misfiring scenic

[petercee]

Hi, you may recall back in Jan this year i mentioned the problem i had with my 1999 scenic 2 litre 8 valve engine, it started misfiring and clattering , we managed to get it home, where it was diagnosed as no compression on cylinders 1 and 2. i sold it to a mechanic,who i was talking to yesterday, curious to see if he solved it, yes, it had 2 collapsed pistons, at 141000 kilometres. it had never exceeded 100ks per hour ,used no oil ,never overheated while i owned it, he put another motor in it. do u think this is to be expected at that mileage. i hope not

[jo proffi]

Originally Posted by petercee

...... it had never exceeded 100ks per hour ,

Ive never heard of a renault suffering collapsed pistons, mind you I've never heard of a renault that doesn't get a good floging from time to time either, so maybe there is some relationship between it being driven so gently and the motor failing.

Jo


PS I'm not saying it is the mechanics fault......But.......I cant help but think something is smelly.

You have a valuable car that you take to him for oil changes.

All of a suden your car fails in unusual circumstances. (please dont say it was shortly after a major service)

It is diagnosed as being stuffed and the diagnosing mechanic buys it off you, cheap as chps no doubt.

The mechanic fixes this problem and sells the car (I guess)

Take a good look at who is the winner and who is the loser in this relationship.


Jo

[petercee]

now thats all cock and bull, the mechanic that bought the car, bought it on trade me, (like E Bay) he had never seen the car before, and certainly hadnt worked on it, he lives in another area. i also saw the old motor with its colapsed pistons, and no it wasnt after a major service either, it had been serviced previously at the authorised renault agent yes, about 4 months previous, oil change, filter, so i guess we need to be carefull about such asumptions. the guy that bought it on trade me is a qualified European mechanic that works on BMWs, hes also worked in Europe on Renaults, and its not so uncommon at all, collapsed pistons are not usually a fault of servicing, what could they do, its a fault of the engine manufacturer, like the electric windows, the moon roof, the fires in the wing mirrors etc etc, these are well documented faults, look at the european Renault car forum, or Parkers UK forums.

[jo proffi]

Sorry, I misread "a mechanic", thinking it was "my mechanic"...
Jo

[danielsydney]

Well never mind the mechanic part should these cars fail with that sort of normal use? it all seems a bit odd to me?

[petercee]

Yes i was certainly suprised, as it was finally going realy well. we werejust crusing along going to a funeral when uit happened, and no warning at all. it had been imported from Japan, but i dont think that sort of car would be flogged over there, im 68 years old and i certainly dont flog my cars, but when i saw the engine out of the car, only the 2 pistions showed any damage, the other 2 looked fine, the head looked okay. i was curious thats why when passing thru his area, i called in to see if he has solved it, he bought a second hand motor and put in it, as reconditioning the other one was out of the question, parts are scarce for them out here. never mind, its all in the past now, i hope u dont end up with one like that one, it was the F3R motor, and i believe only the lags had it over there.

[HONG KONG PUGGY]

Certainly a sad end for your Scenic ownership Peter.
Has the mechanic investigated the engine further than just pulling the head off? I am thinking along the lines of maybe the oil and filter changes were not done as specified, which you do hear about from time to time. If there was crap in the oil and it blocked a couple of the oil ways that feed #1&#2 pistons via the crank spray holes, that would cause failure there.
Only surmising here though.
The other cause could have been a failure of the injectors on those 2 cylinders and the mixture being totally wrong?
Did he check for fault codes logged before the incident?

[Haakon]

Cars in Japan lead hard lives, in that they spend a LOT of time idling in traffic and often never get driven hard (80kph national speed limit). This means the engines can have HEAPS of hours on them but low kms. This is really bad for engines, especially combined with a very blase attitude to servicing (they renew them every 2 years anyway, so why bother?) and the engines can be stuffed ("worn out") at very low kms.

I once spent a weekend doing a second engine transplant on a friends JDM Galant - the 60Kkm old imported engine I bought was completely rooted....

All this sort of treatment tends to lead to a lot of carbon build up on the piston crowns and ring grooves. Then you get it out into "normal" use (or worse give it a bit of stick now and then) and all that carbon suddenly gets hotter then its used to being, and voila! - melted pistons.

Saw this first hand once on an Austin 1800 - had been bought by friends in perfect nick from an elderly gent who had tootled about in it for years. My friends hopped in it and drove it a lot faster than it had ever been in its life and melted 2 pistons in about a week...

[petercee]

yea, i actually owned it for about 12 months, i use only CF grade oils, semi synthetic, it had had a few other problems, the temp sensor for the fuel injection was replaced just after i bought it, the engine mount was replaced, the electric window on passenger side gave up, and the moon roof also gave up, so the motor was the final straw, and yes jap imports can be good or bad, certainly servicing isnt a strong point with them,every 10 good ones will follow 4 bad ones, but mainly with their bigger cars used as hire or taxis, i lived in singa[pore for a few years, and if Japan is as bad as them then its no wonder, cars idle all day with the air con going, and its damn hot there, still the Renault was imaculate when i got it, but ive gone back to Toyota now, boring but reliable, and hold value well.

