Author Topic: Oil Pressure when Cornering Briskly  (Read 3029 times)

116.025

  • Classic
  • **
  • Posts: 145
  • Location: NC, USA
Oil Pressure when Cornering Briskly
« on: 15 April 2006, 11:31 AM »
Hi All,

I've noticed that when I corner briskly in my '77 280SE, that the oil pressure will drop off.  For example, I was taking a corner with the engine turning about 2600 RPMs, at which point the oil pressure gauge is normally pegged on the 3 bar mark (I run 10w-40) and the oil pressure gauge dipped to about 2.5 bar, then dipped again to about 2 bar.  Once I straightened out, it shot back up to 3 bar.  Any ideas?

I'll mention this since it could be related...I've noticed when I take a right turn (it doesn't seem to happen on a left turn, but I can rarely take a left turn the same to simulate) and accelerate briskly, sometimes it will start bellowing blue smoke briefly.  Not sure what's going on there, either.

Thanks for ideas/suggestions.
Chad Johnson

'77 280SE Euro (4-Spd) Sold 1/5/09
'71 220D (4-spd)
'77 280SEL Euro (4-Spd) RIP
'89 420SEL
'78 350SE Euro
'86 300E 5-Spd RIP by Chevy S10
'83 380SL
"Don't Worry, Bobby, even a worn out Mercedes is better than a 2010 cracker-jack box

michaeld

  • Classic
  • **
  • Posts: 433
Re: Oil Pressure when Cornering Briskly
« Reply #1 on: 18 April 2006, 12:11 AM »
116.025,
I hope someone "older and wiser" responds after me, but I thought I'd tell you what little I know...

I'm one of those weird types who is looking at the road while making turns, so I can't even tell you what my oil psi gauge reads.  But I do know this much: it is not uncommon for your pressure to go down substantially when you are idling - but it ought to go all the way up to the top (40 psi) when you start driving.

Right turns pull more "G's" than left; it's possible that the oil is "sloshing" around and your gauge can't keep up?  One thing I'd do immediately is make sure I had a full crankcase of oil (you need over 9 qts of the stuff, you know).  I recently had Pep Boys do my oil change and they shortchanged me 3 qts!  I was furious at the incompetent, sloppy job!  Last time they touch my car! >:(  A low oil level would cause what you are describing.  I had an old wagon that lost its forward gear when I made right turns once: it turns out that the tranny dipstick was NOT original for the car.  It was too long, and I actually had much less fluid than I thought I had.

If no one else comes along with more/better info, and you're still in doubt after checking your oil level, you can buy compression testers relatively inexpensively (about $20), and check each cylinder for compression.

OzBenzHead

  • Vintage
  • ***
  • Posts: 721
  • Location: Northern NSW, Australia
Re: Oil Pressure when Cornering Briskly
« Reply #2 on: 18 April 2006, 12:48 AM »
Right turns pull more "G's" than left ...

I wonder if the converse is true in RHD cars? (Bit like our bathwater spiralling down the plughole in the opposite direction downunder!)

michaeld

  • Classic
  • **
  • Posts: 433
Re: Oil Pressure when Cornering Briskly
« Reply #3 on: 18 April 2006, 04:07 AM »
Ozbenzhead,
You got me, there, buddy!  Of course, you are correct to bring RHD cf LHD.  I forgot the international nature of this forum, and failed to think the matter through in my earlier post.  One should never make assumptions unless they apply to everyone.  My apologies, right hand drivers!

A RHD car would pull more G's on a left turn, as he is on the left side of the road.  Whether one drives on the right side of the road or the left, there is a near 90 degree right angle turn (whether one is turning right or left) versus a more gradual parabolic-sloped turn going the other way.  The greater the angle of the turn - and of course the greater the speed - the greater the G-force.

P.S. In one episode of "The Simpsons," the family goes to Australia.  The US embassy has fitted their toilets with an enormous and massively expensive contraption that forces the water to flush in the counter-clockwise as per the USA.  Homer, watching the flush, begins to cry as this unnatural flush represents (at least for him) everything that is great and beautiful about America. 

OzBenzHead

  • Vintage
  • ***
  • Posts: 721
  • Location: Northern NSW, Australia
Re: Oil Pressure when Cornering Briskly
« Reply #4 on: 18 April 2006, 04:21 AM »
In one episode of "The Simpsons," the family goes to Australia.  The US embassy has fitted their toilets with an enormous and massively expensive contraption that forces the water to flush in the counter-clockwise as per the USA.  Homer, watching the flush, begins to cry as this unnatural flush represents (at least for him) everything that is great and beautiful about America. 

In light of your earlier comments indicating how you feel about your country, dare I comment? No - I'll just keep my belly-laugh to myself.  :P

Mind you, this country's fast going down the toilet, too, and the direction of the vortex is irrelevant.   :'(

michaeld

  • Classic
  • **
  • Posts: 433
Re: Oil Pressure when Cornering Briskly
« Reply #5 on: 18 April 2006, 10:36 PM »
Ozbenzhead,
WAY off topic in regard to a post about dropping oil pressure, but a comment about "love versus laugh" is in order in these sad times...

As you noted, I love my country a great deal.  But that doesn't mean that I can't laugh at it.  In fact, I think real love for something or someone entails a sense of humor.  The United States of America has some of the greatest ideals ever formulated by any government in human history, but the sad reality is that no American generation has ever yet fully lived up to them.  No people is perfect; the United States - burdened with the greed, prejudices, and selfishness that burden ALL peoples - is no exception.

There is therefore much to love about the United States; there is also much to laugh at.  I love my country,  even though it has its share of warts; but I don't much care for the warts.  We ignore our imperfections to our national detriment; we justify or excuse them as cultural imperatives to our national peril.

