2G No compression, Valves are Good.

[breaksdaily]

Ive built a few of these motors and never had any issues like this, rebuilt the bottom end of a project car and used the stock head, everything was disassembled and inspected and head components/valves looked good. This car was not running when purchased and the only thing I saw that was an immediate problem upon teardown was the piston rings, which were all replaced...Yes it is timed correctly this is not my first rodeo with these motors but I usually use all new components in a rebuild like this.

Compression results were 60, 0, 0, 60.
Lifters? idk..

 

[motomattx]

How did you "see" bad piston rings? and what makes you think that the valves arent having problems? looking at them really doesnt get it, they need to be chucked up in a facing machine and touched up to see how bad they are, not seeing any visable problem is not enough with compression numbers like that, there is something major wrong.

 

[breaksdaily]

They were seized in the grooves, collapsed...somebody overheated this motor..alot

 

[motomattx]

I see, then the chances are good that the head has seat damage also, if not valve damage.

 

[breaksdaily]

The valves are not damaged, and they seemed to contact the seat completely normal... Maybe someone cut the seats and now the valve stems are up are too tall...Guess Ill tear the head completely down.

 

[92AWDHX40]

Been there I had no bent valves but my rings sized in the piston no compression.

 

[breaksdaily]

Been there I had no bent valves but my rings sized in the piston no compression.

Exactly what I thought when I tore it down, thought that was my only issue.. apparently not.

Also a few of the wrist pins were locking up and pretty sketchy so I Just dropped in a set of Evo 8 Pistons/Rods...cheap fix.

 

[keltalon]

Did you bleed the lifters? Just curious.

 

[ThunderChild]

What about the bores themselves, Did you hone the cylinders at all? I see you said you rebuilt it, but to some that means slapping new rings and bearings in an old setup w/ no machine work.

I'm suspecting bores, or like keltalon said, pumped up lifters. What about the hg?

 

[breaksdaily]

I never disassembled the head and removed the lifters all I did was clean it up with a lot of purple power and a pressure washer followed by a good oiling to prevent rust. The bores were in good shape also... bottom end was completely rebuilt and head was obviously removed so there is a new HG there... Wondering if this engine has ever ran with this head, maybe someone put the wrong cams in it. All of this I need to check, a lot of unknowns here.

Also compression gauge Is verified good.

 

[ThunderChild]

If u didn't touch the bores and you suspect the motor was over heated that much, I bet they're distorted.

You've got alot to check

 

[breaksdaily]

Just like I thought, valve stems up too high from valve seat machining, lifters too tall leaving valves open, unbolted cams and cylinder holds 120+psi on the Leak down test.

 

[keltalon]

Just like I thought, valve stems up too high from valve seat machining, lifters too tall leaving valves open, unbolted cams and cylinder holds 120+psi on the Leak down test.

Bleed the lifters!!

 

[breaksdaily]

Bled the lifters only and slapped them back in and re installed the cams, leakdown test still showed perfectly sealed when each cam lobe was oriented to have the valve closed over each cylinder, as soon as I reinstalled the belt and ran a physical compression test by actually spinning the motor over im still only getting 30-60psi per cylinder wtf.

 

[ThunderChild]

I smell poop...

How'd you bleed the lifters? I have a hard time seeing the valve seats cut so far as to hang the valves open on fully bled lifters. Is it still low compression between cyl 2 and 3?

 

[keltalon]

Bled the lifters only and slapped them back in and re installed the cams, leakdown test still showed perfectly sealed when each cam lobe was oriented to have the valve closed over each cylinder, as soon as I reinstalled the belt and ran a physical compression test by actually spinning the motor over im still only getting 30-60psi per cylinder WTF.

Where in Brooks are you located I am 15mins from Brooks ? I need to come look and see what you got. Who did you buy the engine from just curious.

 

[ThunderChild]

That's some solid class keltalon

 

[breaksdaily]

Retard mistake and left shrader valve in compression tester hose when I did the leak down test so my "120PSI" good test was a fluke and only pressurized from the hose to the 1 way shrader valve (Never made it into the cylinders ).

Actual test results, No compression held on any cylinder all air escaped via adjacent cylinder spark plug holes (leaking in b/w cylinders)... Head is now off and going to machine shop to get surfaced, Going to check the block surface as well and hope its ok.

In my defense the piston rings on the old stock pistons were completely collapsed into the grooves and shot out thus I thought that was the only reason this motor would not make compression before the teardown so this being a budget themed rebuild I neglected to check the head etc with a straight edge and or have it machined before hand... My last few motors I built were 650WHP+ setups so the block and head were always newly machined surfaces right from the machine shop and every single component was new (3-4K) motor builds.

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[taylork057]

why would you reuse a head gasket?

 

[breaksdaily]

why would you reuse a head gasket?

Confused by your statement, Where did you ever read a head gasket was re-used?

 

[taylork057]

you said you put new pistons in it and it had no compression. you have to take the head off for new pistons. you drive it with 2 cylinders? because the gasket looks used

 

[breaksdaily]

Gasket was new... When you remove the head from a composite gasket especially after torqued with copper spray it destroys it, can never be reused.. The black shown in B/w cylinders is from attempted combustion leaking thru there.

 

[keltalon]

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Glad you found the issue and thanks for updating. There are so many thread that start with an issue and never update the fix.

 

[breaksdaily]

Head was resurfaced and all valves removed and inspected/cleaned... Reinstalled everything and still no compression, leakdown results show head is sealed now but leaking all compression out exhaust ports even with cams removed, they claimed the seats looked normal but now apparently I should've just got them to do it anyway.

About to burn this thing to the ground.

 

[ThunderChild]

Just lap the exhaust valves in, they're prolly pitted. Takes about 30 min with the head off.

Did you also check the block deck for flatness between cylinders?