Catastrophic Failure
 

Some of you may have read my other thread about a misfire I had on my car. There has been another failure and this time it seems a little more serious...

https://www.s2ki.com/s2000/uploads/g...98_1977008.jpg

Effectively the cam (or both cams, the jury's still out on that one) have worked loose and pretty much destroyed everything bolted to the head. I have a number of questions that I need to get my head round before I spend any money.

My questions are:

What could have caused this?

Have there been any other known failures of this nature, and if so what was the net cause?

Is this related to the plug issue?

I'm not a big believer in coincidence. Is there a wider issue with the engine that is a root cause?

Should I replace/rebuild the head on this engine, or will it jus be prone to another similar failure?

For your info, I've had the car since November, it has an indicated 64k on the clock and is an 04 facelift car. In my time it's been driven in a spirited manner but never over revved. It has run smoothly with little ot no vibration (certainly compared to my last car).


Your help and advice is always appreciated :thumbup:

Christ that looks a bit rum :(

I have nothing useful to say on what may have caused it I'm afraid.

I know this is a bit of a plug.

But if you get stuck & require a head, I have a complete engine with a buggered bottom end, but top end appears to be sound. If you're ever interested, let me know.

Wow! that is catastrophic.

I too have a nice shiney head, sat on my worktop, that I removed last week.

https://www.s2ki.com/...rophic-failure/

Would seem to be one possible cause.

Over rev / oil issue in the past. Wonder if the extra heat from that wandering plug caused the final damage.

I still think ( from reading other threads) that this was present a long time ago :(

I think the cause needs to be ascertained before proceeding further.

The bottom end would be ok if it were an over-rev, saving £££ on replacing the entire engine.

However, if the cause is not identified, and you just changed the head, and it turned out thay there were more serious issues, then replacing the head alone would be a false economy.

Sent from my GT-I9300 using Tapatalk 2

Which is a very eloquent précis of my original post ;)

So what could the cause be and/or what should be checked? I'm currently of a mind to inspect the bores and bottom end thoroughly and then fix it.

Worth posting this on the UTH forum on the US side, Billman will almost certainly post a comment. As other have said almost all F20 engine failures are caused by either oil starvation or an over rev at some point in its life and this can take years to manifest itself sometimes. If it were me I would just swap the head.

If it was my money ... i'd drain the bottom end, look for debris. Pull the sump and check the crank / bearings and possibly check the bores for scoring - just to be paranoid. I'd also check thrust bearing and possibly replace bearings / shells whilst it was in bits.

Put a known good head back on and enjoy a LOT more miles in the knowledge that the engine is good.

If you can get all that done for less than the cost of buying another engine that may have hidden issues, my head says that's money better spent. However i'd run that past someone that builds engines :)

Feel bad for you there :( Theses instances are rare, but I have to say increasing of late just on this site.

Starting to wonder if I should ever get another one

Holy s4it Paul, I feel bad having to sell mine but seeing this I'm gutted for you. Can't offer anything constructive but I hope you get it sorted as quick and cheaply as possible. As said, for piece of mind get the bottom end checked else it will play on your mind every time you drive it in the future.

If you do decide to change the engine and need some help shout me up.

Sorry to hear the bad news :(

I would probably do the same .....

It is very possible that the heat from the coil pack failure damaged the cam towers or possibly just fried the oil enough to cause the damage.

I got a set of low mileage cams and valve springs .... if they are of any use to you.

:(

:( Not had much S2000 related luck of late have you?

Maybe a ham-fisted mechanic had rebuilt the top end at some point in the recent past? That'd be my guess. Mine died with camchain failure, which caused extreme badness that was only revealed when the head removed. Could loose cams cause the valves to crash into the pistons in the same way?

:iagree:

Shit sorry to here this Paul and you haven't had the car that long either :(

Shit sorry to hear this Paul and you haven't had the car that long either :(

Yeah, me three. Rotten luck. Again.

So what's happened? bolts backed out of the bearing cup halves, or the shells wrecked by oil starvation?

