectly done.

This does tell us that oil is returning from the head ok or at liest so it dampens the thought the head is holding oil theory imo.The closest to the pully and the second one will suffer although not as badly ,nedence to say there all blitzed and will need a grind when this happen's .

The reason for oil surge imo and the debate will rumble on no doubt ,is washing oil in the sump hence thats were iam going to concentrate my efforts mostly .

I hope this will help simplify some of the area's for the low experienced fella's , My description's are from experience on building and stripping down these engine's (as a hobby and having been around cars for 20 yrs with my old fella whom was a top Fitter) and trying to get some sense of understanding based on findins and studying our collective thought's and differering thought train's We all dont know everything but between us we'll get there ....i hope Ha ha .Patience partience......

Cheer's dazza.

[C_W 3 1 Cars]

No, it surges on right handers as well. It does it both ways. READ MY LIPS. It does it both ways. Why do you think XU10 sumps have the trap door where it is?

 

My opinion is that, yes it will surge on right handers, but only like most other engines will eventually suffer from surge (like the 8v might do), but for left handers is ridiculously easy to lose oil pressure but I can go round a roundabout quickly and the pressure won't drop.

 

I reckon the trap door is where it is because there's no where else for it to go as the oil pump itself takes up so much room on the other side, and the trap door will always open towards the pickup.

 

someone said this "The 8v never surges or should i say the guage never budges even on slick's ."

 

that's simply not true. The XU series have crap pickup design and suffer from surge on cornering - mainly right handers (why do we think the pickup is right side biased- 'cause they drive round roundabouts the wrong way !) but also under braking. The XU Mi has additional problems with the head too. IMO I would fit an electric scavenge pump (as mentioned b4 M5 has 4 of these!) to pump oil from head to the sump.

 

I'm sure the pickup is pretty much central in the sump.

[kyepan 291]

on mini's doing autotests they used to fit special oil pick up pipes, surely getting to where the oil surges to (assuming its in the sump at all) would be a good cheap alternative to external oil returns and drysumps.

[phat205 0]

Why? I'm sure you know as well as anyone else here, and as already pointed out in this thread, it's a characteristic of the Mi's head not returning oil efficiently to the sump to pick it back up again. New or old, again, you cannot beat physics!

 

My Mi has covered 2750 miles from NEW, I still get a small drop in pressure on tight rights

[Livelee 0]

Sorry to bump an old post, but I thought it was better than starting a new one.

 

I've had my mi for a year now, i've done a few trackdays and many autotests. The car has always had it's standard gauge and warning sender. The standard gauge always read max and i've never seen the light come on when driving. I've just fitted a new sender and mechanical gauge. I've gone into the block where the original warning light sender is.

 

I've got a baffled sump but once upto temp I can make the gauge read 0 psi at will. Heavy breaking, left hand bends, right hand bends. All of them will make the warning lights come on.

 

From the last time I drove it before adding the gauge i've added an oil cooler but this shouldn't affect things, should it?

 

I can only assume he car has always been surging really badly and it's a miracle that it's not blown up. Is the place where I have my sender the correct position for an accurate reading? and what should I do to cure the surge problem?

 

Many Thanks

 

Dan

[Kitsune 0]

would it not be a good idea to have a couple of external drains to the sump located at either end/side of the head

 

 

I'm doing a HNC project to this effect and I'm currently in the research phase so looking at the information on here as well as talking to a few engine builders. One of which thinks the oil does not build up in the head (not enough to cause a surge) and that they have designed and used a baffled sump which works in a motorsport application. There doesn't seem to be much on the way of takers for the external drain, although it has been mentioned on here a few times.

 

I also questioned the extended oil pick-up (petert's design) and this came back as being a pretty effective method for a good price although it might not be as effective under certain conditions (heavy braking) but this would depend on the design.

[petert 550]

I also questioned the extended oil pick-up (petert's design) and this came back as being a pretty effective method for a good price although it might not be as effective under certain conditions (heavy braking) but this would depend on the design.

 

How could it be any less effective under heavy braking? If there is more oil above the pickup it has to be better than standard. Also, where can the oil go? Forward, up the long wall? If anything, the most likely point of failure is still a long left hander, when oil has more room to move away from the pickup.

 

I've never seen less than 30psi with the extended pickup, trap door sump, pump baffle, 6.5L design. I suggest you stick some sticky tyres on and try it. Sounds like too much theory and not enough practical to me.