sdh2903
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| posted on 8/6/15 at 06:44 PM |
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Low compression on 1 cylinder
HI all
Started pulling apart the donor today a 1.8 mx5. Engine ran fine all the way on the 150 mile journey home, however I thought today I'd do a
quick compression test. The readings were 200, 200, 140, 200. So obviously an issue with cylinder 3. Reading the t internet doesn't seem these
suffer generally so wondered if any issues had been encountered by the collective?
I forgot to stick some oil down the bore to see if it's a ring issue I will try that tomorrow. Other usual suspects? Head gasket? sticky valve
perhaps? I wasn't planning on cracking the lump open but as I'm now turboing it a bit of a refresh wouldn't go amis.
Steve
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Smoking Frog
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| posted on 8/6/15 at 06:56 PM |
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Did you test at normal engine temperature?
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sdh2903
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| posted on 8/6/15 at 07:01 PM |
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It had been run for 2 or 3 mins if I remember rightly so maybe not fully warm.
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JeffHs
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| posted on 8/6/15 at 07:04 PM |
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Check valve clearances?
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Smoking Frog
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| posted on 8/6/15 at 07:14 PM |
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Do another test at normal engine temperature and WOT.
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sdh2903
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| posted on 8/6/15 at 07:17 PM |
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Will do. The test was done at WOT. Will let it heat up a bit more tomorrow
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britishtrident
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| posted on 8/6/15 at 07:21 PM |
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Most likely is Bent, burnt or sticking valve, it could be broken rings but perhaps. less likely in this case.
The best test would be a cylinder leakdown test you need to buy or McGiver one of these
ebay link leakdown tester £28 and a compressor.
[Edited on 8/6/15 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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sdh2903
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| posted on 10/6/15 at 01:57 PM |
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Well. With the engine run up to temp ran another compression test today and all seems well. 5 psi difference max across all 4 cylinders. Even when it
cooled a little I still couldn't replicate the low compression on cyl 3.
Must have been finger trouble on my part. Anyways thanks for the input guys
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Smoking Frog
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| posted on 10/6/15 at 02:39 PM |
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Good news. I also had the same low reading on cylinder 3 on my 1.6 until I repeated the test at working temp.
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