Compression

[JRDHSG]

Hi all have been slowly fixing up the RVR and its time to turn attention to the motor. I have not had much experience with the 4G63 so a bit of guidance would be appreciated.

It has got 165 ks on it now. I bought it at 100ks. I have changed oil every 5000ks and not abused it. It is due for the belts soon and possibly an overhaul. Blows no smoke though, running stock boost and has a k&n panel filter and stock exhaust with a x force muffler. Goes quite hard.

Just got mechanic to do a compression test.

1/ 135
2/ 115
3/140
4/140

Is this good numbers for this motor? Or does cylinder 2 indicate excessive or abnormal wear? Should I be looking at top end work at the same time as the belts? Im not chasing big power with this car I am looking to get it to be a fun/daily car.

Thanks

 

[4piknup]

I think all are low. 2 is more than 10% lower and has more issues. I think you should be seeing 200+
you need a wet compression test, with oil on the walls, not dumped on the cylinder crown.
If it shows a significant increase (to 200 or so) you will need cylinder work.
no2 needs a leakdown test after the wet test. That will identify if its valves are leaking and how bad they are.

As its a budget/slow build job, id identify what the issue is with no2 with the leakdown test and address that in nearer future with a eye to doing bottom end in the next 50000kms or couple of years or so.

 

[Benzo4gT]

If it goes hard and doesn't use buckets of oil I wouldn't worry about it mate

200+psi Jack? That is a high figure to aim for. I admit I could be wrong but I thought 178psi is pretty much top of the tree

I have close to 180ish psi on all four of mine give or take a few psi with 139k on it, but I suspect the head has been off and had a service though.......

From some of the other forums I frequent 170-180ish is a good figure, mid 130s is getting into rebuild territory.

 

[4piknup]

http://www.4gtuner.com/topic/25940-wet-compression-test-oil-dispenser/#entry321677
my motor hasnt been rebuilt and shows 205-220psi (on my tester btw) wouldnt think a 93t would have more than a 63t.
If 180 was ok, then the op is still showing 30% down. Not urgently requiring rebuild, but enough to be keeping closer eye on oil levels between oil changes.

 

[DOUGMO]

its not really the number that is the issue but the difference, chances are it wont be super smooth with that variation

 

[4piknup]

Chances are the low one has issues.
Its actually the numbers over time. If it had 200psi at last oil change then thats a problem.
Everyone should have own compression tester and record it every oil change to monitor it.

its like a oil sample. One doesnt mean much, but one every interval over a period of time means a lot

 

[JRDHSG]

Thanks for the replies. So my motor is worn but not dire.

I am assuming it would be more cost effective to do a top end rebuild at the same time as the timing belt service?

 

[evo-gsr]

May as well while you have it apart...will save you $$

 

[4piknup]

You need to do the leakdown test to determine what condition the top end is. No good doing top rebuild if its still good and the compression results are from 3 worn rings and 1 cracked rings on cyl2

 

[evo-gsr]

I took top end rebuild as being rings etc....?

 

[DOUGMO]

i wouldnt be tipping much money into it with those numbers

as above, do a leakdown and wet comp test

 

[4piknup]

I took top end rebuild as being rings etc....?

hey, you might be right. I was thinking op was talking just valve work as i think he said pulling the head off in post#1 and didnt say pulling the engine out.
I was reading between lines, not the words. Not sure

hmmm op says top end work while doing belts, still doesnt really indicate he is willing to pull engine. Too me anyway.

 

[4piknup]

I got a really cool endoscope for my engine and its low compression on one cylinder. Plugs into phone and all. Will try it out next week. No need to pull head to look at pistons. $20- sweet