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compression test
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Ray White



Joined: 02 Dec 2014
Posts: 2773
Location: Derby

PostPosted: Sun Jun 30, 2019 4:47 pm    Post subject: compression test Reply with quote

Hi all. I have done a compression test on my engine and would welcome your suggestions. Importantly, all the compressions were pretty much the same however there was a 30 PSI difference between first dry - and then wet tests. 105psi dry. 135 wet.

Would this warrant further investigation?
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Penman



Joined: 23 Nov 2007
Posts: 3947
Location: Lancashire

PostPosted: Sun Jun 30, 2019 4:56 pm    Post subject: Reply with quote

Hi
For me, define Dry and Wet in this case please/
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alastairq



Joined: 14 Oct 2016
Posts: 1087
Location: East Yorkshire

PostPosted: Sun Jun 30, 2019 5:11 pm    Post subject: Reply with quote

Dry...compression tester screwed in, nothing else added to cylinder.....
Wet....small amount of oil added to cylinder before compression tester screwed in, and tested.
A wet test will help to confirm [or otherwise] whether the piston rings are sealing well.
If a compression is 'low', then a subsequent wet test will check the piston ring seal. If the compression rises a significant amount, then rings need sorting [or re-bore, etc?].....If, on a 'low' cylinder, the compression pressure remains much the same, [despite oil being added, on the subsequent wet test]...then that points to valve seal, or head gasket blow.

For Ray, I would say there's a little bit of bore wear, but nowt to worry about for a good few thousand miles yet.
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Ray White



Joined: 02 Dec 2014
Posts: 2773
Location: Derby

PostPosted: Sun Jun 30, 2019 5:20 pm    Post subject: Reply with quote

Thanks very much Alastair. That was what I was hoping someone would say. There isn't much in the way of smoke - certainly not blue smoke - so I shall leave well alone. Very Happy
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Keith D



Joined: 16 Oct 2008
Posts: 914
Location: Upper Swan, Western Australia

PostPosted: Mon Jul 01, 2019 2:56 am    Post subject: Reply with quote

I would agree with Alastair. I would be far more concerned if you found serious differences between the cylinders.

Keith
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Ray White



Joined: 02 Dec 2014
Posts: 2773
Location: Derby

PostPosted: Mon Jul 01, 2019 9:56 am    Post subject: Reply with quote

Keith D wrote:
I would agree with Alastair. I would be far more concerned if you found serious differences between the cylinders.

Keith


I am thinking it confirms the recorded 25,000 miles.
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