350 issues after a rebuild
10-22-2009, 07:46 PM
#21
Drifting
I would have to say something was over looked on your build, When we go through an engine its line honed and the rods are resized everything is measured with a good set of outside mics and we use Sunnen bore gauges to measure housing bores,
So far we have never had any oil pressure issues and we always run standard volume pumps and high pressure (Z-28 pump) on our street and strip builds.
On some forums there have been block that were not cleaned properly and up on start up the bearings were taken out with debris.
Its allways a good idea to plug the oil filter bypass and run a good filter so all the cold oil is filtered before going to the bearings.
So far we have never had any oil pressure issues and we always run standard volume pumps and high pressure (Z-28 pump) on our street and strip builds.
On some forums there have been block that were not cleaned properly and up on start up the bearings were taken out with debris.
Its allways a good idea to plug the oil filter bypass and run a good filter so all the cold oil is filtered before going to the bearings.
Last edited by BLOCKMAN; 10-22-2009 at 07:50 PM.
10-29-2009, 09:04 PM
#22
Intermediate
Thread Starter
Member Since: Oct 2009
Location: West Michigan
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
OK, I put in a standard oil pump, set the pick up at about 1/4 of an inch from the bottom, put in 10W-40 oil and primed the engine and got about 50 psi on the gauge in the car and about 30 on the mechanical gauge hooked in near the distributor. Ran the engine in the garage and the lifters were noisy, but quieted down quick and all sounded good. Pressure in the car was 40 or higher at 2000 RPM and 20+ on the mechanical. I drove the car tonight and it went well until about a mile down the road, the lifters were very noisy. I turned around and went back. The pressure in the car never went below 40 at a cruise of about 35 MPH, but the lifters were very noisy and the pressure at the top was maybe around 5 at idle and 20 in the car. What's next as I am thinking it must be I got the wrong bearings or something. I am perplexed. Suggestions?
10-29-2009, 10:15 PM
#23
Drifting
I would have to say something was over looked on your build, When we go through an engine its line honed and the rods are resized everything is measured with a good set of outside mics and we use Sunnen bore gauges to measure housing bores,
So far we have never had any oil pressure issues and we always run standard volume pumps and high pressure (Z-28 pump) on our street and strip builds.
On some forums there have been block that were not cleaned properly and up on start up the bearings were taken out with debris.
Its allways a good idea to plug the oil filter bypass and run a good filter so all the cold oil is filtered before going to the bearings
So far we have never had any oil pressure issues and we always run standard volume pumps and high pressure (Z-28 pump) on our street and strip builds.
On some forums there have been block that were not cleaned properly and up on start up the bearings were taken out with debris.
Its allways a good idea to plug the oil filter bypass and run a good filter so all the cold oil is filtered before going to the bearings
10-30-2009, 03:17 PM
#24
Burning Brakes
I Still Think It's A Missing Plug
OK, I put in a standard oil pump, set the pick up at about 1/4 of an inch from the bottom, put in 10W-40 oil and primed the engine and got about 50 psi on the gauge in the car and about 30 on the mechanical gauge hooked in near the distributor...The pressure in the car never went below 40 at a cruise of about 35 MPH, but the lifters were very noisy and the pressure at the top was maybe around 5 at idle and 20 in the car. What's next as I am thinking it must be I got the wrong bearings or something. I am perplexed. Suggestions?
I've read the posts that say that not installing this plug will have no effect on your oil pressure; however, I have two reservations about accepting that information. The first is fluid dynamics, and the other is personal experience.
On the fluid dynamics side, the output of the oil pump is measured in flow, i.e., gallons per minute/hour etc., while resistance to flow is measured in PSI. An old rule of thumb was every 90 degree bend added to a fluid system added the equivalent resistance of ten feet of tubing the same diameter as the 90 degree elbow. Now with the plug in place, 100% of the oil from the oil pump (less the nominal amount that flows to the rear main bearing) takes a 90 degree turn (it's actually two turns greater than 90 degrees when combined) and heads towards the oil filter pad area and afterwards all the oil (filtered or not) takes another two 90 degree turns back towards the oil galleries at the top of the engine. The oil pressure is then measured at this point either mechanically or by electrical sensor.
