LA360/10w30 running about 9psi at idle and 25psi at 2,300 rpm at temp. 50psi at idle at cold start. Would running 10w40 add a couple more psi and not be detrimental to any internal components? Figured a heavier weight could help with this Florida heat.
Boarder Line Low Oil Pressure
- Thread starter Mcfarlrm
- Start date
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TrailBeast
AKA Mopars4us on Youtube
Newbomb Turk
Well-Known Member
TB nailed it. We don’t know what your bearing clearances are and if your oil pressure has always been this low or if this just started.
Assuming nothing is wrong with the engine then throw 20W50 in it.
Assuming nothing is wrong with the engine then throw 20W50 in it.
Appreciate the recommendation. I'm not aware of the clearances nor did the previous owner have this info. Oil pressure has always been this way since the day I purchased it a couple years ago. Do I need to add a zinc additive to these? I currently run Lucas Hot Rod with high zinc.
Kendog 170
Let the boy go !
Lucas has 20-50 Hot Rod Oil
slickchick
pedal cars only
sounds like cam or main bearing clearance issues
What gauge do you have? I thought I had a similar issue with a junk yard engine I used once. Turned out that when I swapped the crappy Equus gauge for an Autometer, the low end pressure never went below 15psi at hot idle. Before that it would read zero. Just something to consider.
Cley
Cley
Possible. All internal work was done by previous owner.
Autometer and replacement the sending unit about a year ago.
TT5.9mag
Two atmospheres are better than one
This ^^^. Or lifter bore wear.
cudamark
Well-Known Member
Assuming your oil pressure gauge is accurate, you have some excessive bearing clearance, worn oil pump, or a leak in the oil gallery somewhere. I'd pull it apart and check everything before you spin a bearing.
Dan the man
Well-Known Member
The pressure relief valve in the oil pump could be bad. But, I'm too thinking that it's a bearing clearance issue. Your engine should have at least 30 pounds of oil pressure at idle. The normal is 10 pounds of oil pressure for every 1,000 rpm's. You may want to use a different oil pressure gauge.
Dan the man
Well-Known Member
Thicker oil is not the solution, most likely it's rebuild time.
Newbomb Turk
Well-Known Member
Not true Dan. Everyone is assuming the engine is junk.
Yet no one knows what the clearances are. So why are we assuming it’s got bad lifter bores or bearings? A plug may be missing or leaking. We don’t know.
But bet your *** that the bearing clearances are probably looser than if set them, but I never bought the loose is fast bullshit.
Let’s assume some things.
1. The bearing clearance is .0025 or looser.
2. The engine may have (and should have) full groove mains.
Just those two things right there will drop oil pressure that low.
Put some 20W50 in it and go drive the **** out of it.
Dan the man
Well-Known Member
My bad, I forgot about the plugs.
I have a 325,000 mile 273, rebuilt 175,000 miles ago.
With 10w30 wt the idiot light would come on at hot idle. Sender was new at the time.
I went to 10w40 wt and no more oil light
No actual oil gauge so I don't know what it is running.
I will tell you that 10w40 is like cold syrup in 30 deg or colder weather
With 10w30 wt the idiot light would come on at hot idle. Sender was new at the time.
I went to 10w40 wt and no more oil light
No actual oil gauge so I don't know what it is running.
I will tell you that 10w40 is like cold syrup in 30 deg or colder weather
junkyardhero
Well-Known Member
sounds like the bearings are jusssstttt on the loose side of things and she's opening up a little when she gets hot and dropping some pressure.
i'll echo what others have said up thread and suggest going with a thicker oil and see what that yields.
if you still have less than thrilling pressure after that (and checking your gauge) then it may be time to rethink things.
i'll echo what others have said up thread and suggest going with a thicker oil and see what that yields.
if you still have less than thrilling pressure after that (and checking your gauge) then it may be time to rethink things.
Dan the man
Well-Known Member
That's a good idea but I think that it's only a temporary fix. Like mentioned earlier a plug or something could've not been put in or came loose. It could be a bearing clearance issue or a bad oil pump and possibly the lifter bores could have excess clearance. I don't mean to sound negative here or anything but I think that your not to far from having to take it apart and see what's going on. True, the thicker oil will help for a while but if it's a clearance issue or the pump is bad it will only get worse over time.
It may be temporary, but it could go for years depending how and how much the vehicle is driven.
Cley
Cley
Newbomb Turk
Well-Known Member
Damn Dan, what are you missing? If the clearances were loose when it was machined then it’s not a problem.
I wouldn’t NEVER EVER build an engine to use 20W50.
Why? Because to keep the oil pressure in check you NEED to run loose clearances. I detest that because I have a fundamental working knowledge of how these oiling systems work.
Big clearances make it harder to form an oil wedge between the bearings and the crank. Oil pressure does not keep the crank off the bearings. The oil wedge that’s formed is what does it.
That doesn’t mean oil pressure doesn’t matter as that is what gets the oil to the rods.
A 50 grade oil takes more power.
I could go on but why? The OP’s pressure is low AND HAS BEEN LOW SINCE HE BOUGHT IT and it ain’t ate itself yet.
Like I said, loose clearances and full groove bearings is an oil pressure disaster.
My last personal engine carried a 100 pounds of cold oil pressure. And that was with a 5w30!
This time the clearances are the same (.0021 on the rods and .0024 on 340 mains) but I’m dropping to 0w20. And not some cheap assed bargain basement oil either.
I do what I do because I don’t skimp on **** like oil. I can run tighter clearances because I use a quality oil. If 23 bucks a quart scares you then open up the clearances and use a low quality, higher grade oil.
The cost to set the clearances is next to nothing so why leave them loose? Because we believe the lie that loose is faster and it ******* NOT faster.
Of course, I do block the oil off to the lifters and stop those 16 leaks.
Oil pressure and lubrication are about managing flow and clearances.
I doubt his engine is junk. Going to a higher grade is NOT a fix. It’s the correct oil finally going into the pan.
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Dan the man
Well-Known Member
You have to admit that there is a problem, the oil pressure that he claims to have at a idle would've been enough for me to start seeing what's going on. I don't know of any engine builder who would build a engine to have such low oil pressure at idle. I've never had a engine that didn't have less s than 30psi at a idle. If the machine shop machined it to be that loose that's not good
Newbomb Turk
Well-Known Member
Read post 21 and tell me why YOU think running a 20w50 oil means the engine has an issue. In detail.
I’m waiting your response with baited breath.
Edit: I don’t have to admit anything. You’re the one throwing **** out there.
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You buy a car yet, Dan?
Dan the man
Well-Known Member
I agree with you. The engine does have a issue big time. Do you believe in the use of full grooved main bearings? I could've misunderstood you but I thought that earlier you said that they are a good idea and yet in post 21 your saying that they are not good for oil pressure.
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