If the former, sounds like someone's not re-torqued them correctly after messing with it. The engine does vibrate a lot at high rpm.That would Muller everything.

But yes; assuming there's no shrapnel in the bottom end, a new head (S/H) simply bolts on fairly easily.

Been having a chat through alternate means with S2Ki's chief reprobate

Here's a copy paste of the pertinant bits

My first observation with the photo is look at the intake cam and particularly cam cap#1
It's very black/dark compared to the exhaust cam in particular. That would suggest to me that when you pull the cap off it'll be totally bladdered under there. Seized up and generally a mess of bearing surfaces.

This is total conjecture but may well fit with what you're telling me with the plugs not having been tightened properly (i.e. possibly a sloppy work practice previously).
I reckon some work has been done previously on that cylinder head that has required removing the cam-shaft/caps

When you put the caps back on you have to follow a particular sequence and I'm personally one for putting a spanner on them all at least twice.
You should put the centre cap (#3 normally) on first and tighten it
then either #2 or #4 and tighten
then the other one you didn't do in the previous step (#4 or #2)
then go to the one at the other end of the engine and tighten and then go to the other end of the engine and tighten
(it should look something like tightening order #3 => #4 => #2 => #5 => #1 depends on configuration of engine but I tend to try and end on cam #1 since it is under highest load often, particularly with VVT systems and the like)

Unless you're using a multi spindle robot/machine it is impossible for a human to tighten the caps down as one, there are just too many bolts so you start at the centre and work your way out equally so as to take the cam down as level as possible.

If you screw the order up there are two common failures/results
1) The cam is lifted up on springs on the cam lobes. If you start at one end and work your way to the other you can bend the cam (since it is only cast iron normally you tend to break them if this happens)
2) You tighten the first cap down. The majority of bolt torque (I've heard 80% quoted) comes from the bolt head connecting with the surface it is touching so the bolt achieves torque quite quickly. You then start putting the remainder of the bolts into the caps and tightening them up. Remember you're tightening onto the valve springs though! That first bolt will feel tight as you like when you're tightening it. As the clamp loads increase though as more caps are tightened the earlier tightenings have all their clamp load taken away, the bolt heads come away (at least partially) from the surface and voila you have no torque on the cam cap bolts.

That would be my initial diagnosis

Where would I go next?
- If possible get a torque measurement on the remaining bolts, by the looks of the picture that would be best done on exhaust side (lowest failure amount)
- If I'm right you should find one cap totally loose, another a bit tighter, another tighter still etc (since the caps are linked I'd guess if someone did this they'd tighten all bolts on the same cap at the same time and hence you'll find similar results
- Once you've got the torques strip the rest of the head down being careful to keep everything in the correct order (use paint or tipex or similar to mark the positions on the cast surfaces of the cap if they don't have markings on already)
- Examine for varying signs of wear and damage that wasn't obvious on initial inspection of the assembly (there may be a crack/bend that isn't obvious when covered in oil and bolted into position) You may also feel something different as the bolts come out. A bolt more awkward or hanging my be indicative of distortion

That would be my starter for 10 anyway.


If I'm right then the bottom of the engine should be fine so probably you could get away with just a head change which may save a few quid. History does say that F20C's don't respond well to being repaired though so would depend on cost of replacement head vs replacement engine.



And from a slightly later mail
Obviously the head has to come off so yeah checking the bores is worth doing whilst it is off. If possible also get the head before going to [view any second hand ones]. Take it with you and then you can see any obvious things that might be a problem with it or different between the two.
I can't remember if you have to have the pan off on an F20C to get all the timing gear that goes with the head off. It may well be worth checking the pan for any debris as well and easier to see with the pan off. If anything heavy is sitting in there it probably wouldn't wash out in to the oil (thinking nuts/large chunks of debris)
If the pan is off then you're into the realms of it being worth taking the pistons out and checking bearings are all ok.

Start with getting the head off and a bore check (and ask questions about how they plan on doing it) and then maybe work from there.

Sorry to hear of your misfortune mate :(

Having spoken to you on Facebook before reading this thread it's interesting to see others seem to come to the same conclusion of over rev and top end repair at some point.

