carmodyg

I tried pushing the oil pickup into the oil pump (they are both off the car now). It is not quite as snug a fit as I thought when I removed it from the car. The new Melling pump and the new pickup (that came with the new pan I purchased) seem to be a tighter fit (with the black o-ring installed on the pickup).

The Melling pump came with two o-rings - one black and one green (thicker). The pickup came with one green o-ring which is about the same thickness as the Melling black o-ring. Based on the instruction sheet that came with the pump, black is the correct one for the pickup I have.

The original pickup came with a blue o-ring. The original pan and pickup I had purchased some time ago before I rebuilt the engine. It was a genuine GM pan, so I am surprised it didn't have the correct o-ring????

Anyway, I'm hoping this is the problem. I can't find anything else to blame........

G Atsma

If the pickup has a groove around tube near the end it takes the thicker O-ring.
If a "straight" (no groove) tube, then the thinner one.

carmodyg

Its straight. So its the thinner (black) o-ring. (I didn't try, but I don't think the green (thick) o-ring would go on.)

carmodyg

I ended up replacing the oil pump (with a Mellor M295), the oil pan (now using an F-body which is not as deep as the previous truck pan) and the pan pickup (which came with the new pan). I used the black o-ring that came with the Mellor pump.

I'm in the process of priming the oil system using a fertilizer sprayer pump as described in various posts and Youtube videos. Basically you connect the fertilizer sprayer pump to the oil port on the side of the block using a barb adapter and fill the sprayer with a quart or so of engine oil, pressurise it, and pump the oil into the engine to force air out of the oil galleries, etc. while at the same time filling it with the oil. I started by removing the oil pressure sender, pressuring the sprayer pump and making sure oil is flowing out of the sender port before reinstalling the sender. That part worked fine.

Next I checked to make sure oil is coming out the tops of the pushrods and flowing down the rockers. This part didn't work so fine. There are about 5 or 6 pushrods where I can't see any oil coming out. I've tried turning the crankshaft pulley as shown in the videos but still no oil from those pushrods. Here is the procedure I'm using:

1. Pressurise the pump
2. Wait for oil to come out of one or two pushrodes on each side of the engine.
3. Turn the crankshaft pulley two full revolutions.
4. Repeat steps one and two.
5. Turn the crankshaft pulley two revolutions plus 90 degrees.
6. Repeat steps one and two.
7. Repeat steps 5 and 6 two more times, each time adding 90 degrees to the turns.

I never seem to get any oil out of 3 pushrods on each side of the engine (5 out of the 8 have oil on each side). A couple of the pushrods seem to have oil flowing regardless of the position of the crankshaft?

Is this a problem? When I get everything back together again, and start the engine, is it likely the oil pump will "force" oil up those troublesome pushrods?

Cheers,
Greg
PS> I've loosened the bolts holding the rockers as suggested in one of the videos - the idea is to relieve the pressure on the lifters, so they will get 'pumped up' with oil during the priming procedure. I didn't fully back the bolts off, they're firm enough to keep the rockers in place and also keep the pushrods firm against the lifters without pressing down on them too much. I'll re-torque them once I finish priming.

grinder11

iTrader: (1)

Have you verified the PRs are hollow all the way thru? What brand PRs, and where were they sourced? What brand lifters and where sourced?

grinder11

iTrader: (1)

I touched on the pickup tube having a small crack in it. It might be a PITA to check at this point (definitely would be in a C5!), but you've been lucky so far that there's no damage.......Yet. If the lifters and PRs are the same as before, then I wouldn't worry about them at the moment. You clearly have/had a supply side issue. That is what I'd keep focusing on. Some PRs not oiling are a different issue, IMHO.....

carmodyg

The pushrods and lifters were replaced when the engine was rebuilt. The pushrods are Trend Performance KAP Chrome Moly Pushrods. I checked each of them to make sure they are clear with no obstructions.

The lifters areLS7 High Performance Roller Lifters For LS1 LS2 LS3 L98 Holden Chevy from ATP Autoparts. (no sure of the brand). I read somewhere that lifters come out of one of two factories worldwide, so I wasn't so concerned about brand names when I purchased them.

Not having anything else to go on, I'm assuming at this stage that the o-ring on the previous pickup not being a tight fit was the issue with the supply side. (or else an old worn oil pump which was still the original)

grinder11

iTrader: (1)

I hope you're right. Please post up any further developments......

carmodyg

So I got the engine back together today enough to run it. I only ran it for a minute or two but the results were encouraging. The oil pressure was holding steady at around 30 psi according to the dash gauge (which I previously discovered reads around 10psi less than the reading from the PCM). Revving the engine took it up to about 50 psi.

