carmodyg

Connected the mechanical gauge and these are the results:

- at cold start it's reading 40psi
- after 20 mins of running @ coolant temp of around 200 deg F oil pressure is 28 psi (at idle)
- after a further 10 mins of running @ coolant temp of 202 deg F oil pressure is 26~27 psi (at idle)
- it seems to stabilise at around 26~27 psi.

The problem I found with taking the reading from the PCM is that it jumps around and its hard to get an accurate reading whereas the mechanical gauge appears to have some inherent damping, so the reading is more steady.

26~27 psi is probably still low but not seeing any other symptoms of a problem, I'm inclined not to take any further action. The only issue I'm noticing is a slight 'tick' coming from the front of the engine, but I think once I get it out on the road and start accelerating (rather than just let the engine idle) hopefully the tick will go away as the oil pump forces more oil up the pushrods. Comments welcome........

grinder11

iTrader: (1)

My engine has around 25psi pressure@210° oil temp, but I have piston squirters, which bleed off some pressure. What kind of psi do you see at 2,000rpm, 3,000rpm, etc.?

carmodyg

Here are the results I got at higher rpms:

Cold:
Idle (around 800~1000 rpm) 40psi
2000 rpm : 50 psi
3000 rpm : 60 psi

Hot (~200 deg F) :
Idle (around 640 rpm) 26 psi
2000 rpm: 42 psi
3000 rpm: 50 psi

Still getting a 'tick' from the front of the engine at times. Will try some 5W-30 oil to see if that fixes it.

grinder11

iTrader: (1)

If the tick isn't getting louder, I'd send it, and check the rockers periodically. LS engines sound like typewriters anyway. BUT-If your gut tells you there is something wrong, stop driving it. I'd install a magnetic drain plug and do an oil analysis, doing the analysis first......

carmodyg

I replaced the oil with 5W-30 and the ticking has stopped! I let it heat cycle twice and no sign of any ticking.

When I drained the 10W-40 oil there was no sign of any metal flakes, so I guess that's good news.

The hot idle pressure dropped a little, down to around 23 psi. I assume this is due to the change in oil, but could also be due to the quantity of oil I put back in. When I drained it, I had almost 9 quarts in there, and that's without the oil in the filter. When I refilled it with the 5W-30, I put back in around 6 quarts. That brough it up to the max. line on the dipstick, so I assume its the correct amount.

Anyway, I guess I'm happy with how it going. Will need to take it on an extensive road test just to make sure. But I've got a few other things to take care of before I can drive it any distance (like a transmission problem that causing it to stick in 2nd gear when it warms up).

carmodyg

I spoke too soon. I took the car for a long drive today (around 15~20mins) and the oil pressure dropped down to 10psi (at idle) by the end. The only thing I can think of is that the o-ring on the pickup is still not sealing properly. Will drop the pan again to check it out.

grinder11

iTrader: (1)

Oh, NO!! Anyway, I hate to say it again, but I think you have an internal leak somewhere. I mean, you've installed multiple O-rings, new pump, etc. Can't believe you installed all wrong O-rings, or cut them. Your clearances are either messed up, or you've got a hairline crack that opens when the aluminum gets hot. I once owned a 2.5L "Iron Duke" Pontiac engine. It had been in a frontal collision. When it warmed up it had the finest external oil mist spray you can imagine, aimed right at the serpentine belt!!

carmodyg

I dropped the oil pan and checked the o-ring on the pickup. When I removed the pickup from the oil pump, I noticed a mark on the inside of the oil pump throat. Like the pickup was making contact with the inside of the oil pump.

It then struck me what was causing this. With the double row timing chain, you need to put spacers on the oil pump to make sure the chain doesn't contact the rear of the oil pump. This pushes the oil pump forward by around 4mm. However, the pickup has a backet at the rear which helps to support it. The bracket bolts onto the underneath of the block to one of the bolts used to fix the windage tray. However, with the oil pump being 4mm further forward, when the pickup support bracket is bolted in place, it will pull the pickup back so the pickup tube is no longer centred in the throat of the oil pump. Its pressing on the rear of the o-ring, and I assume the front of the o-ring will allow air in when things heat up.

I bent the bracket back by around 4mm and reinstalled the pickup. The pickup seemed to slide into the oil pump and is now centered as it should be.

I took the car for a drive today. The psi at startup was around 52 psi, an increase of about 12 psi from before. After driving it for around 20 mins, it fell to around 18 psi - still low but its an increase of 8 psi over what I was getting before.

