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pistons burnt cooked.

A

altatlock

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Hi first for me burnt 2n3 pistons,took head off my 67 ol 4 thinking it was valves did compression test 85 to 3 not good,head off slight damage to head,so looked into engine,could not be mice,something had been eating piston crowns.To rich mixture petrol to air,I tuned car,soon after purchase obviously to late,never mind. Can anyone advise on pistons availiability someone mentioned bmc is that a poss,renault mad thought he had heard that that was a cheaper option,ears to the ground buddies,thanks.AL
 
Is your car an 850 if so Tony Toplis has three new pistons and two new liners.
Contact him on 01476573212.
 
Hi ,Thanks for your response,I am not a mechanic so I am treading carefully as to whether or not you can just replace an odd piston ,or the lot and if pistons vary in size and weight shape.But hey am enjoying getting my hands greasey,I am about 4 bolts from taking the body off my 69.4 so my play area is getting a bit cramped,did not expect this problem to crop up. Well thanks again for help will keep you posted,by the way I wasin gosburton lincs last week have old friends up there,nice part of the world.Best Alan
 
Pistons

Personally , I wouldn't change a single piston because of weight and compression differences. A quick look at French eBay shows a set of 747cc pistons and liners for 150€ and a set of pistons,liners and full gasket set for 200€ , neither of which is extortionate in my view

I would prefer to start afresh so that you don't do all that work and then find the engine runs like a bag of spanners !

Having said that - many years ago as a student, I did once replace a single piston on a V6 Lancia Aurelia with a spare piston. I balanced it by adding weights to the inside of the gudgeon pin !! It ran for years and was remarkably smooth ..... so never say never !
 
We are not talking racing engines here ,it was quite common for dealers to replace one or two pistons.
Not ideal but much better than an unusable engine.Tony was looking for about £30 for the three.
I dont think we established whether they were 750 or 850 pistons.
I have two full sets of original renault 956 But they are only in the later cars and not often used in the UK.
Gary
 
Hi All,thanks for your intrest,nothing quite like moral support.Shes an 850,picked up a block n tackle today so work is in progress as well as confidence.Last time I stripped an engine down was an E93A ford flat top, guess that dates me? I have always had my best friend who was an ace engineer do most of my work with me.Sadly the ciggies took him last year ,but he gave me all his tools and he sits on my shoulder when I get the spanners out advising. Keep you posted Alan.
 
I know how you feel I had never taken out a front wheel drive engine until the R6 a few months ago.Just follow the book and it is easier than you think.
Always make sure you keep everything very clean particularly the seat for the liners.
Gary
 
If you can't find them anywhere, I have a genuine piston/liner kit suitable for the '67 845 cc engine. Be aware, pistons and liners for later engines (these fitted with timing chain) are not compatible with yours as they have press fit 16mm piston pins (earlier ones had fully-floating 14mm ones).
 
 
burnt pistons

angel said:
If you can't find them anywhere, I have a genuine piston/liner kit suitable for the '67 845 cc engine. Be aware, pistons and liners for later engines (these fitted with timing chain) are not compatible with yours as they have press fit 16mm piston pins (earlier ones had fully-floating 14mm ones).
Click to expand...

Hi Angel,my engine has a timing chain,am not sure of the exact date of car 68 on paperwork you commented that it had an earlier type suspension when supplied me with the drive shaft,the car is french built lhd first reg jan 68 I have the full service history.Thanks for your interest the liners are firm in there beds,and the bores are unmarked was thinking of just clamping liners,a light hone and fitting new piston n rings what say you.By the way sold my Flaminia,room for 2 more renaults.best Alan
 
Flaminia

I am being "encouraged" (her indoors) to sell one of my 4Ls to make way for an Aprilia - very difficult to decide which one has to go !

Good luck with your engine rebuild
 
I would love an aprilia have been tempted,but practicly no, my flaminia owned for 37 years did approx 650 miles,being builder used pickups vans,her indoors was a bit intimidated,very heavy steering,convertable,didnt like wind in her hair,had bmw,s for years with sunroofs never opened.CHRISTINE as she was called<steven king> was sold with 10 k on clock,will be sadly missed.My renault has seats removed and is my day to day truck,bales of straw n dogs in back ,I plan to restore my 68 4 to near perfect soon as no 1 renault is back on road.Coming over to Montmorillon on 3rd in Mehari to do a few jobs before winter sets in.Enough of me trust your well,bestAlan
 
Those pistons look OK to me from the photos. Plenty of carbon on them fair enough but that comes from the petrol when it's running rich. You'd need to remove that carbon to see any piston damage. No reason to replace pistons unless I'm missing something - is it melted pistons not carbon I'm seeing?

You get a bit of carbon on top of pistons especially if the engine has been running a bit rich (poorly set up in the past maybe). You could scrape it off but be very careful not to put any force on the liners and definitely don't turn the engine over as the liner seals at the bottom will pop out and will need to be replaced.
 
simonandjuliet said:
I am being "encouraged" (her indoors) to sell one of my 4Ls to make way for an Aprilia - very difficult to decide which one has to go !

Good luck with your engine rebuild
Click to expand...

pics of my renault n flaminia being prept for mot
 
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It must be one of the very early timing chain engines (duplex chain maybe?) because I see the early distributor clamp fixing. And these pistons should be 54mm (747cc) as they have the hump on the crown.
Are these tiny gaps at the piston circumference broken off the piston, or just carbon deposits chipped off?
 
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