C20LET, No oil to inlet cam

[Danny w]

Since putting the let into my corsa i had low oil pressure problems.
I took the engine back out and rebuilt the bottom end with new mains bearings and big ends, fitted a new genuine oil pump with sbd nylon relief valve.

I checked the pick up pipe for blockages, and also double checked i re fitted with the rubber o ring.

all new gaskets were used during the build.

Ive had the engine in and primed the pump etc. had it turning over with no fuel relay.
When i cam to firing it started first turn and sounded quiet witht he oil pressure reading above 40 psi/3 bar on cold idle. after 10 minutes or so it had dropped to about 25 psi/2 bar. I kept the car running untill the top end started getting tappy and the pressure kept dropping.

AS i've had this problem before i switched it off as dont want to do any more damage, oil pressure light is wired in correctly too so know it didnt get dangerously low.

now i've just had the rocker off and had the engine turning over, oil flows straight upto the exhaust cam and coats it lovely.. the inlet cam on the other hand is dry as a nuns .... i know this isnt right and there is an underlying problem has anyone got any suggestions of what i should now look for to get this sorted ?

Any help much appreciated

Danny

[Danny w]

Whats recomended for this? head off and clean the oilways?

[Joker]

hi mate, bad luck with all that. Did you get your head pressure tested and checked? maybe your inlet oil gallery is blocked.

[mac1976]

is there not a allen bolt on the side of the head that u can remove and blow out the oilways

[Danny w]

Cheers for the replies, I havent had the head pressure tested no as it hasn't been off since it was previously rebuilt.
Yeah thats what im thinking, what would be the best way to clean or check the inlet oil gallery ?
I have read through the porous head topics and have also seen the cross section let head photo's



what i want to know is how the oil actually flows up to the inlet? does it flow up to exhaust cam then along to inlet cam then down the oil way on the left? or does it flow up both the vertical oilways?

Mac, i had read something that said there is one on the dizzy side and one on the front hidden by the exhaust manifold, could i blow these out while the head is on? or should i be stripping it down and also checking the block?

[mac1976]

its got to be worth a shot wi the head on mate

[lee303]

theres a gallery for each side of the head, cams and lifters etc, fed from the main pressure gallery in the block, did you measure the crank and rods when you rebuilt it? could be you have low oil pressure due to an ovaled rod giving massive bearing clearances or a worn crank journal

[DarrenH]

oil is fed up from the block around the centre head bolt hole (the one at exhaust side of engine, between cylinders 2+3), there it T's off towards the back of the head for the inlet side (turqoise highlight in your picture) but also continues upwards at angle which is clearly pictured too.

then theres 2 line bored channels running horizontally directly inline below both camshafts, some heads have 4 allen blanking plugs at the ends of these two channels, at the distributor end and cam pulley ends of the head. these channels run behind the hydraulic lifter bores feeding the lifters through pin holes. the channel continues on and at the cambelt end of the engine is a pin hole in the cam bearing which feeds oil to a pin hole in the camshaft journals (holes match up every cam rotation). the camshafts are hollow and oil is distributed directly to the cam bearing faces itself, through the cam.

[lee303]

probably full of bits of bearing from the last engine, especially if you didn’t have the plugs out when the head was off, but 3 bar is low for cold oil pressure on a new engine imo anyway, would be thinking more like 5-6 bar really, which probably isn’t to do with the head feeds being blocked...

[Joker]

agreed, if your bearings are lose you'll get low oil pressure as it can't be squashed so there's no back pressure so to speak. See if you have the allen bolts and give it a blow out before taking the head back off again.

[DarrenH]

3 bar willl be enough to feed the cams, this is after all the hot idle pressure. i'd go with the physical blockage idea tbh.

some other more left field ideas. porous mod performed, but headbolt hole not redrilled, or external pipe not fitted (so no oil getting to the rear gallery)

it has an 8 valve block with no restrictor in the rear of the block, or some kind of headgasket anomally

[Danny w]

Thanks for all your replies so far.

Lee303
I havent measured the crank or rods nope as it was 'rebuilt' by someone else.
The car hasn't even done 5 miles since the first rebuild. the first time i lost oil pressure was when i drove to get an mot, saw the guage dropping and the oil light just start to flicker so turned the engine off.

I stripped out the engine and took sump etc off and checked the bearings, they were slightly marked but one was just started to show copper/brass.

I was unsure why i lost oil pressure but thought it may have been an old pump, so 'rebuilt' the bottom end with all new bearings, new oil sump with sbd gear, all new gaskets & seals etc.

i thought this would cure the problem but now noticing that i have no oil getting to the inlet cam coupled with the oil pressure dropping, i guess im clutching straws lol

Darren

Thank you that makes perfect sense, so i could try blowing the head through the grub screws front to back. i am truely hoping its a blockage causing all my problems, the ammount of time and money ive spent and yet i havent even been able to drive the bloody thing
Other two suggestions, are wortha check too thank you

Lee303/joker
Ahh i see im a little worried that the oil pressure is at 3 bar then :/ i personally have never had the head off since first full rebuild, it 100% had a new headgasket, piston rings, stem seals, arp rod bolts, water pump but the old oil pump was left on. the mains/big ends i took out the bottom end had STD stamped on them and were what looked like standard genuine items.

