Oil Pressure Solutions Mi16

[findlay 0]

Well the mesh SHOULD keep the biggest bits of crud out of the pump. The plate covering the mesh (where the hole is) is only clipped on (would prise off with a screwdriver and a few choice swear words when the screwdriver slips and lacerates your hand). There are a few nuts holding the actual pump together so I'm assuming it shouldn't be too hard to strip, clean and re-assemble.

[Wurzel 16]

I've stripped a pump down before but there isn't much to it. Piece of piss and very simple inside. Two gear wheels forcing the oil around with a pressure relief vent.

 

Not much to it at all.

[Mattsav 1]

I had a bit of a surge problem this week.

 

The oil level was a bit low (the top of the dipstick fell off, now I 've got a new one I know the level was on the minimum).

 

When you join the A27 from shoreham there a long left hand slip road that goes up from the roundabout to the flyover.

 

Wednesday I had to go to shoreham twice. Fist time On the way home it was dry and i was giving it a bit up the sliproad. I wasn't paying anyattention to any guages (the oil pressure guage only works when its raining anyway - bloody brown multiplug), the crash barrier and the lorry I was going round sort of took all my concentration.

 

Suddenly the dash lit up and the oil light was on. This was a bad thing for 2 reasons.

1. I had no oil pressure

2. I was booting it round a corner with a boot full of tools and had to hit the clutch quickly. Brown trousers time

 

The oil pressure seemed to take forever to come back.

 

Second time I went up the same slip road it was pissing with rain so I was just potttering along.

At exactly the same point the oil pressure light came on and it seemed to take the same length of time for the oil pressure to return.

 

I didnt have any problems going down the slip road off the A27 which is another long left hand bend but downhill.

 

The amount of cornering force didn't seem to make any difference, it was the length of time that was the critical factor combined with the fact it was going uphill.

The oil would have been building up in the back of the head on the cambelt end.

 

Now I've got a place where i can repeatedly run out of oil I might add an extra drain back to the sump when I have the head off next and see if it makes a difference.

 

I dont know whether Sean has had any problems with this peice of road as its right on his doorstep.

[smckeown 1]

I dont know whether Sean has had any problems with this peice of road as its right on his doorstep.

YEah i was reading that and thinking..hang on thats right next to me. I have never noticed anything yet. Although my problem is i never notice the oil pressure light flashing, so this week i'm having the biggest god damn light fitted to the centre of the dash..so big im expecting to get a tan every time it comes on

 

I'll have the car out of the garage tomorrow and have a go myself. Put the camera on so i can look at it afterwards

 

Were u joining the a27 towards worthing or brighton ? I assume brighton as left hander

 

Sean

Edited October 2, 2004 by smckeown

[Alan_M 66 1 Cars]

Couple of things I noticed when I stripped/rebuilt my Mi16.

 

There are two different sized drain holes on each side of the block.

 

The head has a pressure valve to maintain pressure at 1bar for the lifters.

 

The drain hole on the flywheel side of the block, drains into the srea between the crankshaft main seal and bearing cap 1. There is only 2 x 5mm holes drilled through the cap to allow oil to drain back into the sump.

[Alan_M 66 1 Cars]

I've finding it strange that different Mi's have such varying oil pressure problems

[Mattsav 1]

so this week i'm having the biggest god damn light fitted to the centre of the dash..so big im expecting to get a tan every time it comes on

 

 

I was going towards Brighton

[findlay 0]

To recap:

 

My oil pressure is low when braking hard and on left handers.

 

Suspect slight tilt on the engine and main cause of issues being the larger of the two oil drains has no oil to drain. Also suspect oil pump is unable to pick up and oil to replace the volume sloshing around in the head away from the drian holes.

 

Correct thus far?

 

Possible solutions include baffled sump (to stop sloshing around of oil in the sump) as well as variousl accusump/dry sumping kits.

 

Now here is my "Mad Professor" Idea...

 

We have baffled the sump but we have issues with the head. Why not baffle it?

