oil pressure drop once warmed up

[Rattletrap]

after about 20-30min of driving, aka when the oil finally gets heat in it. I have oil pressure drop.
starts out cold at 40ish and builds like it should to 60+ and as its driven the OP gets down to 20 and will build to 30 but you can start hearing the top end rattle.

I put a "new" pump on it but who knows.
I do not think it would be the o-ring since it does have pressure till it gets warmed up.

Thought was to replace pump and if that doesnt help then I guess i will have to rebuild, URGH!

[bwelch]

Is it a mechanical guage?

[ShawnBoyMoody]

Ugh. I hate LS oil pumps.

[schardbody]

iron block or aluminum?

its pretty common on the aluminum block motors, seems like most people say its the lifter bores heating/enlarging letting pressure bleed off.

i dont know, all LS motors make noise, if you hear one not making noise worry.....

[jmd]

is it a 6.0 that is stroked?

[Rattletrap]

junkyard 6.0 iron block with mechanical gauge.

[Darryl Buckner]

Fram oil filter??

[Matts94Z28]

What filter and what oil is in it?

[ShawnBoyMoody]

This is why I didnt change my worn out timing chain. Gotta pull the pump to get the chain off and I didnt want to chance fooling with it with my bad luck. Maybe I could have made 375 HP if the chain wasn't worn out and retarding the cam 6-8 degrees lol.

[Rattletrap]

Oil is Mobile dino oil and AC filter (I think). New GM pump purchased in Aug. I have original pump. Going to see if its covered under warranty.

URGH

[Matts94Z28]

Do you know the mileage on the motor? Could it be possible that the wrong weight oil is being used and the motor is just wore slap out? I have seen similar issues with the use of incorrect oil weight in combination with "loose" bearing tolerances. However, you wouldn't think that would an issue on a stock motor as long as it doesn't have 300k miles.

[Rattletrap]

Unknown mileage from a 2001 Silverado. 5w30 in it.

[BigdaddyDupree]

My 5.3 has perfect oil pressure and it doesent tap at all.

[Rattletrap]

My 5.3 has perfect oil pressure and it doesent tap at all.the 6.0 in the 71 is quiet too. Love that thing!

[ShawnBoyMoody]

My current 5.3 has perfect oil pressure and it doesent tap at all.

Fixed it for you.

[schardbody]

the iron block motors are alot quieter, my quarter million mile 4.8 is silent, but my LS1 chings and changs like every other one (garbage lifters?). oil pressure is a separate issue than noise though.

[BigdaddyDupree]

my first one made some lifter noise so it seemed. when i pulled it apart it had all wiped out cam bearings

[Rattletrap]

Consensus is to put different oil pump on it and see??

[BigdaddyDupree]

Si

[Rattletrap]

Contacting Scoggin D where it was purchased in Aug 2011 to see if they will warranty it, if not I will purchase new one from some place.
Could put the original one in it and see, that would be 'free'.....

[1iron]

You don't know if the pump is the problem but, you want someone to warrant it anyway?

[Rattletrap]

You don't know if the pump is the problem but, you want someone to warrant it anyway?I am open to all suggestions. the only thing I have seen here and other forums is to replace the pump.
I asked if he would send me a new pump (at my cost) and if the new pump fixes the problem will he warranty the faulty pump. Is that not the way i should handle it?
If both pumps have issues then I have an extra pump here with very few miles that can be used later on something else.

Could it be the O-ring? I guess but thought if that was not seated properly it would not build pressure from the get go.

Do I need a different pump than a stock one? LPE posted on LS1tech that hot oil pressure loss might need more volume.

Listening to all ideas and suggestions, not ruling anything out. Worst case is the bearings are trashed and needs to be pulled. that would suk but I knew that buying a junk yard mileage unknown motor. it happens.

All ears!!

[ShawnBoyMoody]

Might just be best to drop the pan and pull a main cap or two as well as a couple rod caps and see what ya got.

