View Full Version : Low Oil Pressure
nova_saloon
23-04-09, 09:28 PM
Posted a thread yesterday! Basically as i said in the other one, its been tapping alot and it take a while for the oil pressure switch to turn off! Changed the oil and oil filter today to see if that would help and also fitting an oil pressure sender unit for the dash as the other one didnt work, and turned the car on and it sat on no pressure for a about 10 seconds then jumped up to normal after getting in warm it dropped down to under a quarter of pressure!!! but as soon as you mova away it builds up perfectly fine and will go to the other side of the dial. Any suggestions or help, i hoping i dont have to change the pump, dont really want to do that
chimp007_uk
23-04-09, 09:35 PM
dodgy sender and the dials are rarely accurate lol
nova_saloon
23-04-09, 09:43 PM
dodgy sender and the dials are rarely accurate lol
Highly doubt it in this case becuase the oil light does come on and it taps like a biatch! on start up for a wee bit
chimp007_uk
23-04-09, 09:47 PM
Highly doubt it in this case becuase the oil light does come on and it taps like a biatch! on start up for a wee bit
You didn't say the light was on...
Tapping from cold could be lifters if there is low oil pressure then they will pump all the oil out of them and be loud! My xe the other day was loud for 3/4mins as i hadn't run it for weeks.
Best do a wet and dry compression test and check the rings and head gasket. Is it burning oil? or breathing oil through the breather?
nova_saloon
23-04-09, 10:07 PM
I've done the breather mod and cut away that plate at the top. its not burning oil. Quite leaky unfortunatly though and well sometimes i can park up turn off the engine and then i start it literally a minute later and it will tap for a second! but it shouldnt be this bad, i dont perticualrly want to change the pump on it! will try and have a look at the valve next week. Not sure how good the head gasket it, the head was recently rebuild before i bought it so i would of thought they would of changed it then. But thats before i stuck it in my nova. Not sure what to do!
chimp007_uk
23-04-09, 10:11 PM
low pressure could be pump or rings, stem seals would have to be seriously bad to be like that!
I'd do a compression test!
novaguy08
24-04-09, 10:47 AM
if oil pressure is nothing then jumping up, it could be a case that the oil pump gears are wearing out......... dont engage till it warms up due to expansion....... sounds a bit far out there but if they worn out and there no pressure its possible
steg1970
24-04-09, 02:54 PM
Sorry to be the one to break this to you but this will be the main or big end bearings in the bottom of the engine. You will need to replace the bearing shells and re-grind crank.
I've had a number of vauxhall rally engines and even the standard engine in my Impreza road car go in exactly the same way.
Bottom end rebuild i'm affraid.
and re-grind crank.
May not have to, depends how the bad the shells have gone. Its VERY common to not have to regrind the crank.
Sorry to be the one to break this to you but this will be the main or big end bearings in the bottom of the engine. You will need to replace the bearing shells and re-grind crank.
I've had a number of vauxhall rally engines and even the standard engine in my Impreza road car go in exactly the same way.
Bottom end rebuild i'm affraid.
lol
WTF???
Its probably the pump is a bit tired or the relief valve is sticking - if it was anything major it wouldnt get better and would probably get worse as teh oil warmed up and became thinner...
Dont listen to any of the abovelol
he's talking about long tapping with the light in...
iirc the light comes on at 0.5 bar... its not an oil lamp, its a to late lamp.
btw, my old XE was ruined from running without oil (something with a Fcuk airride attitude and a big bump in the road...) and when i put a new sump on it, she tapped on cold, but was silent after about 10 minutes. she was about as fast as a c12nz, but she didnt tap.
nova_saloon
24-04-09, 05:05 PM
lol
WTF???
Its probably the pump is a bit tired or the relief valve is sticking - if it was anything major it wouldnt get better and would probably get worse as teh oil warmed up and became thinner...
Dont listen to any of the abovelol
wasny going to, th reason the crank would need a rebuild is if i drove it and ragged it with no oil pressure, which is a bit silly
Guderian
24-04-09, 06:05 PM
Normal Oil pres listed in the haynes manual i think. If you have noises and low readings at high temp and/or low rpm's then bottom end problems or oil pump failure (or both) may exist.