The order of tightening of the cam carriers is extremely important so it could be something to do with this as fluffy ninja has suggested. To me though the exhaust area of cylinder #3 looks blacker thank in the intake cam...

Out of curiosity which cylinder did the coil pack fry on?

Something that occurred to me after discussion earlier. Why isn't the engine starting? Is it because the cam has lifted due to the cracked caps and you aren't getting valve lift or is it because the cam isn't turning because it is seized? Might impact on the state of the bottom of the engine.

I'd taken that black marking at the #3 position as being just a streak of dirty oil from somewhere but possibly not.

My hunch and really am in the realms of guesswork now is that it has been tightened in the order #5 => #1. That's why #1 is so black. It is still clamped properly but they've progressively lifted from #5 forward and hence distorted the loading in the bearing, caused lubrication breakdown and seizure. An awful lot to infer from a photo though!

There is also the possibility that the plug loosened and the coil pack over heated because of over heating of the camshaft bearings.

If you dropped a valve and it contacted the piston it could do that kind of damage
Check for witness marks on the piston crowns and check for play and uneven piston position at TDC if that's ok then you need to check the head, chances are its mullered as the cam journals are bored as a set so just fitting new caps might not work

That'd be sudden catastrophic though. The heat signs on #1 journal show it has been running in some distress for a while
100% correct about the cambores/matched set thing

It does start, it does run but it sounds 'strained' at tickover. The noise sounds like very severe TCT as opposed to anything overly mechanical.

Could be a blocked oil feed to the effected cam journal, can you see signs of pick up on the bearing surface, I'd be surprised if it got hot enough to do damage by just a loose coil pack as long as the oil feed was ok

This was the coil pack that failed:

https://www.s2ki.com/s2000/uploads/g...397_124114.jpg

Need any bits sand blasted?

;)

That suggests the bottom end is free but top end is doing its best to seize. If the top end goes solid there's a good chance it'll twist the cam sprocket off. The tct you think you are hearing may be the chain loading going through the roof as the top end is being forced around against its will

Yep that was my thought based on the noise it made - still you'd not have thought the noise would equate to the physical damage.

Which would explain the slight weep of oil from the allen bolt at the front of the head. If the chain's been straining it will have moved the bolt slightly and disturbed the seal...

Outstanding work Hun, I could have written that myself...

Memo to self - always check the laptop before commenting :banghead:

Chaps, your input has been invaluable and has really helped me get my mind on a plan of action; which is thus...

1. Boroscope the bores to check for damage
2. Remove the sump and check the bottom end for damage/correctness
3.Remove damaged components and replace as required
4. Get back in the car and enjoy it again...

Well that's the plan anyway... I'll keep y'all up to date :)

5. Install gyroscope to keep correct way up?

Do you REALLY think that would help? :LOL:

Depends if the nominated responsible adult is present :)

Give me a shout if you need a hand to UxE the head etc...always happy to help :)

Sent from my GT-I9300 using Tapatalk 2

When are you going to write "The complete idiots guide to writing off an S2000" then Paul. You've kinda done 2 already. How many other ways do you think you can do it.

Nothing constructive I can say Paul but hope you're back in the car soon. At least we can rely on the s2k support vehicle a little longer ;-)

Thanks to all who have commented, contemplated and offered help. the strength of this community is a credit to those in it. :thumbup:

"Loftust is always there to help pull a head off"

Excellent post by fluffy.

:thumbup: thank you :)

Paul, also when you take the sump off, drain the oil through a fine sieve so you can see if there are any metal deposits in it. A borescope can be used to save you lifting the head off but it sounds like you'll have to do that anyway. However, using one will allow you to save on labour charges of stripping it down if any of the cylinders are scored beyond a re-bore.

A quick update for y'all....

Whilst there is a lot of aluminium sludge in the sump, none appears to be in the oil pump; the shell caps are all torqued correctly and there is no end float on the crank.

