24 replies to this topic

[GraemeC]

I always thought, and I'm happy to be worng, that the oil filter was on the 'wrong' side of the pump (ie after it in the direction of flow) in the a series?
If so then a magnet in the filter will only collect the bits that have just knackered the pump!

[Guess-Works.com]

Yes, but the theory is... the pump is a fairly robust item and with even deep scoring/wear still functions to some extent... the filter prevents the realy small particles getting into the mains and big ends, which is realy where it matters...

Never thought too deeply about it, but is it better for a pump to push or suck oil through a filter ?

[GraemeC]

Good question.

Mine does both

[nomininolife]

I did see a few years ago, a ring of magnets that were attached around the oil filter. I dont know if they still exist, or if they work.


David

[Jamie]

thanks guys, I think i'll get a replacement from minisport as suggested, i think its better safe than sorry really.

With regards to the pistons if i have the bores honed will i need a bigger set of piston rings or just the standard ones???... Also can the cam bearings be pressed in/out without having to take it to a machine shop????

thanks for your help.

[nomininolife]

There should be some numbers stamped into the top of the piston, if you dont have a '+' figure then they are standard size.

The cam bearings are machine shop only, they need pressing in then 'line boring'.


David

Edited by nomininolife, 31 January 2007 - 06:00 PM.

[Sprocket]

Nope!

If you need to line hone the cam bearings your doing something wrong!! And its not as easy as just knocking them in. For the price of getting it done at a machine shop, its not worth the worry really. I'll be very honest and say that if the cam journals are not scored and is still a good fit in the bearings, just leave them alone.

A deglazing hone will not require oversize pistons. Best to use a new set of rings though for the pistons you have, whether oversize already or still the originals. A hone like this really depends on the severity of wear, id have said at 60thou miles there will be a slight ridge at the top on the thrust side of the bore. Run your nail up the bore, if you are able to feel a change right at where the ring would stop, then there is wear. Take this advice though, if there is still a ridge at the top after a hone, fitting new rings may cause the top ring to fail. What happens - the original rings and bore wear together. A new ring will be a different shape, will hit this ridge and possibly break. Half the answer to this is keep the original top ring. If the bore wear is slight, a hone may remove this ridge altogether and a full set of new rings should be used.

As for honing yourself, my veiw on this is get the machine shop to do it, that way you know the angle is right which is critical to ring seal and lubrication.

Edited by Mini Sprocket, 31 January 2007 - 09:14 PM.

[Sprocket]

Personally I've never used one.... mainly because the last thing I want to be doing is introducing a potential blockage into the oil feed...

Thing is though, how much C**p do you get off the sump plug?? certainly not so much that would block this passage. Also there are now two magnets to trap the C**p that only one magnet used to, so half as much on each. This extra magnet should be cleaned at the same time as the oil is changed and with the majority of people recomending changing oil at reduced intervals, i dont see it as an issue.

As for fitting a filter before the pump, all well and good if the filter doesnt pose as a restriction. As the filter works, trapping crud, its resistance increases. On the suction side of the pump, this reduces the pump suction further below atmospheric so the pump now has to work harder to lift the pressure to the desired level and will wear quicker as a result, not to mention potential for air leaks reducing oil pressure and pump capacity. Also, if the filter head you are using does not have a bypass, there is the possability of the filter colapsing when he filter becomes restricted, but then you shouldnt let it get that bad.

Personaly pump pre filter is not such a clever idea and dont know of many aplications where this is the case, and this applies to most heavy machinery lubricating systems. A screen is ALWAYS before the pump, removing potentialy pump destroying particles, and the filter is ALWAYS after the pump to remove the finer particals that would damage the soft bearings. Oil pumps have hardened roters that can withstand the abuse from these fine particles.

When has the filter after the pump ever been a problem when its serviced regularly?

Pre filter is overkill if you ask me

Edited by Mini Sprocket, 31 January 2007 - 09:39 PM.

[Big_Adam]

on magnets.

I used a big ass one from a record player and stick it to my oil filter housing. Crashed and bashed over things and it's still attached to the outside of the filter.

[fikus01]

trouble is at that point its still gone thru the pump, i can see merits in it i guess but the filter shud do that anyway!