F4R.774 Piston Detonation

[Trophyboy2017]

Managed to strip down the head today and dropped it into the ultrasonic bath for cleaning.

Checked the valve seats and all in great condition. Various debate with regards to lapping the valves in. Been told that i shouldnt need too as new engines are machined to within minimal tolerances but im old School and still might give them a quick hone in. I'm using the same cleaned valves again and going into there original ports.

Head pre and post ultrasonic chemical bath.
It was always drilled into me that cleanliness and precision was the key to building a good engine.

Sent from my SM-G935F using Tapatalk

 

[Crybert]

Just wanted to add what a website this is. Diagnosed the guys issue from a thread. Outstanding

 

[Philpooma]

Cheers buddy. Managed to get the b*****d off with brute force haha

Brains always beat metal eh.
Now you can get on with your epic projet :up:

 

[Philpooma]

Now thats a clean head.
I think that you cant go wrong with the "Old school" approach, especially with cleanliness

 

[White16valver]

Kudos to all the people on here who can actually spanner lol

 

[JamesBryan]

Definitely lap the valves in mate, all it would take is for one to not seat properly and you'd be stripping it all down again.

 

[Trophyboy2017]

Definitely lap the valves in mate, all it would take is for one to not seat properly and you'd be stripping it all down again.

Cheers James
Deffo gonna give them a lap in as i doubt it will take long and have piece of mind that ill have a good seal on the valves.
Not looking forward to getting those collets in though. Trying to figure out a knack to it haha

 

[Trophyboy2017]

Kudos to all the people on here who can actually spanner lol

I'm self tought mate after messing round with cars for years. Stripped my first engine given to me by a neighbour when i was 14 as i was curious to know how they worked and put together lol.

 

[White16valver]

I'm self tought mate after messing round with cars for years. Stripped my first engine given to me by a neighbour when i was 14 as i was curious to know how they worked and put together lol.

I'd do that, put it back together, then wonder where those few random nuts and bolts left over at the end were supposed to have gone LOL

 

[bloke]

I'd do that, put it back together, then wonder where those few random nuts and bolts left over at the end were supposed to have gone LOL

weight saving

 

[andybond]

The valves were severely coked up and solid chunks of burnt soot on them. Could it have been an over fuelling issue leading to detonation?

That looks like ringland failure to me , caused by the car running lean.

Its one of two things I believe that caused it - or a combo of both
1) Failed injector
2) pump weakening , but not failing

Its not got much in the way of detonation on the top of the piston , so I dont think it was boosting its bits off.
The coking will have been oil blowpast from the failed landing and the by product of it burning in the chamber instead of it being in the sump.

You could get the injectors tested , same with the pump. Or you could forget it and carry on with a mega build.

 

[McGherkin]

Damage confined to one cylinder suggests injector more than it does pump.

 

[andybond]

Damage confined to one cylinder suggests injector more than it does pump.

I see where you are coming from , however I have seen a few instance of just 1 ringland failure with a weak pump. I cant tell what end its at but I am guessing its closer to the flywheel than not ..

 

[R3k1355]

The fucked cylinder was in the middle of the block.

 

[andybond]

The fucked cylinder was in the middle of the block.

You cant have middle on a 4 cylinder

It was 3rd cylinder ? So only one from the end.

Be dead curious to find out what caused it ..

 

[Trophyboy2017]

I'd do that, put it back together, then wonder where those few random nuts and bolts left over at the end were supposed to have gone LOL

Haha i was like that on my first engine build years ago and had nuts & bolts left everywhere. Just chucked them in the bin lol.
Much different now though, they have all gone off to the zinc platers in seperate clear sarnie bags

 

[Trophyboy2017]

That looks like ringland failure to me , caused by the car running lean.

Its one of two things I believe that caused it - or a combo of both
1) Failed injector
2) pump weakening , but not failing

Its not got much in the way of detonation on the top of the piston , so I dont think it was boosting its bits off.
The coking will have been oil blowpast from the failed landing and the by product of it burning in the chamber instead of it being in the sump.

You could get the injectors tested , same with the pump. Or you could forget it and carry on with a mega build.

Hi Andy
Thanks for your input on this. The damaged piston was Cylinder 2 so yeah near the flywheel end.
I'm with you and definately think it's been a fuelling issue thats caused it.
I'll be replacing the injectors with 630's for piece of mind as ive heard the OEM ones are rubbish.
I'm still learning all about the megane and its build as ive been into VW etc but is it me or is the meg fuel rail a rubbish design with it being single fed from one end and no return? Do they suffer from fuel starvation which can cause ringland failure?
Has anyone designed an uprated fuel rail with return? It's something id really like to modify while im building it back up.
I'm wondering if the 250 rail will fit as i know its fed from the centre and has the fpr fitted on it.
Any ideas on updated pumps or does the 250 pump fit in the 225??

Cheers
Chris

 

[andybond]

I'll be replacing the injectors with 630's for piece of mind as ive heard the OEM ones are rubbish.

You will have to get the 630s mapped in buddy. You cannot sling them in and hope.

