swift1894 Posted February 28, 2013 Report Share Posted February 28, 2013 My 4LW always runs at 45lbs oil pressure, although the oil pressure adjuster says 35 lbs on the top. Should I be worried? Link to comment Share on other sites More sharing options...
Split Pin Posted February 28, 2013 Report Share Posted February 28, 2013 (edited) Depends on if its the correct nut or not. Engines after serial number 147676 were set at 35 lbs sq in, the point at which there was a change from Thick wall bearings to thin shell bearings. Better to be to high than to low, cannot see it doing any harm just using more power to generate the extra pressure if not needed. Steve Edited February 28, 2013 by Split Pin Link to comment Share on other sites More sharing options...
RLWP Posted February 28, 2013 Report Share Posted February 28, 2013 {snip} Better to be to high than to low, cannot see it doing any harm just using more power to generate the extra pressure if not needed. Steve Unless it is an Austin Seven with spray lubrication. Higher pressure means a blocked jet and no oil Richard Link to comment Share on other sites More sharing options...
Timleech Posted February 28, 2013 Report Share Posted February 28, 2013 (edited) Depends on if its the correct nut or not. Engines after serial number 147676 were set at 35 lbs sq in, the point at which there was a change from Thick wall bearings to thin shell bearings. Better to be to high than to low, cannot see it doing any harm just using more power to generate the extra pressure if not needed. Steve Is there a firm logic for the change to a lower pressure? My engine now has composite bearings, thick wall shells lined with thin wall ones. I run it at around 45 psi, though it does drop a bit on a long run (until I get the oil cooler piped in!). Edit for the OP - are you a born worrier? First the fuel pump return spring, now too much oil pressure, and leaks, what next Tim Edited February 28, 2013 by Timleech Link to comment Share on other sites More sharing options...
martyn 1 Posted February 28, 2013 Report Share Posted February 28, 2013 (edited) Is there a firm logic for the change to a lower pressure? My engine now has composite bearings, thick wall shells lined with thin wall ones. I run it at around 45 psi, though it does drop a bit on a long run (until I get the oil cooler piped in!). Edit for the OP - are you a born worrier? First the fuel pump return spring, now too much oil pressure, and leaks, what next Tim The lower pressure choosen by Gardner was as previously stated with the change from thick wall bearings to thin wall shells, this change also included a change of bearing material that did not require the volumn of oil previously needed to prevent overheat/wear. being set at the higher on the later bearings will not hurt but being to low will. So if its a little high I wouldn't be overly bothered. Martyn Edited February 28, 2013 by martyn 1 Link to comment Share on other sites More sharing options...
swift1894 Posted March 1, 2013 Author Report Share Posted March 1, 2013 Edit for the OP - are you a born worrier? First the fuel pump return spring, now too much oil pressure, and leaks, what next Tim Yeah..... I think it's the wrong shade of grey :lol: Link to comment Share on other sites More sharing options...
Timleech Posted March 1, 2013 Report Share Posted March 1, 2013 The lower pressure choosen by Gardner was as previously stated with the change from thick wall bearings to thin wall shells, this change also included a change of bearing material that did not require the volumn of oil previously needed to prevent overheat/wear. being set at the higher on the later bearings will not hurt but being to low will. Martyn One consideration may be that if the pressure is set lower, all other things being equal, more oil will be run to the governor and timing gear etc, which are fed from the bypass pipe. This would allow the oil to run hotter before these become starved of oil. One of the first things to suffer in a worn Gardner tends to be the governor gear. Also some engines have the oil cooler in the bypass circuit, and there is a risk of thermal runaway if the cooling isn't quite adequate - oil gets hot, less is bypassed, less is cooled, oil gets hotter, vicious circle. Cr*p design, really. This risk ought to be reduced with a lower oil pressure. Unlikely to be an issue on an English canal boat, though. Tim Link to comment Share on other sites More sharing options...
Split Pin Posted March 1, 2013 Report Share Posted March 1, 2013 Is there a firm logic for the change to a lower pressure? My engine now has composite bearings, thick wall shells lined with thin wall ones. I run it at around 45 psi, though it does drop a bit on a long run (until I get the oil cooler piped in!). Edit for the OP - are you a born worrier? First the fuel pump return spring, now too much oil pressure, and leaks, what next Tim I have pondered this on more than one occasion, the answer would seem to be that (as Martyn says) the need to get sufficent oil into the bearing to control its temperature, rather than actually produce the oil film to prevent contact between the bearing and journal, I found a piece about bearing design here (Bearing design) It takes a bit of reading. Another point is that the thin wall shells are slightly narrower so the need to get the oil film to the edge of the bearing is less,also there is no "oil groove" at the mating points on the shells, so less likelyhood of not keeping a good film where needed. Bypass oil feed to the governer is marginal at best even when bypass pressure is being generated, the amount of oil that passes into the governer housing is regulated by the size of the hole at the end of the pipe, when the engine is running the oil is being thrown off by the governer balance weights,therefore litle of it is getting to the parts that really need it.ie the trunnion blocks and the centre spindle. I worked on 3LW that was getting water into the oil, this was eventually traced to a leaking block, internally into the push rod chamber, having sorted this a few days later I got a phone call to say that the engine was stuck at full throttle, the governer had rusted up to the point that it had siezed, this was on an engine which had been rebuilt about 5 years previously which had good oil pressure all the time Steve Link to comment Share on other sites More sharing options...
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