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#2
05-03-10, 03:49
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Tired engine......
Bonjour Michel
All oil is thicker when cold and the oil pressure will be high. Once the oil gets hot and thinner and water like it will leak from every bearing on the crank and on the camshaft. You may have just one or two worn bearing but it is enough to drop the oil pressure...... some sludge circulating in the oil system could explain the fluctuation or you have a worn bearing that may be moving...spinning on the lower end of a rod and drip more and somethimes less. Old M37 would run well on 20 to 25 pounds warm..... below that I would get scared of doing damage....... If you care about saving the engine before you get real bad damage..... don't drive it..... tear it down before you need a major regrind or score a cylinder wall...... if everything is worn loose you will never find oil thick enough to bring the pressure up...... Parts are readily available check out......www.vintagepowerwagons.com make sure you look at the Canadian 251 engine parts Another excellent source of information is.....http://www.dodgepowerwagon.com Like Gilles offered I may also have parts also....... you might be able to get away with just flipping the engine over and doing crank main and rod bearings ....... I even polished cranks by hand with progressively finer emery paper.... not a good job but the darn thing ran good..... they are fairly forgiving compared to modern thight clearance engine..... Do you have a Dodge military shop manual for the engine..? Dodge flat heads are not hard to work on...... except you have to take the whole darn block to the machine shop to get a valve grind job. Boob
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Bob Carriere....B.T.B C15a Cab 11 Hammond, Ontario Canada 
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#3
05-03-10, 13:49
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Valve job..
Boob..
You surprised me... Quote... "except you have to take the whole darn block to the machine shop to get a valve grind job." What ever happened to lap sticks..? Oh,,,I forgot..You were not an old flat head kid.. Jeez..every kid that ever worked on their Fords when I was growing up got a lap stick for their 10th birthday..and a couple of tins of valve grinding compound..coarse and fine.. How else could you do your valves AND get your valve clearance adjustment..?? My machine shop was in my dads garage.. Get your rebuilding stuff here..at least look at it.. http://www.goodson.com/
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Alex Blair :remember :support :drunk:
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#4
05-03-10, 16:37
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I was more modern.......
Hi Alex
I have found at a farm auction a hand driven device...... almost like a small hand cranked drill...... it holds the rubber cup and when you crank the handle the rubber cup turns about two revs one way lifts automatically ...goes down and turns two revs the other way just like a wooden handled tool..... real neat and twice has fast. Its called progress...... Try going to local machine shops that sends out most of there work to either Montreal or Toronto and ask for a 3 angled valve job..... watch the look on the kid at the counter!!!! Boob
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Bob Carriere....B.T.B C15a Cab 11 Hammond, Ontario Canada
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#5
05-03-10, 20:29
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Hi, if your cold and hot oil pressure is within the normal range but it rises and falls with increasing and decreasing rpms (when hot) that too is normal. However, if the oil pressure fluctuates at a constant rpm, idle or a set rpm, then I would take a look at the pressure relief valve, particularly the spring as it may have lost its set, the ball and seat as either may be pitted, or there may be dirt or sludge in the chamber.
Cheers, Dave
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#7
06-03-10, 01:45
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That sound correct.....
Bonjour Michel
The oil line that goes to the oil filter has the pressure sensor conencted there..... the line that leaves the bottom of the filter is the return clean oil line to the engine and has even lower pressure. It could be the electrical connector is contaminated with oil and you have a bad connection. Have you tried installing a cheap mechanical gauge from Canadian tire. You just need to instal a tee fitting between the oil line and the filter...connect the mechanical gauge to the tee fitting and you should get a reading that you can compare to the electrical gauge. If you have no knocking sound to the engine the temporary gauge may be a good way to do a test to see if the electrical guage is good.... or you maybe able to remove the existing sensor switch and instal a fitting to connect the mechanical gauge..... Good luck Boob
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Bob Carriere....B.T.B C15a Cab 11 Hammond, Ontario Canada
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