Hi guys,
I just cranked up my 28 for the first time in about 25 years. It seemed to run well and would idle okay if everything was just right (choke has to be more than half closed and it would load up if the throttle was too far open) but no serious leaks or anything. What I did notice was that according the stock gauge, I only had about 3psi of oil pressure under idle, and 5 when it was reved up a bit. It seemed to be running cool enough,..what pressure should I be getting?

thanks much

Chris

Hi Chris,

There are many ramifications to the oil pressure noted in the 4-cylinder engines. The only engine to have a pressure fed bearing is the 1925 and it is to the center main. We generally say that ANY oil pressure is acceptable in these engines. Things are more stable in the engines up to 1926 as they had gear driven pumps. We could expect pressures around 10 PSI at normal cruising speeds and perhaps 5 at idle. The later engines had a vane type pump which is short on pressure and strong on flow which is really what we are interested in. Pressures with this type pump are slightly less than the gear type. Also consider that the weight oil used will affect the pressures observed. The rule is we need SOME pressure and if we don't have any indicated it is time to shut it down and find out why.

Thanks a ton Ray!
I saw that the gauge goes up to 30 so I was concerned.
I'm running strait 30 weight at the moment. I seem to remember folks were suggesting a 30 wt non detergent.

10-30 detergent is a better recommendation.

One thing I would do if it were mine would be to pull and clean out the oil pan and check the pick up screen. You will be suprised how much crud will settle out of the old oil that was in it while stored. Even on a well maintained engine that had non detergent oil used in it. The general rule is to use non detergent oil if no filter is used. (I just say that because there are a lot of 28 engines I have seen with the filter removed years ago) Pulling the pan and cleaning it was generally a yearly maintenance item even if the "Book" didn't suggest it. By the way, my 28 puts out about 12 psi cold and goes down to 5-6 warm at a "fast" idle.

boy, I guess I was thinking that detergent oil would be more likely to pull crud that had been happilly in place for years, back into the mix. I had planed to change out the oil after giving it a little run time anyway, so I'll change to 10-30 (non-detergent?). I have no oil filter at the moment, it was bypassed at some point and only the bracket remains.

Bob, I saw exactly what you described when I had the pan off. I've been slowly working through things to make sure I wouldnt damage anything on the first start, so that included pulling the pan and scaping out the goo, cleaning off the pump screen, bypassing the gas tank, going through the carb etc. I was actually just planing to see if I had spark, and then cranked it over on a whim and it fired up. :) Unfortunatly it was at 11:30pm and one of my neighbors called the local athorities. My wife has been teasing me all week about makeing the police blotter in our local paper.

Use detergent oil, let's get all the uglies out of it. When you change oil again and pull the pan again and clean it up you will be in good shape.

You must have really good relations with your neighbor?????? Not!

That crud that was in there would have most likely stayed in there unless it was driven for a time where it vibrated heavily and "liquified" but it would resettle when shut down. Bad thing is if it is deep enough it can block off the pick up screen and or some of the fine stuff get pulled up into the pump wearing it and the bearings out. It is best to just remove it and be done with it. The detergent oil vs non detergent oil issue gets raise quite often on an antique tractor site and is always a huge debate as a lot of folks are "loyal to their oil". One thing I read on "yesterdays tractors" web site was from a lubrication engineer at the american petroleum institute or API as you see it on bottles of oil. They grade oil based on bearing surface load useage, engine materials, fuels used, additives required and a ton of other things that we would never dream of being factors. He stated that detergent oil doesn't acually clean anything, but keeps the sludge formed from worn metals, carbon and very fine dust particles getting into the crankcase from settling out in the pan overnight or over a period of time. Since it sat for a while though, I would bet you saw lots of crud built up on the crankcase walls and some of it may have been flaking off, if you didn't wash the inside of the crankcase that stuff will come loose again as the oil splashes against it, but not so much from the detergent. My Olds truck manual mentioned washing the oil pan out at intervals by just putting kerosene in the pan after the oil is out and rocking the truck back and forth and then draining it back out right away or as it was still being rocked. It was mentioned in the section about winter driving to remove water from the pan but did say it would remove other deposits in the pan as well. It would be good to drain and change it more often the first few times. A clean engine is a happy engine. Sorry to hear about your neighbors lack of a sense of humor! Years ago I had a guy live next door who had about a 1961 2 cylcle Saab (3 cyl?). He said he couldn't get a muffler for it anywhere. It wouldn't have bothered me much except he let the car warm up for at least a half hour everyday before leaving for work at 5AM. It flat wouldn't go down the road unless it was warmed up good. He worked 7 day a week and his driveway was 10 ft off my bedroom window and sure rattled things. Never did sleep good in that house!