RotaryResurrection

iTrader: (24)

Please explain the reasoning behind replacing the sender?

1) it is visually fine and was never unplugged or disturbed
2) it registers what is probably accurate pressure when the engine is cold.
3) there is no significant valvetrain noise when the engine is cold.
4) as the engine warms up, pressure slowly drops.
5) as the engine warms up, valvetrain noise becomes more pronounced.

Sounds to me like the oil pressure is actually low, not just a faulty gauge.

RandomHero

iTrader: (24)

FWIW, when 1slow01z71 and I took my oil pump apart after it failed, the oil pump looked brand new inside. It's a very simple design with only like 4-5 parts including the screws and housing. The pickup tube oring had a flat side on it, but it wasn't so terrible to give no oil pressure. I'm still willing to bet that's the issue.

Tootall

iTrader: (79)

well it's a crap load of detailed work to do all over again. If you're 100% sure that everything else is solid, and that nothing else was disturbed, then try a sender.

Do you have a vid of the tapping/knocking/grinding noise that it's making. From what you're describing . . it might be a bad bearing. . . . either a cam bearing or a main bearing.

Replaced the valve train - What did the cam look like? Were there any gouges, or chunks missing? Did you cut open the filter it see what was inside of it?

I recently took apart an engine with a spun cam bearing. A cam bearing literly spun itself out of the block, and stuck itself to the cam. The owner said that hit had great pressure on start up, but after that it would loose pressure, then it would have none, and that the engine would still run hard.

You could have bearing or lifter tray material blocking a passage somewhere. How did you bend a few push rods? What's the story behind it?

RotaryResurrection

iTrader: (24)

I guess I'll do that after I put in the new oil pump and cam retaining plate/seal if the problem is not resolved. I have already paid for those parts so there is no use in second guessing it now.

IT sounds like it is more on the driver side of the engine, but since I am on that side of the truck when it is running it might be my imagination. It sounds like valves tapping to me. It's not a knock like a main or rod bearing. IT seems to be most pronounced right at 1500-2000, and is quieter elsewhere. At times when the oil pressure is above 40 it seems to be less than when it is below 40.

The cam had a broken lifter grind on one lobe, but I cannot tell that it actually removed any significant amount of metal by comparing that lobe's base circle to the others that are still perfect. There were no score marks on any of the cam bearing journals. I replaced the cam with a custom one (which necessitated longer hardened pushrods) and also went with new ls6 valve springs, and new valve seats while the heads were off. I checked the valves closely for any bending and there was none that I could see.

Well, my old cam came out easily and the new one slid in very easily as well. There were no scorch or scratch marks on the cam journals, only on the one lobe with the bad lifter. For pics see https://www.performancetrucks.net/fo...0&postcount=20

One morning the truck would not start which has never happened. I had to floor the throttle and crank for about 20 seconds to get it to fire. It ran on about 2 cylinders and sounded like an old tractor for a few seconds, then gradually one by one the cylinders would pick up and eventually it cleared up and ran normally once it was warm. I figured it was a bad tank of gas.

Since there is no drain on our tanks I figured I would try and run it all out. The next day it was hard to start again, but again it started and eventually ran okay. The third day it would not start, and did not try. I sprayed a bit of starter fluid in the throttlebody and then it tried. But there was some backfiring through the intake. Once it did fire to life, it ran rough, but it never cleaned up 100% of the way. I could tell all cylinders were not working. I also had a lot of valvetrain noise. I pulled the valve covers and found 3 loose rockers, and then 3 bent pushrods.

By this time almost all the gas was out so I pulled the fuel pump via my custom access door under my back seat, and vacuumed the rest out with a shopvac. I replaced the fuel filter, blew out the fuelpump pickup sock with compressed air, and put in brand new fuel injectors with rails from a zero mile crate motor.

I replaced all the pushrods and all seemed well. But after a couple of days I had a little tap that got more and more after a couple tanks of gas. Then it got more pronounced and also my oil pressure started to flicker rhythmically with rpm, which indicated the bad lifter was bleeding off pressure for a second. I was still holding 40psi at idle and 60-70 above 2500rpm at this time, though, and the flickering was only at idle.

