Questions and Answers
Nissan Micra
Q. Dear Mr. Ciulla, I have contacted you on a couple of occasions and your suggestions were welcome, though I have to admit they didn't actually solve the problem.
My car: Nissan Micra L, 1987, 988cc, 85,000 miles, A/C, manual transmission. My driving is exclusively short journeys of 1 to 5 miles of slow careful driving so the engine never really gets hot.
There are a couple of reasons that I wanted to look at my valves but I've never looked at them before so please forgive my ignorance. I followed Haynes manual and turned the engine to one position to check one set of valves and then to another position for the other set. However, I found that on the valves to check there was some movement in that rocker arm. If I tried to check the clearance as it was, it was much to low, but if I lifted the rocker arm with my hand to the top of it's play the clearance was much to high.
As I say I've never looked at this before so I'm probably sounding like an idiot but I wonder if this sounds right to you and how am I supposed to check the clearances with this movement.
Also, how can I check if my valves are sticking?
I'm still having the carbon fouling on my middle two plugs you tried to help me with months ago despite changing just about everything and there is a slight rattle/tap sometimes (though the other K10 I hear going by aren't so quiet either), so I thought the valves were worth checking. It's nice and smooth running though - recent oil change, clean PCV system, PCV valve ok, secure vacuum lines, change carb, change fuel pump, check fuel filter, exhaust ok, check float level, check fuel lines, fuel tank and fuel cap, test idle speed counter (as Haynes ) and idle-compensator valve, choke valve opening/closing ok, swapped distributer cap, cleaned all electrical contacts I could find, new Bosch plugs (couldn't get NGK ).
I get some slight pinging on accelerating from low speed sometimes - when the engines working at it's hardest I guess, which is really irritating. I know getting the engine nice and hot on a long journey is good for cleaning carbon but that seems like a separate issue as far as the plugs are concerned because they foul quickly. The division between the two inner and the outer plugs is even more distinct now I've got new plugs - the outer two could be accepted as ok.
Thanks,
KevinA. I'm sorry that my suggestions didn't help you, but you have to keep in mind that they are just that; suggestions. If I could diagnose and repair every problem on every car over the internet, I would never have to go to work. All I can do is give you the best possibilities I can with the information provided. That coupled with the fact that you have a car that is not imported into the USA and for which I have no service information on limits me to general possibilities that would apply to any make or model of car.
I remember that one of your questions dealt with carbon fouling of a couple of spark plugs. With the information you previously provided, the valve seals would be the most likely cause. But the slow short trips you make will also lead to the same problem. You need to drive the car for a good 15 or 20 miles and at a speed above 50 mph to get the engine hot enough to burn off all the carbon that has accumulated inside it. Also the short trips will allow raw gas to get into the crankcase and dilute the oil to the point where driveability issues will arise. After a good long drive at speed, I think a lot of your problems will disappear.
As for the valve adjustment, the rockers will move up and down. That's due to the normal valve clearance. The amount of the up and down movement is what you are adjusting. Nissan likes its intake valves to be adjusted to 0.010" cold and the exhaust valves adjusted to 0.012" cold. You should check your manual and verify the correct valve clearance for your particular engine. The clearance is checked between the cam lobe and the rocker arm. We used to have a saying, A tappy engine is a happy engine", that is to say a slight tapping meant the valves were not too tight and the engine was running well.
To check for sticking valves you'll need a vacuum gauge. Hook it up to manifold vacuum and watch the needle. It should be steady. If there is a rapid fluctuation, you have sticking valves.
Additional Information provided courtesy of ALLDATA