So yes, Ozbenzhead, I laugh at my country.  That episode of "The Simpsons" was particularly funny, in that it underscores the American habit of forcing every other environment to be like our own ("Americanization") even while we fixate upon shallow appearances while ignoring underlying realities.  People who love America can direct attention to these national "warts" (by humor or other means) - with the hope and faith that that which is exposed to public attention can be healed and overcome.

I guess that makes me a "comic patriot"!

In any event, Ozbenzhead, feel free to join with me in laughing at BOTH our countries' shortcomings.  I have greatly admired Prime Minister John Howard (it's obviously your choice and right whether to do so yourself!).  And I have counted Australia and Great Britain as two of my countries greatest friends and allies during a time when much of the world despises us - and despises us not merely because we have failed to live up to our ideals, but because of the ideals themselves!  Friends have the right to laught at each other, Ozbenzhead.  And we have a whole history as allies to draw upon!   

Nutz

  • Vintage
  • ***
  • Posts: 587
  • Location: Hawaii (Maui)
    • W123 Gassers
Re: Oil Pressure when Cornering Briskly
« Reply #6 on: 18 April 2006, 11:09 PM »

You probably notice it more on a sharp left turn right? This would be because the oil is propelling to the opposite side of the engine from the oil pressure line.No big deal and sure there is no chance of oil starvation unless your oil level is critically low.

116.025

  • Classic
  • **
  • Posts: 145
  • Location: NC, USA
Re: Oil Pressure when Cornering Briskly
« Reply #7 on: 19 April 2006, 10:13 AM »
Micheald, stories like that are why I do all my own oil changes...one person in my church had an engine destroyed because the filter wasn't tightened enough, and another nearly lost their engine, but decided not to drive the car when they found a rather large puddle of oil in the driveway the next morning.

Styria, I did check the oil, it was a few millimeters above the beginning of the minimum notch, and the oil filter has been in less than 3000 kms...what got me wondering was it used not to dip until the oil was well below this (we won't get into how low it got a couple of times before I caught on to the fact it needed a quart every 320 kms or so...)  I ought to do a compression check one of these days, though she still pulls pretty strong since she doesn't have any of the US emmissions equipment on board.

Nutz, I'll have to observe if it's worse on a left turn than a right, because I'm not sure.  Glad you and micheald pointed out the oil sloshing thing, makes me a little less concerned.

And yes, I am from the US and talking in Kms...my 116 still has the original KPH speedo (imported to the US in '82) showing almost 415,000 kms.

Yeah, I think we should all feel free to laugh at our own country and those of our 116 bretheren.  I fear the entire Western world is swirling in a vortex... :'(
Chad Johnson

'77 280SE Euro (4-Spd) Sold 1/5/09
'71 220D (4-spd)
'77 280SEL Euro (4-Spd) RIP
'89 420SEL
'78 350SE Euro
'86 300E 5-Spd RIP by Chevy S10
'83 380SL
"Don't Worry, Bobby, even a worn out Mercedes is better than a 2010 cracker-jack box

s class

  • W116 Addict
  • ****
  • Posts: 4,151
  • I'll keep the 116's, the rest can go
  • Location: Squeezing 3 W116's into a double garage
Re: Oil Pressure when Cornering Briskly
« Reply #8 on: 20 April 2006, 02:14 AM »
116.025,

I have a 1980 W116 280SE (116.024) with 423 505km this morning, so we have something in common.

Yes, when cornering there will be sloshing, but this should not result in a dipping oil level unless :
a) the oil level is very low
b) there is damage to the oil pump pick-up
c) the engine is very worn.

I will deal with these one-by-one :

a) has already been mentioned by another poster, and the risk here is if the dipstick or dipstick tube are not correct.  The solution is the next time you do an oil change, actually measure the quantity of oil you are adding.  Then start the engine to fill the filter and then measure the oil level correctly as follows : (to note where it reads on the dipstick)
Another possible cause is measuring procedure.  YOu must check the oil level when the car is warmed up to normal operating temp.  What I usually do is when filling petrol, once the tank is full the car will have been standing for 5 mins or so since driving, allowing some oil to drain back into the sump.  THen I check the level.

If you check the oil level once the car has been standing overnight, almost all the oil will havew drained back into the sump and you will get a misleading indication which shows a much higher oil level than if measured correctly.

b) THe oil pump is an alloy assembly right at the front of the engine.  It has an alloy suction intake extending down into the front steel part of the sump.  The alloy ends about 2" or so above the floor of the pan.  This alloy suction intake then has a rubber bellows mounted on its lower end which extends the pickup to within millimeters of the floor of the pan.  THis rubber bellows also holds a wire gauze strainer.  The rubber bellows suffers with age and heat and I have often seen them crumble and disintegrate. 

If your bellows is gone, effectively the oil pump pickup ends about 2" higher than it should, so you can get pump cavitation especially if the oil level is on the low side.  Remember that when you are driving, the engine is throwing the oil around a lot inside, so the residual level in the pan is much lower than when the engine is shut off. 

Replacing the oil pump pickup bellows is an easy job, but it requires removing the front steel sump pan which is messy and the gasket is a little pricy.

c) If an engine is very very worn there will be excess clearance in the bearings and bores and the oil pump will battle to keep up and maintain pressure as the oil leaks away through the enlarged clearances.  If this was the situation you would have other symptoms like big end noise and very heavy oil consumption. 

Hope some of this helps. 

'76 6.9 Euro, '78 6.9 AMG, '80 280SE, '74 350SE, '82 500SEL euro full hydro, '83 500SEL euro full hydro , '81 500SL