need some advice. Was getting my 408 tuned a month ago and spun a rod bearing. Builder/ machine shop blamed it on high volume pump sucking stock pan dry. Motor was put back together With stock pump, had less than 5psi hot idle so builder added a shim and went to 15w40. Hot idle is now 10-12 cold is around 60. My Tuner pulled it off the dyno because it's only making 45 psi wot at 5500rpm. Builder says its finer tuner says no way. What do you guys think?
Oil pressure help
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yellow rose
Overnight Sensation
Your builder is FULL OF ****.
Number 1) a high volume oil pump can NOT suck a pan dry, unless the clearances or so loose that it's junk any way.
Number 2) it's not a Chevy. You can use up to 16-17 lbs per 1000 RPM at WOT. No less than 10 lbs per 1000 RPM at WOT.
Number 3) you will kill every rocker with 5 pounds of hot idle oil pressure. They are the last to get oil. With 5 pounds on the gauge, you probably have ZERO at the rockers.
Your tuner is way smarter than your engine builder. Take it apart and figure out where the oil is going. Using a 15w40 oil that thing should have 80 pounds at WOT and 35-40 at hot idle. If you are using full groove mains (and you should be) you need a HV pump and the pressures I posted. If you have to run a 20w50 to get the oil pressure up, you have clearances that are way too loose. Personally, I run .0020 on the rods and .0023-.0024 on the mains. I have about 60 psi at hot idle and about 90 hot at 7200 RPM on Torco 5w30 racing synthetic. You've got issues and the engine builder is nuts.
Number 1) a high volume oil pump can NOT suck a pan dry, unless the clearances or so loose that it's junk any way.
Number 2) it's not a Chevy. You can use up to 16-17 lbs per 1000 RPM at WOT. No less than 10 lbs per 1000 RPM at WOT.
Number 3) you will kill every rocker with 5 pounds of hot idle oil pressure. They are the last to get oil. With 5 pounds on the gauge, you probably have ZERO at the rockers.
Your tuner is way smarter than your engine builder. Take it apart and figure out where the oil is going. Using a 15w40 oil that thing should have 80 pounds at WOT and 35-40 at hot idle. If you are using full groove mains (and you should be) you need a HV pump and the pressures I posted. If you have to run a 20w50 to get the oil pressure up, you have clearances that are way too loose. Personally, I run .0020 on the rods and .0023-.0024 on the mains. I have about 60 psi at hot idle and about 90 hot at 7200 RPM on Torco 5w30 racing synthetic. You've got issues and the engine builder is nuts.
Lustle
Well-Known Member
First. Find a new builder. Why would he build an engine, then blame the engine he just built on not making enough oil pressure? If he had such a problem with high volume pumps, why did he use one? And no. The pump doesn't suck the pan dry. What CAN happen is the pickup is too close to the bottom of the pan and sucks the pan to it. Then boom no pressure/too low pressure and engine is dead. Which also would be a builder problem.
Cold idle is 60 psi and hot is 10? That's a crazy drop. My car idles 80 cold in park, 60 hot. 50-60 cold in gear, 40-50 hot in gear. It then gains 10 psi per 1000 rpm under throttle. That's with 10w30 royal purple. Personally I would use a HV setup on almost any small block except for a really basic simple rebuild. Any engine with some kind of performance will appreciate the high volume pump. The rockers will love you for it.
yellow rose
Overnight Sensation
Lustle has a good point and I forgot to ask. What pan and pick up. If it's a stock pan and pick up, the pick up MUST touch the bottom of the pan. I have seen engines with stock pans run out of oil when the builder set the pick up clearance 3/8-1/2 off the bottom. The stock pick up is not designed for that. It should touch the pan when installed.
Just one more thing to look at.
Just one more thing to look at.
67Dart273
Well-Known Member
On a side note, the "White Whale" had an oil pressure problem........lost pressure........on the highway.......twice.
I'm CERTAIN it is poor design in the "new improved" oil pickup. If you are using one, I highly recommend you go back to the "old school" type pickup, here:
Well guys the "White Whale" is very ill, engine time......
The old and new pickup. The "new style" is at the right, you can see how small it is, and it can SIT FLAT on the pan. "Older style" from 80's LA is at left, THAT ONE went into the 97 5.2 Magnum
I'm CERTAIN it is poor design in the "new improved" oil pickup. If you are using one, I highly recommend you go back to the "old school" type pickup, here:
Well guys the "White Whale" is very ill, engine time......
The old and new pickup. The "new style" is at the right, you can see how small it is, and it can SIT FLAT on the pan. "Older style" from 80's LA is at left, THAT ONE went into the 97 5.2 Magnum
diymirage
HP@idle > hondaHP@redline
you got 2 different opinions, because both parties have different interests
the builder will claim its ok, since he build it and doesnt want to be responsible if something goes wrong (again)
the tuner will claim it is not ok, making it a pre-existing condition, because he doesnt want to be responsible if the engine is on his dyno and fails
the truth is probably in the middle somewhere
Your engine builder's a dumbass. Find a new one.
rustycowll69
Well-Known Member
I don't think I'd be satisfied with your hot oil pressure at idle, nor completely happy with WOT pressure. I would expect much more out of a fresh build than that. The pressures you're reporting are what I would expect out of an engine with 150-200k miles. Did your "builder" list the clearances in a report? Did he mic the brgs and journals? Did he use plasti-gauge?