Without the plug in place, a certain amount of oil goes straight to the top while some other amount still fills the void in the oil filter pad system by filling the oil filter and the associated oil passages. My point is whatever amount of oil is filling this later part of the system, it certainly isn't 100% of the oil from the pump and a goodly portion of the oil from the oil pump is by-passing at least two 90 degree turns in the system prior to measuring the resistance to flow (PSI). I don't see how the oil pressure could be the same with or without the plug in the block. (However, I don't know all the ends and outs of the Chevy oiling system and still have nightmares about term papers due on fluid dynamics even though I'm haven't been in college since the 60's!
)On the personal experience side, back in the mid-90's, we had a local Corvette owner came into the shop complaining of low oil pressure convinced that his engine builders had installed a standard oil pump in his rebuilt 1970 LT-1 engine instead of a high performance Z-28 pump. However, when we dropped the oil pan, the installed Chevy oil pump had the correct Z-28 bypass pressure spring making the pump a high performance unit.
Knowing that his engine builders were in fact Navy enginemen moonlighting rebuilding high performance engines of all makes and sizes, I surmised that all their block preparation and machining was outsourced to other shops while the actual measuring/building of the engine was done by the two guys in their spare time while not on duty. We checked to see if all the oil plugs had been replaced/reinstalled correctly since we knew that the engine had been hot tanked prior to machining. Sure enough, the only plug missing was the one forcing all the oil to the oil filter pad area. Replacing this plug resolved the problem.
Now if you checked and the plug is in place, your engine needs a complete teardown, re-measurement, and possible re-cleaning. Something isn't right to allow your oil pressure to be that low at idle. If the block was hot tanked with the oil gallery plugs in place and not cleaned out afterwards, Blockman is correct in saying that leftover debris (crud) in the galleries could be blocking off oil flow to the lifters making them noisy.
One other item that bothers me is the 20 PSI difference between your mechanical oil pressure reading and your other (electrical sensor?) gauge reading. Has the mechanical gauge been checked recently for calibration? I would recommend checking this out because although both readings are low, there is a major difference between the two.
Hope this helps you resolve the problem!
10-30-2009, 04:50 PM
#25
Melting Slicks
I had the same thing happen on a 3.8 Buick I built some years ago, noisy lifter when it warmed up and the oil was hot. turned out that I didn't seat one of the plugs behind the timing gear deep enough and on start up the plug was pulled out. once the plug was installed all was good.
10-30-2009, 05:40 PM
#27
Burning Brakes
That plug under the rear main should be removed for cleaning by your machinest. This i have missed twice and it DOES affect oil presure the way your engine is. Its a vette, easy removal of oil pan (no crossmember issues) pull it down check for the missing plug and pump and strainer while ur there and avoid killing your bearings....my 2 cents
10-30-2009, 05:43 PM
#28
Burning Brakes
Sorry to read that you're still having problems. When you reset your oil pump's pickup height, by chance did you check to see if the oil passage plug under the rear main seal was installed? (See previous drawing for plug location.)
I've read the posts that say that not installing this plug will have no effect on your oil pressure; however, I have two reservations about accepting that information. The first is fluid dynamics, and the other is personal experience.
On the fluid dynamics side, the output of the oil pump is measured in flow, i.e., gallons per minute/hour etc., while resistance to flow is measured in PSI. An old rule of thumb was every 90 degree bend added to a fluid system added the equivalent resistance of ten feet of tubing the same diameter as the 90 degree elbow. Now with the plug in place, 100% of the oil from the oil pump (less the nominal amount that flows to the rear main bearing) takes a 90 degree turn (it's actually two turns greater than 90 degrees when combined) and heads towards the oil filter pad area and afterwards all the oil (filtered or not) takes another two 90 degree turns back towards the oil galleries at the top of the engine. The oil pressure is then measured at this point either mechanically or by electrical sensor.
