HELP!! loud bang and engine revs up when dip clutch.

[Stueylouey21]

Hi, looking for some ideas as my car is stuck at home.
Was driving home last night in my 172cup and was accelerating away from a roundabout just round the corner from my house. There was a loud bang and then knocking noise coming from the front end. ( couldnt tell exactly where from) i literally rolled the car home and now when you push the clutch pedal down the engine revs go up to about 3000rpm.
Not going to drive it untill i can get to a garage, but its my daily and deperatly need it back asap!
Any ideas would be great :/

Cheers Stuart.

 

[MartinR]

Spat a spark plug. ?

 

[Stueylouey21]

Didnt even think to look for that.. could it be something that simple?!

 

[MicKPM]

Does it start and rev okay? Engine sounds normal or like a tank?

Sounds like either a gearbox or driveshaft/CV issue at the minute

 

[Stueylouey21]

Just started it quickly.. its very noisy. sounds like its being run with no exhaust on.. but the noise is coming from the front end.. hard to tell exactly where!

 

[Stueylouey21]

So yeah.. like a tank!

 

[MicKPM]

Spark plug then - Check its not pulled the thread out of the head to as it may need time-serting

 

[Stueylouey21]

Is this common then? Ill have a look when im home tonight

 

[MicKPM]

Not common per say but known to happen from time to time. Any updates yet?

 

[Stueylouey21]

Just took the manifold off and sure enough its blown the spark plug out. I have taken some pictures of the damage and will post them up shortly. Looks like the top half of the thread in the head is nackerd aswell

 

[MicKPM]

Bugger, not good. Number 3 by any chance?

 

[Stueylouey21]

 

[Stueylouey21]

Sorry for the poor pictures but it was the best i could do!

 

[Stueylouey21]

 

[MicKPM]

Unlucky but you better check the others are secure to before the same thing happens.

Have you tried putting a plug in?

 

[Stueylouey21]

I took all the other plugs out.. to be honest none of them felt very tight! Is it just them coming loose that causes this to happen?

Yeah i tried one of the other plugs, screwed in one turn the went tight.. didnt want to force it. Looks like there is some damage to the threads but the threads further down look ok. Any chance of just tapping a new thread?

 

[MicKPM]

Sounds like they've been put in but not torqued up. You may be okay but ideally it needs a timesert (i hate helical but this would work to).

 

[Stueylouey21]

Is that a head off job? And how difficult/expensive would this be roughly?
Also do you know what plugs i need and what the torque should be?

 

[Stueylouey21]

 

[sonny172cup]

Unlucky but you better check the others are secure to before the same thing happens.

Have you tried putting a plug in?

What causes this Mick?

 

[MicKPM]

Plugs should be NGK PFR6E-10 and to timesert the head would need to come off.

Helicoil Vs Timesert argument has been done to death on here and on the Internet in general. My personal position - I hate Helicoils because they're pikey