cylinder 1 - 140psi
cylinder 2 - 144psi
cylinder 3 - 145psi
cylinder 4 - 145psi

untouched low milege stage 1 YB engine does this look a healthy engine?

 

Yes as 4/5psi difference is nothing

 

must say cylinder one the plug hole was a little dirty so the tester wouldnt screw in as far as the other cylinders maybe resulting in that 5 psi loss?

 

wouldn't worry over that mate tbh

 

the only thing with this engine is it knocks when cold but goes when warm,sounds top end is this the famous 2wd piston slap or are my big ends going,has 55psi oil pressure at idle cold?big ends only knock when warm dont they when the oil thins if worn?

 

i wish i was popular

 

Piston slap is very common on higher milage YB's, mine use to slap until the engine was warm.

The engine on mine itself was reliable, just not the rest of the damn thing

If it was your big ends they knock when it was cold, warm, tepid, freezing etc etc. Your compression results look good, as it's not the pressure you look at but the differential accross the cylinders. I tend to use 1 Bar as the beginnings of a problem.

Have you done a leakdown test? Was that a 'wet' comp test of a dry one?

 

Is it a knock or a tap. As a general rule a heavy knock is likely to be bottom end and a light tap is usually top end.

 

its a knock when cold it really sounds up top but clears once warm,test was dry.so can rule out big ends then as it would do it all the time yes?

 

From what you've said I'm 99% sure it's piston slap when cold.

 

this s low milege though

 

Don't mean shit with a cossie though...... How many miles have you owned it? It's one of the fastest performace hatchbacks of the 80's and 90's. Just because you treat her right doesn't mean the first owner did. I bet that car was thrashed stupid for the first 20k of it's life.

 

is that about right for the comp test then i guess, i will be doing mine soon so hope for the same, mine has done about 118k on original bottom end as far as i am aware

 

2wd engines suffer from piston slap when cold because of the straight gudgeon pin in the piston. One the piston warms up and expands in the bore slightly the slap goes away. 4x4 pistons use an off-set gudgeon pin which eliminates the slap. Cosworth racing pistons also slap when cold. hope that helps mate

 

If for instance you get a low result of say 120-125 across all 4 cylinders what could this mean?

 

Nothing. Your engine is wearing evenly? The actual figure is not important, UNLESS they're all 10psi or something.

If they're all 120-125 then thats good I'd say!!

Squirt a bit of oil down the bores through the plug hole and do another test, see if they increase a bit.

 

is it just me who thinks this is silly high?

 

Most cossies i have had run about 4-4.5 bar when cold, thats over 60psi, then around 2-2.5 bar when hot.

 

i was more worried about it being low mattbut appears normal

 

sorry never twigged it was cold oil pressure

mine is same as guzzlers at idle hot/cold

 

My comp reading on my freshly built engine were exactly 100psi across all 4 cylinders..

 

If you want to check if it is big ends.

Leave the hand brake on, put it in first and then slowly bring the clutch to the biting point. This will put the engine under load. If the knocking gets worse when you do this then it is the big ends.

 

only does it when cold mate,as has been said big ends would knock all the time and surely oil pressure would be low?

 

it'll be piston slap; even in the original ford manual they say about a noisy engine when cold

if it clears when warm its almost certainly piston slap

mine had done 54k and it slapped and sounded awful when cold, as soon as it was warm, it was quiet as a mouse