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M50 nikasil block? (archive)

[ Follow Ups ] [ 5-series (E34) Message Board ] [ Msg. Board FAQ ]

Posted by WillO on November 03, 1999 at 18:29:26:

In Reply to: Re: At $100 hr I would have to moonlite. posted by Pete on November 03, 1999 at 12:27:30:

: ly well , can I check anything without booking it into BMW dealer , who here in UK charge equivalent of $100 per hour , I also have hesitant oil pressure from cold , maybe 2-3 seconds before oil light goes out , together with top end rattle , which dissapears when light goes out....(218,000 miles)...look forward to hearing..

: : When you first start up a cold motor the oil is thick and takes a while to get up to the head. A hi miles car may have a little wear that may prolong the time it takes oil to get to the head where the tappets may rattle a bit. Not a big problem. Try a synthetic oil to help this. Synthetic will get up to the top faster. Here in Pennsylvania, USA we have Castrol Syntec, the 5w50 would do nice. 2-3 seconds on the lite is a bit long but then the sensor may be a bit lazy after a billion miles. The hunting of the cold motor might be due to being in open loop on the Motronic while the Lambda sensor(O2) warms up. Throw in a little vacuuum leak and it hunts more. AND throw in a little extra blowby gas into the crankcase from a well worn set of rings and the car's Motronic will swing till it switches to closed loop and the Lambda takes over. The 5W50 synthetic would be my recommendation and find the little vacuum leaks. Probably turn 300k!

: : Will
: : 91 525iA
: : 88 325iX
: : 85 K100RT

: Will , hi my friend , ok I`ve read your response carefully and I must say it makes a lot of sense , I am currently running Total 5w 50 race oil that I get from work , before this I had castrol Magnatec , I didn`t notice much difference , I get different symptoms from day to day with the hunting , some days I start from cold and it performs seemingly better than best , another day she wouldn`t pull your forskin back....Also , I get a real hollering noise from around the inlet manifold which I presume is plastic , at about 3000 revs , and you can rev through this , dissapears at around 4000 , .....I really love the car , and she drives like a 50,000 miler , so I`m desperate to get it all sorted....thanks for your time Will , feel free to E-mail..

The plastic manifold has a different resonance than the aluminum which has little. There is noise associated with the manifold but a "howl" might also be where you have a vacuum leak. Put mild stress on the manifold with your hands and see if there is a change in the noise as you rock on the manifold with your body weight. Not to much stress/weight! And take a good look at ALL the hoses. Really look, then look some more. Check out the o-ring at the crankcase vent, wiggle it. Replace if suspect.
Keep looking for deteriorated hoses, look some more. You have an Aluminum block? Me thinks you do. There were aluminum blocks in the UK on the 2.5 ;there is a bit of a bugaboo about nikasil alloy blocks. Check locally with a dealer or a reputable source in the UK about the 2.5 alloy block. There was some remediation from Bmw if I am not mistaken. But again check locally.


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