Matt930 Posted 12November, 2013 Report Share Posted 12November, 2013 Ok, so this is copied and pasted from my post in Pelican Parts Tech Forum "Hi Guys, I'm a little lost on this one. Basically when the car is cold, it idles with oil pressure against the bypass spring (75 odd PSI), but as it comes right up to temperature it drops to basically 0.4 bar Even if I've been belting the **** out of it and its quite 'warm', it still does meet the 10PSI / Thousand Minimum, but at idle there really is basically nothing when it gets this hot... Engine doesn't knock, rattle or make any noises, its never let me down or other wise to make me think it is actually a block issue. I've changed the Oil Pressure Sender unit, its fine. Its also idling a little low at the moment, so maybe that's not helping. I will try ripping out the pressure relief valves next weekend when I'm doing my new oil cooler and hopefully there is something wrong with the pistons there. But I wanted to ask does anyone think that it might be a oil pump? Its basically like it works fine in operation, but at idle, the pump efficiency is just not there... Anyway, thoughts would be appreciated. Matt" Link to comment Share on other sites More sharing options...
Russ Posted 12November, 2013 Report Share Posted 12November, 2013 it's normal as the engine ages. so long as the oil pressure comes up under load you'll be fine mine does this, as have all the old Mercedes-Benz cars I've had Link to comment Share on other sites More sharing options...
wasserkuhl Posted 12November, 2013 Report Share Posted 12November, 2013 What type of oil are you using? ie: Brand and weight. I'd recommend you use a Mineral 20W50 and drain it every 5000km's/annually whatever comes first. a Higher ZDDP or Zinc content is desireable and provides a higher level of protection to your engines internals due to its specific metallurgy. Modern Synthetics and thinner grades can be innappropriate for the older Mezger six and cause premature wear. Can Of worms, this is purely my experience based on evidence and lubricant analysis. Link to comment Share on other sites More sharing options...
Matt930 Posted 12November, 2013 Author Report Share Posted 12November, 2013 For what ever reason, I found that using the Penrite Mineral stuff degraded Oil pressure really quickly (even the 'operational' pressure) - say within 2000Ks. So I just swapped to their synthetic 10W70. With this stuff, at 180 temp (where mine seems to like to run itself) I get an even 1bar / 1000 up to the pressure release at 4Bar. I racked up and 'very spirited' 1500ks over the weekend and she is exactly where it was - the one oil leak has lessened too. Anyway, for what its worth... Thanks for your posts BTW guys. Keep'em coming Link to comment Share on other sites More sharing options...
wasserkuhl Posted 12November, 2013 Report Share Posted 12November, 2013 For what ever reason, I found that using the Penrite Mineral stuff degraded Oil pressure really quickly (even the 'operational' pressure) - say within 2000Ks. So I just swapped to their synthetic 10W70. With this stuff, at 180 temp (where mine seems to like to run itself) I get an even 1bar / 1000 up to the pressure release at 4Bar. I racked up and 'very spirited' 1500ks over the weekend and she is exactly where it was - the one oil leak has lessened too. Anyway, for what its worth... Thanks for your posts BTW guys. Keep'em coming So, what weight was the Penrite Mineral stuff? 10W 70 will give you good hot running protection, however I am concerned as to whether the 10W 70 is Full synthetic or Hydrocracked synthetic(ie: mineral/synthetic blend) Please contact Penrite and ask how much ppm ZDDP this 10W70 has you are looking for >1200 ppm. I use a 20W60 Valvoline Product and when its new it reads over about 1.5 Bar at idle and goes up 1 Bar with every 1000Rpm's. I can tell its getting old as the Pressure/Rpm relationship falls when it is starting to degrade and hold some colour. I would also suggest that your 10W70 is getting a better pressure reading at 1000Rpm due to cold start 'flow' as opposed to weight. A 20W50/60/70 should provide you with enough cold start protection and Flow. IMHO 10W for a( higher mileage )Air cooled engine in Australia's climate is a touch too thin for cold start protection. Just my opinion!!! Link to comment Share on other sites More sharing options...
