matts355

just finished building a 186 screamer.bored to 190,blue 202 crank,186 rods,forged flat tops,solid cam n lifters,J.P high volume oil pump,elec. dizzy,stage 4 head and roller rockers. all the good stuff. ive only got a standard radiator in at the moment and are getting around to putting a triple flow aluminium one in.so it is overheating quite easily but more concerning is the drop in oil pressure as soon as it reaches around 160degrees Fahreneit.it will go tp 40psi no worries when start it up,at idle and when driving.then drops to 30 then keeps going down.took it for a 70km/h drive for bout 15mins and temp was ok at 170degress but oil pressure was not going past about 23psi.
would it mainly be overheating maybe thinning oil too much and thus it cant get the pressure,or oil pump no good for it and should try my old standard pump which works perfectly fine. .
thanks for any ideas

_Daniel_

Oil type and weighting might help the guys answer your question?

matts355

had thin oil in to start with as is brand new rebuilt..but had the same prob so went a little thicker to 25w 60..will hold 40psi even when idling but then just drops off when get to 160degrees and wont get back up.exactly the same thing as the thinner oil

big horn

i had this exact problem and i was using a jp high volume oil pump. I chucked the standard one on and it fixed it

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matts355

Ahh ok thanks mate.i will probably try that if it fixed the prob.
cheers

matts355

thanks big horn,problem solved!its weird though the j.p pump was actually a standard type.and yet the old standard pump works better!what a waste of money the j.p one is!

big horn

Yep i wouldnt bother with the j.p pumps waste of money.

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matts355

problem is NOT fixed!!!!!!took at for a proper drive today,stayed at 40psi longer but dropped slower then eventually wouldnt go past 25psi.wtf is going on??!! maybe pickup is blocked? can anyone help?
cheers

paulzig

Did you check the clearance between the bottom of the sump and the pickup? Did you have 10-15mm?? As the engine heats up, oil gets thicker and may not be able to pass thru the pickup strainer if it is bottoming out on the sump...

matts355

didnt check clearance.just used a 186 pick up from a HD sump.cleaned it and put it on..didnt SEEM to bottom out. .

paulzig

It doesnt have to bottom out, it just has to be too close ... I usually stick some play dough on the pickup then put the sump on to make sure I have about 10-15mm or so.

Have you checked or replaced the oil filter??

matts355

ah ok..probably something i should have done to check first.i was using a Z160 when the prob first happened,then to a Z130 for more capacity.everything is brand new.except the pump now which is the one off my old engine.maybe the J.P one isnt the prob after all.either way its probably an engine out fix im guessing?

paulzig

Maybe someone else will drop in here with something that we may have missed mate.. Could be air leak somewhere, but it wouldnt be my first guess.. One thing I would NOT do is drive it if pressure drops like that when driving, dont want you to do the bearings... When Idling, and you rev it up a bit does the pressure increase?? You got 2 pumps doing the same thing so I'd be tempted to discount them as a cause.

matts355

yes,after driving today after i thought prob was fixed definetely not driving it! when its idling it after the pressure drops.it will go between 10 and 20psi.when rev it to 1500 or bit more it will go slowly but not past 25

big horn

yeah ok that fixed our problem sorry worth a try

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