Compression testing

[Guest]

Going to be re-assembling my williams engine soon and get the hybrid on the road. Is there a way to make sure the compression readings will be good or will i only be able to find out once the engines back together?

Theres nothing to suggest they would be bad its just me worrying and not wanting to get it back together and then having to strip it again meaning new HG,cambelt and headbolts.

What actually causes the readings to be low?

Im still a noob at this engine stuff you see

Thanks

 

[Guest]

Bust Headgasket or broken/worn piston rings cause low compression. Or ofcourse a hole in the block.....

 

[Guest]

valve leakage a major one!!!!!!!

 

[Guest]

Would you say valve leakage was the main one as i can have that tested before reassembly yeah? Thanks for the replies.

 

[Guest]

Yep you can get cylinder heads pressure tested. It's always recommended you get the head skimmed and pressure checked

 

[Guest]

Head's been skimmed and i've just finished putting new valve seals and re-grinding the valves/seats. Think i'll send it off to be tested to be sure.

 

[Guest]

defo do pain to find out they are low again

 

[Alta Vista [Bot]]

Head's been skimmed and i've just finished putting new valve seals and re-grinding the valves/seats. Think i'll send it off to be tested to be sure.

test the head by re fitting the valve springs turning upside down and filling the head chambers with diesel...

bottom end cant be tested until engines run up to operating temp and tested complete..

 

[Guest]

Head's been skimmed and i've just finished putting new valve seals and re-grinding the valves/seats. Think i'll send it off to be tested to be sure.

test the head by re fitting the valve springs turning upside down and filling the head chambers with diesel...

bottom end cant be tested until engines run up to operating temp and tested complete..

Surely that isnt a great way of testing it though as Diesel is thicker?

 

[Alta Vista [Bot]]

when a cylinder head is pressure tested it usually means the cooling system water ways for leaks..

they can be crack tested also..

best way to check valve seats is with diesel...

petrol can be used as its thinner but not necessary really..

 

[Guest]

Will the diesel leave any residue in the head which could affect it in any way? Sounds silly but im guessing the only way to get a bit of diesel is to go down the petrol station with a jerry can?

 

[Alta Vista [Bot]]

no it won't

can use petrol etc but will need to be a better seal....diesel heating oil paraffin

 

[Guest]

So will there be no leakage at all, or a tiny bit, when using diesel? Obviously if it pisses out theres a problem lol

 

[Alta Vista [Bot]]

should be virtually none over an hour or two..

 

[Guest]

I used paraffin

 

[Guest]

So something like this matteh?
http://www.diy.com/diy/jsp/bq/nav/nav.j ... earch=true

 

[Alta Vista [Bot]]

yeah will be fine...

 

[Guest]

yeh, think I picked mine up from a shell garage

 

[Guest]

Would the paraffin not slowly evapourate?

 

[Alta Vista [Bot]]

maybe but your only testing over a few hours...do it somewhere cool..