Very Low Compression!!!!

L

littletodd18

Member +
Hi all,

Have had the starlet back on the road with the new engine for a week, yesterday i decided to give it some abuse for the first time, see how it pulls... boost stayed at 0.75 bar which is good but once i was home i noticed it was idling very very thumpy...

Done a compression test today and results are
Piston 1: 12 Bar
Piston 2: 11 Bar
Piston 3: 6.5 Bar
Piston 4: 12 Bar

I also noticed quite a thick layer of mayo in my oil cap, can head gasket failure cause low compression in just 1 piston?

If not what could it be?

Mike
 
lingl9z

lingl9z

Member +
does it sound like a subaru? could be ringland damage on no3 common problem if running stock manifold with higer boost! hg could in some cases cause this i guess!
 
L

littletodd18

Member +
lingl9z said:
does it sound like a subaru? could be ringland damage on no3 common problem if running stock manifold with higer boost! hg could in some cases cause this i guess!
Click to expand...


Yes that is exactly how i would describe it actually, i hate the stupid car!

I was only running 0.75 bar, is that too high for a stock manifold?
 
herbie

herbie

Member +
you can run a stock manifold on 1bar

edit: if you have a good tune.
 
Last edited:
L

littletodd18

Member +
herbie said:
you can run a stock manifold on 1bar
Click to expand...

How come the rings have gone then? Was it just on it's way out and i finished it off?

I am seriously annoyed with the dam car now! Off the road for 6 weeks, £500 for a new engine, first time i ragged it since it's been on the road and now this!
 
danturbo4311

danturbo4311

Member +
put a bit of oil down cyl 3 see if that raises compression if so its rings or cracked piston (on the ringland) also did you set the ignition timing correctly with a timing gun/strobe light
 
finx

finx

Member +
sounds like blown head gasket.
need to know does it use any oil? use any water? oil in the water? high pressure in the cooling system? ie it frothing and bubbling out the radiator car on idle?
 
L

littletodd18

Member +
finx said:
sounds like blown head gasket.
need to know does it use any oil? use any water? oil in the water? high pressure in the cooling system? ie it frothing and bubbling out the radiator car on idle?
Click to expand...

Hasn't used oil since it's sounded like that but i did only drive it home, there was nothing round the rad cap but some of the water had gone into the over flow bottle so it does indicate it's got hot, it has been running at normal temp...

I will be doing another compression test this evening but i will put some oil down cylinder 3 and see if that raises compression, if so then i can only assume it's piston/ring damage but if not then probably HG i imagine?
 
L

littletodd18

Member +
sx_turbo said:
ringlands broken on piston 3 very very common
Click to expand...

That's what it seems to be but the fact that theres mayo in my oil cap and the HG is leaking oil in the corner makes me think it may be HG.

All will be revealed this evening anyway!

Thanks for the advice given though people, it is much appreciated...
 
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