Author Topic: Low oil pressure... what causes it? 450SE  (Read 6121 times)

13B

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Re: Low oil pressure... what causes it? 450SE
« Reply #15 on: 31 March 2008, 10:38 PM »
Thanks Koan ... appreciate your help as always...

Another idea I'm thinking if things don't improve is to attach my Autometer oil pressure 0-100PSI gauge and go for a drive.  Since the dash Oel pressure reads 3bar max, and in all likelihood will read 3bar at 100km/h.  with a full range oil pressure gauge I can rev the thing out under load and see what the actual pressure reached is.

Its highly likely the engine is loose as hell (sure sounds like it) but if in its new higher operating range (3500-6000rpm) it makes enough pressure to protect the engine.  60PSI+ at 6000rpm I would consider acceptable given the age of the engine.

 Will shoot a video shortly showing the improvements in oel pressure and engine smoothness I've made recently.  Sounds and drives like it should now..  suspect the PO misdiagnose the faulty MPS and adjusted every setting for everything know to man to try to compensate for it...

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

koan

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Re: Low oil pressure... what causes it? 450SE
« Reply #16 on: 01 April 2008, 06:40 AM »

If you have a gauge that can be connected up easily to verify the instrument cluster it would be worth doing.

I'm assuming The pressure reading you give are with fresh, clean oil, not diluted black stuff of unknown kms.

koan
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s class

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Re: Low oil pressure... what causes it? 450SE
« Reply #17 on: 01 April 2008, 09:26 AM »
If I was you, I would still spend an hour and pull off that sump pan.  Well maybe another hour with degreaser first of all before starting removal of the pan.  ;)

It is worth it firstly to panel beat the sump, and second of all to verify that the oil pump pick-up gauze isn't clogged with crap.  I've seen them that way. 

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

13B

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Re: Low oil pressure... what causes it? 450SE
« Reply #18 on: 12 April 2008, 01:22 AM »
2 hrs work and 2 oil changes and I've got the oel pressure not reading pretty much correctly - as good as I reckon its going to be given that its a rattly old engine.... must adjust the tappets when I have a moment...

First oil change was to get out the black crap excuse for oil which stank of petrol dilution.  It was replaced with 5 litres of K-Mart's finest $9.99 crapola 25W-50 oil and a bottle of Nulon oil flushing agent.  As per instructions run for 20 min no load and drain and change filter.  The oil that came out, even though only in for 20 min, was black and full of crap.  I guess the nulon worked.

2nd oil change I've decided for the 1st time in my life to use a so called "high milage" oil which is supposed to be helpful with worn rings, worn valve guides and worn valve stem seals.  Pennzoil "High Milage Vehicle" 25W-60 was used and on the 30 min drive which included a bit of low speed traffic and higher speed freeway driving I can report that:

Idle oel pressure when fully warm is not less than 1.0bar
Oel pressure at 3000rpm is indeed 3.0bar or more
Normal driving at 60km/r shows an indicated Oel pressure of 2.5bar
Smoke on overun and prolonged idle due to valve stem seals has diminished
Oel pressure still doesn't fly up to 3.0bar the instant you hit the accelerator, but it is a linear increase at least...

The oil pan wasn't removed yet but it will have to be soon so I can install the sensor for my autometer oil temp gauge, at that point I'll just bash it flat and check the pickup on the oil pump, replace the gauze, etc. 

This thing is looking better all the time!

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

oscar

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Re: Low oil pressure... what causes it? 450SE
« Reply #19 on: 13 April 2008, 06:55 AM »
Re the pan, I meant to post this pic last week before I went away but forgot, it's straight from the manual but it looks though the oil pick up is practically sitting on the pan.  If the pan is as bad as what you say, makes me wonder if the pick up tube is damaged as well.  Anway, it's all working now which is great.  If the oil pick up is the problem, I can't imagine it's going to get worse before you bash the pan flat.  Your still getting adequate pressure so that's good.

1973 350SE, my first & fave

13B

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Re: Low oil pressure... what causes it? 450SE
« Reply #20 on: 13 April 2008, 04:28 PM »
Thanks for that.  At least now I know what to expect when I take the sump off. 

Looks like a design which the oil pickup ability could be seriously compromised even if there was a 0.5" dent in the sump in the right place...

If you get to see the number of classic cars that I do (whether holden, ford, mazda, etc.) you know its almost impossible to find one still in daily use that doesn't have a dent in the sump...

Oscar, what are the items the diagram is referring to: A, 1 and 2 ?
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K

oscar

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Re: Low oil pressure... what causes it? 450SE
« Reply #21 on: 13 April 2008, 05:05 PM »
"A" is supposed to measure 58.5 mm.  It doesn't list what 1 & 2 are unfortunately.  A lot of images get repeated in the manuals and sometimes a generic photo of a different model might be used to demonstrate a common part and I've found they often come without labels.  I'll have another look for the image later and fill you in if it gives up any more info.

This second shot is all I could find of the oil pick up.  It's on the next page and I dismissed it yesterday thinking it was a m110 until I looked closely just now.  But it is a m116/117 with the upper part of the oil sump removed as well.  Don't think you'll have to remove that much unless you want to dig around but again, no labels in the text for this pic unfortunatley.

1973 350SE, my first & fave

13B

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Re: Low oil pressure... what causes it? 450SE
« Reply #22 on: 17 April 2008, 08:49 PM »
Thanks Oscar... another question, for anyone who knows.... how does one remove and install the plastic roundy thing on the bottom of the oil pickup?  I was at a wreckers today removing a good used sump, and busted the roundy thing on the oil pickup trying to remove it..

So if anyone knows, please tell - how does it stay in there, and how do you remove it?

I.
450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K