As has been suggested, piston or piston ring wear (and head gasket failure) have no effect on oil pres.
I have had cav and astra engines apart, i assume this is the same and the oil pump sits on the front of the crank (and is powered by the crank)
As you know already, often economics (and your valuable time) can mean that an engine transplant is often preferable to a nut and bolt rebuild.
iirc it was a c20xe?
oil pressure should be measured with a warm engine on iddle. it should be 2.5 bar.
nova_saloon
24-04-09, 10:49 PM
yeh is a c20xe i can only use the dial on the dash which can be tempremental, will get hold of one and let you know, held it at 3,000rpm to see if the oil would fill the tappets and oil pump would kick in and it did after abotu a minute, was rather confused about that and then after that the oil gauge would read just over a quarter on idle! sound right to anyone?
how was the oil you replaced? and is the new oil still looking new? no metal in the old oil?
when you hold her on about 3000/4000 rpm, do you hear any tapping sounds from the bottem end?
nova_saloon
25-04-09, 11:12 AM
there was a lot of noise but was all coming frmo the tappets, and no metal as far as i know, but when i get home i will run a magnet through the old oil to check. yeh the oil is still looking good once i done it and it stopped tapping drove about 150 miles and ive just checked the oil and its golden, and started it afterwards no pressure on tick over then after about 10 seconds gave about 2,000rpm and it got oil pressure and quietened down. sounds like a tapping on the underneath but its not that loud really.
nova_saloon
25-04-09, 11:37 AM
not sure wether the oil pump has gone or just the relief vavle is sticking, and now got me worried about my main bearings
nova_saloon
26-04-09, 09:40 PM
did valve still ****ed well upset. everyone die
what make and grade of oil are you running?? if it is too thin, it will do strange things
I don't think there is anything daft like a non return in the filter on that engine is there? some engines need filters with them fitted, but I am no expert on xe engines
nova_saloon
26-04-09, 10:05 PM
what make and grade of oil are you running?? if it is too thin, it will do strange things
I don't think there is anything daft like a non return in the filter on that engine is there? some engines need filters with them fitted, but I am no expert on xe engines
10w40 semi synthetic, basically on wednesday i started it went to work stop tapping once drive way was cleared get to work, (on flat) at break went to move the car started up started tapping for a second and went, then when i went to go home started tapping, but then wouldnt stop for a whole 10 minutes with the oil light on the whole time! then has done it since, but hold it at about 3000rpm it will suddenly get pressure and then will keep pressure after that, but exactly high, but sumetimes it might be fine for about a minute. took the valve out cleaned it, put it back in today started it up still no pressure and tapping and couldnt run it for to long as it was noisey and late so i just left it with no pressure!
ok. oil pump is pretty much shagged then. or the strainer is blocked up with crap. a replacement gear set isn't too much money, but the work is a bit of a pain. I think you need to take the sump off & have a poke about.
my mum's mk1 astra did something similar a few years back, and she gave me it. I found out the screws holding the plate on the back of the pump had come loose. it never ran properly after i sorted it & i used it till it was too rough & weighed it in.
nova_saloon
26-04-09, 10:16 PM
was thinking of just replacing the pump, but its tight in there and its hours of work that needs to be done and im worried that ill put it all back together and then the bearings will go so then i will need to do that and the oils seal will go! just fed up at the moment, and tis not easy as its my everyday car!
I cant believe you are still driving it - wont be long till your bottom end has enough and spits its dummy!
:roll:
Replace the pump or at least have a crack at the relief valve.
kent14sr
27-04-09, 10:44 AM
Oil pump - had similar problem myself not so long ago. Take the warning signs and replace it before the damage is serious!! (if it isnt already)
if it was running with the light on, youre pretty much F*cked. the light comes on when pressure is under 0.5 bar iirc.
when doing the pump, you already have the sump of, so its only 2 bolts to check a bearing. and dont use the old bolts for the bearingcap.
I bet someone put the sump on with a load of dodgy sealant and the pickup is blocked up.
Get the sump off it and have a look instead of hoping its going to go away!
Guderian
27-04-09, 05:57 PM
Agree with Lee, drop the sump and also open a big end bearing while you're under there. If it's ok check the next one. If it's wiped itself out on the crank then that makes your next decision a little easier.
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