Discussion
On my recently acquired 1.6 91 Eunos the oil pressure goes off the guage at 6kg/sq cm when cold and even when hot runs at 5+kg/sq cm at 3,000+ rpm. Is this normal or might I have a faulty oil pressure sender or guage? It's running on 15/40 synthetic (Halfords, no less!) and there's no apparent running problems. However, I don't have an owner's manual so I'm not sure if that's the correct viscosity?
Also, and while I'm on, there's no cat fitted. Is this normal for a 91 Eunos or has it been decatted?
Had the geometry set last weekend at WiM and with new tyres on, so far it's proving to be everything I'd hoped when I bought it (or him - he's called Eustace the Eunos). Not the smartest example ever but cheap and very cheerful!
Also, and while I'm on, there's no cat fitted. Is this normal for a 91 Eunos or has it been decatted?
Had the geometry set last weekend at WiM and with new tyres on, so far it's proving to be everything I'd hoped when I bought it (or him - he's called Eustace the Eunos). Not the smartest example ever but cheap and very cheerful!
Back again. A quick check of Halfors website shows them recommending 10w and lower.
A 91 Eunos would have had a cat fitted from the factory but they are often decatted and there is no legal requirement to have a cat on a pre 93 import. So it is not an issue as long as your emissions are OK
A 91 Eunos would have had a cat fitted from the factory but they are often decatted and there is no legal requirement to have a cat on a pre 93 import. So it is not an issue as long as your emissions are OK
Oldandslow said:
I'd say that maybe 15w/40 was too high a viscosity oil. I run 10w/40 and know of others on 5 or 0. I'd expect it to be 4-6 on startup and drop to between 2 and 4 (Eunos metric guage). I doubt it's doing any harm but I'd consider changing it at your next oil change.
when it's hot, a 15W-40 is the same viscosity as a 10W-40, 5W-40, ow 0W-40. however, your oil pressure does sound too high. first and easiest, do an oil change for a half decent quality 10W-40 at least. (15W-40 has no benefit whatsoever over 10W-40)
I've got a 92 1.6 Eunos and it passed the MOT emissions test just fine with no cat.
As for the oil pressure that is quite high - mine gets around 4 to 5 when driving cold (about 3 at cold idle) and around 1 to 1.5 at hot idle and between 2 and 4 when hot driving, but my engine is a rebuilt unit and so very clean inside - if the engine is old and gunked up a little then the pressure would probably be higher.
I'm using 5W40 fully synthetic oil as apparently 10w40 is a bit too thick.
Also, I have been told to always use a genuine Mazda oil filter rather than any other brand.
As for the oil pressure that is quite high - mine gets around 4 to 5 when driving cold (about 3 at cold idle) and around 1 to 1.5 at hot idle and between 2 and 4 when hot driving, but my engine is a rebuilt unit and so very clean inside - if the engine is old and gunked up a little then the pressure would probably be higher.
I'm using 5W40 fully synthetic oil as apparently 10w40 is a bit too thick.
Also, I have been told to always use a genuine Mazda oil filter rather than any other brand.
Edited by anonymous-user on Wednesday 13th May 21:52
Actually, since my original post I've just re-checked the notes the previous owner passed on to me and I got it wrong - it's actually using 5/40 and was changed quite recently, so it looks as though the oil itself should be OK. I've been caught out in the past with a faulty gauge on a Lotus Elan that nearly caused me to park up on the verge and walk home, so disastrous did the oil pressure look (i.e. virtually zero)! Turned out to be just fine with a different gauge fitted.
However, a bit of investigation is obviously called for.
However, a bit of investigation is obviously called for.
Hello Bruce,
Mine reads that, then occasionally flicks down to more normal levels. One thing you cna be sure, most cars will not 'gain' oil pressure unless a thick oil is used or the pump relief valve spring is changed, it is rare for them to stick.
The gauges on these are not accurate in calibration, and I know on mine there is something electrical that gives it around + 1 kg/cm when it feels like it. So, in short don't worry about it. If you are, then get a mechanic to hook up a good mechanical gauge under the bonnet just to check, but I can pretty much assure you, if the gauge isn't staticaly stuck off the scale (i.e. it moves as you say it does) then you've nothing to worry about.
I use the genuine filter, change oil every 6000 miles (10000 km) and tend to use Halfords synthetic. ENgine seems lovely and clean inside despite 100000 miles now.
Mine reads that, then occasionally flicks down to more normal levels. One thing you cna be sure, most cars will not 'gain' oil pressure unless a thick oil is used or the pump relief valve spring is changed, it is rare for them to stick.
The gauges on these are not accurate in calibration, and I know on mine there is something electrical that gives it around + 1 kg/cm when it feels like it. So, in short don't worry about it. If you are, then get a mechanic to hook up a good mechanical gauge under the bonnet just to check, but I can pretty much assure you, if the gauge isn't staticaly stuck off the scale (i.e. it moves as you say it does) then you've nothing to worry about.
I use the genuine filter, change oil every 6000 miles (10000 km) and tend to use Halfords synthetic. ENgine seems lovely and clean inside despite 100000 miles now.
I did wonder if someone had fitted a stronger oil pressure relief valve spring (or packed the old one with washers) but now I've realised that the valve is co-located with the pump behind the crank pulley, I think that's unlikely. As far as I can tell the engine is standard and no one would strip it down just to do that (surely?)!
I have lots of evidence of regular and frequent oil changes over the past five years so I'm 90% certain it's a sender fault. I'll take a look at the weekend and see if i can source an alternative to test it.
I have lots of evidence of regular and frequent oil changes over the past five years so I'm 90% certain it's a sender fault. I'll take a look at the weekend and see if i can source an alternative to test it.
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