I am working on my build, and have successfully replaced my EVO9 springs with Cosworth singles, (kelford CAMS, etc). In the process I am pushing air into the cylinder via an adapter to force the valves up so they don't fall in when I remove the retainers. Blah blah, a good write up with pictures coming when complete.

What I noticed is that in cylinder #1 the intake port is leaking more air than any of the others. Its consistent and audible. Both cams are off, so no pressure on the valves at all. They should be fully closed. This had me worry that there could be damage to the valve or valve seat, but I don't know enough about HEAD, , to determine.

Can folks let me know if there are tests I can complete to confirm or deny valve damage, or sealing issues. The air is not leaking out the pistons (I have the oil pan removed and the motor on a stand). Its specifically coming out the intake port on Cylinder #1. It was not so much that my air compressor couldn't fight it, so I could still change the springs, but I worry if there is damage that requires removing the head and getting it worked on/fixed/ported, etc.

Thank

Yes, take it easy, I accidentally posted this in the ECUFlash forum, I then asked for a mod to remove it or move it. I waited a few days, and am reposting here now, where it belongs.

 

Q15H gave some tips and here are the results.

I did a leak down test on all cylinders in a number of ways.

All at 100psi

1 - 20% leak
2 - 10%
3 - 10%
4 - 5%

I also tried different things as I noticed a slight difference by turning the crank a bit. Its surprising how much power that 100 psi into the cylinder is when you are trying to fight it holding a breaker bar on the crank bolt.

Can any share any experience on those values, as it would imply that valves are bent, not sealing, or otherwise need repair/rebuilding.

I am way over my budget on this build, as I keep discovering things.

Thanks

 

Could be valve seats

 

Looking at a few posts of leak down numbers I see folks with huge numbers in the 50%. That makes me think whoever did their test is just not adjusting the crank for the cam positions to keep the valves closed.

Would the engine builders here consider a 20% leak down in cylinder #1, which I have something that needs repair, or normal for a 50k evo9. I am trying to figure out if I need to take the head off or should start putting this thing back together.

 

Drop that head, get some valve grinding compound and figure out what the problem is...it may just need to be lapped...Did you get a vavle job? Dont spend a lot of money and then short change the details and have to do it all again at twice the price.

 

Meckert. Thanks for the tip. This is pretty much as far as I have ever gone on any project. I just had to google what lapping is, and found a couple of ghetto drill and hose ways to do it.

Is there a specific type of compound I should use for our evo9 head and valve?

Yeah, I don't have any more money. So it has to go back together as is, or find some labor (non parts) way to fix or improve it myself. Is there anything I should be careful of for a beginner that has never taken a head off.

I have the motor on a stand, and pretty much bare. But I know the head studs need to come on and off in a particular manner.

Will I need a new head gasket? Or can I just re torque the old one? Any guidance appreciated.

 

if you break the seal of the current head gasket yes you will need a new one. when removen a head loosen the bolts furthest from each other so you release the heads torque evenly. i know you say your on a budget getting this thing back together but dont cut corners or youll be pullin the motor right back out again.

 

It wouldn't be a valve seal.

Valve seals are for oil.

What you have, since there is no cams so no chance of overlap is a valve guide/valve face sealing issue. 20%, it all depends. I have had carbon build up on engines by the seat and cause this.

While pressure is applied on the cylinder. And the spring assembled. Tap the valve (i use a brass punch)and see if the leaks down changes. If it does, it was just carbon buildup.

 

4RETECH, I tried that several different times. Particularly because I had to 'tap' all the springs initially to break them free of the seats to change the springs. So I did that, but using a copper hammer on the valve stem light. Just so I could see the valve move down and return. I could not change the readings. They remained the same. I did dozens of tests with the leak down including where I change the position of the piston. I did have different behavior in other cylinders depending on where the piston was at, but it required strong resistance of the breaker on the crank bolt to fight the 100psi. However, piston #1 was always around 20%.

Is there something I can spray in there to clean the carbon build up, if there is any?

I was thinking to take the spring out again, turn the valve several times and replace the spring and retest.

Does everyone agree that the head gasket cannot be re-used? (can you tell I'm broke):roll eyes:

Thanks!

 

I know this is a serious topic, but I had to add this. When I read the title I clicked the link and passed my phone to my girl and said, "here babe, they've got a question for you".

 

 

Comedy solves all. HEAD helps too I guess.