So I tore it down and found the bad lifter and cam lobe. I replaced all the lifters with ls7 lifters.

Truckshop

iTrader: (17)

if you don't want to buy a sender(i don't think that is your problem) then put a manual gauge on it and verify pressure. but i think a new oil pump will fix it. it does not take much material at all to ruin an oil pump. a few scratches inside it will give the oil a place to stay while the vanes pass over it. that is why it gets worse as the temp gets up. the oil gets thinner. long story short put a oil pump in it so that you can drive it and enjoy the new cam!!!

RotaryResurrection

iTrader: (24)

To be honest I am thinking about sticking a stock cam and pushrods back in it while it is apart for the oil pump this time...

I am having a lot of valvetrain noise and I am still not 100% sure that I have the correct pushrods. I had a whole other thread regarding that and couldnt seem to get any real help except for one guy on here. Even when the pressure is in the 40-50 range when dead cold I still have significant valve tap. I can't imagine having to drive it around with it making that much noise long term.

OF course i am also thinking that as weak as my pressure has been, the lifters may still not be 100% filled even though they have probably an hour of run time on them.

****, I dont know what to do. At this point I just want to drive it without worrying about tearing every bearing in the engine out of it. I've had everything off it except the block and rotating assembly itself and it seems the more things I do and the more money I put into it, the worse it gets. Before long I will be up to the cost of a good stock used replacement engine.

Plus, it idles rough as hell even with a 1/4" hole drilled in the throttlebody. Damned drive by wire throttlebodies not being adjustable, that was the only way I could think of to keep the truck running at idle until I can get a tune for it. Even with a 275A alternator my lights are dimming at idle and the thing is about to die constantly. If I could hold it at 800 then it would be so much smoother. And then I look at, hell, this tune is gonna run me another 400 bucks on top of everything I have now.

The cam is supposed to be fairly mild...251/218 .545/.555 114

Truckshop

iTrader: (17)

don't give up. i know it sucks but this is when you learn the best. i still think an oil pump will fix it. what length pushrods did you go with? i think it needs 7.45. plus if oil pressure is not right they will not prime completely and will be noisy. the solution to your tune is wheatly or someone who is cheaper than 400 bucks.

Tootall

iTrader: (79)

you can always pull one of the vacuume/breather lines off the valve covers to get the engine to idle until it's tuned.

cam retainer plate - I found out how easy they crack with a sucky cheap *** torque wrench, and it's not much . . . are you sure that it's not cracked, or on backwards for that matter?

has the engine ever been out of the truck? Has the bypass block in the back ever been removed? It' at the rear cover.

RotaryResurrection

iTrader: (24)

Oh, I'm not giving up...it has to be fixed. IT just sucks that I work on some of the most complex production car engines ever made and something so stupid as this is keeping me from driving the truck. I also hate doing a job more than once, because I am pretty meticulous about my work.

I went with 7.45 pushrods. I used a pushrod length checker. I saw that the only lengths offered in hardened pushrods by sdpc was 7.4, 7.45 and 7.5. I used a method I found posted on ls1tech for finding preload and pushrod length. I set the pushrod to 7.5, then tightned the rocker bolt slowly until it loaded slightly. Then counted 2+ turns to full tight, which was too much. I tried a 7.4 and found it to be loose, and would not preload at all. I set the pushrod to 7.45 and came up with 1.5 turns of the rocker bolt to full tight, and the recommended amount for proper preload/length was 1.25-1.75. So I figured 7.45 was the ticket.

They still sound really loose to me, though, but are tight when checked by hand.

RotaryResurrection

iTrader: (24)

Really...why would that make a difference? YOu mean...pull the line and CAP IT to increase vacuum?

I dont think it can go on backwards, can it? I mean, because of the seal being on one side? IT was not cracked when I put it back on. I did not tighten it severely so I can't see it being cracked. We'll find out at the end of the week when the new parts get here.

Not since I've had it, and not that I can tell prior to that. IT had 66.7k when I got it and how has 88.5k.