Newly Rebuilt Mi16 - Low Oil Pressure?

[Dave_McC 0]

From my other thread I've finally got my newly rebuilt Mi16 running and took it round the block this morning.

 

Bit of background:

 

Engine had done 125k miles. I've pretty much completely rebuilt it - reground crank (0.3mm undersize), new main and big end bearings, rods checked by QEP, new piston rings, liners honed, oil pump dismantled and clearances checked, Peter T extended pick up fitted, uprated oil pump spring fitted.

 

Engine is running the oil to water oil cooler - plumbed into the heater circuit so oil warms up nice and quick. Oil is 10W40 mineral oil (cheapo Halfords stuff to aid bedding in - will switch to a semi synthetic when it's done 500 miles or so).

 

At hot idle (1k revs), the pressure gauge is sitting on the first 1 marker - ie just above the red zone. At 2k revs, gauge is at 2nd white marker. By 3k revs, needle is vertical - just below 3rd white marker - and it stays at that point as revs increase. For all of this the oil temp gauge was on the 2nd mark.

 

As I thought the readings were low when I started it a week ago, I swapped the gauge sender unit yesterday to the one which was on my old 1600 - which made no difference to the reading.

 

To me this seems a bit low - from memory this is no higher than the old 1600 used to run. The engine sounds absolutely fine - no hydraulic tappet rattling or any other untoward noises.

 

Can anyone else with an Mi installed post up what oil pressure you're getting?

 

Thanks

 

Dave

[yeti-dj 7]

Sounds exactly the same as my Mi16,

 

the peugeot pressure gauge isnt the most accurate thing in the world at the best of times...

[Dave_McC 0]

Cheers - that's just the reply I was hoping for! Engine certainly sounding sweet. There's good reason why oil pressure gauges are also often called "worry gauge"!!!

 

Dave

[unariciflocos 49 1 Cars]

My gauge is 0 to 8 bars, I'm getting 4 bars at cold start and just an insignificant drop at running temp idle, 6 bars under revs (5-6k) and just under 2 bars at idle with hot oil (after some power laps). I'm only running an uprated oil spring and 10w60 full synthetic oil.

[Stu 18]

At the risk of repeating stuff already said, id get yourself a proper gauge in there mate.

 

I had more or less the exact same readings on my fresh Mi, and like you i worried a little , so i got hold of a proper gauge and a low pressure warning light operating @ 25psi and i never comes on now, bar after a mega session at Donny or whatever at idle.

 

Cold idle is 80psi ish, normal hot idle 25-30psi. Extra hot 'just had the s*it kicked out of me' idle 20-25psi-ish.

 

Thats with 10w-40 semi synth generic GSF stuff.

Edited March 9, 2009 by Stu

[Dave_McC 0]

Cheers

 

I know a proper mechanical gauge would be the way to go (had to do that in my Caterham after god knows how many dodgy senders) - but I want to keep the interior looking stock so don't want to be adding gauges.

 

Anyone know what pressure the stock stop light comes on at? Is it the usual manufacturer 5psi or whatever - your engine is already goosed - or is it a sensible pressure. I've rigged one up on the Caterham which comes on at 25psi - comes on at idle when it's been ragged! I could always swap the standard stop pressue switch for a higher pressure and rely on that - at least it would be accurate!

 

It wouldn't be so bad if the senders weren't so damned inaccessible....

 

Dave

Edited March 9, 2009 by Dave_McC

[Stu 18]

Yeah thats a big problem with the inlet, id take it off to do the job, makes things so much easier.

 

I put mine in the air vent case, and the low oil pressure warning down by it too.

 

 

From memory i think the stock sender is 7-10PSI?

[welshpug 1,657]

stock switch is 14Psi.

[Dave_McC 0]

Stock sender is better than some oe stuff then - but still gonna be curtains for the engine if it sees 14 psi under load!

 

The stop light isn't coming on at hot idle - so I'm getting at least 14 psi at idle - and by 3k revs I'm getting 3 to 4 times that (assuming the gauge is vaguely linear - big assumption.....) so maybe 45 - 60 psi - which is 3 to 4 bar. I'd be happy at 60psi. 45psi probably marginal.

 

Once I've got a baseline I don't really need the accurate OP gauge - it's not a track car so I'm not too worried about surge - just keeping an eye that the OP doesn't deteriorate over time.

 

Dave

[Henry 1.9GTi 36]

my mechanical gauge definately worries me

 

hot idle 20psi 4k rpm 55psi revving its tits off 60psi all with standard Mi pump and spring.

 

Annoyingly when revs are rising very very slowly I see the gauge go from 40psi around 1.5-2k rpm then as revs go up slowly to 2.2-2.3 the guage goes up to 60 then knocks back down to 50 before rising to 55psi with high rpm. weird. as said a worry guage. but perhaps there is something to worry about lol

[Dazza 4]

I would add that my Mi16 205 did the same on a new engine build , ive fitted the mechanical Guage into my dash and have 3 x LED's built into my rev counter screen fascia ( very pround of it to looks mint) ive got my warning "PSI light on and preyer " at 35 PSI and at idle when warmed up propperly its just flickering albeit when off a track sesson ive 20 Psi and there on big time my full fascia is bright red .

From cold i see high 60's and usually around high 30's normal useage.

 

I fitted the warning system because i killed 2 brand new Mi16 engines on track , 1 died of oil starvation on a right hander with the PSA Baffle kit fitted and i remember it very clearly , 3rd gear 5000 rpm's just opening the taps on exit and my eyes on the track and oil guage when it litterally dropped from half pressure ( pointing at 12 oclock to 11 oclock and by then the mettallic finger nail up the hair comb like sound filled my ears and it was gone baby , battery lights on and were outta there ...there was not a hope in hell of me having the reflex's to stop this happening it was all done as that guage dropped in a micro second.

 

I now see minimum 35psi on that same bad memory corner with new engine and sump set up , that said iam watching those led's until half way through the day when my wallet worrying sub-sides and i enjoy the trackday.