 

By baffling the head (which looks without cams, lifters etc. to be a very voluminous space) and running possible 3 baffles across the head and one down its length to the exhaust side of the plugs we could reduce the oil disappearing from the exhaust cam and the 2 drain galleries under both conditions where my car has issues...

 

Opinions?

[base-1 17]

my symptons are very similar to Matt's - any kind of extended left hander, its the time thats the killer rather than anything else, although hard cornering lets it go quicker, mine still loses pressure on slight downhills though

[KRISKARRERA 2 1 Cars]

LOL I'd rather have surge problems than oil leaks anyday. Still, both can be deadly.

[Rob Thomson 6]

It is very strange how different people with the same engine have different problems. I wonder whether this is more a reflection on different instrumentation than on genuinely different engine characteristics. I replaced my gauge sender a couple of years ago and it totally changed the way the gauge behaves. I imagine that most original senders on these engines will be buggered by now.

 

For what it's worth, my 309 Mi16 suffers from surge through long fast left-handers, but it's worst through slow right-handers; roundabouts are a perfect example. But right handers taken at 80 or 90 don't seem to cause any problems. Very, very odd. I've only witnessed surge under braking when the oil level has been very low. But I've only ever had the warning light come on once - through the 'esses' at Prescott.

 

Why would you want to baffle the head? Surely you want the oil to return to the sump as quickly as possible - not be trapped in the head? Am I missing something? I am immensely hung-over so that's entirely possible.

 

My father and I had a look at an old pump the other day, and reckoned we could reasonably accurately determine the rate of flow of oil around the engine at different engine speeds. We reckon that at just 2,000 rpm the engine's using the best part of 24 litres a minute (We're assuming that the relief valve opens above 2,000 rpm, and thus above that speed flow to the engine remains about the same). That is a massive amount of oil (about a pint per second) - and makes me wonder whether baffling the sump is actually a good idea; you might run the risk of preventing oil flowing back to the pick-up!

[KRISKARRERA 2 1 Cars]

We reckon that at just 2,000 rpm the engine's using the best part of 24 litres a minute

That's one hell of alot, u sure that's right?

[findlay 0]

Why would you want to baffle the head? Surely you want the oil to return to the sump as quickly as possible - not be trapped in the head? Am I missing something? I am immensely hung-over so that's entirely possible.

lol... well my theory is that the exhaust cam sits in an oil bath so there is obviously a very large quantity of oil sitting in the head. By baffling the head and inserting 15-20mm high baffles (it looks like 25-30mm could be possible) you would contain some of the oil which would tend to run away from the g/box end drain gallery under left hand corners but also allow clearance for the cams. The baffle running the lenght of the head would contain the oil from sloshing forward under heavy braking.

 

I can't see how it would stop oil draining back under normal running conditions given that the baffles would be covered at that stage.

 

Anyone agree/disagree?

 

Or am I

[C_W 3 1 Cars]

I do'nt think baffling the head will gain anything (I'm not even sure where you would put any baffles!), and as already said I would say that that could slow oil return down even further.

[C_W 3 1 Cars]

The head has a pressure valve to maintain pressure at 1bar for the lifters.

Where is that in the head? and how can a valve in the head maintain pressure?

 

I know that each of the oil gallery banks for the followers have non-return valves to maintain some oil by preventing it draining back when the engine is switched off. But I don't know of any other valves in the head.

[Alan_M 66 1 Cars]

Sorry, the words are 'Two non-return valves (set at 0.4bar) maintain a residual pressure in the hydraulic lifter supply lines'.

[nick 3]

What about external oil drain lines from the exhaust side of the head?

 

Nick

[Antoni1.9 0]

If anyone wants a Peugeot sport baffle - I am taking mine out -

 

1 owner from new, 1 track day only, never raced or rallied and spent its life in synthetic oil.

 

Needs to be used with the metal sump which i can supply.

