still oil problems

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nimhbk

New Member
still crap oil presure

Changed the filter as it was way to small which we thought was the problem....No Good :cry:

Right oil sump is of no dents in the pan and the pick up looks fine.:)
Checked the 18 row oil cooler for blockages.

Start engine and it rattles for about 2 minutes as the oil pump seems to only kick in then, and then the rattles stop and sounds fine apart from the low oil presure.:cry:

was thinking maybe the 20 year old oil pump has decided it wants to go to the scrap yard heaven.

starts on cold at about 9 bar (after you wait for the oil pump to either start or find some oil) then drops to 1 bar, and then your lucky if you can get the presure to go above 4 bar if you rev it hard.

All this happened after my radtec rad rattled itself to death and burst on the intercooler.

it ran very hot for about two miles where the water temp went sky high and the revs went up and down like a yoyo.

Got home and filled the rad and the engine ran smooth but the oil presure was shot.

but the oil pump as stated just did not want to start until rev to about 3-4000 rpm

Have checked the oil as i wondered if i had fryed the stuff, but it looks as good as the day (two weeks ago) i put it in.
 
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pulsarboby

Guest
i didnt think it was the oil filter nick, but didnt want to dissapoint you, filter unless blocked wont drop the oil pressure.

i personally think its either the bigends have wear which will drastically lose oil pressure if so, or the oil pump itself is badly worn and not able to pump properly once engines hot and oil has thinned down.

you need to completely remove the alluminium sump to renew an oil pump so whilst youve dropped that i would check and renew all the bigend bearings and check the crank for any marks or scoring, if theres any sign of scoring on crank (even very small score marks) then your wasting your time and money by replacing the bigend bearings as they will simply not last.
you do not need to remove the head to do this!
 
N

nimhbk

New Member
Thanks bob would the big ends be effecting the oil pump starting from starting as that's the strange thing it only starts when rev hard
cheers bob nick
 
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pulsarboby

Guest
could well be nick, either one could cause failiure to the other
ie if the shells had wear then the particles could have scored the oil pump and caused that to weaken!
or if the oil pump was initially worn then the low oil pressure could have caused premature wear on bigend and possibly main bearing shells.

you really wont know anything for sure untill you drop the sump and carry out some visual checks
 
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nimhbk

New Member
ah i had my rocker cover sand blasterd

i wonder if i did not get all the shirty sand out when i put bloody thing back on

and its circulated around the engine fuc@ing everything up
 
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pulsarboby

Guest
aaaah! your not the first to kill an engine after having that done:oops:

i had exactly the same prob around a year ago which destroyed one of my engines:doh: the bits of grit lie under the inside of the breather track in rocker cover.

remove that cover straight away and get around 2 ltr of parafin and mix it with engine oil then run engine till hot at idle (dont rev it) that will flush all the crap out (hopefully its not to late) you will still need to remove and renew the oil pump as it will be scored to boogery, lets just hope its not mullered your crank also. if not then buy a new set of bigend shells and mains too and with a little luck you may get away with it.

flush the thing through before removing and replacing any parts though, but remove the rocker cover first and clean that out 'whilst off car' thoroughly before flushing (especially under the breather rail as thats where the little bits of grit lay)
 
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nimhbk

New Member
Oh dear lol
vanity might of cost me some cash

does that mean bob I will not be able to rebuild this engine using the block.
What do people replace if there doing forge pistons etc.
Cheers nick
 
Fast Guy

Fast Guy

Moderators
Staff member
Did no-one learn from Sandy Chans adventures with sandblasting his block??

If anything too small a filter would raise pressure as it would be more of a restriction to flow.

9bar on start up sounds very high. Nissan only require 0.98bar minimum at idle and about 3.4-4.4 abouve 3200rpm. I'm surprised you haven't been blowing seals.

Hot oil will cause low pressure if you've overheated the engine or been running low on oil.

The oil pump isn't electric, so it doesn't just start it's running all the time.

A worn bottom end or worn oil pump could cause low pressure and a slow initial pressure build up. (most likely cause based on the sand mentioned)

There's also a pressure relief valve which to be honest I don't know how it affects oil pressure if it was to be stuck open. I'm guessing it could cause lower pressure.
 
red reading

red reading

Active Member
oil pressure relief valve if stuck open will cause low oil pressure.High oil pressure will occur if stuck closed,if you have had your rocker cover media blasted and not cleaned it out before fitting i would suggest you take the engine out strip it ,clean it and inspect everything and rebuild it,a lot of blasting company's use steel shot rather than sand now as it is more economical/recycleable than sand,and if that is in your engine it will scrap it!!
 
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pulsarboby

Guest
sorry nick i misread your post earlier i thought you meant powdercoated the rocker cover, same difference i suppose though as the grit gets in everywhere and thats what killed one of my engines.
 
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nimhbk

New Member
That's what I did mean bob, I will give your engine flush treatment a go next week when my friend gets back as I will fuc@ that up as well.
And look at the crank for damage like you said.
Hopefully it may just be slighty damaged, knowing my luck it will buggered, and a lot more than a oil pump and big end bearings.
 
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pulsarboby

Guest
you dont want any sign of damage at all to the crank or it will mean its boogered! even the slightest scoring and youll be wasting your time and money fitting a new set of shells etc.

as danny 'red reading' said, if its marked at all then it will be engine out and rebuild jobbie.
so good luck youll need some to get away with it.
 
N

nimhbk

New Member
Purchased the oil pump this morning from the site I put up the other day £160 delivered and the bearings of eBay.
They also had cp pistons for just under £400 delivered what size do I need for standard engine 86 mm
also if the crank has been damaged does that mean get a second hand job or can it be Machined cheers bob
 
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pulsarboby

Guest
yes 86mm is standard but dont order pistons untill bores have been checked for ovality and scoring, if theres any light markings in them then that can be honed out, but you really need a bore dti gauge to check for ovality.

as for the crank......its a grey area tbh i personally do not like ground cranks in forced induction engines but thats my own opinion with regard to race use which i know for a fact they will not last!
if the cars not running a great deal of power or boost then it should be ok, but i would rather use a good s/h crank assuming you can get one, they are very difficult to find in good condition thats why we snap them up if there are known good ones for sale, as they are the key to a good build.
 
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nimhbk

New Member
will ask my friend if he fancies doing an engine rebuild with a bit of help from me, Producing the tea.

He has all the equipment

He charged £500 to rebuild a rotary engine on the old mates rates and that got to be a lot harder sr20 det.

So if he has time and fancies doing it may as well give it go.

instead of buying a s/h motor
 
red reading

red reading

Active Member
If you are rebuilding the engine get a complete gasket and seal set from nissan/replace all the pipes on the back of the engine as this will save you alot of agro in the future
 
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