Oil questions.

Discussion in 'General IH Tech' started by scoutdude, Jun 26, 2020.


  1. scoutdude

    scoutdude Farmall Cub

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    Hello. I am going down the line of issues and trying to get the scout(304 v8) ready for long hauls. I was using T6 15w-40 but I recently drained it for Zrod 10w-30. I have an aftermarket oil pressure gauge and it reads accurately(mechanical gauge used to verify). While running the t6, cold idle was 50psi, and warm idle was around 5 psi. After switching to Zrod 10w-30 cold idle is at 40 and warm idle is at maybe 1 or 2 psi.

    when running the thicker t6, there was a slight ticking sound on the driver side. When I put the lighter oil, the ticking went away. When warm idle, I don’t hear anything bad with the lighter oil. It Sounds fine.

    The oil pressure concerns me. I haven’t taken the oil pan out(should have done that after the first oil change). I really don’t want to waste 6quarts of new oil. Should I drain oil into a clean bucket, pull pan and inspect for sludge, and then put the drained oil back in? Should I keep on keeping on? Should I run MMO or sea foam? Should I ASAP refill with a high viscosity oil? Thanks for all the help. This place has been good to me.
     
  2. Greg R

    Greg R Lives in an IH Dealership

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    No thicker viscosity is needed. The cold pressures aren't bad. It's the hot oil pressures that are of concern. Drain the oil into a clean container. You can re-use it strained through some cheese cloth. The filter will take care of the rest. Clean the pan and pull and clean the oil pump's pickup strainer. If the pick up is clean or not very dirty, I would then inspect oil pump clearances and relief valve bore.
     
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  3. BinderBookie

    BinderBookie High Wheeler

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    The manual states the minimum idle oil press with 30 grade oil heated to 200F is 10 PSI. At 1800, it should be 40-50 psi with 30 grade at 200F. I doubt your oil is at 200F, so if all you are getting is 2 PSI you probably have issues of some sort. The old yardstick was 10 psi per thousand rpm, but it varied somewhat according to if the engine was a low pressure/high volume system (like IH) or not.

    The typical reason for low pressure is loose bearing clearances on an engine that's tired. A worn engine is the equivalent of a hose with lots of pinholes... the pressure at the end is low. The oil pan and oil pump stuff suggested by Greg are a possibility as well (especially the pressure relieve valve) and have the benefit of being relatively simple to do. Wouldn't hold my breath, but it's worth trying.

    You can drain the new oil into a clean container and reuse it, most certainly. If you knew how dirty new oil is, you wouldn't worry. Noria (a lubricant training outfit) has documented a lot of new oil as high in particulates and the oil actually gets cleaner after it circulates thru the oil filter a few times.

    FYI, in my IH diesel, I saw a difference of around 4-5 psi between 15W40 and 10W30 @ 200F... but that was a nice tight engine.

    Good luck!
     
  4. scoutdude

    scoutdude Farmall Cub

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    Thanks for the detailed posts. That’s gives me some comfort about draining the oil. I laughed a little at the oil getting cleaner going into the engine haha. That’s awesome.
    Tonight or tomorrow, I will drain the oil, pull the pan and inspect/clean. It has the dual drain holes, I assume that makes my scout a candidate for 7 quarts? It’s a very early ‘74.
     
  5. winchested

    winchested Y-Block King

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    Yup 7qts if you do any high speed driving.

    Just run it til you can afford to rebuild it.
     
  6. mallen

    mallen Y-Block King

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    Id definitely check the pickup. Would I expect that to fix the problem? Maybe not, but sometimes you get luck. Like others said, try to track down what the problem is, and then go from there. It might be worthwhile to pull the valve covers and make sure oil is going where it should.
    The very first thing I would do is take the sender out and look and see if a piece of crud got in there. Bot because I think thats the issue, in fact I very much doubt it is, but because its literally the easiest thing you can do. If you have not verified the gauge reads correctly since you noticed the problem, do so now. Make sure it reads good both high and low. Just because you checked it yesterday, does not mean it works right today. And just because it read the same as the mechanical gauge at 50psi does not mean that its not reading 2psi when it should read 10. Once again, I doubt that's the case, but its super easy to check. You might get lucky.
     
    Last edited: Jun 27, 2020
  7. scoutdude

    scoutdude Farmall Cub

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    Dropped the pan. Screen has some things in it. No metal in the pan so that’s good. I am finding gasket sealer in the pan/screen, found a small leaf, and some rubber pieces. I haven’t checked the book for oil pump instructions but I assume it tells you what to check on the pump, as far as tolerances are concerned?
     

