Bugger

[IvanTheTerrible]

Just finished a rebuild on the wifes 5L oil pump out of her drag car. During the rebuild I opened up and blended the galleries and shimmed the spring to raise the pressure. Now I have a problem I have never encountered before. The following are pictures of 1 of 3 cut open oil filters that have been fitted to the motor over the last 5 days.

Photo0044.jpg (114.4 KiB) Viewed 7749 times

Photo0044.jpg (114.4 KiB) Viewed 7749 times

Current pressure reading is 20KPA at 1000rpm and about 450KPA at 4000Rpm

[immortality]

Did you block the oil bypass inside the oil pump?

How much did you shim the oil pressure bypass spring?

What type of oil do you use and did you warm it up before giving it a good rev? This seems to be a common problem with Holden 308/304's that have had the pump bypass blocked off and the engine is revved when the engine is cold.

450kpa/65psi is a fair bit for a 5 ohh at 4000rpm.

Standard or HP oil pump?

I'd also suggest running the larger type oil filter.

[IvanTheTerrible]

Yep. The bypass is blocked and it is shimmed just under .100". I have tried Z160 and Z30 and this happened to both. The engine was at operating temp before it went over 1500Rpm. Modified alloy pump. Haven't done this mod on a 5L since EFI and never had a problem even at 70PSI in the past. Thinking of either dropping the pressure or changing to a dual remote filter.

[immortality]

There is a guy on the AussieV8 forum that modifies the bypass passage to relieve the pressure at the oil filter rather then after it to stop the oil filter imploding like this, otherwise a high quality filter would be the way to go like one of those alloy filters with stainless filter medium that is serviceable like the system1 filters.

Edit: what oil are you using?

From what I have seen, the standard type oil filters simply cannot flow enough oil through the filter element on a cold start so some oil always goes through the bypass. Depending on what oil you use you may be able to go to something a little thinner on a cold start, although your low rpm oil pressure seems very poor. Maybe try a oil filter that has a built in bypass.

[v6bucket]

I think you may have a typo, 20kpa is only 2.9psi, maybe 200kpa.
I use a similar setup with the Holden 6's, use 45w70 oil & haven't collapsed a filter like that before.

[IvanTheTerrible]

It was 200Kpa, I just can't type. Oil is Hpr 30, 20w-60. Currently contemplating either reducing the pressure, changing to an inline screen filter or dual remotes.

[immortality]

That definitely sounds better.

You can probably afford to drop a little pressure.

[Holden202T]

i just talked to my mate that owns an engine reco shop and said "what would make a filter element collapse ?" his first question was have they blocked the bypass valve

he reckons the only way you'll sucessfully send everything through it at that PSI is to get a hydraulic type filter thats rated to enough PSI.

the other thing he also reckons is you need about 10psi for every 1000rpm ..... if thats the case 65psi at 4000rpm is probaby too much.

[IvanTheTerrible]

10psi per 1000rpm is what they recommend for a standard engine. This is the problem with 5L Holdens. There are so many people saying so many different things. at least I have the whole of the off season to figure this out.

[Holden202T]

well the bloke I talked to about it used to race and build 253's for AMCA class at the speedway and he was very successful, he now races in the late model class and also uses the same ratio for this 436 cube chev that revs to 8000rpm all night long

i'm not trying to say its right or not i'm just saying what he does and has told me!