Fix The Head Or Change The Engine???

Before I start, theres nothing wrong with the R, its my Clio DCI but its a general query so principals are the same.

Got mega compression issue in one cylinder and waiting to get a leakdown test done, or find someone that has a leakdown test kit first would help lol

Taking worst case scenario and its piston rings etc instead of sticky valve etc, would you redo the head or would you get a new engine?

Can get an engine for 525 and it fitted for 700 (havent shopped around too much) but its just the bare engine and have to transfer all my existing parts like manifolds, injector pump, starter, alternator, turbo etc over to the new engine. My thinking is that if I am changing the engine bits to a new block, I may as well get a new block (or in this case a redone block) instead? Chances are the new engine may develop the same fault miles down the line anyway.

Is my thinking sound or flawed?

If it was me i would just replace it with a different lump ..... most of the engines up for sale have most of it still attached ie pump inlet  just missing ancillarys like starter motor alternater and turbo wich isnt really that hard to swap over .

First off. If its ringlands on the pistons that's gone, its not the head that needs work  
Pistons are in the block.
It will be cheaper to buy a good used engine than rebuild the knackerd one.

Is it the 1.3 ? To be honest with you by the time you pay for a leak down test either you buy one or get a garage to do it then strip it either way new headgasket  new headbolts skim the head and carry out what work that needs to correct whats wrong you might aswell grab a good second hand engine give yourself 2 days to do it if its your first crack at doing a swap .

Cheers for that. Gonna run an engine an flush when I get it back and see what that does. Garage where it is, apparently independent renault specialists, didnt even advise or try that first, just went str8 to leakdown test.

Spoke to Renault dealership and he advised do an engine flush first and see if that fixes/eliminates sticky valve issue.

Heres hoping.

Tbh i would of done the leakdown test as this will tell you more then a comp test and pinpoint more where it is  ...so i wouldnt of said the garage was  not far out in there assumptions on doing it if you can have more of an insight into the problem then you have more choices in your next step of action .

we had a 1.5 dci in work, it would spin over with low compression and not start, customer was told new engine needed.

spray in some easy start and eventually it would fire up!

we added a can of engine flush, run it, drained it.

re-filled with 4L of Flushing oil, and drove it hard for about half an hour.

drained this and filled with new oil/filter.

and its been fine since, and completed another 20k miles.

we believe it was stuck piston rings but wont ever know.

yep as suggested the other day steph, get a leakdown test done so as to determine whether in or ex valves leaking or bottom end prob with pistons / rings

on those the lifters tend to jam up after a while so valves may not be opening correctly and a flush through with paraffin/oil mix could possibly cure the problem

Engine flush is way to go but doing the leak-down test will give you an idea on what you are attempting to cure.
I never bother with used engines unless one in question is seriously bad or parts an issue.
Never know what you get with used engines, if you got some experience & a good machine shop you get a real good known engine, buying used & even rebuilds is a lottery ...

You can buy a leak down tester for around 120 quid  mark .

or make one from an old spark plug

Well, after speaking to Renault and doing the engine flush, not only is it running better (still smoking but nowhere near as much), but the coil warning light is now off as well.

Will see how long it lasts but looking better anyway

yep could well have been the lifter oilways blocked
the chances are that the piston crowns and combustion chambers on the head are garmed up in oil/carbon deposits now so will take a while before it clears

get some injector cleaner and pour a couple of tubs in the fuel tank with a full tank of fuel and take her on a good run so everythings nice n hot, you may find that will sort it out

On the one i did it took 3 engine flushing sessions to cure it