Oil pressure

N

nate46and2

New member
I have a question about oil pressure. I have a 72 Scout II with a 345. I have an after market mechanical oil pressure gauge. When starting the Scout cold my pressure gauge goes up around 30 or 40 which from what I've read on here is normal. The problem is once the Scout is warmed up the pressure drops down around 10 at idle and even at 2 or 3 thousand rpms it stay around 10. Today I noticed a drip of oil coming out of the fitting where the line goes into the block from the guage, which im wondering could be the problem. What do you think the problem might be? Oil pump, gauge its self? Thanks
 
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Well, you could fix the "leak" at the fitting - though I do not think that is the problem.

Gauge? -- do you have friend / mechanic with another mechanical gauge to check against yours?

Is the stock oil pressure gauge hooked up / working?

If it is, it should "match" the mechanical gauge: 30 - 40 would be slightly less than the "half" Mark; 10 lbs would be the 1/4 Mark or slightly less.

Oil pump - possible, but I have never read many posts about people replacing the oil pump on IH sv engines.

Another possibility -- delaminated cam bearings. You need to drain the oil and pull the oil pan to check for metallic bits in the bottom of the oil pan.
 
I agree with Robert on the pan pull , if nothing else for peace of mind and the ability to shim up the pump spring. But lets eliminate a a few things first.
What weight oil are you running, what brand of filter, what brand of oil. 10/30 or 40 is going to run with less pressure on the idle side of things than 15/40, granted it should climb back up quickly on acceleration, once warm you will notice a decline in pressure as you stated, it should recover though.
If your gonna pull the pan, which is a good idea, go back with a good grade of 15/40 or 20/50, a wix, baldwin, or purolator filter and give her a extra quart, for the long runs to prevent starvation.
Read the post on oil pump shimming, did mine on a motor with 80k+, great results, good idle pressure and 50 + goin down the road
 
Thanks for all the input. That sounds like a good plan, I just bought the Scout, the previous owner has been running 10w30 oil in it. Ill drop the pan and check for metal shavings, my oil pan gasket is leaking pretty bad anyway so ill be killing two birds with one stone. Ill read into shimming the pump springs, and switch my oil to 15w40, and a quality filter.
 
Before you pull the pan, I would recommend cutting the oil filter open. Inspect the element for metal. Rinse the paper element in solvent and take a look in the pan. Ignore iron filings from cutting the can if you saw cut it. You will always find a few flecks but for bearing damage you should look for gray(babbitt) and copper. Usa a maginet to pick out iron like frok a cam/lifter issue.
This method is an accepted way to determin the fitness of aviation recip's. I cut mine every oil change.
 
From my experience, a cold start oil pressure of 50-60 psi for an IH 304/345 with 15w40 or 20w50 oil is more normal. A hot idle oil pressure of at least 10 psi is desireable, with 10-20 psi being the factory spec (with sae 30 oil). At cruise rpms with hot oil, I get around 40 psi with 20w50.

As said earlier, oil filter quality often affects hot idle oil pressures on the IH v8s.
 
I'll add in a few more comments about oil pressure to the excellent responses already given.

Oil pressure can also be effected by fuel in the oil, which makes the oil thinner, and consequently reduces the pressure, and also by something which a lot of people do not realize..... The quality of the oil.

So first of all, I would make sure that the carb is not over-fueling and you are not getting fuel wash down in your engine. That will not only effect oil pressure, it can also do some major damage to the engine.

Secondly, it is a characteristic of engine oil that the pressure will be higher at cold start-up because the viscosity of the oil is heavier. Viscosity is a term used commonly as "thickness" which is partially correct, the correct description is "viscosity is a measurement of resistance to flow." after the engine warms up, the oil pressure should drop to within normal parameters, but the higher the rpm's are, the more pressure you are going to show on your gauge. It is not unusual in high performance v-8 engines for example to get readings of 80 to 90 lbs on the oil pressure gauge. But for standard every day drivers, that of course would be much lower.

The higher quality engine oils, like swepco's will reduce the amount of oil pressure when the engine is started up cold, and raise the oil pressure when the engine is warmed up, that is the way it was designed... It would be impossible to have the oil pressure the same at cold start-up as it is on normal, or hot engine temperatures, that is the physics play out.

I never recommend 10w40 engine oil in any engine as the vi improvers used in that weight go away rather quickly and it leaves you running on a 10wt oil.

