Cylinder #2 down on compression. SOLVED.

[allencr]

check the block means engine out and off the the machine shop i guess
NO. A suitable straight edge and some instruction from any book, like High School auto shop training, machinist or maybe even the FSM, straight across between the bores, along the sides & criss-cross, no more then 1-.002in. Also clean shiny metal, no black smudges of built up carbon.
Headbolts are torque to yield, so i thought im doing the right thing by buying new ones..?
If they are really funny looking on their shank with thick & thin or spiral sections, not straight, & Factory says non-reusable, then yes, but don't replace if the only indication is because of their use of angle for tightening method
Head is torqued as per workshop manuals, head bolt instructions. 20nm,40nm, 90degrees on 3rd pass. im using a "warren and brown" torque wrench (not a cheapy) The specific number is less important then consistency to me, so dirt cheap or overly priced it'll get the job done as long as it's always giving the samereading. Dry threads & galled washers & un-oiled bolt heads cause HG failures way more then optimistic torque wrenches.

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[Jerry2]

No help sorry, just subscribing to the thread. Plenty of empathy though due to suffering the same sort of issue on my 22RE. All the replies are very enlightening.

Cheers Jerry

[Aust162]

Stuc, I have no idea on the history of the motor, but I have a feeling it was running something bigger than a ct9 on it by the way the guy was talking prob is the ringland that's cracked . Cheers for the offer on yours but I'm keen to fix up mine. If u have or know of a good bottom end for sale, lemme know.

Ok, I had about an hour spare to play around with it today. Did a DIY leakdown on 2 (and 3 as a comparison) . At tdc compression stroke I was getting a lot of air escaping from the oil cap.. Rings seem to be the issue at this stage. Cyl 3 was having a fair amount of air blow from the oil cap too though. Going to do the leakdown again and also some wet and dry comp tests.

Since fitting the new head gasket and bolts I've had the motor running for max 20 mins. If I end up pulling the head off again do you think I could reuse the head gasket and bolts or would that be not a good idea??

Thanks

[Omegaman]

If the aim is to put new rings, i would put new head gasket.
The compression pressure increase will probably cause the old gasket to shat itself.
But i would replace all the rings with a full new set, new gasket and be done with it.
Its the only way, that will eliminate any further issues.

[Aust162]

Comp test today with the throttle wide open. all plugs out. As you can see i repeated the test on cyl 2. what has me concerned is the oil barely raised the compression of that cylinder.i was expecting an increase of 30+psi. I added extra oil and still that didn't help raise the compression.

Now Im not sure what to do?! it sounded as though the air was leaking out of the cylinder while doing the test but i couldn't trace where it was going.

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[dnegative]

Motor out, new shells and rings all round
Crack test the block and have it decked.

[Omegaman]

I'm now thinking valve not sealing. before any dismantling, can you do a leak down test.
It's the one with compressed air into the cylinder. Then see if u get air out of the exhaust or intake.

[allencr]

...the oil barely raised the compression of that cylinder.i was expecting an increase of 30+psi.

That's what a broken not worn top ring does.
Also, 190 is pretty high for any turbo, has the head been cut/machined a lot?

[andrew_mx83]

Cracked head, or poor block surface
from a quick read all your symptoms are of the HG not sealing, either the block is low between a water jacket and #2 bore in which case any new gasket will not seal, or the head has a crack from a water jacket to #2 chamber. This wouldnt show up on a vacuum test, the story about 'over servicing' is total BS, a vac test checks that the valves are sealing and is totally irrelevant to crack testing, unless it had cracked through a port


Oh and hylomar is the shiznit, definitely keep using it on the HG and any paper gaskets you install.

[Aust162]

I've got a few pics here
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[jonathan yee]

Im with stuC, cracked ring land.

[badger]

hey there I am a diesel fitter by trade and very rarely use wet dry test as pressure testing with compressed air can tell you so much more than wet dry test. If engine is still together wind over to TDC all valve shut #2 cyl remove spark plug and fit adapter. can drill out old spark plug and silver solder to air fitting. Pressurise cylinder leaking out of manifolds = leaking valves, bubbles in water = cracked head, head gasket, cracked block etc. Air from dipstick tube = worn rings , cracked piston etc. If I have read your post right sounds like the sump/crankcase is pressurising which to me indicates most likely a cracked piston. Hope this helps.

[Hurricane]

had a quick read, sounds like you have cracked ring lands or broken compression ring.
ive done this before on a turbo 3tc, broke the rind lands in one section of the pistion, was not running 100%, one cylinder low in comp,
pressure in the crank case, all plugs fine.

leak down test as stated afew times will tell you were its coming from.
use a stethoscope (spelling) with the vac line on only, or a length of vacum hose (small hollow tube) to listen for the leaks.

Use Badgers post as a guide to the air leak sorce.

note that your rings even brand new will not seal the air 100%, so you will get air leak noises in the crank case.
what you want to do is see if one cylinder is louder than others.

mechanic by trade here also.

dan.

[Aust162]

allencr - i don't have any history on this motor. i know the head was machined at least once before i just had it done.(you could see the previous machining marks and they didnt look quite right)
No idea if the block has been decked. thanks for your posts btw.

Badger and Hurricane. thanks for your posts too. Leakdown test tomorrow arvo as i have the day off. half my problem is that i've been playing around with the motor for 30mins here, 30mins there after work in my driveway, in the dark and trying to setup my air comp and rig up this leak down tester i made. Im not 100% confident in my tester and my methods since ive never done a leak down on a motor before! (this is the first motor i've lost compression in)

One thing that may be worth mentioning is: when i had the head off last, i pour about two small cap fulls of wax and grease remover on top of cyl 2 piston. i did this to see if it would leak past the rings and it didnt. held the fluid for 5mins, then i decided to wipe it out.

The fact that the adding oil to the cylinder when comp testing it barely increased the cylinder compression has put some doubt in my mind, but hopefully as Allencr said ( a cracked ringland or broken ring wont "Up" the compression like it would say on a worn ring)

What is a good psi i should set my regulator to when doing the leakdown. i tried it on 45-50psi and it turned the motor over. should i lock a bar onto the crank pulley bolt to prevent that or should the leakdown test be done at lower pressure, say 10-20psi? (i dont think that psi would turn the motor over)

[Aust162]

Spent the morning setting up the leak down tester and ive tested all 4 cylinders individually twice each. at tdc comp stroke i dont get any air blowing from the exhaust, the intake (t.body) or bubbling in the coolant which im happy about.

With my air reg set @ 25psi on cylinders 1,3,4 im getting a small amount of air blowing out the valve cover breather, dipstick tube and oil cap.On this engine the crankcase has 4 ways to vent crank gas pressure:
oil cap
oil dip stick
pcv valve (which blows through TB)
breather tube barb on top of valve cover

NOW when i do this test on cylinder 2 (the problem cylinder) i get a SH*T load more air blowing out the valve cover breather/dipstick. At least 3-4 times the amount of blow by.

Im now convinced the ring is broken or the ringland is cracked.

Im going to leave the motor in the car, take the head off, drop the sump and undo the bigends and pull the pistons through the top.

Ill post some pics soon