 

 

(I will stick this on the for sale board later)

 

 

But seriously - the Mi was rebulit meticulously - The accusump is 6 pints and plumbed into the gallery - we have been doing some calcs on this at work - we think the Mi just has a huge demand for oil flow compared to the 8v - mainly due to the piston spray bars etc etc - we will work out this flow next week. This is why the accusump output dramatically slows below about 40 psi.

 

I am going to check the pressure rating on the valves in the spray bars.

 

I have a theory as to why some engines are worse than others - my Mi had done 89000 miles and I reckon it probably had 1 oil change by the internal condition.

 

On checking the spray bars before refitting - i concluded that i had 1 faulty one as i could not blow through it, whereas the other 3 were clear. On dismantling the "faulty" one, i discovered that they have a valve which only allows oil to flow once a certain pressure has been reached.

 

It turned out that i had scrapped the only good one !!!

 

So, If like my car was , your spray bars are jammed open - your oil flow rate will be very high, so if the pump pick up misses the oil in the sump, instead of feeding critical parts like bearings etcs, any remain oil that you have will be squirted up the arse end of the pistons !!

 

You are also going to take much longer to build uppressure on a start - leading to accelerated bearing wear etc etc.

 

In the documentation, it states that in the event of the oil system failing, the accucump can supply 15 to 60 seconds of oil to protect the engine, based on engine type and speed. - This does not appear to be the case in the Mi.

 

I will contact accusump about this because £350 is a lot of cash to waste.

 

Regarding the left / right issues - all Rob & I can say is that Rob was watching the pressure gauge on the accusump (which we know is accurate) when we were carrying out the turns - and his report is what happened.

 

Anyway, best of luck to you all

 

Regards

Antoni

[migti 0]

can these valves in the spray bars be replaced?,

 

i see what you mean if they are jammed open as if its low on oil press ie surge then this wont help to keep the pressure up to at least keep the bearings lubricated

 

sounds like ill be taking the rocker cover off tonight then!

 

j

[C_W 3 1 Cars]

They're not valves in the spray bars, they are just spray bars with pin holes in them to let oil out under the pump pressure. If the oil isn't changed you can get sludge buiding up and it's possible these can get blocked.

 

If a lot of the comments and theories above are true then I think Martin/CRF450 should succeed in preventing oil surge/starvation with his new engine, as I believe he is removing the piston oil spray bars, removing the hydraulic tappets and using an oil restrictor to the head (somethinkg like a 10th of the size??).

[Wurzel 16]

The spray bars with the valves in are under the pistons in the main block and can't really be dismantled.

 

I too thought they were blocked until I tried to shove a bit of locking wire down it to clean it out and instead, pushed in the ball bearing.

 

It turned out I had only one knackered valve so replaced it with a spare.

[C_W 3 1 Cars]

Sorry, I didn't think they had valves in them!

[Antoni1.9 0]

Hi Chris,

 

The piston spray bars have a liitle ball bearing and spring valve just behind the little protrusion that fits into the oilway in the block.

 

If you gently put this in a soft jawed vice , you can remove it - mine just needed a good clean up.

 

If you damage it a little, you can clean it up gently with a file.

 

As I said, we are going to do some calcs this week - but I'm going to see peugeot sport to see what they did because I cant believe how bad it is.

 

PS - my blocked spray bars may account for some of the the stupid amount of bore wear that i had in my engine.

 

Honda Civic type R engined Elise - here I come.

 

Antoni

[C_W 3 1 Cars]

It might be worth PM'ing martin(crf450) as I'm sure he's removing these spray bars as apparently they aren't essential (as far as I'm aware they are for piston cooling rather than extra lubrication anyway) - I think he also mentioned that you lose a bit of power from them too.

[crf450 0 1 Cars]

Antoni, I've talk about what I know about this topic a few moths ago in detail, do a search on my old posts, I'd go into detail on what I know about this subject but I'm off on holiday for a week and the missus is bugging me to load the car up.

Cheers Martin

PS I've tried a late turbo diesel oil pump (much bigger) on my car and it didn't make any difference to surge what so ever.