The swepco 306 engine oils in all weights (except 5w30) will have a very high zinc content, and only meet the api rating as high as "sl." phosphorous and zinc (zddp) give more protection against wear, and the newer "sm & sn" rated gasoline engine oils are designed more for newer makes of engines (since 2007) and have much less additives it those formulations.

I see that you are in utah, so I don't recommend using 20w50 year-round, go to 15w40 which is actually rated for use between 4 degreesf and 120 degreesf - you May even want to go to 10w30 during the winter if your vehicle is not garaged.
Swepco 10w30 engine oil has a pour point of -31f, the 15w40 is -27f and the 20w50 is -4f.... That means that the oil will still "pour" at those temperatures, but is is still going to be heavier than it would be during the summer months, in fact 10w30 might be a good choice for year round use in your location, but it will not have the higher pressures you are looking for, especially after the engine is warmed up. The pour points mentioned are very close to most of the so-called "synthetic" oils on the market, but many of those also have a low additive package.

Hope that helps many of you out there.
 
Thanks for the great responses. I wont lie I had no idea how much oil weight and quality of filters effected oil pressure.
 
Like the old saying the only dumb question is the one not asked. Just always remember to search first on any question you have, if its IH related it's probably been tossed round on here more than once.
Good luck on your project and feel free to ask for help!!
 
Here's even more technical information about viscosity, I had to dig way back in the files to get it......
 

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erik vanrenselaar said:
from my experience, a cold start oil pressure of 50-60 psi for an IH 304/345 with 15w40 or 20w50 oil is more normal. A hot idle oil pressure of at least 10 psi is desireable, with 10-20 psi being the factory spec (with sae 30 oil). At cruise rpms with hot oil, I get around 40 psi with 20w50.

As said earlier, oil filter quality often affects hot idle oil pressures on the IH v8s.
Click to expand...


Hey kidz, sorry to resurrect this thread from the dead, but I just stuffed that 'rebuilt' 345 in my traveler, ran it in park for 2-3 minutes, and I'm seeing 70 psi (on my sun pro gauge) when I blip the peddle to around 2500 rpm. Letting off the gas to about 1200 rpm and I'm seeing 35--40-ish. 10/30 basic o'reilly's oil, rebuilt (and re-shimmed) oil pump.....and a new/old monkey ward spin on filter. I think that's too high. What say y'all?....


(edit-2-add) oil is still luke warm so I just swapped out the m/ward filter for a motocraft. Will come back with the results soon. But my biggest fear is that I over-shimmed the pump. That would suck. Like a lot....:mad2: )
 
Its on the high side, but the engine had not fully warmed up either. Hot pressure is what we're really after. 60 psi is about the most one normally sees from these engines when cold. 10w-30 oil is a bit thin especially for the socal climate. You should be running 20w-50, which would actually increase the pressure reading even more. Also, if you haven't yet read overdrivesteve's recent submission regarding oil filters, I recommend you do so. Its very informative.
 
erik vanrenselaar said:
from my experience, a cold start oil pressure of 50-60 psi for an IH 304/345 with 15w40 or 20w50 oil is more normal. A hot idle oil pressure of at least 10 psi is desireable, with 10-20 psi being the factory spec (with sae 30 oil). At cruise rpms with hot oil, I get around 40 psi with 20w50.

As said earlier, oil filter quality often affects hot idle oil pressures on the IH v8s.
Click to expand...

Thanx s/boy. My friend up the street with another traveler stopped by a while ago----we found one small vacuum leak that steadied my vac gauge a bit and helped to smoothe out the low idle. Let her warm up 'til I saw 170 degrees then ran her around the block real quick before parking her for the night. Saw a more (less scary) 58 psi at 2500-ish rpms, about 22---24 psi at idle. Much better. So in the morning I'm gonna hit the freeway and do that 'motoman' twenty mile break-in procedure and set the rings. Then head home and change the oil. As far as the 10/30 goes, my theory was that 1). It's been only in the 60's here lately, and 2, that the thinner oild would help dispel a lot of the assembly lube inside the motor. Which it did, if the color of the oil that I poured out of that m/ward filter was any indication----kinda a honey/silver color, after just 5 or 6 minutes of fast idle.

I'll go with 20/50 tomorrow and then see what the first batch of oil looks like---could be a fun little science experiment...:lol:
 
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