Repair Or Replace..?

[Anthony 1,003]

Open the throttle if you didn't do so

[jonXS 30 1 Cars]

was the engine cold? i thought you did it when the engine is warmed up.

 

or drip a tiny bit of oil down the spark plug holes if its cold.

but dont quote me on that. just what i thought was the done thing

 

jon

[MiniGibbo 142]

Open the throttle if you didn't do so

 

Didnt do that.. does it need to be full throttle then..?

 

was the engine cold? i thought you did it when the engine is warmed up.

 

or drip a tiny bit of oil down the spark plug holes if its cold.

but dont quote me on that. just what i thought was the done thing

 

jon

 

It was warm, i took it for a drive before hand.

 

EDIT: A drop of oil is a "wet test" according to the manual and only needed if you find a low cylinder to iminate between rings and valves, i didnt get that far as i knew mine where so far off something was wrong.

Edited June 23, 2012 by MiniGibbo

[Anthony 1,003]

Yes, you usually need the throttle open to get an accurate result.

 

On a healthy engine, you should get a large proportion of the overall result on the first compression stroke and then the remainder over the next 2 or 3 compression strokes - you shouldn't really need to turn the engine over for 10+ seconds to get sensible figures. It will depend on the accuracy of the compression tester - which can vary somewhat, especially on cheaper ones - but I would expect something in the order of 175-190psi on a healthy engine, and perhaps more importantly, roughly equal results across all four pots.

 

You don't need to put any oil down the bores, other than after a low result to see if it dramatically increases, which would normally point at poorly sealing rings.

[MiniGibbo 142]

Yeah it shot up fairly quickly within a couple of seconds, the forth cylinder was slower.

 

That one jumped up two thirds then made the jump to just below the others after another turn or two.

 

So what you're saying is when I turn the engine over I should have my foot flat on the floor on the pedal..?

[Anthony 1,003]

Yes,

[MiniGibbo 142]

Cheers mate, I've given up for the day and plan to play Xbox for the remaining time but I'll have a go tomorrow..

 

I reckon cylinder four will be my problem. Does the stem valves go on just one cylinder, I assumed they would go on all four at the same rate..?

 

ESP given the state of all the plugs which are showing signs they all burn oil.

 

One cylinder being lower than the others gives me the impression it may be the rings on cylinder four which if it is lower tomorrow I'll wet test it.

 

If it jumps as you say it'll show rings If wet testing doesn't affect it the manual says that's good signs it's the valves..?

[Miles 331 1 Cars]

Having the throttle open will get you a increase but bot huge as the inlet's never totally sealed from the outside world, Also with the stem seals going or gone will not effect the readings

 

As Anthony's said the oil in the bores confirms if it's the ring's or Valves, if it increases with the oil then the rings are on there way, if nothing then it's the valves

[MiniGibbo 142]

Just tested the car again, this time using full throttle while cranking the engine,

cylinder 1 dry 5bar wet 6bar

cylinder 2 dry 5bar wet 6bar

cylinder 3 dry 5bar wet 6bar

cylinder 4 dry 4.5bar wet 6bar

 

Im not sure what to make of that really, all i can think is if that is accurate then why does the car run so well...? it never feels underpowered, missfires or idles irracically.

Peugeot state the cylinders shouldnt be under 10bar dry.

Opinions..?

[Darrens205GTI 10]

If as you say it drives ok, I'd suggest you borrow another compression tester, it could be its reading low especially as all readings are the same.

[MiniGibbo 142]

Don't know anyone with one dude, I could pay a garage for a test but they'd ultimately tell me the same thing, the forth cylinder is lower than the others..

 

At the moment I'm thinking of pulling the head off as it has to come off what ever happens then having a proper look with the intention of changing the bottom end if it is scrap to a 1400 ally bottom end.

 

 

1400 bottom ends with my Rallye head I'm lead to

Believe will make anywhere upto 120hp.. (Im dubious and think 105-110 is more likely)