Without the plug in place, a certain amount of oil goes straight to the top while some other amount still fills the void in the oil filter pad system by filling the oil filter and the associated oil passages. My point is whatever amount of oil is filling this later part of the system, it certainly isn't 100% of the oil from the pump and a goodly portion of the oil from the oil pump is by-passing at least two 90 degree turns in the system prior to measuring the resistance to flow (PSI). I don't see how the oil pressure could be the same with or without the plug in the block. (However, I don't know all the ends and outs of the Chevy oiling system and still have nightmares about term papers due on fluid dynamics even though I'm haven't been in college since the 60's! )
On the personal experience side, back in the mid-90's, we had a local Corvette owner came into the shop complaining of low oil pressure convinced that his engine builders had installed a standard oil pump in his rebuilt 1970 LT-1 engine instead of a high performance Z-28 pump. However, when we dropped the oil pan, the installed Chevy oil pump had the correct Z-28 bypass pressure spring making the pump a high performance unit.
Knowing that his engine builders were in fact Navy enginemen moonlighting rebuilding high performance engines of all makes and sizes, I surmised that all their block preparation and machining was outsourced to other shops while the actual measuring/building of the engine was done by the two guys in their spare time while not on duty. We checked to see if all the oil plugs had been replaced/reinstalled correctly since we knew that the engine had been hot tanked prior to machining. Sure enough, the only plug missing was the one forcing all the oil to the oil filter pad area. Replacing this plug resolved the problem.
Now if you checked and the plug is in place, your engine needs a complete teardown, re-measurement, and possible re-cleaning. Something isn't right to allow your oil pressure to be that low at idle. If the block was hot tanked with the oil gallery plugs in place and not cleaned out afterwards, Blockman is correct in saying that leftover debris (crud) in the galleries could be blocking off oil flow to the lifters making them noisy.
One other item that bothers me is the 20 PSI difference between your mechanical oil pressure reading and your other (electrical sensor?) gauge reading. Has the mechanical gauge been checked recently for calibration? I would recommend checking this out because although both readings are low, there is a major difference between the two.
Hope this helps you resolve the problem!
I've read the posts that say that not installing this plug will have no effect on your oil pressure; however, I have two reservations about accepting that information. The first is fluid dynamics, and the other is personal experience.
On the fluid dynamics side, the output of the oil pump is measured in flow, i.e., gallons per minute/hour etc., while resistance to flow is measured in PSI. An old rule of thumb was every 90 degree bend added to a fluid system added the equivalent resistance of ten feet of tubing the same diameter as the 90 degree elbow. Now with the plug in place, 100% of the oil from the oil pump (less the nominal amount that flows to the rear main bearing) takes a 90 degree turn (it's actually two turns greater than 90 degrees when combined) and heads towards the oil filter pad area and afterwards all the oil (filtered or not) takes another two 90 degree turns back towards the oil galleries at the top of the engine. The oil pressure is then measured at this point either mechanically or by electrical sensor.
Without the plug in place, a certain amount of oil goes straight to the top while some other amount still fills the void in the oil filter pad system by filling the oil filter and the associated oil passages. My point is whatever amount of oil is filling this later part of the system, it certainly isn't 100% of the oil from the pump and a goodly portion of the oil from the oil pump is by-passing at least two 90 degree turns in the system prior to measuring the resistance to flow (PSI). I don't see how the oil pressure could be the same with or without the plug in the block. (However, I don't know all the ends and outs of the Chevy oiling system and still have nightmares about term papers due on fluid dynamics even though I'm haven't been in college since the 60's!
)On the personal experience side, back in the mid-90's, we had a local Corvette owner came into the shop complaining of low oil pressure convinced that his engine builders had installed a standard oil pump in his rebuilt 1970 LT-1 engine instead of a high performance Z-28 pump. However, when we dropped the oil pan, the installed Chevy oil pump had the correct Z-28 bypass pressure spring making the pump a high performance unit.
Knowing that his engine builders were in fact Navy enginemen moonlighting rebuilding high performance engines of all makes and sizes, I surmised that all their block preparation and machining was outsourced to other shops while the actual measuring/building of the engine was done by the two guys in their spare time while not on duty. We checked to see if all the oil plugs had been replaced/reinstalled correctly since we knew that the engine had been hot tanked prior to machining. Sure enough, the only plug missing was the one forcing all the oil to the oil filter pad area. Replacing this plug resolved the problem.
