Engine: 140 1778cc B18: 142S only firing on 3 cylinders

Hi all,

I'm just learning about cars, so my questions will probably seem really basic. My 1968 142S is only firing on 3 of the 4 cylinders. It's not the spark plug or the distributer because the plug is sparking (and I replaced that spark plug tonight and checked the wire from the distributor to the plug).

What should I look for next? Is it the valves? As someone with almost no mechanical experience but a lot of enthusiasm should I dig in to that engine myself?

Thanks,
Dustin

[bb54]

hi, im not familier with the lay out of your engine, but if you know which cylinder isnt firing, id get hold of a compression tester and see if the compression is ok.
this will tell you if the valves are sticking open.

is the plug that accompanies the non firing cylinder sparking as strongly as the firing cylinder plugs ?

wayne

[classicswede]

A compression check is you next step as already stated.

There are a number of reasons why this could be happening
poor compresion can be caused by the following

tappets too tight - could be worth checking
burnt valve
worn valve seat - not very likely
damaged piston rings.

You will need to chack all the cylinder and the one that is missing should have a lower pressure than the rest.

Is it a total miss or more intermitant?

[Steve121]

I had this happen during the first long (and spirited) drive with my Volvo 121 after I'd bought it, unfortunately is was also accompanied by the engine being covered in oil through every orifice. Turned out that the piston rings on 2 cylinders were broken! (still went well tho)
Scored bores meant a rebore though also a chance to tune the head and stick twin SUs on it. Had the rebore done with a local engineering company for peeanuts, pistons new old stock so wasn't very expensive to rectify at all.