Jump to content

45 lbs oil pressure


swift1894

Featured Posts

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 by Split Pin
Link to comment
Share on other sites

{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

 

:smiley_offtopic: 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

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 :o

 

;)

 

Tim

Edited by Timleech
Link to comment
Share on other sites

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 :o

 

;)

 

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 by martyn 1
Link to comment
Share on other sites

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

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 :o

 

;)

 

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

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.