shimming oil pump for extra pressure, thoughts and comments

[slide86]

ive been hearing a little bit here and there bout doing this. a mate who has been having dramas with his run round car has done it and says its worked.

what i am talking bout is putting a washer behind the relief valve spring to make it harder for the relief valve to open, thus increasing the oil pressure. he said that he got an extra 15 psi from doing this.

what are peoples thoughts bout this type of idea? good/bad? i know that too much oil pressure could be a bad thing, but how would it go on an old engine that is starting to loose a bit of pressure?

[jonra23]

If you are loosing oil pressure due to worn components shimming the relief valve will have no effect.
Relief valve will only open when pump capacity exceeds the bleed off fcapacity rom the bearing clearances, likely not to be happening if engine is worn.

Higher viscosity oil may help but is only a band aid fix.

regards
jon

[slide86]

yeah i think it was supposed to only be a band aid. i was just interested to see what others thouhgt and other side effects of doing it/

[oldcorollas]

if you look at a decent oil pressure gauge.. above around? 3000-4000rpm, the pressure relief starts opening. if you shim it (as recommended in the Tosco 3K guide), then it will open later, at a higher pressure.

as Jon says tho, it will have no effect until higher revs, and it is the excess bearing clearances etc that are reducing the pressure (it's all bout volume and pressure )
and as he said, thicker oil will do the trick (and better for the bigger clearances)

[30psi 4agte]

There is some info on this on mthe club 4ag site.

You have prob already seen it

I havent tried it but it has crossed my mind as a i run large bearing clearences and the oil pressure can be quite low down in the rev range.

I ended up going down the thicker oil track.

[oldcorollas]

in your case the pressure relief may not help

an oil pump has no problems making pressure. it is a relatively fixed displacement pump, moving a fairly incompressible fluid.
the reason you have oil pressure is because the volume of oil pumped is higher than the volume shed by the bearings etc..

to increase low oil pressure, you can only make bearing clearances smaller.. or run a larger volume pump. (or run thicker oil to reduce the shedding rate from bearings etc)

[MR 1JZ]

we just did this on a mates CA sprinter, fresh rebuild and he wanted more oil pressure due to CA18's having shitty pressure from factory, one tiny washer made about 15-25psi worth of difference and he is more than happy with it

[Joshstix]

Yep I shimmed the pressure relief on my 3S the first time I built it. The nice thing about the Gen3 3S is that the plug for the pressure relief is a bolt that is accessable from the outside of the engine, right on the sump so you can do it without needing to pull down the engine.

As outlined above I did this for greater oil pressure at higher revs.

[nb86]

oldcorollas is right here about the pressure differential between pump and bearings etc. but there is another phenomenon which i have experienced on one of my cars and a couple of others i have worked on.
this is when the bearings are still within tolerance but for some reason or another the relief spring weakens with age and begins to open prematurely.
if your pressure guage is low at idle and doesn't increase with rpm, i would suggest that this is the case. if so, shim the relief spring and you may have a fix (at least for a while).
if the pressure climbs with rpm then it is the other case and shimming the spring will do nothing.

[kingmick]

There is some info on this on mthe club 4ag site.

You have prob already seen it

I havent tried it but it has crossed my mind as a i run large bearing clearences and the oil pressure can be quite low down in the rev range.

I ended up going down the thicker oil track.

you using H series bearings!

[kingmick]

many thing can happen! piston can get sticky in the bore of the relief, spring sag, pump gear wear, bearing wear etc
Depends on how the engine has been treated and oil used and change intervals etc.

[Rodger]

I've found through my experiences during my competitve days and recently from running the bearings in my 2T that:-

Oil pressure had not been the big issue.

Reliable and consistant oil flow was the bigger issue.

I ran the big end bearings dry mostly because of oil surge in the sump, as the OEM pump did not recover quick enough. That was a stock 2T pump and sump at a track day at Wakefield.

My competition 2T has the TRD pump and I baffled the sump very early on to avoid this.

Now effectively I have proven to myself I should have concentrated on the sump and not to worry about shiming the OEM pump.

Sump, pump, sump, pump, blah

Regards

Rodger

[nb86]

many thing can happen! piston can get sticky in the bore of the relief, spring sag, pump gear wear, bearing wear etc
Depends on how the engine has been treated and oil used and change intervals etc.

very true. oil pressure problems come from all over the place. i once had a circlip fail, dropping the piston and spring into the sump. no oil pressure obviously but i killed the engine in time..... no damage thankfully.
and yeah, standard oil system + track days = bad news.
same goes for cooling systems...

[feral4mr2]

while where on the oiling of the engine topic, going slightly off topic...

what benifit would there be in making your sump larger to hold more oil? i've been thinking of putting a hammer head on my sump for my next gte.

[kingmick]

advatages: more oil means more stable temps under heavy load times for longer, more oil that isnt in the engine to scavange at g loading times, oil will last a bit longer at a higher temp etc etc.
The above works for race engines and road cars to a lesser extent.