How terminal is this..... aux belt jumped the cam belt

[G Hut]

Ph1 172
Cut to the chase how bad is this engine gurus....?? we talking pistons, valves and bottom end?

Crank locking pin is in, clearly the horseshoe tool isn't going in there . It runs but quite lumpy, then at 1700rpm when dephaser advances it sounds like a 1990 french derv, unplug the dephaser that symptom stops.

Assume the noise I hear when dephaser advances is the valves clipping the pistons and will have likely damaged bottom end, how much clearance is there in these engines?

As to how it happened, Bedford track day on Monday breaking into hair pin just before the pits and hear gravel like sound, coast into pits. Aux belt less than 12 months old and all pulleys new also at same time

Looks like lump of tyre rubber bounced up through small hole in the lower wheel arch liner under valance

This jumped the aux belt that sliced on the AC compressor pulley

and then wrapped all the trimmings round the bottom pulley jumping the cam belt I suspect

The noise like gravel at about 3sec was the aux belt going, squeal is the CL6 pads

Advise on likely damage appreciated

 

[R3k1355]

Hard to say, it's not uncommon for them to be a tooth out after a failed cambelt change, but if you've jumped a few teeth pistons may have hit valves.

You'll need to reset the cam belt, then leakdown/compression test.

Could chuck a scope down the spark plug hole and see if there's any visible damage on the piston first.

 

[botfch]

Difficult to answer, fix the timing then compression test if you don’t want to pull it apart straightaway.

 

[PP200t]

I can’t help I’m sorry, but I’m gutted for you. Hopefully it’s not too bad to fix and you get it sorted. 🙁

 

[dangerous dave]

Cam down the plug hole will see the dints in the pistons.

As said, re time, compression.

If its got it, Full send it into the horizon

 

[G Hut]

Update, firstly thanks for the advise so far everyone, appreciated

Borrowed a bore scope this afternoon and as follows

Exhaust side of pistons lovely and black, all look just like this

Inlet valves.... Cy4 & 3 have two small silver marks

Cy 4 seems to have the worst damage assuming the silver is a small clip on bottom left valve cut in piston to

Cy3
Small hit bottom left valve again but to right edge

Cy 1 and 2 dont have sliver but assume the slight yellow discolouration is the valves just glancing the surface of the pistons taking the carbon off?

Will get some time next weekend to reset the timing and compression test

Thanks again

 

[Brigsy]

Its still running, id reset the timing and if running ok comp test it. If all checks out, prob got away with it.

My only worry would be has it weakened the valves with them lightly kissing the pistons.

 

[G Hut]

Update and found the real root cause... not track debris

Got genuine Renault timing tools delivered and started the strip down, upon stripping cambelt covers off there was aux belt bits everywhere, they really do try and rip the cambelt off when they fail

Then found top alternator lug broken off, this is clearly what threw the belt, thought that breaking was odd. Then went to undo the bottom bolt to remove it and..... it wasn't there completely gone, just some nice witness marks where it had been bouncing around.

Also at some point it the past it has been timed up haphazardly as nice tipex marks on the exhaust pulley, I had cam belt done at Renault about 4 years ago then aux belt at a local indy last year due to noisy idler

On the hunt for an alternator and bottom bolt now, will continue to retime, all cambelt pulleys came off nicely. The timing tools are proper quality items, I now understand why cheap ones will bend as you need a breaker bar to undo the cam pulley bolts!

 

[dangerous dave]

Update and found the real root cause... not track debris

Got genuine Renault timing tools delivered and started the strip down, upon stripping cambelt covers off there was aux belt bits everywhere, they really do try and rip the cambelt off when they fail

View attachment 1694220


Then found top alternator lug broken off, this is clearly what threw the belt, thought that breaking was odd. Then went to undo the bottom bolt to remove it and..... it wasn't there completely gone, just some nice witness marks where it had been bouncing around.