Tear the engine completely down and measure every bearing clearance for starters.
rustycowll69
Well-Known Member
maybe before that, try dropping the pan and putting plasti-gauge on the bearing in the bearing caps, retorque them, pull them back apart and see what that tells you. If you find some excessive clearance, then by all means tear it down.
famous bob
mopar misfit
better make up ur own mind, there is some b.s. in the above posts !
Hey if you can afford to lose an engine? Letter rip!!!!! I agree with the oil pressure being to low for my liking.
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RAMM
Well-Known Member
It is highly probable that your lifter bores are worn out and oval shaped. This is VERY common with the SBM and their stupid 59 degree lifter angle. J.Rob
Is that oil bung, inside the engine just in front of the distributor missing (not installed) ?
nm9stheham
Well-Known Member
I can't explain the difference in info. But, the clue to there being a very real problem is that the builder added a shim behind the pump's relief spring to get up to just even marginal oil pressures.
The 10-12 psi hot idle would be OK on very light weight oils, but is lower than a new, well clearanced build would normally be. And there is NO WAY that a shim would need to be added behind the oil pump relief springs to get up to just 10-12 psi hot idle. The relief spring is not even opening at idle, and any shim should not effect pressure at all, if things are normal. So this says that there is probably something wrong with the relief spring or bypass valve in the pump. Was the oil pump replaced in the build?
At higher RPM's, the pressure relief springs in the oil pump are either 55 or 72 psi, and the pressure sensor is very close to the pump outlet; there is only the oil filter between the oil pump output and a new filter should not be dropping more than a couple of psi. So 50 psi would be the very low end for a good new build; and having only 45 psi WITH a shim added behind the relief spring shows that something is waaaay off. Again, the pump relief spring or bypass valve are suspects.
The next order of business are the plugs in the oil system. There are a number of plugs in the oiling system that will lower the oil pressure if left out:
- At the front of both oil galleries; these may cause only slight loss in pressure as the cam retainer plate is in front of them, and may block most of those holes even if the plugs are not there
- At the rear of the driver's side oil gallery, in front of the distributor shaft
- A couple more are in there somewhere that I can never remember
It is COMMON for one of these plugs to get left out, both by home builders and for-hire builders. The result is low pressure.
With the initial low pressures, these plugs ALL have to be examined. With the builder adding a shim to the pump's relief spring to get the pressure just up to 10-12 psi hot at idle, and with 5 psi prior to that, odds are 80-90% IMHO that they left out an oil system plug somewhere.
And then there is the wear in the lifter bores and bearing clearances as mentioned above.
These same symptoms have been brought up multiple times here, and the problem always seems to be a plug left out of the oiling system. And I'll agree that the builder is a problem if he thinks that:
- The Mopar oil system can pump the pan dry; the oiling system is not like some other systems where that can happen
- He added a shim to the oil pump's relief spring in a new build; these pumps reliably turn out gobs of good pressure, and he does not appear to know how the pressure relief system works.
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Is there an interference with the pump body and perhaps the use of studs, the pump may not be mounted properly! trimming is needed to make **** fit.
67Dart273
Well-Known Member
I was even thinking it might be more simple.......like an oil gallery plug
moper
Well-Known Member
Bingo. The only way to do it is start with measuring clearances and then moving forward with a plan. HV pumps are needed for race clearances and sustained high RPM. They are crutches on whipped tired big-clearance engines. But if the clearances were properly set, a std pump with the high pressure relief spring would be fine.
rustycowll69
Well-Known Member
I agree the most likely scenario is the "builder" left out one or more oil gallery plugs. I am surprised this wasn't discovered in the oil priming step. If this is the case, the "builder" must have little to no experience in SB Mopar. That's like SB Mopar 101.
famous bob
mopar misfit
I disagree w/ a part of one of the above posts. I sucked the oil pan dry w/ 6 qts in it w/ a hand drill on the engine stand. And I`ve never read, or seen a pick up setting on the bottom of the pan. Is that a small block thing? I`ve always shot for 3/8" clearance myself. chevy, 440 stroker,or 426 hemi.
nm9stheham
Well-Known Member
That's interesting......what engine? Was the cam setting so that the rockers on one side or the other were receiving continuous oiling? If so, that is likely the reason: it did not have the normal 'cam hole oil flow interruptor' in operation to limit flow to the rockers/heads. I've sucked the pan dry racing but it was totally different engine with no top end oil control, like with the 'cam hole oil flow interruptor' design used the SBM/BBM.
Pickup ON the pan makes some sense for a side entry pickup, like the stock SBM, BBM, and also the /6. It is prescribed in one FSM here to be touching the pan for the /6; I have not found a similar reference for the SBM or BBM, but I don't have all years of FSM's. If it is off the pan a bit, it does not seem like it would hurt except that you lose that last half qt of oil pickup. I suppose it might flow a bit better off of the pan...
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