Next step is to put it all back together and get it out on the road and see how it goes. Before I do that I need to re-route the transmission cooler lines. The new oil pan seems to be wider than the previous one, and the space between the oil filter and exhaust is now very narrow, meaning the transmission cooler lines are resting against the exhaust - not a very desirable situation!

Regarding the issue I found when priming the oil system with my sprayer pump, I can only assume the pump did not have enough pressure to get oil through all the pushrods at the same time, or the tube I used to connect the pump to the port on the block was not wide enough - I used a 1/4" ID tube but maybe it needed to be 3/8".

Greg

carmodyg

I took the car out for a drive today. It seemed to be running well, that is until the engine warmed up. The oil pressure slowly started to drop as the engine got hotter. Eventually it dropped to 0.

I'm at a total loss! I've replaced the oil pump, oil pan, pickup and o-ring. What else could it be? Maybe a hairline crack in the block or one of the heads which opens up when the engine is hot. But I would expect to see oil in the coolant or coolant in the oil if that was the case. Both the oil and coolant look fine.

When I had the pan off I checked for any 'walking' bearing on both the camshaft and crankshaft, but couldn't see any.

Any ideas, anyone?

MySons68C20

0 at idle only or other rpms? Since your factory gauge is off by 10 psi did you verify 0 with a mechanical gauge?
Were there any other indicators your oil pressure was truly that low?
Sorry if some of this was asked before I didn't reread the entire thread.

carmodyg

Just to describe the setup a little better: I removed the factory oil pressure sender from the top rear of the block and screwed in a hex 'riser'. In the side of the riser is a 1/8" NTP port into which I've screwed the sender for the dash gauge. In the top of the riser I've screwed in the factory sender which goes to the PCM.

As I mentioned in an earlier post, I've checked the dash gauge against the reading from the PCM. The PCM is about 10psi higher. So when the dash gauge reads 0, the PCM is reading 10. If I give it some throttle, the pressure increases. by about 10~20 psi on both the dash gauge and the PCM.

If I let the engine idle for a while, the PCM goes down to 2 psi and the dash gauge actually goes below the 0 mark.

I'm pretty sure the sender for the dash gauge is not showing an accurate reading. I intend to replace it. Also, not sure if the hex riser is causing the pressure readings to be inaccurate?

strutaeng

The hex riser (the one that screws into the block and the sender screw into it, right?) should not have any measurable effect on oil pressure readings...

carmodyg

That's good to know.

I would expect the oil pressure to go down as the oil temperature increases - the viscosity of the oil will decrease as temp rises. However, minimum oil pressure for an LS1 is about 7 psi I've read in other posts. My oil pressure is going down to 2~3 psi when the engine is hot.

I've had ongoing issues with engine temp. The temperature of the coolant is getting up to 220~225 deg. F after running for around 10 mins. Then the fans kick in and temp drops about 10 deg. I've read these temperatures are not unusual for an LS1. Could it be that at these high temps it makes the viscosity of the oil so low that the pressure drops to these low levels? (really grasping at straws here, but I am totally out of ideas!!!).

grinder11

iTrader: (1)

Sorry if you've stated before, but what viscosity oil are you running? I don't think this is the issue, but worth asking. It almost sounds like you have an internal leak somewhere in the block. In other words, a crack in an oil galley somewhere. However, I have 8 piston squirters in my engine, and pressire doesn't get nearly that low. Have you tried a different oil filter? If the PO removed the oil bypass, the filter could be plugged. Maybe @RonSSNova can give some ideas.

Y2K_Frenzy

I believe the fan is set to come on around 230* F on stock LS1’s, and I think oils don’t start to break down until something close to 300*. I don’t think your oil pressure issue is temperature related. Since the stock fan setting is 230’ish degrees everyone would be having low oil pressure if the oil was “thinning out” at that temp.

carmodyg

I've currently got Shell Helix HX7 10W-40 in there. The filter is a K&N HP1017 which I think is a good quality filiter.

The issue is temperature related as when the engine is cold I have good oil pressure (around 40psi). Its when it gets hot the trouble starts. As you say, could be a crack in an oil gallery that opens up when the engine gets hot. How would I check for this?

Scarebird

How much oil did you put in this?

My Gen V build used a Holley pan and the stock 5.3 dipstick/tube, which showed full when actually down 2 quarts...

carmodyg

5.5 litres which is about 6 quarts

Y2K_Frenzy

What I was saying though is it sounds like your engine is running at normal operating temperatures, and oil is able to withstand “normal” operating temperatures so the problem probably lies elsewhere.