I hate to say it but the oil pumps either gonna pump or its not. If you are getting hot and losing pressure its probably not the pump but rather the rods and mains. A high volume pump might help but is a band-aid really.

[Rattletrap]

Might just be best to drop the pan and pull a main cap or two as well as a couple rod caps and see what ya got.
hmm....PITA but better than trashing it i guess. just a few more bolts at this point.
408 time?!!?

[ShawnBoyMoody]

Either that or let me feel that 6.0 and you can take my 5.3 lol.

[Rattletrap]

Either that or let me feel that 6.0 and you can take my 5.3 lol.
bring it, I can make that 5.3 scream :eek2:

[BigdaddyDupree]

i dont really know you shon but this is how i dealt with the matter. my truck had little to no oil pressure for the first two years it was together. i could drive it to charleston or goose creek to my job and at idle it had 5 lbs or less. cruising was 15 and wot was 25. never really made any noise other then some lifter noise. and in that motor i put in a new pump before we put the motor in. drive it til it blows

[Rattletrap]

i dont really know you shon but this is how i dealt with the matter. my truck had little to no oil pressure for the first two years it was together. i could drive it to charleston or goose creek to my job and at idle it had 5 lbs or less. cruising was 15 and wot was 25. never really made any noise other then some lifter noise. and in that motor i put in a new pump before we put the motor in. drive it til it blows
I have thought about that, just run it till it goes but I do not want to F up the heads, I got too much in them to mess them up.
LT1 was knocking like hell one night, raced all kinds of cars on the street, drove it an hour back home knocking, crank had a nice 1/8" groove cut in it. LOL

[1iron]

Contacting Scoggin D where it was purchased in Aug 2011 to see if they will warranty it, if not I will purchase new one from some place.
Could put the original one in it and see, that would be 'free'.....

I didn't get the have them send another one at your cost from the earlier post. Seemed to say something else. All good for me.

[1997b4c]

500 cash final offer shon.

[Rattletrap]

500 cash final offer shon.for the wheels?! or the 6.0? LOL

[Rattletrap]

I didn't get the have them send another one at your cost from the earlier post. Seemed to say something else. All good for me.tenfour, that post left out those details, agree!

[schardbody]

hot oil pressure most likely isnt the o ring but to verify you can add like 6 more quarts of oil and see if the pressure comes back up.

at this point the oil level will be covering the pump so any leak between the pickup tube and pump would still suck oil. dont run it like this long, get it hot to where the pressure drops then add the oil and see if pressure changes.

[bwelch]

put some 20w50 in it and a ton of gas!

[Rattletrap]

put some 20w50 in it and a ton of gas!Upstate vs LC definition of ton....U guys need alot more than we do :mrgreen:

[Matts94Z28]

Upstate vs LC definition of ton....U guys need alot more than we do :mrgreen:

Damn. :eek2:

[Rattletrap]

Going to use the Summit Bux and get the Melling high pressure pump and measure pick up tube to be sure I get the correct O-ring. might be up and going TH night-LMAO

That pump b/c of this post by LPE:
http://ls1tech.com/forums/8743784-post28.html

[1997b4c]

Upstate vs LC definition of ton....U guys need alot more than we do :mrgreen:

:hide: lol

[bwelch]

One of the Melling pumps doesn't clear the timing cover when used with a double roller timing chain. I think its the high volume one though

[Pesce Nero]

Going to use the Summit Bux and get the Melling high pressure pump and measure pick up tube to be sure I get the correct O-ring. might be up and going TH night-LMAO

That pump b/c of this post by LPE:
http://ls1tech.com/forums/8743784-post28.html

why not try 10-40 first?

[TurboWS6]

I had a very similar issue last year with my LQ9 pulled the motor and found this. My oil pressure was like 35ish cruising the highway hot. 45-50 cold at idle then 60 plus until it warmed up

Main bearing
http://i1269.photobucket.com/albums/jj585/preston99ws6/IMAG0268.jpg
Notice how pretty much all the babbit material was gone, motor still had 35ish as stated above.