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  8. Greg R

    Greg R Lives in an IH Dealership

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    Yeah, this is a good inspection. I'd wager 40% of the inlet screen is blocked, which would affect hot oil flow. RTV on the pump body flanges is also scary. I do NOT promote RTV, especially on anything in a lubrication system other than the absolute minimum on a reservoir or pan sealing. The Service Manual will give details on pump inspection and how to check clearances.

    Checking the pump, while the pan is off is a process of elimination you can do with the engine in the vehicle. If the problem is found there and fixed, it may save you from doing an overhaul. Start simple and work up.
     
  9. David Banner

    David Banner High Wheeler

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    While the pans off you can pull a bearing cap and a rod cap and get an idea of overall wear.
    There's good pics in the oem manual and I'm sure online for visually evaluating the bearing cap wear.
    If you're familiar with plastigauge you can do that too.

    Was the metal on the screen magnetic or not?
    Same question with the sludge in the corners of the pan.
     
  10. scoutdude

    scoutdude Farmall Cub

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    I drug a magnet through the pan and then wiped the magnet on a cloth, followed by another pass of the magnet. I have only found a small ant size piece of magnetic material. It’s pretty jagged, looks like something you’d find in the dirt in your yard.

    What’s the best way to clean the screen? Do I need to take the pump apart? I will try to figure out how to check a bearing or two to see wear.
     
  11. scoutdude

    scoutdude Farmall Cub

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    I pulled the spring because it was the easiest, nothing weird in there. Clean oil, spring measured 2.215”, and no burs. There was also nothing magnetic in the screen. I cleaned out the pan and found some more ant sized pieces of metal with my magnet.

    I would like to take the cover off the pump to check the gears like the manual suggests but I don’t have a gasket and I understand that the gasket is part of a kit. The engine has been in good shape, new gaskets and such from peeking and proding over the years. The old working odometer has 60,000 miles On it. Should I just clean the screen with a brush and some acetone, then put it all back together?
     
  12. jeff campbell

    jeff campbell Lives in an IH Dealership

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    Put it back together.
     
  13. BinderBookie

    BinderBookie High Wheeler

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    I will say is that, often, we MOST regret the things we did not do when we had the chance. Assuming your gauges were accurate, that low pressure indicates some sort of a problem. I've seen engines with more stuff on the screen than that with perfectly fine oil pressure. It was suggested to have a look at several rod and main bearings. That could be a good indicator of what you might have ahead. Rod bearings are relatively easy to change in this situation if you see them amiss. You CAN do mains in situ but it's a PITA. Both these would presuppose a crankshaft in serviceable condition.
     
  14. scoutdude

    scoutdude Farmall Cub

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    Yeah I agree with the regret portion of putting things back up with not double checking. Considering all the orange rtv everywhere, I wonder if some is clogged up somewhere.
     
  15. scoutdude

    scoutdude Farmall Cub

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    Another question, how is it that the oil pressure is at the optimal performance cold, but when it’s warm it performs poorly. I am not so much asking why does the oil pressure drop as it warms but why does the oil pressure start off and then declines. Do the scouts bypass the filter while cold and then goes through the filter when it starts warming up? Sorry for the novice questions

    this is also in Texas heat above 90 or so with 10w30. If that makes a difference.
     
    Last edited: Jun 28, 2020
  16. winchested

    winchested Y-Block King

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    Any engine bypasses the filter when really cold.

    Cold oil doesnt flow as fast low flow high pressure, high pressure low flow that's how hydraulics work.

    Spend the $60 buy the melling oil pump rebuild kit from rockauto.com and rebuild the pump. It has all the specs, new gears and new gaskets.
     
  17. winchested

    winchested Y-Block King

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    You also need to check top end oil flow when you've rebuilt the pump and put it back together.

    You very well could have blocked passages.

    I run 15w40 like most and have zero lifter/ top end noise.
     
  18. scoutdude

    scoutdude Farmall Cub

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    I wouldn’t be surprised if I have blocked passages considering all the rtv I found. I’ll just buy the kit like you suggested. I’d rather have the peace of mind.

    I have taken the the valve covers off and turned on the engine. It seemed to flow just fine but then again I don’t know engines inside out. Body work is my area lol.
     
