misfire

[len]

so today i pulled onto the motorway and car misfired,,,,,to be honest i thought the fuel pump was failing so i limped home..the engine doesnt sound happy , particularly the lh head ,its seems a bit cammy if you know what i mean......I took the cam covers off to make sure its not a chain problem and all lines up properly,,,,,timing is correct. oh maybe coincidence but one of the little throttle plastic elbows had come off (broken) which i have replaced.
any ideas what my problem is ?
thanks in advance
Len

[Tdm]

If one of your Carb Linkages is not working - you will get very uneven running, but you say you have replaced it - Is it still misfiring?

[len]

misfire seems to be gone....its just sounds awful......i did do a water pump rebuild about 6 weeks ago...it sounds like something is knocking but not a big or small end sound.
could my water pump be make a knocking noise ?

[Tdm]

With regards diagnosing where strange sounds are coming from - has anyone tried or got a Car Stethoscope such as the one pictured below - I wonder if they work?

[Jeff]

A long screwdriver works too, put the handle to your ear and touch the end where you want to hear.

[Tim Ward]

Yes have one, surprising what you can hear. A lot more accurate than the screwdriver method, as you can see the end and move it about, Tim

[Staggard]

From my point of view its irrelevant what you use to hear the sound if you don't know what the sound represents, If you know what you are listening for a screwdriver is perfectly good. If I had walked in the workshop with a stethoscope I would have defiantly have been greased up.

[len]

i will try the screwdriver tomorrow. the rough sound seems to be coming from the left head. Both heads were off last christmas and were overhauled ,

[Greengiant]

Len, I hope you haven't caught anything off my car!
I have found a long handled screwdriver has worked well for listening to noises.

Martin

[len]

Hi Martin
yes bit strange really....cars been running so well,,,,cant figure it out yet,,,maybe tomorrow !

[len]

ok so....
today have had another look and listen,,,i think the knuckle on the carb linkage breaking caused what i thought was a misfire ,,,,
the knocking i am afraid sounds like its coming from the bottom of the engine ....just a coincidence with the carb knuckle....not good news ,its probably a big or small end....
As you say Mr Staggard its ok listening to the screwdriver but you need to be able to understand the noise,,,,i dont to be honest but thats my best guess.
i need to find someone who does ....
cheers
Len