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Engine re-build or not?


Sideways Tim

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I'd like your advise please chaps. '72 MKIV Spitfire with original engine - done 125k (probably) no idea if the engine has been re-bearinged at all during it's past life. I had rocker oil feed issues last year resulting in seized rockers - cured with a new oil pump and an external oil feed (metered). Since  then it has run fine - Le Mans and back including 4 hours non-stop up the motorway from the south coast to home and not missed a beat.

My worry is that oil pressure has always been on the low side, circa 5 psi at idle when hot. I run Morris's 15/50 Motorsport oil and the engine seems perfectly happy.

I'm off to Italy in June - about 3000 miles and want to make sure we get back, so my question is this - should I just crack on, or should I strip and rebuild the engine before we go?

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Hello Tim,

too late now but you could have checked the bearings when you fitted the new oil pump. What oil pressure do you get at cruising speed, say 3,000 rpm hot. And is the oil pressure gauge accurate? The other clue is whether the engine is quiet or not?

Alec

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Hot oil at 3K rpm and the gauge reads 40-50psi. No idea if it's accurate though!

As I say it all sounds ok to me, I occasionally hear a bit of a rumble and the cam followers were pretty worn when I re-built the head shortly after getting the car. Perhaps I'm reading too much into it and should leave well alone.

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I used to use cheapie oil,either of these two.
Whatever was on special offer !!

After a long run my oil presure at tickover was this with the oil light flickering

I now use "millers classic sport 20/50"

My oil presure after a long run is now

I could not belive what a diference it made
Use a good oil !!  

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5 psi at idle and 40-50psi at 3k suggests a worn bottom end to me.  Should be 40-60 at 2000 rpm (book figure) and 10psi + hot idle.

This doesn't mean it's about to give up though it is worth bearing in mind that howling down European motorways for hours on end not to mention driving over the Alps is a fairly severe test.  Gauges do also vary so might be worth trying another.

Wynns and STP both make excellent oil additives that prop up sagging oil pressure and reduce oil use.  Wynns has seen my Vitesse through a couple of 10CRs now! (more oil-use than low pressure though).

Nick

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my self, first thing is new oil filter, as if its blocked, ye only getting by pass pressure.
2nd is oik the PRV set up out, and clean up, / lap in, as there may well be crud sticking it open a wee bit.
years ago  one of  mine was low, and a good re lap/ clean oot, saw the gauge go up over 15 psi at hot oil temp.
any thing but a 20 weight  +  oil will give low pressures too.

M

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uksnatcher wrote:
Might be time to treat it to a new oil pressure gauge, sounds like your worry gauge may be reading too low.


That would be nice :)


Nick Jones wrote:
Does it rattle when started from cold? (until oil light goes out).  Again not necessarily terminal but an indication of wear.

Nick


Maybe, just a little bit, when it thinks I'm not listening.

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Nick_Jones wrote:
Does it rattle when started from cold? (until oil light goes out).  Again not necessarily terminal but an indication of wear.

Nick


Mine does, but it's got the best pressure it ever has now. I've convinced myself it's big lumps of STP moving around in the sump until it gets warm and melts.   ;D

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