i have a couple of pics of the bottom end/bearings when i took it apart if you fancy a look? i'll post them up

Thanks again for your replies

[Danny w]

after the first oil pressure loss i was greeted with this in the sump, fresh oil too and hadn't done 5 miles



the worst shell, cylinder 3



all caps removed

[lee303]

3 bar willl be enough to feed the cams, this is after all the hot idle pressure. i'd go with the physical blockage idea tbh.

says 3 bar cold idle up there ^^ 2 bar after ten minutes to warm up which isn’t super hot, which is not enough, especially on something rebuilt with new bearings etc

having read the ops' new reply, the engine will still be full of swarf if you haven’t totally stripped it to bits and cleaned it out, it gets everywhere when you have a bearing fail like in the pics and is a bastard to clean out properly, your oil pump is may be scored up now too, unfortunately i think you need to take it all apart, measure everything and clean it all out properly and hope you haven’t done any major damage

[Danny w]

Thanks again for your reply lee, i shall try unblock the oilways with a compressor and see where i stand but as you say the oil pressure isn't right i have heard a few people say this. I really dont know what to do with this engine as cant stand to spend more money on it if there is a mojor underlying problem.

[lee303]

does the bottom end knock when you rev it? this sound so similar to how brians v6 was when we tried to just replace some bearings following low oil pressure running(we had them lying around so thought why not) but it was soon gently knocking away again, one of the rods had gone oval, i guess trying it is the way to go, but i think eventually it’ll be a strip down to measure the crank and rods etc

[DarrenH]

says 3 bar cold idle up there ^^ 2 bar after ten minutes to warm up which isn’t super hot, which is not enough, especially on something rebuilt with new bearings etc(

sorry, didnt mean to imply 3 bar is "normal". i meant the deflated figures he is achieving are the same as a good 20XE at hot idle, its adequate pressure to push oil to the inlet cam bearings and lifters

or to put it simpler, only achieving 3 bar(or 2) its not the reason the inlet cam is dry.

[Gordo]

Looks more like a partial or full blockage in the main oilway(s) or possibly a partial blockage in the pickup mesh filter or perhaps a fracture or something in the section side of the filter, that would allow air to be drawn into the pump.
Just a problem at the top end wouldn't affect the bottom end lubrication and would increase the pressure, if anything, as there'd be less leakage.
The only other thing I can think of is a partially seized oil pressure relief valve, that's allowing the oil to bleed off, but that would be expected to have a more significant pressure reduction - 3 bar is normally plenty for oil circulation at idle.

I expect the bottom line will be the 'engine builder' screwed up. Keep a look out for bits of cleaning cloth , I've known other people to leave bits in to stop debris falling into openings and then to forget about them.

Oh, are you using an oil cooler - is it correctly blumbed and clear of debris?

[anniman1]

have you had that block drilled for underpiston oil squirters?

[Danny w]

Hey guys, again thank you for the replies.

So far no knocks from the bottom end, on idle or when revved. Shame as when i first started it it sounded soo smooth untill the top end ran dry and started tapping.

Darren, cheers yeah that makes perfect sense to me.
Oil way will be blocked and also a low pressure problem

Gordo:
that makes sense aswell, i'm 100% getting oil to exhaust cam but none to the inlet cam. as for th oil pick up i cleaned this out when i did the bearings/pump, it has the rubber O ring on it too but i can see where your coming from about letting air in if not seated properly, maybe worth a check on that.
i fitted a brand new SBD nylon relief valve to the pump and it seemed to slide ok so wouldnt have thought that could be stuck .. unless swarf has got it stuck.

the oil pressure was at 40 odd PSI on cold start but it did significantly drop you could almost watch the guage dropping over the space of ten mins, i switched it off before it got too low as really didnt want it to do the bearings again.

yeah that could be a factor and oh yes i am using an oil cooler, one from an XE/LET standard vaux, currently plumbed in to the oil sandwich plate, wasn't sure if the lines had to go on certain way or not? i never checked it for debris unfortunately but clean did seem to flow through

Anniman: nope i havent altered the block in any way as was hoping for this build to be a good strong healthy standard engine running about standard power

[lee303]

sorry, didnt mean to imply 3 bar is "normal". i meant the deflated figures he is achieving are the same as a good 20XE at hot idle, its adequate pressure to push oil to the inlet cam bearings and lifters

or to put it simpler, only achieving 3 bar(or 2) its not the reason the inlet cam is dry.

looked at it yet danny?

[Danny w]

looked at it yet danny?

I've been out and blown the oil ways in the head .. the ammount of metal fragments that shot out was unbelievable. i now have oil upto the inlet cam.

but i still have very low oil pressure, think like you say its either going to have to be a complete strip down again or get a new engine built

[lee303]

bummer mate, hard way to learn a lesson sadly, it is very difficult to get the engine clean after a bearing fail as the bits are so small, time to have the sump off...

[steveboyslim]

Has the head been sealed to stop oil in the water problem ?
Either way it eill need a full strip and clean out all the oil ways, you may need to bin the oil cooler as they are nearly impossible to clean out.

Steve

[debeerd]

Maybe the oil pickup is bent a bit and not sucking enough oil up.
What you could do is drill 4 or so 8mm holes on the side of the pickup.
So that in case it is too low, it will still suck up enough oil.