I have three realistic options; 1) rebuild this engine, with the risk we've missed something an it could go bang pretty quickly 2) buy a re-con engine with the risk it's been done badly and it'll go bang pretty quickly or 3) buy a second hand engine from a scrappy and risk that it has been damaged/abused and goes bang. Of the three options I think number one is the one for me; it has the benefit of being the least expensive and more importantly the bottom end has been inspected. Add to this the fact that before it's demise the engine made a very respectable figure on the recent S2Ki Dyno Day (210.6) and doesn't smoke, and I think it makes sense (unless there's a compelling argument I've missed :ponder: ).

So the search for a low mileage complete head starts here...

I think you're probably around about right. Unfortunately the only truly right answer will be the one made in hindsight when it either works or it doesn't. I know you saw my post on the reconditioned engine thread so the odds of the options you're quoting are all about equal odds of having a problem. Therefore cheapest option makes the most sense. Fingers crossed and hope all goes well

Thanks Fluff, much appreciated :thumbup:

It's been a while, so I thought I'd post an update on the (slow) progress I've been making.

Typically, having made up my mind to re-build this engine the seemingly never ending stream of undamaged heads for sale at a reasonable prices dried up. So I decided to take Floppy up on his offer of the head from his hydro-locked engine. Progress from this point in has been slow, as the car isn't my daily driver I have said I'm in no rush and am happy for the chap to fit work on my car around other priorities in his workshop.

So, the new head was stripped and inspected and found to be in good shape. My (very) knackered head was removed from the car and stripped. The straight valves from the knackered head have been lapped into the new head and the cams should be going on this week. The target delivery time is mid November but that may slip a bit; I'm not that bothered, it's been so long another couple of weeks isn't gong to make a big difference.

Fluffy, no chance of the rods being over stressed if the top end was seizing up?

Paul,

I think youve taken the right choice with this, its a gamble as to whether there is any long term unseen bottom end damage but its worth the risk. The only thing you can do is give it a few easy miles and then give it an absolute beating so that if its going to blow up it does it early. No point never having 100% faith in it. Just make sure you have some sort of recovery sorted if things do go wrong.

I'm very interested in the progress, end result and price of your rebuilt head as it's something I'm sure I need to do. Are you uprating anything in the head or just a stock rebuild?

My thoughts exactly, tempered with the knowledge that I'm going to be broke for a while after I pay the bill; the level of hooliganism will be directly proportionate to the size of the S2000 emergency fund ;)

I did think about getting it gas flowed but don't really have the cash currently so I'm keeping it stock :)

Unlikely I would have thought. The tension in the chain will have increased the driving forces in the engine (the valve train is seizing so takes more effort to turn it over) so average gas pressure will be a little higher I guess but not hugely so and peak pressure shouldn't be any more. It's a bit of a guess having never tried to measure it though but I can't see it being any worse than having laboured the engine a bit. The chain/sprockets are likely to be the weak point if it were seizing that badly though.

Bigger threat to the bottom end would be valve collision with the pistons but the failure mode on this engine would be taking the valves out of the line of fire since they're not being opened so far. Usual disclaimers of having not seen the engine yada-yada :)

What is the best way to monitor oil pressure in the cylinder head?

Pressure gauge from one of the breathers upstream of the PVC.

Fluffy :thumbup:

You went beyond my level of knowledge ...

Care to give link to an after market part, or a picture?

I thought the PCV valve deals with residue crank case air only, not oil.

Ah sorry, I thought you meant vapour pressure. You mean oil lubricating the cams etc... pass on that one. You would need a drawing of the oil galleys in the head. Tricky.

Right.

So, let's say, if an oil control nipple clogged up, then the oil pressure will be too low in the cylinder head, yet the oil pressure sensor connected to the ECU won't see that since that sensor only measures oil pressure in the engine block. Do I have that right?

Correct. I had a D16Z6 (Civic ESi) engine let go due to oil starvation to part of the block. When it was pulled apart, oil level was fine. Must have been a hangover from the previous owner (I should have spotted it when I bought the car, but that's another story).

Crux is - keep your oil clean and changed regularly.

From the VTEC solenoid

Yes, that's right!