I'll take it for another drive tomorrow, hopefully it won't go any lower than 18 psi.

carmodyg

Also, I increased the idle to 800 rpm (previously it was 640 rpm). This has increased the oil pressure up to 26~27 psi at hot idle.

grinder11

iTrader: (1)

I once ran a double roller. I remember well those aluminum spacers. Still have them. They, and the double roller setup are in a box under the bench. Don't know why I'm keeping them. On my setup I had to clearance the inside of the timing cover, and a several of the hex head cap screws that hold the oil pump cover plate on. I didn't realize you were running a double roller setup. Sorry if I missed that......

carmodyg

Most of the posts I read on the double roller said it should go on without too many problems. If I'd known how many problems it would cause, I would have stuck to a single! This is what I've had to do:

1. Spacers on the oil pump
2. Countersunk screws on the oil pump cover
3. New, deeper timing cover. Even then, I still needed to mill around the crankshaft opening to get the clearance.
4. Modify the pickup bracket

And for street use, a new single row chain would probably be fine. I guess you learn from experience.......

G Atsma

Double roller chains for LS engines are sold mostly to SBC guys who think they HAVE TO HAVE IT because SBC's needed them.
Most LS's do not. The cam does not drive the oil pump or a distributor and therefore doesn't have the associated drive stresses.

grinder11

iTrader: (1)

As I said earlier, I once ran one, too, back in 2005 while dinosaurs still roamed the earth. Main reason I didn't use it for my LS7 is it had no provision for a front mounted cam position sensor. Gary makes a damn good point that most never bring up, and that's parasitic drag. The LS chain has a gravy job without the distributor and the oil pump dragging on it. I guess a double roller on an LS is extra insurance. But it's like taking out a life insurance policy on a 98 year old; just not needed at this point. However, a good HD chain like a C5R, or its latest incarnation, is always a good idea.

carmodyg

I've been doing some research on oil filters. Most oil filters have a so called, "relief valve" or bypass valve built into them. Its purpose is to bypass the filter element if the oil pressure gets too high. Typically most filters will operate the bypass valve once th oil pressure gets up to between 15~25 psi.

I checked the filter I am using now, a K&N hp1017 - its relief valve operates at between 11-17 psi. (I assume this means it will operate at a minimum of 11 psi up to 17 psi depending on factors not stated in the spec sheet -maybe it will vary depending on factors such as oil temperature, oil vicosity, etc???).

So if the oil pressure is always above 17 psi, does this mean the oil never gets filtered? Would it not be better to have an oil pressure which is below 17 psi (at idle) so the relief valve does not operate all the time, and the oil over time will be properly filtered? Am I missing someting here?

Also, I've come across the Moroso brand of racing oil filters. They claim that most filters overly filter the oil by trapping particles down to 10 microns whereas their engineers claim you really only need to filter down to 20 microns. So their oil filters result in less pressure drop (~2.5 psi) than most other filters. Their relief valve is set at 20 psi, which seems more resonable. (probably stiill too low as it seems most LS engines run at around 25 psi at hot idle).

Welcome any opinions or experiences from other members.

Che70velle

iTrader: (6)

Dont forget it worked the mechanical fuel pump up until about 1987 also. That timing chain was busy.

carmodyg

Did a little more research, the psi rating of the relief valve is a differential value, that is the difference between the input pressure and the output pressure. That makes sense. So the current filter I have fitted should be fine in that case.

RB04Av

This is not correct.

They open (bypass) the filter if the pressure drop across the filter gets too high. This typically happens because the oil is too thick to flow through the filter media, or the media is too plugged up (dirty) to allow the oil to flow freely. The concept being, dirty oil is less bad than no oil at all. And yes, the bypasses in most filters open somewhere around 12 - 15 psi of pressure drop. A new filter will usually drop (restrict flow) far less pressure than that.

Therefore the bypass valve CANNOT cause low oil pressure, nor does it respond to the pressure that a gauge might read. No matter how high the pressure is, the valve will stay closed and not bypassing, as long as the filter flows relatively freely.

carmodyg

I think that's what I said in my previous post? (in not so many words....)

Y2K_Frenzy

Is the oil pressure really as low as you think it is? No knocks or anything like that?

carmodyg

From time to time I'm getting a slight ticking coming from the front top of the engine. But it seems to disappear when I take it on a long drive.

The oil pressure starts out at around 50 psi when cold, and drops to 25 psi when it warms up. I've noticed it will go as low as 20 psi sometimes. I've read a lot of posts that say their engine runs at 25psi at hot idle. This doesn't seem to be unusual for an LS1. Absolute minimum psi on a stock motor is 3 psi from what I can find.

When I drive the car, it will get up to 30~50 psi depending on the revs. I'm assuming the increase in oil pressure will pump more oil up the pushrods, and therefore the slight ticking stops after I drive it for a while.

Is 20psi at hot idle a problem? This may be just how it is for an engine thats done around 200,000 kms (125,000 miles). Apart from the slight ticking noise, there seems to be no other ill effects.

I've changes both oil pressure senders (the one for the dash gauge and the one for the ECU). I've also verified them against a mechanical gauge. So I'm confident the readings are correct.