Boarder Line Low Oil Pressure
- Thread starter Mcfarlrm
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Took it out today to run through the RPM range while checking the pressure. Stays pretty consistence through the RPM range at temp. Where I live is typically back roads and never exceed 2,500 rpm. However, took it out on the main road for a few miles consistent at 50mph and 2,700 rpm. Started to hear top end ticking like it's coming from the valve assembly. Immediately went back to the garage and the tick started to slowly go away as it idled for a bit.
Swinger 340
Well-Known Member
I also live in Florida. Years ago, I had a 175,000 mile 340 with an oil pressor drop and started using straight 50 and went another 50,000 before blowing it up, my fault, going 65 in first gear, POW!!!!
My buddy with his BBC with twin turbos, last time we were at the races, he lost oil pressure.
Super low, duel oil pressure gauges reading the same.
Expecting the worst, last weekend started to tear into the engine, what he found was the VR-1 had totally broke down in 300 miles.
It was thinner than water when it was drained, no viscosity at all.
Fresh oil change, using the same weight VR-1, oil pressure is back to normal.
Only thing we can think of, is the heat from the turbos, basically cooked the oil.
Super low, duel oil pressure gauges reading the same.
Expecting the worst, last weekend started to tear into the engine, what he found was the VR-1 had totally broke down in 300 miles.
It was thinner than water when it was drained, no viscosity at all.
Fresh oil change, using the same weight VR-1, oil pressure is back to normal.
Only thing we can think of, is the heat from the turbos, basically cooked the oil.
With this line of thought you could reverse the words and say the thickest it asks for!
I currently have a low pressure 318. Before I tear into……the car and install a 340…….its getting thicker oil!
Yes, whatever keeps it from blowing up.With this line of thought you could reverse the words and say the thickest it asks for!
I currently have a low pressure 318. Before I tear into……the car and install a 340…….its getting thicker oil!
I sucked alot of water down the carb in a 304 Jeep CJ one time in a water crossing about 200 miles from home.
Water really done some damage, kept putting 90 weight in the crank case, to make it home.
Hey, I just saw this post, I posted the same exact issue in another thread. 60 psi when cold, but after its hot, down to like 10-12 psi. Mine is a freshly built crate engine, 360 magnum. The builder suggested that for a stock oil pump that is within spec, and if I wanted to, just swap from 10W-30 Lucas Hot Rod oil to 20W-50.
Brian
Brian
Brian, what does it have going down the road at around 2K?
It's running 10-12psi/1000 rpm, so maybe 25 psi at 2000rpm. My slant six (build by Doug Dutra) had 70 psi cold, 50 psi at 2500 rpm, and 30 psi at idle hot, but he built the oil pump and we used like 0.004" on the bearings when we built it.
I'm less and less worried about this pressure, seeing that it is very common in these magnums apparently.
It's just weird that it is really good pressure when cold, at all rpms, but drops so much once warmed up. Again, I may swap to 20W-50 when I change the oil next, just to see how it behaves. I'm not too worried after reading up on this and getting feedback on this forum.
I'm less and less worried about this pressure, seeing that it is very common in these magnums apparently.
It's just weird that it is really good pressure when cold, at all rpms, but drops so much once warmed up. Again, I may swap to 20W-50 when I change the oil next, just to see how it behaves. I'm not too worried after reading up on this and getting feedback on this forum.
That seems a little low, but understand, I don't have what I'd call a ton of experience with Magnums. I've built several, but for other people. I always use high volume oil pumps.
Yeah, slants usually have a lot of oil pressure when done right. Mine idles at 75 cold and the only reason it's not higher is because the relief valve is open. When it's hot, it idles around 45-50. As soon as you blip the throttle at all, it zooms up to about 75 and stops like a rock right there, because the relief valve opens. Otherwise, it'd run right on up to 100...or whatever. lol I don't run a high volume pump in a slant, just a standard volume pump with the high pressure spring.
I wonder if the high pressure spring might help with your issue. Not as easy to get to as the slant, but it might be worth a try if you decide to do something.
10 40 sure as **** ain't going to hurt anything if that's your biggest worry. If it ain't knocking and you ain't finding glitter I'd just watch it closely for awhile if you ain't doing anything hard.
Both my never opened up stock magnums make 40psi hot idle. I'm using 10w40 but it don't make much difference
My slant 6 has the oil pressure it does with 10/30. I've tried 5/20 in it once, because I had some and it still made the relief valve in the pump open. Whenever I see people trying to make a difference with oil pressure changing oil grades, I shake my head. Now if you're trying to match bearing clearances, that's one thing.
Your pressure is fine, I would not put the heavier oil in it.
Why take a chance on seals leaking etc.
Yeah, I'm going with the builder's advice, he said this is within spec for a stock oil pump. Runs fine, no indication of any damage when I changed the oil. I'll keep an eye on it, but otherwise I'm just going to enjoy my ride.
Just to be clear, I have an LA not an Magnum. Not too sure if that changes anything. Oil looks good with no glitter but I am getting a bit of valve tick at temp and only when running at higher cruising mph/rpm. Once I drop down below 2,700ish cruising rpm the tick slowly goes away. I did throw some stabilizer in, which gave me a bit more psi. I have yet to run it at higher cruising rpm to see if the tick went away.
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