Oil pressure follow up

A while ago I posted a question about the oil pressure on my Grey Marine rebuilt engine. I was getting what I thought were low readings and they were inconsistent as well in that the readings vs RPM didn't seem reasonable. I decided to replace the electric gauge with an SW mechanical gauge. It wasn't hard because all the plumbing was there as there was a mechanical gauge as part of the original failed tack. I repeated my experiment running the engine for 1 hour under load and measuring oil pressure vs RPM. Still perhaps a bit low and the rebuilder said I should put a couple of thin washers under a spring, which I need to try but I thought I should share the graph as it is interesting to see the difference in readings between the electrical and mechanical gauges. Allen [image: Inline image 1]

We have rebuilt 11 Perkins 4.108 diesels this year. Each one is tested with a direct reading mechanical gauge and we encourage the new owner to install a mechanical gauge. Sometimes due to engine location, running the plastic tube a long distance is unadvisable, so an electric gauge must be used. On my Cal 46 with my Perkins 4.236 located aft with a vee drive and the pilothouse about 30 feet away, I have an electric gauge in the pilot house and a mechanical gauge mounted on the engine. I always check both gauges and when motoring long distances, we check and record both readings each 3 hours when we change watches. We do not go on deck alone, so at watch change we are both awake. I feel it is good practice to do a visual check on the engine each 3 hours, check the mechanical oil pressure gauge and check the vacuum gauge on my fuel filters. After 32 years of owning my Cal 46, I still love her, but my health issues and 75 years do not allow us to roam, so she will be for sale next year. Tom 7 Bobbie Vandiver, Cal Cruising 46, hull #3, Bayou Chico, FL From: Allen Edwards <al… [at] gmail.com> To: "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> Sent: Wednesday, December 4, 2013 6:40 PM Subject: [Cal_Boats] Oil pressure follow up A while ago I posted a question about the oil pressure on my Grey Marine rebuilt engine. I was getting what I thought were low readings and they were inconsistent as well in that the readings vs RPM didn't seem reasonable. I decided to replace the electric gauge with an SW mechanical gauge. It wasn't hard because all the plumbing was there as there was a mechanical gauge as part of the original failed tack. I repeated my experiment running the engine for 1 hour under load and measuring oil pressure vs RPM. Still perhaps a bit low and the rebuilder said I should put a couple of thin washers under a spring, which I need to try but I thought I should share the graph as it is interesting to see the difference in readings between the electrical and mechanical gauges. Allen

Just curious if the gauges were installed at the same “pressure point” in the system. Most engines have a pressure relieve prior to the filter, too much oil pressure (clogged filter or passageways) and the high pressure is by-passing the filter. It appears the “electric gauge” may be at a point in the system that it regulates the max oil pressure before the filter. The “manual” is at a point in the system, ante-oil pump, but pre-relief valve.. YMMV John From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf Of Tom Vandiver Sent: Thursday, December 05, 2013 6:47 AM To: Ca… [at] yahoogroups.com Subject: Re: [Cal_Boats] Oil pressure follow up & Cal46 We have rebuilt 11 Perkins 4.108 diesels this year. Each one is tested with a direct reading mechanical gauge and we encourage the new owner to install a mechanical gauge. Sometimes due to engine location, running the plastic tube a long distance is unadvisable, so an electric gauge must be used. On my Cal 46 with my Perkins 4.236 located aft with a vee drive and the pilothouse about 30 feet away, I have an electric gauge in the pilot house and a mechanical gauge mounted on the engine. I always check both gauges and when motoring long distances, we check and record both readings each 3 hours when we change watches. We do not go on deck alone, so at watch change we are both awake. I feel it is good practice to do a visual check on the engine each 3 hours, check the mechanical oil pressure gauge and check the vacuum gauge on my fuel filters. After 32 years of owning my Cal 46, I still love her, but my health issues and 75 years do not allow us to roam, so she will be for sale next year. Tom 7 Bobbie Vandiver, Cal Cruising 46, hull #3, Bayou Chico, FL _____ From: Allen Edwards <al… [at] gmail.com> To: "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> Sent: Wednesday, December 4, 2013 6:40 PM Subject: [Cal_Boats] Oil pressure follow up A while ago I posted a question about the oil pressure on my Grey Marine rebuilt engine. I was getting what I thought were low readings and they were inconsistent as well in that the readings vs RPM didn't seem reasonable. I decided to replace the electric gauge with an SW mechanical gauge. It wasn't hard because all the plumbing was there as there was a mechanical gauge as part of the original failed tack. I repeated my experiment running the engine for 1 hour under load and measuring oil pressure vs RPM. Still perhaps a bit low and the rebuilder said I should put a couple of thin washers under a spring, which I need to try but I thought I should share the graph as it is interesting to see the difference in readings between the electrical and mechanical gauges. Allen Inline image 1

