Whats involved in a Crossflow "refresh"?

[Big Brother]

There are loads of references to crossflows needing a "refresh", usualy at certain mileages depending on spec (Sprint, Supersprint etc) and amount of "blow by"

 

What is involved/done in a basic refresh?

I'm not talking about upgrading - ie forged pistons, cams etc, just the basic overhaul to keep the engine healthy.

 

any ideas?

 

Steve

 

"The original X-Power"

www.Se7en-Up.co.uk id=green>

 

[greg]

The Caterham built crossflows usually suffer from naf pistonitise - aka fitting a 1300cc design into a high performance engine.

 

They usually give up.

 

Hence the need to strip and replace the pistons - this usally would also need ends, and rings, and whilst you are there you might as well do the head ....

 

Talk to an engine builder like Roger King for a full run down of what a simple strip and refresh would cost.

 

Please take the above with a huge pinch of salt as I let Roger K fetle my new Xflow.

 

Greg, Q 86 NTM (Green 185BHP XF)

[I.Mupferit]

Steve,

 

The most effective re-fresh is to throw away the X/Flow and install a Zetec teeth.gif. Go on do it, you know it makes sense.

 

BTW are you going to the Phoenix next week, there is something (not 7 related) I badly need to discuss with you.

 

Brent

 

[Big Brother]

I was wondering how long it would take for the "throw away the X-flow and fit a Zetec, K-series, VX, BIKE ENGINE!, comment to surface wink.gif

 

Brent,

Hope to be at the Phoenix Wednesday so should see you there.

In case you cannot wait, you can always mail me direct.

 

All,

OK, so pistons and rings may (will) need to be replaced.

Possibly big end bearings too.

What about the block? Will it need re-boring or is a hone normally sufficient?

Anything else?

 

Steve

 

"The original X-Power"

www.Se7en-Up.co.uk id=green>

 

[greg]

Block depends, you could get away with a hone (depends on previous use).

 

Whilst you got the engine apart, would a new cam not be nice (and followers) ? Whilst you there you might as well get the head done, oh and theres always another bit .....

 

Greg, Q 86 NTM (Green 185BHP XF)

[Jimbo]

My Xflow was suffering from massive pressure in the crank, so I assumed excessive blowby the pistons. I fitted new pistons with rings and whilst doing this realised what a state the head was in - gasket was blown and valves were touching the pistons. So I fitted a new (unleaded) head. All work was done without removing the engine, including a hone with a tool from the local motor factors (NOT halfords!).

Hard to say whether the pistons or head did the trick but the engine is now fairly sweet. Not quite in the 2 litre Zetec level of smoothness, but rather the repairs were cheaper and easier!

Throughout I got excellent advice from Steve of Vulcan engineering.

 

J

[oilyhands]

Xflow pistons are very tall above the gudgeon pin and carry a lot of their weight there too, its likely that this will create a fairly defined lip / ridge at the top of the bores, if you are buying forged pistons (which come with rings) then it doesnt make sense *not* to bore the block to the next / largest available oversize commensurate with its capabilities. A refresh would normally be bearing, rings, maybe timing chain and oil pump, valve stem seals and any other perishables that have suffered, that said an engine is a can of worms and you never know what you may find once you start to strip it. If you are just re-ringing then a hone of the bores (provided they are withing spec.) and for new bearings a polish of the crank journals will suffice.

 

Oily