QuestionQUESTION: Hi. My corsa lite 2004 1.4i cambelt snapped. Replaced cam belt and water pump and started it up. Car fires and runs but very rough. Almost like its only running on 2 cylinders. What could the problem be? Bent valves? I pulled out all spark plugs and checked that they were firing and they were fine. I noticed number 2 bore was smoking when I pulled out the spark plug. Hope to hear from you soon.
ANSWER: the 1.4 is generally "safe" and should be OK valve wise.
You have timed it with the timing marks on the cambelt sprocket
lined up with the cambelt cover/ cylinder head? (not sure where the cam mark is on newer ones)
and the notch on the crank sprocket lined up with Zero degrees on the crankcase?
You are 100% sure they are right, not one tooth out??
If timing is 100% --> Next you want a compression test (Thumb over plug-hole will do) to check for bent valves - If a valve is bent there'll be basically no compression at all on that cylinder, compared to loads of compression for a good valve. put your thumb over plug hole 1 and turn the crank FORWARDS with a ratchet, if there's plenty pressure that leaks slowly move onto plug 2. and so forth.
If all cylinders have pressure....
Leave the battery off for an hour to reset the ECU.
Try again.
- If the valves are bent it's not a hard job on such a small engine, or you can just swap the head.
*** When you had the head off you would have seen where the pistons and valves came together (if they did), there would be crescent-moon shaped indentations in the pistons and a shiny edge to the valves where they dug in - did it look ok?
---------- FOLLOW-UP ----------
QUESTION: The battery wasn't disconnected since the cam belt snapped. Could the ECU maybe be trying to rectify itself? The engine management light stays on. Could that cause eratic idling? Thanks for the help. Quite nice to have people who actually know what they talking about.
AnswerIf everything else checks out OK (timing, compression) then leave the battery out for an hour or more - When the belt snaps the cam and crank become out of sync obviously, the ECU will go into limp-home mode or just be "wrong" in some way - Leave the battery out for at least an hour, half a day if possible - when you power it back up it should default to factory settings - if there's still a problem after this AND the timing is correct AND you have compression in all cylinders then you might have to have the ecu reset manually by a garage Plus scanned for error codes at the same time just in case something else has gone wrong.. dont rule anything out.
Good luck :)
