Oil Light on at Low Revs Once Warm

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Tmo

Active Member
Posts
157
Location
Hampshire
Hi everyone, my 3.9 has finally now had a couple of trips out and I've put 100 miles on it since the rebuild.

What it has started to do though is show the oil light once it's warm when at idle and just above idle, then once pulled away or revved it clears.

Is this just another v8ism or is something actually wrong?
 
I've run anything from 10 / 40 to 20 / 50 in myn and many others such a small change in oil grade should cause issue with the oil pressure switch.

These old V8's have hardly any oil pressure at isle when warm anyway they have more flow. Take a rocker cover off and fire the engine up to make sure you have adequate flow to the rockers.

Probably just a bad switch (assuming you build is OK)
 
I was over at RPi yesterday so ran this one past there engine builder for you. His immediate question was have you fitted new rockers. If so they are known to be faulty and leak too much oil out :)
 
I think I may have put the wrong grade oil in it god knows how. The temp gauge sits smack bang in the middle all the time now it's working but when it's sat in traffic for a good 15 mins a loud tapping starts and then gets worse like its tappet related noise?? Once driven away it then goes I think this could be why the light stays on too
 
I was over at RPi yesterday so ran this one past there engine builder for you. His immediate question was have you fitted new rockers. If so they are known to be faulty and leak too much oil out :)

Thanks for asking that there what I would do to get in with RPI, no I haven't fitted new rockers and have no leaks at all it's the first land rover engine I've owned that doesn't leak oil for a change!!!!
 
I think I may have put the wrong grade oil in it god knows how. The temp gauge sits smack bang in the middle all the time now it's working but when it's sat in traffic for a good 15 mins a loud tapping starts and then gets worse like its tappet related noise?? Once driven away it then goes I think this could be why the light stays on too



BAD BAD BAD..find out why.sounds not good!!.bet it aint the oil..unless you tunning 0-30..

personally i would stay clear of rpi..re rockers..what **** are you people fitting to your engines???plenty good aftermarkett rockers out there..buy from reputable dealers!!
 
I used to work for RPI. Holly wasn't trying to sell me anything was just simply offering me advise. :)

Each to there own though.
 
Right I've been told that big end shells are worn and are causing the low oil pressure which is why the light stays on at low revs then once hot it then stays on and is starving top end of oil which in time will later on damage head? Anyone got any guides or topic on doing it?
 
Sorry forgive me STP?

Are sump bolts re usable or do they need replacing?

cover crank and bearings with loads of oil when refitting...stp is an additive.(not used much today due to oil being better)..but its thick..and hense wont dissapear (creep out) if you rebuild and dont start it up for a week or more...

thing is engine bearings must be "wet" when first start up or you will destroy them..

also once back together, remove plugs and crank till you have oil pressure (oil light goes out) before starting for real..
 
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