Compression testing
- Thread starter Argenta
- Start date
This is not a good way to diagnose the headgasket because it usually takes much much more pressure to leak past a weak spot in the headgasket (remember, this is compression, not the pressures that take place during combustion, that's ~5-10 times as high)
What are you trying to achieve with these numbers?
If you want to know where and if cyl2 leaks (substantially), then you have to do a leakdown test and maybe some other tricks.
What are you trying to achieve with these numbers?
If you want to know where and if cyl2 leaks (substantially), then you have to do a leakdown test and maybe some other tricks.
Squirt some oil in and do it again. If it stays the same then it’s valves, if it goes up then it’s rings or bores. Most likely.
Update on this: Compression results was a result of faulty tester actually.
So, did a leakdown test (very even results 72-73psi) refurbished injectors, cleaned tick-over valve (forgot its english name), new plugs, coils, 2nd air pump functions controlled... To no avail!!
As long as the secondary air pump is on (50-60seconds in this weather) the idle is pretty lumpy. After that - even Steven.
Does anyone have any ideas..?
My only idea left is new engine mounts. However there's no vibration/noise i.e. engine touching anything.
So, did a leakdown test (very even results 72-73psi) refurbished injectors, cleaned tick-over valve (forgot its english name), new plugs, coils, 2nd air pump functions controlled... To no avail!!
As long as the secondary air pump is on (50-60seconds in this weather) the idle is pretty lumpy. After that - even Steven.
Does anyone have any ideas..?
My only idea left is new engine mounts. However there's no vibration/noise i.e. engine touching anything.
I had an occasionally rough cold start and it turned out to be the air shut off valve attached to the plenum.
Worth a check as it doesn’t take long to remove. If you shake it you should feel something moving inside. It might be gummed up so give it a clean by spraying some carb cleaner in there and shaking, let it sit, shake again etc.
Worth a check as it doesn’t take long to remove. If you shake it you should feel something moving inside. It might be gummed up so give it a clean by spraying some carb cleaner in there and shaking, let it sit, shake again etc.
If that’s under the plenum I assume it’s the ISV? The one I meant is a small plastic one-I think it’s to do with the brake servo.
I don’t have the standard s54 part number but the csl one is 11617833647. Have a google and you’ll see what I mean. It comes off somewhere on the back right as you look at the engine from the front.
Edit-this is the csl version, I can’t remember if the valve is the same across all s54 and it’s just the pipes that change. That’s probably the case but it will serve as a reference.
No guarantee it will work but I spent ages chasing a really rough cold start that would immediately disappear after the warm up sequence and it turned out to be that.
I don’t have the standard s54 part number but the csl one is 11617833647. Have a google and you’ll see what I mean. It comes off somewhere on the back right as you look at the engine from the front.
Edit-this is the csl version, I can’t remember if the valve is the same across all s54 and it’s just the pipes that change. That’s probably the case but it will serve as a reference.
No guarantee it will work but I spent ages chasing a really rough cold start that would immediately disappear after the warm up sequence and it turned out to be that.
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