[HONG KONG PUGGY]

Haakon, I'd never looked at Jap imports that way.
I will steer a mate away from an import diesel front cut for his NA diesel Hilux then and we might look into fitting a fan to the original engine instead.

[jo proffi]

Originally Posted by petercee

.... but when i saw the engine out of the car, only the 2 pistions showed any damage, the other 2 looked fine, the head looked okay..

So was the root cause of the failure of cyl 1 and 2 established ???

Jo

[jo proffi]

Originally Posted by Haakon

Cars in Japan lead hard lives, in that they spend a LOT of time idling in traffic and often never get driven hard (80kph national speed limit). This means the engines can have HEAPS of hours on them but low kms. This is really bad for engines, especially combined with a very blase attitude to servicing (they renew them every 2 years anyway, so why bother?) and the engines can be stuffed ("worn out") at very low kms.

Thats exactly why when my mate took me alont to be a PIA and pick the crap out of his prospective buy, a JDM MG v8, '95 with 30,000km on the clock , I told him he was absolutely insane and that the cars were all shite, in worse condition than many 60's cars i've seen, and to leave another $10k in reserve for a MAJOR service.
He bought it anyway, and time will tell how shagged this car is.
At least he followed my recomendation to stay clear of the neat ones because they had had cheap resprays with thick rippled clear coat, and bought the one that was full of dents and shallow scratches on its original paint, but was honest for an old car.

Jo

[68 404]

I've been thinking...

Crap fuel (and consequent ongoing pinging) could do 'orrible things to piston crowns.

Maybe some very low octane rubbish with some ethanol thrown in for good measure?

Just a thought

Dave

[petercee]

ive read up a bit on how this could have happened, one reason is overfuelling, and just after i bought the car, it would start first pop, then stall at the first lights, and damn hard to restart, turned out it was the tempreture sensor in the thermostat housing,the one that controls the fuel injection, it was faulty causing the engine to overfuel and stall (flooded) so maybee that was possibly the cause, still a fault of the engineering on these cars, ive never heard of such things happening on Jap cars, so if your renault has those symptons get it sorted in case you end up with similar problems, the sensor was only $85.0 fitted

[petercee]

out here in NZ, Jap imports are the in thing, they used to be absolute crap in early days, some pretty shoddy dealers were importing junk, winding the speedos back and making big dough, it probably still happens, but customs do a thorough check now, most cars would do 10,000ks a year, so if its 10 years old, it will have done at least 100,000ks, so how to believe some of these import commercial vehicles, ie busses come in 10 years old with only 30,000ks on them, ask your self, and as for diesels, they certainly dont service them, so 100ks would be equal to 1000 ks in wear, i wouldnt touch a jap import diesel, unless it was say only 1 year old with about 15,000ks on it. boy they can cost an arm and a leg to fix.

[Haakon]

Originally Posted by petercee

ive read up a bit on how this could have happened, one reason is overfuelling, and just after i bought the car, it would start first pop, then stall at the first lights, and damn hard to restart, turned out it was the tempreture sensor in the thermostat housing,the one that controls the fuel injection, it was faulty causing the engine to overfuel and stall (flooded) so maybee that was possibly the cause, still a fault of the engineering on these cars, ive never heard of such things happening on Jap cars, so if your renault has those symptons get it sorted in case you end up with similar problems, the sensor was only $85.0 fitted

Very unlikely I'd say - might eventually result in a fried catalytic converter, but not pistons. Extra fuel means a cooler flame (rich). Unless it had been doing it all its life and that led to the carbon build up, but surely a stalling engine would not have been tolerated from day one! Not a Renault engineering fault at any rate - most modern EFI systems are set up this way with a coolant temp sensor, Jap included. The hard carbon of the type likely to melt pistons is more usually I believe related to poor maintenance, cold, slow and short trips, and crappy oil.

All my injected Renault's always start first pop - its one of the nice things about EFI

[jo proffi]

Originally Posted by petercee

ive read up a bit on how this could have happened, one reason is overfuelling, and just after i bought the car, it would start first pop, then stall at the first lights, and damn hard to restart, turned out it was the tempreture sensor in the thermostat housing,the one that controls the fuel injection, it was faulty causing the engine to overfuel and stall (flooded) so maybee that was possibly the cause, still a fault of the engineering on these cars, ive never heard of such things happening on Jap cars, so if your renault has those symptons get it sorted in case you end up with similar problems, the sensor was only $85.0 fitted

As chance would have it, I have a laguna with the same iron block donk as was in your car, and its got hot start issues, and stalls in peak hour traffic too.
It has 220,000km on the clock, but I have absolutely no fear that I'm going to bust a piston.

Jo

[petercee]

it could be the EFI coolant temp sensor, as if faulty, it tells the system it needs more fuel, and it floods, the TDC sensor on these is also renown for needing the odd clean up, but that normally means hard starting all the time, not just when hot, i dont think a scenic is the type of car a petrol head would buy in Japan, its not exactly a hot rod, so i dont believe it would have been flogged, more like a servicing issue,since ive owned it ive always used a CF grade oil, semi synthetic 15w 40 grade, Magnatec.or similar. i guess it will remain a mystery.