Now if you checked and the plug is in place, your engine needs a complete teardown, re-measurement, and possible re-cleaning. Something isn't right to allow your oil pressure to be that low at idle. If the block was hot tanked with the oil gallery plugs in place and not cleaned out afterwards, Blockman is correct in saying that leftover debris (crud) in the galleries could be blocking off oil flow to the lifters making them noisy.
One other item that bothers me is the 20 PSI difference between your mechanical oil pressure reading and your other (electrical sensor?) gauge reading. Has the mechanical gauge been checked recently for calibration? I would recommend checking this out because although both readings are low, there is a major difference between the two.
Hope this helps you resolve the problem!
: thumbs:
10-30-2009, 06:46 PM
#29
Drifting
That plug under the rear main should be removed for cleaning by your machinest. This i have missed twice and it DOES affect oil presure the way your engine is. Its a vette, easy removal of oil pan (no crossmember issues) pull it down check for the missing plug and pump and strainer while ur there and avoid killing your bearings....my 2 cents
I leave that plug out on dry sump engines and no oil pressure loss
Go over this thread
http://speedtalk.com/forum/viewtopic...er=asc&start=0
10-30-2009, 09:30 PM
#30
Burning Brakes
10-31-2009, 02:41 PM
#31
Drifting
That plug under the rear main should be removed for cleaning by your machinest. This i have missed twice and it DOES affect oil presure the way your engine is. Its a vette, easy removal of oil pan (no crossmember issues) pull it down check for the missing plug and pump and strainer while ur there and avoid killing your bearings....my 2 cents
While we at it and its a one peice seal block we dropped the rear main cap pusned the plug out that is in the block ( this block had a round ball rather then a cup plug.)
Ran the engine and no oil pressure issues at all as we tested with the same oil same oil temp only differance was the oil in the filter was about half the temp as the oil in the pan.
I went through this with the customer and expained what I was up to and the test the customer was going to tear it down for a refreashen after a season of running.
Again when the plug is left out the oil will not flow throught the filter thats why the temp differance.
When the oil leaves the pump it goes to the plug and the oil is routed through the filter and it goes through the filter to the upper side of the plug and goes to the oil galleys from there.
If the plug is left out once the oil filter is full it goes straight to the oil galleys no whaere else so it can't loose pressure any where.
We actually saw maybe a couple of extra pounds of oil pressure at the same temp maybe because we plug the oil fitler bypass and force ALLLL the oil through the filter and leaving the plug out there is less restriction.
Now if you leave the plug and shyt gets pushed into the bearings you may see a decrease in pressure for sure.
Again if the plug is left out where does the oil go where your going to see a pressure loss??????????????????????????????
Last edited by BLOCKMAN; 10-31-2009 at 02:43 PM.
10-31-2009, 02:48 PM
#32
Drifting
I'm guessing that you tap back into the main oil gallery just above the oil filter pad area and plug the rear main bearing cap since the oil pump is no longer attached thereby rendering the removal of the plug moot. If the entire oiling system is sealed on the lower end, then the dry sump's pump can pressurize the oiling system at a constant preset pressure.
But I have seen guy plumb right back in the block using the upper hole where the oil filter would be.
10-31-2009, 05:04 PM
#33
Burning Brakes
...When the oil leaves the pump it goes to the plug and the oil is routed through the filter and it goes through the filter to the upper side of the plug and goes to the oil galleys from there...If the plug is left out once the oil filter is full it goes straight to the oil galleys no where else so it can't loose pressure any where...Again if the plug is left out where does the oil go where your going to see a pressure loss??????????????????????????????
If we can all agree that oil pressure (PSI) is actually the result of resistance to the output flow of oil from the oil pump, then by removing the additional 90 restrictions in the path of all the oil from the pan through the pump to the filter then back to the top of the block should decrease some of the oil pressure although the pump output remains constant (a whatever RPM we choose for the example). Less resistance = less PSI. (Assuming pump output remains constant.)
Like I said, I'm not an expert in SBC oiling systems, I just question some assumptions based upon what I was taught in fluid dynamics. BTW, thanks! I appreciated the link previously provided to others discussing the same topic. I'm just still skeptical, that's all.
