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compression test results

Posted: Fri Oct 08, 2010 6:54 pm
by sg1
Help... can anybody interperate my compression test results?

1 - cold 110 Psi, hot 108, plug black
2 - Cold 110 Psi, hot 108, plug black
3 - Cold 115 Psi, hot 115, plug black
4 - Cold 115 Psi, hot 125, plug brown

Best regards,
SG1

Re: compression test results

Posted: Fri Oct 08, 2010 7:06 pm
by bmcecosse
Utterly knackered engine.......... ! What engine is it ? may be 'just about' ok for a side-valve.

Re: compression test results

Posted: Fri Oct 08, 2010 7:12 pm
by sg1
Alas it is a 1098, 1968 1000.
SG1

Re: compression test results

Posted: Fri Oct 08, 2010 7:15 pm
by MarkyB
Probably cream crackered.
Any better hot, or with a little oil down the bores?
Does a lot of smoke come out when it is running? If so what colour, Black or Blue?

Re: compression test results

Posted: Fri Oct 08, 2010 8:27 pm
by bmcecosse
It's well gone....... :cry: Decent 1098 would be 160/170 psi.

Re: compression test results

Posted: Fri Oct 08, 2010 9:09 pm
by sg1
Thanks for your help. RIP
SG1

Re: compression test results

Posted: Fri Oct 08, 2010 9:55 pm
by sgray
Couldn't it just be the head?

My 948 was giving 80,30,80,80 before I changed the head and now it's 150 across the board. And the head just cost me £50

Re: compression test results

Posted: Fri Oct 08, 2010 10:34 pm
by mike.perry
bmcecosse wrote:Utterly knackered engine.......... ! What engine is it ? may be 'just about' ok for a side-valve.
Not even any good for a S/V, mine are 130psi. The book says 150psi for a 1098. Maybe you are better off with the 948.

Re: compression test results

Posted: Fri Oct 08, 2010 11:24 pm
by millerman
Forget the doom and gloom merchants!

Are you 1).satisfied with your car's performance and 2) does it use very much oil

If the answer to 1. is yes and 2. no, then keep driving and service regularly

Re: compression test results

Posted: Sat Oct 09, 2010 12:16 am
by bmcecosse
I suppose it is entirely possible that the valves and seats in the head are all knackered. Usually just one or two fail before the hopeless performance forces the owner to do something about it! So, yes - there is no harm in lifting the head and checking it for any problems.