View attachment 1694221


Also at some point it the past it has been timed up haphazardly as nice tipex marks on the exhaust pulley, I had cam belt done at Renault about 4 years ago then aux belt at a local indy last year due to noisy idler

View attachment 1694222

On the hunt for an alternator and bottom bolt now, will continue to retime, all cambelt pulleys came off nicely. The timing tools are proper quality items, I now understand why cheap ones will bend as you need a breaker bar to undo the cam pulley bolts!

Theres always a chance it's been tip ex timed, but you have to remember that theres a sequence of rotations that need doing when settling the belt.

It's much easier if there's a dob of tip ex, as you're heads down in the wheel arch.

Always a chance its an absolute jobber tho.

 

[Clionutta]

Mate you are a lucky. Don’t buy a lottery ticket you have had a win.

 

[G Hut]

Compression test complete this morning, cold engine. Engine is Ph1 172 all standard, 74k on clock and full service history

5 cranks and repeated 3 times on each cyl to get these results and from what I understand these are good but please let me know if they look odd. ??

To note it was cy4 and cy3 that had the small silver marks on pistons

Cy4 being the timing end

	Cyl4	Cyl3	Cyl2	Cyl1
Dry psi	180	180	170	190
Wet psi	190	195	190	200

Now things are looking good will be ordering new timing belt kit and cam end seals for timing end and going to do the rocker cover reseal while in bits

Thanks for all the advice appreciated

 

[Brigsy]

Looks ok to me, send it.

 

[JamesBryan]

Solid compression results them.

 

[Clionutta]

Some guys in Australia have just put together a YouTube video on doing the job you are about to undertake. Worth a watch if it’s your first time

 

[Crayola]

Good compression results, nice and strong

 

[G Hut]

Spent a couple of hours tonight cleaning up and then resealing the rocker cover to stop the weep they all seem to get.

Timing belt kit and new seals on the way and hope to get all fitted and timed up again at the weekend

 

[Brigsy]

Have you used silicone on the cam cover or anaerobic sealant?

 

[G Hut]

Well spotted, it was the special loctite si5980 oil flange sealant
Spotted this guy using and understand he was a race engine builder and stated lasts a bit longer than the Renault stuff



This is where I get told that is a disaster waiting to happen , please do tell me if so

 

[bren172]

Noice. look forward to more updates over the weekend

 

[Touring_Rob]

As Brigsy alluded to earlier, the valves on these are a little weak, I believe the heads are friction welded onto the stems. My concern going forwards would be if the valves (the ones that touched pistons) have been slightly damaged which could mean they fail later. When they do fail the entire head comes off and utterly destroys the bottom end.

Depends how risk adverse you are, with the cams out you are 80% of the way to whipping the head off but suddenly you are into new inlet valves and relapping everything so time and money goes up a fair whack.

 

[Brigsy]

Id be tempted to use the proper anaerobic sealant as there is a chance any thats squidged out might block oilways in the head or end up in the sump blocking the oilpump strainer.

Ive never personally had to revisit a cam cover after sealed with loctite 518 or the renault equivalent blue anaerobic sealant, all have been fine. No need to worry if a little squishes out as it will mix with the oil.

 

[Rojer]

You got lucky so don't risk it by using the wrong sealant.

 

[G Hut]

As Brigsy alluded to earlier, the valves on these are a little weak, I believe the heads are friction welded onto the stems. My concern going forwards would be if the valves (the ones that touched pistons) have been slightly damaged which could mean they fail later. When they do fail the entire head comes off and utterly destroys the bottom end.

Depends how risk adverse you are, with the cams out you are 80% of the way to whipping the head off but suddenly you are into new inlet valves and relapping everything so time and money goes up a fair whack.

How much would it go up to do that do you think

New inlet valve set £160
Valve seals?
Gaskets head, inlet and exhaust etc

Would I need new head bolts or can they be re used once?

Any other items?

Thanks

 

[Touring_Rob]

How much would it go up to do that do you think

New inlet valve set £160
Valve seals?
Gaskets head, inlet and exhaust etc

Would I need new head bolts or can they be re used once?

