Rover 4.6 V8 Rebuild questions

[debaron]

Hello all

Having some problems with the engine. Ticking/knocking on startup for a few seconds (not always - tends to be only after I've left it several days without driving) and oil pressure light stays on for the same time so I'm gonna rebuild the engine.
Checked all the usual - pressure relief valve and dismantled all the lifters and reset preload but still there.
I did the top end build on it originally so am familiar with that side of things but need a few pointers on the bottom end.

Hoping you guys can help!

- If I remove the pistons from the bores will I need new rings? i.e. can I whack them back in without losing compression? The motor is a 4.6 with uprated compression. Currently 195 psi at last test and is pulling good vacuum.

What can I reuse and what should I replace? Obviously the main and big end shells but been told the big end cap bolts are stretch and therefore one use only. Will be going ARP studs for main caps.

Any other tips and pointers?

Cheers

[Steve_D]

Serp or pre-serp?

If the compression is good I would leave the bottom end alone.
Your problem IMO will be the cam plus the oil pump if pre-serp.

Cam and pump can be done with the engine in the car so I would do that first and only remove and strip the engine if this does not work.
If you strip down to the cam and find it good (highly unlikely) you can make the decision then to go further and pull the engine.

Steve

[debaron]

Steve_D said:

Serp or pre-serp?

If the compression is good I would leave the bottom end alone.
Your problem IMO will be the cam plus the oil pump if pre-serp.

Cam and pump can be done with the engine in the car so I would do that first and only remove and strip the engine if this does not work.
If you strip down to the cam and find it good (highly unlikely) you can make the decision then to go further and pull the engine.

Steve

It's a pre-serp and unfortunately the big end shells show evidence of oil starvation so expect the same of the mains meaning the crank and pistons need to come out.

Just need to know if I can reuse the rings and pistons as is without compromising compression or the liners?

[PaulKemp]

I would compression test the cylinders, if all ok then you can reuse just make sure the pistons go back in the same bore and ring gaps are in the right position
To re ring with new you should also do a light hone to give the rings something to bed on

[debaron]

PaulKemp said:

I would compression test the cylinders, if all ok then you can reuse just make sure the pistons go back in the same bore and ring gaps are in the right position
To re ring with new you should also do a light hone to give the rings something to bed on

Compression test was around 195 for all cylinders (within 7%) so happy with that.

Is there a trick to getting the gaps back in the right place?

[PeterBurgess]

Stagger the ring gaps for peace of mind but remember rings rotate at approx once per 1000 rpm. Which means every so often all the gaps may line up anyway! Make sure you mark them for 'top'.

Peter