The manual gauge is on the end of a piece of copper tube that runs from the engine to behind the instrument panel, about 3 or 4 feet of tube. The electrical sender was connected in the exact same spot behind the instrument panel at the end of the same piece of tube. The pickup spot could not be more identical. I removed the oil filter a couple of years ago. I change my oil with less than 50 hours on it, which I have been told is fine. The oil filter take off is now the take off for the tube that goes to the gauge. That is also where the oil gauge takeoff was before the stock gauge broke. Allen. On Thu, Dec 5, 2013 at 6:11 PM, john raxter <jr… [at] triad.rr.com> wrote: > > > Just curious if the gauges were installed at the same “pressure point” in > the system. Most engines have a pressure relieve prior to the filter, too > much oil pressure (clogged filter or passageways) and the high pressure is > by-passing the filter. > > > > It appears the “electric gauge” may be at a point in the system that it > regulates the max oil pressure before the filter. The “manual” is at a > point in the system, ante-oil pump, but pre-relief valve.. > > > > YMMV > > John > > > > *From:* Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] *On > Behalf Of *Tom Vandiver > *Sent:* Thursday, December 05, 2013 6:47 AM > *To:* Ca… [at] yahoogroups.com > *Subject:* Re: [Cal_Boats] Oil pressure follow up & Cal46 > > > > We have rebuilt 11 Perkins 4.108 diesels this year. Each one is tested > with a direct reading mechanical gauge and we encourage the new owner to > install a mechanical gauge. Sometimes due to engine location, running the > plastic tube a long distance is unadvisable, so an electric gauge must be > used. > > On my Cal 46 with my Perkins 4.236 located aft with a vee drive and the > pilothouse about 30 feet away, I have an electric gauge in the pilot house > and a mechanical gauge mounted on the engine. I always check both gauges > and when motoring long distances, we check and record both readings each 3 > hours when we change watches. We do not go on deck alone, so at watch > change we are both awake. > > I feel it is good practice to do a visual check on the engine each 3 > hours, check the mechanical oil pressure gauge and check the vacuum gauge > on my fuel filters. After 32 years of owning my Cal 46, I still love her, > but my health issues and 75 years do not allow us to roam, so she will be > for sale next year. > > Tom 7 Bobbie Vandiver, Cal Cruising 46, hull #3, Bayou Chico, FL > > > > > ------------------------------ > > *From:* Allen Edwards <al… [at] gmail.com> > *To:* "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> > *Sent:* Wednesday, December 4, 2013 6:40 PM > *Subject:* [Cal_Boats] Oil pressure follow up > > > > > > A while ago I posted a question about the oil pressure on my Grey Marine > rebuilt engine. I was getting what I thought were low readings and they > were inconsistent as well in that the readings vs RPM didn't seem > reasonable. I decided to replace the electric gauge with an SW mechanical > gauge. It wasn't hard because all the plumbing was there as there was a > mechanical gauge as part of the original failed tack. I repeated my > experiment running the engine for 1 hour under load and measuring oil > pressure vs RPM. Still perhaps a bit low and the rebuilder said I should > put a couple of thin washers under a spring, which I need to try but I > thought I should share the graph as it is interesting to see the difference > in readings between the electrical and mechanical gauges. > > > > Allen > > > > > > [image: Inline image 1] > > > > >