Leon 24 Posted April 3, 2006 I've been suffering from low oil pressure on bends and under breaking a lot more recently. Just as a test, I tried accelerating whilst the light was on.... just to test my theory. Sure enough, the familiar big end death rattle. So I whipped em out today and put in a new set. What a tedious job, the sump is the worst bit by far, the rest isn't too bad just repetitive and messy. Considering the engine has done 200,000 miles with no rebuilds etc they aren't as bad as I expected. Okay so maybe that's a bit of a lie, there was a huge amount of pitting on every bearing, as well as plenty of other damage. This is the first time I've attempted this with the engine still on the car. What a mess! Almost impossible to keep anything clean, grit flying everywhere.....yuch. Not something I wish to repeat. I've taken it gently round the block, thrown it round a few sharp junctions with no notable loss of pressure. Pressure is also higher at idle too. The engine sounds and feels sweeter too, so it was worth doing even if it only settles my nerves for a few thousand miles. Share this post Link to post Share on other sites
matty_gti 20 Posted April 3, 2006 hi, ive got low oil pressure when it idles and when i put my foot on the break it travels a far bit with no resistance so i release and try again then i can feel it breaking. Is this what you had beofre you changed the shells?. Share this post Link to post Share on other sites
Leon 24 Posted April 3, 2006 hi, ive got low oil pressure when it idles and when i put my foot on the break it travels a far bit with no resistance so i release and try again then i can feel it breaking. Is this what you had beofre you changed the shells?. No, I was getting low oil pressure on roundabouts, corners (even Motorway ones) and when I braked hard from high speeds. At idle the pressure was always low but not critical, it's gone up a notch and a half on the guage since I did the shells though. Share this post Link to post Share on other sites
eddie_1.9 1 Posted April 4, 2006 I've never done this before but thought the engine had to come out and then flipped upside down and the crank removed to do the shells. I can see that the bottom shell is accessible by removing the big end cap/clamp but how do you get to the top shell with the crank in position? Share this post Link to post Share on other sites
Leon 24 Posted April 4, 2006 You give the big end a tap to loosen the end cap - once this is off you can get one hand each side of the crank, reach up and push the piston upwards, and then to one side. When it's at one side, you can pull it back downwards to fit the new shell. When you're done you can push the piston back up and pull it down central over the crank, then refit the cap. Be careful because sometimes the rod "locks" at an angle and won't move side to side but with a bit of gentle persuasion it should go back staight again. All this is much easier if you've stopped the engine with the valves slightly open, or you can just remove the plugs. To get them where I wanted them (bottom dead centre) I grabbed both road wheels at the same time and turned gently with the car in 5th gear until 2 & 3 were at BDC, after those were changed I did the same so I could reach 1 & 2. Hope this helps. Share this post Link to post Share on other sites
smckeown 1 Posted April 4, 2006 i have always wondered how worn bearings have such an effect on oil pressure. Anyone care to explain it to an engine novice... Share this post Link to post Share on other sites
Martin@PRD 0 Posted April 4, 2006 (edited) Nice catch Leon you will find, the shells dont look that bad. Ive had the same problem with my 8v though didnt know untill I lifted off around 6k from hard counering, sadly its knocking its tits off now, I just hope I havent spun a bearing or damage the rods. Anyway here is a Mi16 big bearing (nearest flywheel) Edited April 4, 2006 by Martin@PRD Share this post Link to post Share on other sites
Leon 24 Posted April 4, 2006 Christ almighty Martin, that's what you call "knackered" Makes mine look mint! Will be interesting to see if my oil pressure remains at it's new higher level when the car is fully run in, but the oil light hasn't come on once since I did the job, and it used to come on at almost every corner before I did the job (still driving slowly - I only cane it down the lanes at night) Only bad point is I now have a leaking sump. Typical! Share this post Link to post Share on other sites
Sam 4 Posted April 4, 2006 i have always wondered how worn bearings have such an effect on oil pressure. Anyone care to explain it to an engine novice... My understanding is that the bearings are under constant pressure from the oil pump, if they are worn the oil can escape, meaning the pressure is lower? I'm probably way off though. Share this post Link to post Share on other sites
cybernck 402 1 Cars Posted April 5, 2006 No, I was getting low oil pressure on roundabouts, corners (even Motorway ones) and when I braked hard from high speeds. i get this when i'm running ultra-low on oil, but not otherwise. Share this post Link to post Share on other sites
B1ack_Mi16 67 Posted April 5, 2006 The oil-pump is only a feed pump for oil out to the bearings, the hydrostatic loads is taken up by the oil-pressure generated between the bearing and the crank journal due to speed difference (rotation) of the crank. More/less bearing clearance will influence on the load capacity, this will also be influenced by choice of oil viscosity. Share this post Link to post Share on other sites
