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| Mknoxc Member Since: 17 May 2021 Location: Sussex Posts: 2   
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I have acquired a 1992 Rover V8 3.5 engine s/n 24G10456B. It came out of a fire truck so has not had a lot of use. I have performed a compression test on the cold engine and six of the cylinders were good at 120 psi (it’s 8.13 to 1), however cylinders five and six are 105 and 100 psi. I squirted some oil into the cylinders and now cylinder five is 120 psi and six is 110 psi.
My question is should I replace the piston rings in those two lowest cylinders that are 100 and 105 psi cold, or can I expect them to be OK when engine is warm? |
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23rd Nov 2022 10:47am |
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| Mknoxc Member Since: 17 May 2021 Location: Sussex Posts: 2
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Thanks for the reply. I ended up doing a full tear down and found all the pistons are worn. Also one bore is below limits (naturally the one with the lowest compression) so I’m going for a +10 rebore and new pistons to match. Cheers!
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19th Jul 2023 3:31pm |
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| 1986RRC Member Since: 11 Mar 2022 Location: Nicosia Posts: 4 
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Hello. I have a question in relation to compression tests as well. Does anybody know what readings or range in Bar should a healthy, newly overhauled 3.5 V8 efi High Compression 9.35:1 engine should give? Std measurement pistons fitted with new liners. Thank you |
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14th May 2024 10:34am |
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| TexasRover Member Since: 24 Nov 2022 Location: Paris Posts: 1060  
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Well just yesterday I did a compression test on the left bank of my P38 4.0 rover V8. The compression rating is also 9.35:1 and I got readings between 160-180 PSI.
Hot engine, throttle open 4-5 cycles (needle steady), no oil added I was trouble shooingt a suspected head gasket issue, but concluded (so far) it's an exhaust issue. |
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14th May 2024 10:47am |
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| TexasRover Member Since: 24 Nov 2022 Location: Paris Posts: 1060
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Just had a quick look at the record I have from a 1984 RRC with a 3.5 Carb engine which I used to own. Also 9.35:1 compression ratio and the readings were 145-155 psi
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14th May 2024 12:10pm |
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| 1986RRC Member Since: 11 Mar 2022 Location: Nicosia Posts: 4
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OK.....well not sure how mine was operated. I just know that I have readings between 9.5-10.5 Bar in the 5 cylinders. The remaining 3 are dead, 0 compression. And this is a recently overhauled engine!!!! I am laughing at the situation BUT I am not sure if I should be crying or chasing with a shotgun the machine shop owner and my mechanic here in Cyprus! I am in the market for a new engine because the Automotive Engineer I commissioned to examine the engine reported that many things went wrong. Block was skimmed 0.16mm, RH cylinder head 0.15mm and LH cylinder head 0.31mm (and note that I am 2nd owner. Not sure if first owner had cylinder heads skimmed before). Tragic... this is the skill and quality of machine shops and mechanics here in Cyprus. Thanks for your reply. Regards |
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14th May 2024 5:44pm |
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