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Discussion Starter · #1 ·
I have a 1984 BMW 325e that I've put tons of effort into, rebuilding the top end since it had been sitting for over 2 years. The problem is a miss in cylinder 5 at idle until about 1000 rpm where it begins to disappear. It has a refurbished head, just adjusted valves, injector is working, I have plenty of spark, I've ran out of things to try! I compression tested it and the compression came out to about 80 while the other cylinders were at about 135. I adjusted the valves which helped but it still misses at idle, although sometimes there isn't much of one at all where it's maybe the tiniest rumble or nothing to about to stall. I can't think of anything wrong on the bottom end that wouldn't just be a total loss of compression and power. When I run alongside my friend's 325es I can keep up no problem when above 1000 rpm and his car is running at 100%. I've done the IAC valve, my AFM wouldn't cause a single cylinder problem, nor would vacuum lines. I even moved around injectors after cleaning them and still the problem is only at number 5. Any ideas would be appreciated, I'm just at the end of my rope. :confused
 

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If you adjust these valve clearances cold on these small 6cylinder cars and you set them to 0.25mm they will be tight

Run the car till the temp needle it just over the blue mark
Then readjust the valve clearances

If it still misses chech the ht leads and rotar cap

But it sounds like a tight valve clearance or it has a sticky valve

If the head is a recon and was from a engine that had the cam belt snapped on it
This is know to happen if the valve guides have not been replaced after valve to piston damage
 

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Discussion Starter · #3 ·
Adjusted Valves

I already adjusted the valve clearance, it was a bit loose so I snugged it to the .12 that was recommended for when the motor is warm. This might have made a slight improvement. Should I adjust again when it's cold? And what would I want to do for a sticky valve? Thanks for your response.
 

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I already adjusted the valve clearance, it was a bit loose so I snugged it to the .12 that was recommended for when the motor is warm. This might have made a slight improvement. Should I adjust again when it's cold? And what would I want to do for a sticky valve? Thanks for your response.
If it has sticky valves it will need the head stripped down check to see if a valve stem is bent or has picked up and new valve guides will need to be fitted
 

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Discussion Starter · #5 ·
I haven't gotten to ripping the head off since I'm busy, but I've noticed that my exhaust crackles like there is rock in it. Could that be a hint that an exhaust valve is stuck open?
 
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