I'm wondering if the 250 rail will fit as i know its fed from the centre and has the fpr fitted on it.

I dont think it will , without modification. Anyone tell me otherwise ?

 

[Trophyboy2017]

You will have to get the 630s mapped in buddy. You cannot sling them in and hope.

I dont think it will , without modification. Anyone tell me otherwise ?

Yes will definately be getting the 630's mapped in as soon as its built. Seriously thinking of adding an AFR gauge to keep an eye on the fuel/air ratio.

Be interesting to hear from anyone if anyone is running the 250 fuel rail and pump.

 

[White16valver]

It looks to me like this is the perfect opportunity for a step-by-step photographic guide to building an engine, if you fancied it :wink: lol

 

[Trophyboy2017]

It looks to me like this is the perfect opportunity for a step-by-step photographic guide to building an engine, if you fancied it :wink: lol

Haha well i certainly don't mind doing a photographic/detailed guide to building an engine (F4r.774) if the mods will allow it with me being a megane lad
It's my first Renault build and im sure I may make a few mistakes along the way but there's some fantastic tech lads on here that will put me right I'm sure of it.

 

[Trophyboy2017]

What I do need if anyone can point me in the right direction is torque settings for the F4R.774 engine plus crank end float measurements etc
Any detailed specifications would be a massive help in the build

 

[bloke]

what solution do you use in your ultrasonic by the way?

 

[Trophyboy2017]

what solution do you use in your ultrasonic by the way?

I'm not sure bud as its already in the tank when I use it but I'll find out Friday when im back in as the drum is next to it.

 

[bloke]

cheers, looks like it's a decent one though.

 

[npt]

are you sure that bore will hone out? looks like a rebore or scrap but maybe just the photo's, I'd also guess that if the car was running on all cylinders while idling prior to the eml flashing then i'd say that injector has suffered poor spray pattern prior to failure

 

[Trophyboy2017]

are you sure that bore will hone out? looks like a rebore or scrap but maybe just the photo's, I'd also guess that if the car was running on all cylinders while idling prior to the eml flashing then i'd say that injector has suffered poor spray pattern prior to failure

Yes machine shop said it will deffo hone out no problem. That lightish colour on the bore is melted alu piston and comes off with a brass scraper and local heat.
Only minimal lip on the bore top too.

Think it's deffo been injector/fuel pump related bud and once i have this built ill send the old injectors away to be tested. But at £60 for testing i could buy most of my bottom end gaskets so will have to wait.

Also, maybe 500 miles ish prior to this happening i sent the injectors away to be ultrasonic cleaned. Maybe one has stuck closed i don't know as i just banged them back in after a quick look. It did develop a small misfire now and again but scan gauge never came up with any faults and it would come and go. Maybe this was the start of it all :weary:

 

[bloke]

might be able to get them tested for you.

 

[Trophyboy2017]

might be able to get them tested for you.

That would be a big help if you could :up:

 

[bloke]

will check today, should be fine for it but just want to confirm though. where are you?

 

[Trophyboy2017]

will check today, should be fine for it but just want to confirm though. where are you?

Great, just let me know. I'm in Cheshire

 

[bloke]

where about?

 

[Trophyboy2017]

It's been a few years since i had any engine work done and had a price from a guy local to me who's name has popped up many times via my mechanic mates.
Are these prices the norm nowadays?

Head Skim - £30
Block Skim - £40
Bore honing - £20 (£5 per bore)
Chemical Wash - £10

 

[Trophyboy2017]

Well returned from holiday and not the best news I had on the block machining.
The damaged bore is beyond honing as it has a small hole in it caused by the melted piston and rings. Just trying to figure out my options really.
A) full rebore with oversize pistons which to be honest is out of my budget.
B) Rebore & sleeve damaged bore to standard size but chap said other bores are quite worn. Just waiting to find out what the upper tolerances are for the F4R.774 block.
C) Find a decent 2nd hand block and just have it skimmed & honed.

Does anyone know if the 225 had its own block made or was it used on other models?

Any info would be much appreciated as feeling a little deflated at minute :neutral::tired:

 

[JamesBryan]

225 / R26 blocks should be the same.

 

[Trophyboy2017]

225 / R26 blocks should be the same.

Cheers James.
Just asking as ive noticed some pistons are marked B and some marked C with mine been C. Wanted to know what difference was. Model year perhaps? Mine is 2005 Trophy.
Did the Laguna 2.0 16v use the same block?

 

[JamesBryan]

Cheers James.
Just asking as ive noticed some pistons are marked B and some marked C with mine been C. Wanted to know what difference was. Model year perhaps? Mine is 2005 Trophy.
Did the Laguna 2.0 16v use the same block?

Laguna was 714 then 764 i think.

 

[JamesBryan]

B and C will probably relate to the chassis number BM0M and CM0M.

 

[Trophyboy2017]

B and C will probably relate to the chassis number BM0M and CM0M.

Thanks for clearing that up James as i did wonder what the difference was.

 

[Trophyboy2017]

B and C will probably relate to the chassis number BM0M and CM0M.

Thanks for clearing that up James as i did wonder what the difference was.