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Author: Subject: Zetec silvertop compression test
AlexXtreme

posted on 23/3/19 at 10:09 PM Reply With Quote
Zetec silvertop compression test

I have been putting putting off testing the compression on my 1.8 silvertop for some reason. Had a slight misfire when cold and had a feeling that it was something serious. .. so did not want to find out it was something serious!
Anyway I have 2 cylinders at 165psi and 2 at 170psi with a slightly loose compression tester (with poor the adapter I could not tighten it up on each cylinder). No idea on how many miles the engine has done. I think around 50k.
Does this sound OK? The engine had been run but had stopped around 45mins before I tested the compression.

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rusty nuts

posted on 24/3/19 at 07:17 AM Reply With Quote
I wouldnt be concerned with those figures but I had a Zetec engine with a lumpy idle that had had the compressions tested several times, passed emissions test etc that when tested with a cylinder leakage tester showed a burnt inlet valve.
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perksy

posted on 24/3/19 at 09:07 AM Reply With Quote
The readings are within 10% of each other which is good

Leakdown is the best way of testing

Test should really be done with a wide open throttle and with an engine at normal operating temp

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AlexXtreme

posted on 24/3/19 at 09:19 AM Reply With Quote
It was wide open throttle though it had cooled a bit as I could not find the adapter for the compression tester in my garage..
My thought was as there was little difference between the values the slightly lower than expected was due to the temperature rather than anything else.

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perksy

posted on 24/3/19 at 09:26 AM Reply With Quote
To be fair as their within 10% of each other I wouldn't be worrying

Is the Zetec on carbs or injection?

You've already checked plugs & leads?

In a previous thread you mentioned moving the Coil pack, Have you done this and are you happy with the wiring etc ??


[Edited on 24/3/19 by perksy]

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AlexXtreme

posted on 24/3/19 at 12:15 PM Reply With Quote
Built leads from scratch and measured resistance so know they OK. Plugs are pretty new and adjusted.

Carbs (twin webers) and after re-balancing them, the tickover seems now OK. Why do they go out so quickly and it is always the same pair :-0?

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falcor75

posted on 24/3/19 at 12:47 PM Reply With Quote
165 and 170 are close enough to not be an issue. Do a leakdown test, even if the engine is cold you can identify potential leaks. Found a crooked exhaust valve on the #3 cylinder on one of my aircooled engines that way.
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AlexXtreme

posted on 24/3/19 at 01:09 PM Reply With Quote
I won't be doing this now but for my information, how do you do a leak down test without an air compressor?
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britishtrident

posted on 24/3/19 at 03:11 PM Reply With Quote
If it is a Silver Top misfire from cold start can be due to hydraulic tappet jacking especially in cold weather. They are very sensitive to oil grade.





[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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britishtrident

posted on 24/3/19 at 04:30 PM Reply With Quote
quote:
Originally posted by AlexXtreme
I won't be doing this now but for my information, how do you do a leak down test without an air compressor?


It can be done with a 12v tyre inflator as long as it is a heavy duty one usually sold as "4x4" or suitable for "off road"
The leakdown tester I now use is an AM Pro brand it wasn't expensive from eBay these days I tend just to do a cranking compression test with an oscilloscope.





[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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