The culprit was the fact that the builder never put the bolt in the pickup tube to oil pump flange and the pickup tube slid out a little. All was good for about 25K miles then out of nowhere the oil pressure started dropping. Took this pick as soon as I pulled the pan. When I put it together this last time I used lock tight on that bolt just to be sure.
http://i1269.photobucket.com/albums/jj585/preston99ws6/IMAG0259.jpg

Sorry man but your motor sounds like it doing exactly what mine was before I had the crank turned and put new bearings in. Its a PITA but you can pull it apart and fix it for probably 300 or so.

[Rattletrap]

why not try 10-40 first?how much pressure has been seen to be 'picked up' from 30w to 40w?

[blueyed tuner]

Check the GM Bulletins on the make and model of the engine. At one time there was a bulletin out that stated GM had some pumps with faulty relief valves. You would start engine up cold with good pressure and as the engine warmed the relief valve would stick open, as the engine would cont to warm to operating temp the oil gets slightly thinner and if the relief doesn't close slightly at this temp you have low oil pressure. When the engine cools the relief unsticks and closes so when time for the next start up your oil pressure seems to be normal. It will drive you insane. May not be the problem, but something to check I guess. I will check and see if I can find the bulletin info.

[Pesce Nero]

how much pressure has been seen to be 'picked up' from 30w to 40w?

i dont know because i have never put pee in my oil pan before. 5-30 just seems awefully low for any engine to me although i realize some of these newer motors call for that weight.

[Rattletrap]

Check the GM Bulletins on the make and model of the engine. At one time there was a bulletin out that stated GM had some pumps with faulty relief valves. You would start engine up cold with good pressure and as the engine warmed the relief valve would stick open, as the engine would cont to warm to operating temp the oil gets slightly thinner and if the relief doesn't close slightly at this temp you have low oil pressure. When the engine cools the relief unsticks and closes so when time for the next start up your oil pressure seems to be normal. It will drive you insane. May not be the problem, but something to check I guess. I will check and see if I can find the bulletin info.

would this be the case on a new pump from 2011?

i dont know because i have never put pee in my oil pan before. 5-30 just seems awefully low for any engine to me although i realize some of these newer motors call for that weight.
5w30 is recommendation from GM for these motors

[LXtasy]

Just shoot it

[bwelch]

I run 10w40 synthetic in my 5.3 with a "ton" of miles.

[jmd]

Just shoot it

just what i would expect from you. lol

[blueyed tuner]

would this be the case on a new pump from 2011?

Well, that is a valid point. You would think they changed the way they make the new pumps. Well I was trying, maybe if or when you pull it down you can check and see if there are any signs of it sticking. I will make an effort to find that bulletin to see what years it covered.

5w30 is recommendation from GM for these motors

This is correct and usually if anything thicker is used it makes the valvetrain noisy, Just saying.

[gearmesh, inc.]

The old skool rule of thumb I always heard was that you need 10 psi of oil pressure for every 1k rpm you plan on turning. That would mean 70 psi for 7000 rpm.

Anyone have any other thoughts on this old skool rule of thumb?

[WILLIAMJRDN]

I know it doesnt help any but i'm running a high vol/ psi pump from LEP with 5w30 cold idle 50-55 and hot is 40-45. Garth told me i'de se higher if I ran through the stock system (14qt. system)

[Rattletrap]

UPDATE:
Cold OP is now 50, starts getting warm and goes to 40. Test drove it and did not go below 40 but have other problems which I think is in the tune and battery is not charging (which I knew) so when it dies it has to be jumped off....which I had to push it thru a 4way stop to a gas station and then walk 1.1 miles (since I didnt want to wake wife and 18MO from nap-such a nice guy).
Starts right up when hooked up to good battery.

This is a Melling High Pressure pump.

[WILLIAMJRDN]

Sounds good

[Rattletrap]

I have 2 thoughts about it:
loose engine should be fast but probably wont last long....