10 replies to this topic

[oli18]

Hi,

I had a 2nd hand engine installed by my local garage (998cc) recently and when i got it it was fine. Then a day or 2 later, it started to lose power. I went back and they replaced one of the sparkplugs which was very very black and it worked fine again.

Now 2 days later again, the car is doing the same thing. i have a feeling the new sparkplug is again black.

If it is, what could be the cause? Valve stems on that cylinder? Taking it back to the garage but would like your opinions if possible.

Cheers,

-Oli

[Jimmyarm]

If its really black, its suggests that that cylinder is running excessively rich, compare it to the others and see if there is any difference.

[Bass Man]

Check compression

[Silicon Skum]

Hmmm, sounds like you need to do a compression test, could be bad rings / bore wear.

SS

[fikus01]

low compression on that cylinder, could be a leaky valve!! do a compression check!

[nomininolife]

Is the spark plug sooty black or gungy black?

David

[oli18]

Is the spark plug sooty black or gungy black?

David

Sooty black.

I hope they can fix!

Thanks for the help so far.

Edited by oli18, 24 January 2007 - 12:26 PM.

[minipip]

are they all the same because if they are then turn ur mixture down as that is running sooo rich

[oli18]

Took it to the garage today that put the engine in and they called to say that they adjusted the points and opened them up a little and it now runs a lot better . Will pick it up later today so we'll see if that has solved it.

Can anyone tell me how opening up points makes a sparkplug become sooty?

Cheers

Oli

[Jimmyarm]

I know what I want to say but I cant type it in a way that makes sense !

The answer basically is yes, having the points wildly 'out' can make that happen because of the way the spark makes the combustion happen but there are specific setttings for the points and they would have to be really really wildy out for it to cause a spark plug failure imo (I know as I have run mine quite a bit out of the accepted 'gap' or 'dwell' ).

Ask the garage to do a compression test as said above if the misfire comes back.

Did they rebuild the engine before putting it in or did you supply it etc ?

[oli18]

Hi Guys,

Well, after i got it back last time (whent the points were adjusted) it started doing the same thing again after a day. I took it back again and they have changed the HT leads which seems to have done the trick. I have driven it around a few days now and it drives great again!

So good lesson if it happens to anyone else on the forum, it's worth checking the HT leads....it only cost me £15 for a new set!

-oli