Worn big end/main bearings?

[itchyfeet]

I have a bit of a rattle cold idle, it's soon gone and I can't hear it hot, could this be big ends or do they tend to rattle all the time?
It doesn't sound like your typical tappet rattle but it could be tappets if only cold, the question is could it be big ends?

Oil pressure is a bit low hot but has been consistant for a year as has the rattle on cold idle.

cheers
Paul

[Titus A Duxass]

As far as I remember big ends tend to give more of a grumble/rumble than a rattle.
And the oil pressure light will take sometime to go out and could flicker at tickover.

But it's been a long tiime since I have heard an engine with big end issues.

[123-jn]

I would say a rattle on cold idle is more likely tappets due to the low oil pressure taking time to fill up. The only engine I had with big end trouble was a Ford 1.6 cross flow in a transit which was ok cold but as she warmed up the oil light would come on at tickover and flicker up to 1500 rpm before going out. Under load it knocked as you pulled away , that was the big ends. Quite a heavy knock, the mains rumbled at tick over again due to oil pressure. Once you were cruising all was ok until you came to a hill or tried to speed up!!! (luton body very heavy!!! almost 200,000 miles)

[123-jn]

Thanks for the jelly trifle. Lovely Not quite a Fraud transhite though.

[silverbullet]

Piston slap when cold.
Loose little ends rattle when hot.
Mains rumble, big ends knock at higher rpm.
DJ I had that blew a big end had 50psi cold cranking oil pressure but sounded just like a Mk3 Tranny diesel over 2500rpm.

[itchyfeet]

Interesting thanks sounds like not big ends then which is good.
I did wonder about pisoton slap.
I think I'm going to reset tappets first and do a compression check.
I heard some awful noises coming from tappets before

Is new tappets on an old cam an option or will the new tappets chew up the old cam bedding in?

[silverbullet]

The tappets are glass hard, the cam is less so, especially once the hard skin on the lobes has broken through.
New tappets seem to have a generous chamfer on the working end, oem were a lot crisper but it shouldnt matter on a std engine.
I would measure the valve lifts and see how bad the cam wear has become before spending good money on an old wheezer.

[itchyfeet]

Checked timing and compressions today, up at 11.5-12 bar warm, I did swap heads a couple of years ago.

I'm leaning towards tappets being old and a bit noisy ( they always have been) it was reconditioned about 80,000 miles ago but who knows how well and maybe tappets were not replaced.

I also once lost the sump plug and oil on a motorway which is why I'm always suspicious if engine noise.

Think I'm going to chop out push rod tubes fit big mouth and tinker with swapping tappets to see what happens.

[itchyfeet]

Reset tappets today, that was harder than I thought.
Done it before when engine out and heads have been off but never done it on an installed engine.

Needless to say it would not start, no compression, I guess time is needed between the adjustment and trying to start to allow the tappets to bleed down from the preload which opens valves killing comoression.

Went to 1.5 and then to 1 turn and still would not start.
Waited a bit, turned over by hand a few times and eventually could hear compression.

Started eventually but rough as, as it warmed up back to normal..
Compression test shows its now OK.

Road test tomorrow.

[Bubble Meister]

And.. how was the road test?

[itchyfeet]

And.. how was the road test?

Ok but noisier then when it was 2 turns at idle.
I need to do it again but what I learned is you won't be able to start an engine straight after preload some time needs to elapse.

Another strange thing of note is that the tappets were all set to two turns when heads were last off.

When I looened them off I counted, cylinders 1 and 3 were 2 turns, cylinders 3 and 4 were over 3 turns. I mused over how that could be, surely they should be virtually no turns or valves would be open?