Any other items?

Thanks

If I were doing it as properly as I could but also trying to keep to some kind of sensible budget,

I would pull head, replace inlet valves (either all or just the cylinder that show contact), re-lap all valves including exhausts (because its free and why not), consider replacing steam seals, have a wobble on each valve to check for guide wear (hopefully none) then button it all back up. No need for valve seats unless possibly there is severe guide wear in which case the head needs to go to a machine shop so take their advice.

So minimum would be 2 inlet valves, head gasket, you can measure bolts to see if they can be reused, and valve stem seals. £120?

More realistic would be a set of inlet valves, head gasket, new head bolts, stem seals £220-250? Edit - it will be more like £300 as head bolts are more than I remembered if you use genuine ones.

More anal would be to upgrade valves etc. But at this point things need some careful man maths to make sense of.

 

[Touring_Rob]

Can save a bit by using Victor reinz gasket set which includes stem seals

Victor Reinz Head Gasket Set Clio 2 RS 02-31655-01

Victor Reinz Head Gasket Set Clio 2 RS 02-31655-01

www.pure-motorsport.co.uk

And non genuine head bolts:

Glaser F4R Head Bolt Set

Glaser F4R Head Bolt Set

www.pure-motorsport.co.uk

There's a set of odd valves on ebay too, can't decide if they are a bargain or if they would tweak ocd too much 😂

Renault Clio 172 182 Nitrided Intake Valves *SET OF 8* Single Piece Valves Used | eBay

Wossner Nitrided Intake valves x6. Supertech Nitrided intake valves x2. Standard size valves, full set of intake valves. Mixed set of intake valves, removed from one engine, fully functioning 240bhp turbo converted;.

www.ebay.co.uk

Equally - I am not saying you should do this! Your cheapest out is to do as you were and put it back together with correct timing. In farness to your engine you would not have such good compression if any of the valves were deformed, its just I know people have had issues with FR4 valves who haven't had contact so I would be a little nervous for the first few track days/enthusiastic drives then forget all about it after they were done

 

[Touring_Rob]

editedit * sorry you said valve seals, I read valve seats. Yes do seals.

 

[G Hut]

Can save a bit by using Victor reinz gasket set which includes stem seals

Victor Reinz Head Gasket Set Clio 2 RS 02-31655-01

Victor Reinz Head Gasket Set Clio 2 RS 02-31655-01

www.pure-motorsport.co.uk

And non genuine head bolts:

Glaser F4R Head Bolt Set

Glaser F4R Head Bolt Set

www.pure-motorsport.co.uk

There's a set of odd valves on ebay too, can't decide if they are a bargain or if they would tweak ocd too much 😂

Renault Clio 172 182 Nitrided Intake Valves *SET OF 8* Single Piece Valves Used | eBay

Wossner Nitrided Intake valves x6. Supertech Nitrided intake valves x2. Standard size valves, full set of intake valves. Mixed set of intake valves, removed from one engine, fully functioning 240bhp turbo converted;.

www.ebay.co.uk

Equally - I am not saying you should do this! Your cheapest out is to do as you were and put it back together with correct timing. In farness to your engine you would not have such good compression if any of the valves were deformed, its just I know people have had issues with FR4 valves who haven't had contact so I would be a little nervous for the first few track days/enthusiastic drives then forget all about it after they were done

Need to do some man maths here, will be resealing with loctite 518 in any case. Cheers

 

[Touring_Rob]

Welcome, good luck.

 

[JamesBryan]

The Loctite SI 5980 is just black silicone and definitely not the one to be using unless very careful.

The guy in that video, James, he's built loads so knows how much sealant to put on so it's probably ok for him. Too much and it'll ooze out into oil ways.

The 518 @Brigsy mentioned or the Victor Reinz eqivalent are the ones to use.

The headbollts can be re-used if the length under the head doesn't exceed 117.7mm (bolts must be coated with oil if re-using).