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Dropped valve?


caterhamnut

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🙆🏻feck and poo.

Driving last night, overtaking along a duel carriageway and a noise, followed by stuttering running/missing and a bit of metalic clunking! Pulled over, engine idles and starts/runs but roughly with the odd metallic thud on the cam cover (dropped valve being pushed up by piston?) - oops!

Had just fitted DTB's and the engine was running sooo nicely. Lovely idle and smooth, but was waiting to go to Steves RR for a map check - the map was the one we ran with the big single TB - Peter C did a great job at scaling the fueling etc, but wanted to check it.

 

I'm hoping it isn't a self-inflicted accident, where something I haven't done up properly on the DTB and air box set up has come off and been ingested!

Engine sits at Marks awaiting inspection.....

 

Still, on a brighter note, before this it was running very very quietly - those Scouse air boxes (thanks Dave J *thumbup* *smile*) work well, and it had a very smooth idle, with a nice booming noise at higher revs. Hopefully the problem won't be too great. Hoping for about 200bhp on the RR (simply from bolting the DTB's onto the 184bhp engine) but much more concerned at having a nice drivable engine. The single TB was great on track when flooring it, but a bit lumpy and rough around town (as predicted) and it is true what others have said - if the car is arubbish to drive at slow speeds, you certainly don't use it as much as before....

 

Was hoping to get the car up to the 50th for the Arch stand, so lucky it blew last night and not whilst Tony P was driving it up.... 🙆🏻

 

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The latest Autoteknix airbxoes have no internal clips or appendages, everything is external so there is zero chance of ingesting a clip. If the fasteners are correctly done up with loctite then there are no issues, however it is easy to forget the loctite.... make sure that the trumpet studs and nuts are loctited too. This is in common with *any* induction system.

 

Oily

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*thumbup* cheers guys. Hoping it isn't going to be too bad - I have faith in the lack of too much noise! *gulp*

As you say Dave, any clips where all bonded in nicely, so I have no fears its anything to do with the air box *thumbup* - if it is it will be user error on my behalf and not using loctite (the usual ' I'll do them all up now, make sure it all works, then go back and do 'em properly..... 😔 excuse!)

I shall report back when I know...

 

www.mycaterham.com

here

Videos

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101,000 miles car

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Sorry to hear the news Angus, however shouldn't be too difficult to fix.

Was hoping to get the car up to the 50th for the Arch stand, so lucky it blew last night and not whilst Tony P was driving it up....
Tony drove my car back from Spa & managed 34mpg on the Autoroute. Pretty outstanding for a 227BHP DVA engine with mapping by the 2 Steves!

 

 

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*thumbup* Just goes to show that a k-series, built and maintained properly, is still a very good, reliable, economical engine (present problems excepted, but I still come out on the engines side bearing in mind the mileage and use we have got out of them!!)

I suspect Tony was also being pretty careful!

Although Peter C is getting similar figures with his aswell...

 

www.mycaterham.com

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101,000 miles car

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*eek* *eek* *eek* Oh dear.

 

Sorry to hear this....we are all, after all, allegedly human and thus prone to the occasional error. I find mine are ALWAYS blameable on someone else.

 

I'm sure you will recall (nudge nudge) being INTERRUPTED while putting that airbox back on, eh?

 

Meanwhile.....I think I'd feel safer if I took my airbox off and checked those dratted little trumpet fixings....... 😳 *eek* ☹️

 

Lucy in the Sky with Diamonds..ooooh hooo hooo!!...

😬 😬Abbey Road Time-Machine *eek* *eek*

 

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Thanks guys - Regin and Mav, many thanks for your offers *thumbup* *smile* - most kind.

Looks like we have been reasonably lucky.

Taking the sparks plugs out showed signs of damge on one:

here

 

Looking through the exhaust ports before disassembly we could see that the valves on one cylinder were not seated and therefore showed damage.

Taking the head off showed the damage. The good news was that the washer was still sitting on the piston, and looks to be whole. Piston is obviously marked, but not excessively so and not cracked (I hope!) Spot the washer sitting centrally.

here

 

Here is a before and after shot of the washer. Pretty well hammered I'd say!!

here

 

The damage to the head will require a little work - new valves obviously and some cleaning up of the surface, along with re-seating of the valves in the head.

here

 

All in all, could have been worst, as others have found out, so consider ourselves very lucky! Re-assembly will involve loctite, lockwire as danny suggests and also soem blobs of silicon on the bolt heads! *smile*

 

Once fixed its off to The Steves to tweak the map - as you can see it is a little sooty right now...

 

Thinking about it UF, I am sure that someone didask me something whilst I fitted the trumpets.....

...alas I was actually on my own when I put them on, so entirely me 😔

 

www.mycaterham.com

here

Videos

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101,000 miles car

 

Edited by - angus&tessa on 17 Sep 2007 21:36:28

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Sorry to hear about this Angus, but as you say, it could have been a lot worse. When I had my K-Series I fitted studs to the TB's with a nylock nuts on the back of the TB's and then secured the trumpets with nylock nuts - bit overkill, but reasonably secure *cool*

 

BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

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