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  19. winchested

    winchested Y-Block King

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    .awesome that's good news.
     
  20. BinderBookie

    BinderBookie High Wheeler

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    IMO the oil pump is a remote possibility, so I wouldn't waste money buying parts until I had the pump apart and checked. When I wrenched for a living (ASE Master Tech plus factory trained by Land Rover, Ford and Porsche), we used to call that, "Throwing parts at the problem until something fixes it." Verify the problem before you buy parts. You have an opportunity to look at bearings and such; do that. If you see an issue with the pump, fix it. If you see issues with the rod bearings, replace them if you can't pull the engine now and do it all. It will buy you some time and probably enough pressure to bring you up past the minimum. Mains, I would avoid at this stage. Mainly, consider this "exploratory surgery." You could put it back together and run it... it would probably survive quite a while, especially if you run an 1800 rpm pressure test and it's at or near spec, but in a sense it will be like a grenade with the pin out and the safety handle held down with old Scotch tape.

    In Texas, the warm weather allows more flexibility on viscosities because you don't have much cold. In theory, you could go back to a 15W40 grade and void most cold start issues (you cold start a 70F so, hey!). You said the 40 grade delivered 3-4 more PSI at idle. WOuldn't go thicker than 40. The more important pressure spec is 1800 anyway. BUT I worry because if you are getting 2psi now... an I seriously doubt the oil is 200F, what will it be when the oil DOES get to 200F. If you have an infrared heat gun (pretty cheap at Harbor Freight), get a reading on the oil pan at a point between the bottom of the pan and the oil level. It will read lower than the oil actually is, probably by 20 degrees at least, but it will give you an idea. Next time you check pressure, do it on a hot day and work the crap out of the truck and get that pan temp up as high as possible... then take a pressure reading. That will more or less be your real-world, worst case scenario.

    Oil is "thicker" when cold and "thinner" when hot. Those are not actually very technically accurate terms but they will do. Cold oil has more resistance to flow so more pressure is created pumping it and flow is reduced. Pressure is an indication of resistance to flow. Multi-viscosity oil reduces the viscosity swings from temperature. The main method for that uses VII (Viscosity Index Improvers). Say you have a 10W30. The base oil might be a 20 grade. To that is added VIIs. When the oil gets hot, these molecules expand and make the oil thicker. When the oil is colder, they contract. There are other additives that change the Viscosity Index (the measurement of the range in which the oil can maintain a stable viscosity near it's base rating... such as 30 grade) as well. The "10W" does not indicate an actual viscosity, such as 10 grade, but rather is a cold flow performance/pumping rating.

    Thick oil may cause the oil filter to bypass. That happens from differential pressure (DP or Delta-P) between the oil filter inlet and outlet. Thick oil has trouble pushing through a filter. The oil filter has a maximum DP rating, so the bypass valve (within the filter or in the block depending on the engine... most often the filter) is set to keep it well below that so that pressure doesn't blow thru the filter media. Oil filters do not usually bypass completely but it's something you want to avoid as much as possible (for obvious reasons). As the filter loads up, it gets more restricted, so DP will naturally increase over time irrespective of oil viscosity or temperature.

    I've blathered about this before but I ran a differential pressure gauge on on of my trucks for several years and knowing the relief valve specs, I could note when it bypassed. With the right oil viscosity (OE spec) and some sense from the driver (easy driving until the oil reached about 120F... yes I had an oil temp gauge) I could avoid it, even in sub zero weather. With thicker oil than specified, it was very hard to avoid. For long engine life, choose an oil that flow well at all times within the temperature range in which the engine operates and avoid high revs and hard work until the engine warms up. With thicker than needed oil, that becomes almost impossible in a cool climate.

    People are too fixated on pressure when it's flow you really want. What is high pressure but the reduction of flow. In balance, pressure is the only flow indicator we have, so the important step is to know the designed pressure @ temperature specs and then use the lightest oil that will keep your engine within the designed pressure @ temperature specs. I will paraphrase an expression from my days as an off-road driving instructor for Land Rover... a thin as possible, as thick as necessary (the original was; "As slow as possible, as fast as necessary."). The factory IH manual lists a minimum of 10psi at idle for 30 grade oil at 200F and 30-40 @ 1800. In your case, you didn't meet the idle spec with either 30 or 40 grade oil. You apparently didn't measure the 1800 rpm pressure, or at least didn't relate it.
     
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