Concerning the 462 in my truck, I have noticed that the oil pressure readings seem to act a bit strange. So far the only guage I have to rely on is the stock guage/sending unit, which is almost 20 years old. On cold start, as soon as the oil pump builds pressure, the pressure gauge will be pegged at 60psi. This activity seems normal. I noticed that if I drive on the highway in drive, the pressure at the beginning of a trip is 55-58psi, but after driving a while, the gauge will fluctuate, somtimes dropping as low as 45 psi, but it generally stays around 50psi. If i'm driving say, 70MPH in drive and the gauge drops to 45, there doesn't seem to be any change in the reading anywhere from 45 to 80 MPH. If I make the same trip in Overdrive, the pressure will stay around 55psi the whole time, even though the motor is turning less RPM. My oil pressure at idle is generally 22-25 psi, but after driving in Drive on the highway for a period, and the pressure has dropped, it will idle at 16-17 psi. If I do some stop and go city driving after getting off the highway, the idle oil pressure will come back to 22-25 psi after a mile or two. I didn't know if an old gauge/sending unit could be acting up, or if I really have a problem. The other issue I've noticed, is that sometimes my motor will make a sound like a rod knock, but only on a warm start, after the motor has been run for a while, then sits at least a couple of hours, but is still warm. It doesn't make any noise on a cold start, or on a warm start if it's been sitting only for a short time. It only will knock a couple of times, and as soon as the oil pressure starts building, the sound goes away. I double-checked my torque converter bolts, they were tight. My oil pump is a stock melling replacement, with the booster plate. It pumps a tremendous amount of oil, I was checking for a noisy lifter the other day with the motor running and a valve cover off, and I was amamzed at how much oil comes up through the pushrods, and I gave it a little crack of the throttle (probably not even 2000 rpm) and I ended up with oil all over my truck's inner wheelwell and frame rail! I'm using a NAPA(Wix) 1042 filter, it's actually for Buick V6's in the mid 70s. It's smaller than the PF24, but I would have to hack up the truck's frame to use the bigger filter. Could using the smaller filter be a problem? This motor has about 3300 miles on it. I first noticed this warm knock about 1500 miles ago, just a few days before I went to BPG nats. I'm open to any suggestions and ideas that anyone might have. Thanks
Do you know your bearing clearances? Mine does that, I was concerned right from the start as my mains are all around .0025, rods .002, people have told me this is too much clearance and I think that may be your problem also. As for the pressure fluctuations, mine does that also, but I think it's from the variance in oil temperature. I have asked about this to many people and they all say that Machine shops tend to go with extra clearance in order to avoid comebacks from out of spec align bores or other reasons. I don't think it will hurt anything, I am running synthetic 20w-50 and it seems to help a little bit. What weight oil do you run? :bglasses:
I plastigauged all of my mains, but only 2 rods. I was getting quite frustrated trying to plastigauge without smearing the plastigauge when dis-assembling the rods, so I just put the remaining 6 together without checking. The crank was not turned, just polished and I used standard sized bearings. The measurements were right about .002" across the board, +- .0002" Also, I'm running 10w40 non-synthetic oil.
I know what you mean about plastigage, sometimes it's tough to read. I had trouble telling b/c as the clearance becomes larger, the width if the squished plastigage becomes increasingly harder to read when it's so narrow. You should try using thicker oil, but if you are going to synthetic you should be sure that your rings are seated first........I'd wait until you drive it at least 2 or 3,000 miles before adding synthetic, and you have already done that. :bglasses:
Just something to think about. I had a knock that would come and go and it took me forever to find where it was coming from. It ended up coming from the oil pan. I dented the front side of it, ever so slightly, when I dropped the engine in.ou: MARK
