18r low oil pressure problem

[cranker]

I have a 18r engine which has only done 117 000K's from new. Runs sweet as but the oil light comes on at idle once the engine has warmed up, it gradually gets worse as in I have to up the revs more and more to make the light go out as the oil gets hotter. The problem only started after i dumped the old oil (that was in there when i bought the car) and put in some synthetic shell oil because i wanted to use up the bottle. I then ditched that (thinking it was too thin) and put in Valvoline oil meant for older engines so its a bit thicker but the problem is still there. I know this generally means oil pump or bearings but any likely causes, common issues?

[o_man_ra23]

valvoline oil could be a cause. Try some Penrite every day 25w60 (the thick shit). Also could be the oil switch on its way out... try a new one. And what oil filter are you running?? If you are using a crappy (valvoline is in this category) oil filter, you will have dramas. Try a Ryco, or genuine Toyota item (I dont think they are much dearer either).

The last thing it is likely to be is, of course, engine wear, including pump and bearing wear. An unlikely culprit is a leaky pressure relief valve.

[blacktop]

Just my 2c
But i think the Penrite every day oil is absolute shit, why??? cos a penrite rep told me it is, they don't even want to have the Every Day stuff merchandised next to there HPR series.

I was going to say oil, but then i read the first post

[o_man_ra23]

Compared with the HPR series, or the Sin series, yes it is shit... and the rep doesnt make money by selling the cheap series of oil. I have not had a drama ever running the every day 20W50 in either of my 18R powered Celicas, or the missus' excel (they all run better after switching from GTX2, and the oil stays cleaner for the entire 8000km interval that I run)

Having said that, if you had an 18R-G I wouldnt recommend it, I would definitely say go up to the HPR series. I may even use Sin in my 18R-GTE and will definitely use Sin in my 3S-GTE. But the 18R-C just simply does not require/justify that level of lubrication and protection.

[cranker]

I dont think oil alone would cause this problem, I'm running 20-40 or 20-50 whatever it is is basic standard oil that any older engine should be happy on. I have a mechanical oil pressure gauge ill hook that up and see what it says.

[o_man_ra23]

But as I said... your running valvoline.

Check the pressure relief valve (big bolt on the side of the oil filter housing, has a spring and piston behind it) for debris... it could be holding open.

But, really I wouldnt worry too much about it... the 18R is a hardy engine, and I have owned quite a few with low oil pressure problems, of which not one has died after several beatings.

[GT1978]

I'm no oil expert so this is a stab in the dark but maybe a seal has been compromised by the synthetic when it went through causing a small internal leak. Something like the o-rings in the lower chain tensioner. Or perhaps there is a leak in the head oiler system. I think from memory there is a whole lot of tubing with banjo style bolts distributing oil to the rockers or the cam or something.
Or alternatively it could be a bit of grit holding the bypass open or worn bearings as previously suggested.

[brett_celicacoupe]

i have the same problem but its been like that for over a year, engine still runs like a clock, no knocks.

it might be that your running a RA40B in a RA40A body? the instrument cluster is different between the models so i suspect the oil pressure sender is also. RA40B has a scaled oil pressure needle where as the RA40A just has a idiot light.

try changing your sender as well

[o_man_ra23]

The RA40B has an oil pressure sender, which is a big round thing, and uses the pressure guage. The RA40A has a pressure switch, which is either on or off... turns on when the pressure drops low, which then lights up the light.

Really I wouldnt worry about it... just keep an eye on your oil level.

[thechuckster]

when my old 18RC got noisy i scored a drum of h/duty desiel engine oil off a mate (he had an oil-burner SWB cruiser) and used it - was like treakle but quietened down the chains and general engine noises a bit (until it refused to rev over about 3.5k from lack of compression).

[blacktop]

18RC's are the best for that,

I wanted to but a Hilux with an 18RC and the guy said to me "you might have to put it in low range to get up the driveway or at least get a run up" his driveway was about as steep as a small mound of dirt you could kick flat!

Get a new oil pressure sender (pretty cheap i think), then just do an oil change and check to amount of oil you put in, what is an 18rc oil capacity 4.5ltr???

[o_man_ra23]

he needs a new oil pressure switch, about $8 from any auto parts store.

[cranker]

Well the mechanical gauge wouldnt fit, (parrallel thread vs tapered thread) so I chucked on an oil pressure switch off a similar vintage corolla I'm stripping. Problem solved! Assuming the switches are supposed to operate around the same pressure level it must have been a dickie switch, so now I'm ready to continue with the plans to fit a better carbie (heard Falcon carbies are good, can pickup crappy XF's from the auctions for scrap value), cam and shave the head.

[blacktop]

wouldn't the sender read different pressures for the different applications?

and yes XF Carbs are pretty good when chasing more power.

[o_man_ra23]

XF carbs arent so good when chasing economy though

If your chasing power... find an 18RG... only ever build an 18RC up if you can readily admit to everyone that your completely loopy (I can, but decided it was easier to get EFI for the 18RG than the 18RC... and I wanted Turbo)