Now I need an after market attachment that measures the oil pressure on the input side of that solenoid so I can see the oil pressure in the cylinder head whether VTEC is engaged or not.

But there are other oil passages for lubricating the camshaft journals and the entire valve train. I'm not sure low oil pressure in those places will be caught by this method.

I have another update for you. We're really starting to make progress now...

The engine is mostly back together and I should have it back on the road at the end of the month... Fingers crossed

Fingers crossed for you mate; hope to see you both at the next Ricky run

To bring this episode to a close, I have the car back and it's running very nicely indeed.

I have a very big bag of broken bits which will be going directly in the bin; here are some more photos of the damage https://www.s2ki.com/s2000/public/st...lt/augen40.gif

[attachment=51674:image-3135573499.jpg]

[attachment=51675:image-1283261889.jpg]


[attachment=51676:image-1347559614.jpg]


It appears that the bearing on the central pulley (the one between the cam pulleys) has seized solid. This has led a re-think on the actual route cause of the problem. The loose plug is the main suspect, although we can't rule out the pulley bolt being over tightened and causing the heat build up that is apparent on the pulley (sorry no photo, it was too dark to get a decent shot).

Once the car was complete it stubbornly refused to start. The ECU was the suspect as posts on the subject both here and on Honta Tech seemed to indicate it was a not common but regular issue on cars that have suffered this type of damage. It turns out there were two faults; firstly the inlet cam position sensor had been whacked by the flailing cam but this only showed on very close inspection. It was replaced with a unit from Mugen888 (cheers Brian https://www.s2ki.com/s2000/public/st...t/thumbsup.gif). The second issue was a little more difficult to find, but it turns out the exhaust cam position sensor positioning bracket had been bent when I transported the head from Floppy to the workshop, thus only receiving two of the required four pulsed from the cam. The ECU got a bit flustered and refused to send a spark. Once this was sorted it was happy days. The car has covered 150 miles now and as already stated, is running very nicely indeed.

Either way, I'm really looking forward to getting the geo done (that's where I was going when this all kicked off) and getting back to driving my car.

I have to confess that in the months I have been without it I had been contemplating a replacement, but now I have it back such thoughts have been banished https://www.s2ki.com/s2000/public/st...lt/biggrin.gif I'm now hoping for some nice dry days so I can get out on the road and have a bit of fun to re-acquaint myself with the car again https://www.s2ki.com/s2000/public/st...lt/driving.gif

Good news indeed - now be nice to this one ;)

Good news that there's life after a failure like that ! A warning of the horror show pics this early on a Monday might be in order ;)

Another oil change in the near future might be a worthwhile precaution in case there's anything foreign floating around in there

Pleased for you that it is all running ok now :thumbup:
As others have said....be nice to this one and try not to roll it :hidebc:

Good news Paul! :D

Great stuff Paul :thumbup:

Paul
Please try and take care of it this time :LOL:

Great your back on the road :thumbup: :burnrubr:

great stuff paul, look forward to seeing you soon!

Great news. Bet it snows now stopping your fun. Or adding to it of course!

Pleased it's all working properly again, Paul.

Keep the rubber side down & the shiny side up.

Good to see it back on the road and nice to meet you again on Saturday

Cheers all, feeling the love and all that.

I can confirm that I have been treating this one like little princess before it broke and will continue to do so... Honest https://www.s2ki.com/s2000/public/st...ult/tongue.gif

I have said this before, but the strength of this community is a credit to those who contribute to it. thanks for you support and advice https://www.s2ki.com/s2000/public/st...t/thumbsup.gif

:eek: :brokehrt: :cry: :sad:

As the modified title indicates, the engine has now decided to retire from actually being an engine.

I hadn't really opened the car up until yesterday. Once the geo was sorted I thought I'd open it up and give it a test. It struggled to VTEC, so today we had a look at the at the VTEC solenoid. It was clean and ok. Whilst the oil pump was the main suspect I had no oil light warning so assumed the pressure was good. I made it about two miles and the engine lunched it's self.

To say I'm gutted is an understatement. It's time to find a short engine and get on with fixing it again :(