Matt930 Posted 12November, 2013 Author Report Share Posted 12November, 2013 Opinions Welcome! Main reason for running that one was that i went into Thredbo last weekend, where they predicted SNOW all weekend. Given that mine goes straight to 60PSI when idleing cold, i thought lower cold reading couldn't hurt! Sometime when summer really heats up, i will be changing it out to something 20W. Oil Spec Page Penrite 10W70. 2200+ Zinc, Full Synthetic PAO ESTER type. So far, its held on a lot better than the old shit i was running already! Link to comment Share on other sites More sharing options...
wasserkuhl Posted 12November, 2013 Report Share Posted 12November, 2013 Opinions Welcome! Main reason for running that one was that i went into Thredbo last weekend, where they predicted SNOW all weekend. Given that mine goes straight to 60PSI when idleing cold, i thought lower cold reading couldn't hurt! Sometime when summer really heats up, i will be changing it out to something 20W. Oil Spec Page Penrite 10W70. 2200+ Zinc, Full Synthetic PAO ESTER type. So far, its held on a lot better than the old shit i was running already! Thats good stuff. Yeah, I don't ever factor snow into Australian climate but I can see your rationale there! I'd be swapping out to a 20W 50-60-70 for the heat. Link to comment Share on other sites More sharing options...
Matt930 Posted 12November, 2013 Author Report Share Posted 12November, 2013 Yeah. Bumped the idle up so it sits just under 1000 rpm, and it sits about 6-8psi (bloody hard t read on that scale) and given that when the power is on, it Sits a little below zero (not on 0) I'd say it's ok. Certainly nowhere near the 2 bar some people get, but ok. Anyway, now it's had the air bypass corrected, the harsh burbling off throttle is reduced significantly... Might be time to get this thing sorted on a dyno... Thanks for your help Link to comment Share on other sites More sharing options...
Matt930 Posted 19December, 2013 Author Report Share Posted 19December, 2013 Ok, Well my little Saga is Continuing... I've been running the above Full Synthetic 10W70 Pentrite oil which has been Bloody awesome in terms of Longevity and pressure readings - even when VERY hot. ***BUT*** I now have 2 other issues. I now have oil leaks in places i did not know oil could leak from! and also My oil pressure decides to drop to about half what it should be randomly for quite some time at a time... I think the detergents might have loosened some shit that is now clogging randomly somewhere in the engine... Anyway, anyone have any experience with this sort of stuff? its really getting to the point of just dropping the engine i think... Link to comment Share on other sites More sharing options...
tazzieman Posted 19December, 2013 Report Share Posted 19December, 2013 Matt you're not the only owner to spring leaks with synthetic. Also , is your gauge/wiring fully functional? Sender>wiring>gauge? Link to comment Share on other sites More sharing options...
J.J. Posted 19December, 2013 Report Share Posted 19December, 2013 what year is your car? Link to comment Share on other sites More sharing options...
tazzieman Posted 19December, 2013 Report Share Posted 19December, 2013 1976 Link to comment Share on other sites More sharing options...
J.J. Posted 20December, 2013 Report Share Posted 20December, 2013 have you tried the Brad Penn "Green" oil? Link to comment Share on other sites More sharing options...
Russ Posted 20December, 2013 Report Share Posted 20December, 2013 aren't leaks common when changing from mineral to synthetic? Link to comment Share on other sites More sharing options...
CarreraG50 Posted 20December, 2013 Report Share Posted 20December, 2013 have you tried the Brad Penn "Green" oil? +1 Great stuff, Link to comment Share on other sites More sharing options...
Matt930 Posted 24December, 2013 Author Report Share Posted 24December, 2013 Sweet, I'll try that one next, to be honest I'm far more concerned about why it just drops a shite load of pressure for no reason... I really think I'm going to have to drop this thing... Tried a new oil filter today, drove a spirited 100k with no issue, but then 5 k from home she dropped again, back to fine by the time I got home... To give an idea, I can cruise down the highway at about 40psi normally, but when its down, it's lucky to be a smudge over 20. It's a significant drop. It was doing this before and continued after changing out the pressure gauge. Any ideas? Or just bite the bullet and drop the bastard? Link to comment Share on other sites More sharing options...
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