Hello members,
I am really hoping someone can help me out here. I went to a shop today because I'm having issues with my mew 2.4 Evo 9 built. Little info on the built.
Long Rod 2.4 with wisco pistons, Manley TT rods, GSC s2 cams, GSC standard valves, GSC springs and retainers, kiggley HLA. Now on to the problem. My car runs on 2 cylinder when it's on. The timing is dead on. The weird part is when they did a leak down test on a brand new motor I had around 4 to 5% leak. When they do a compression test cylinder 1 gets 10 psi of compression and cylinder 4 gets 0. I know it's not bent valves or bad rings because the leak down proved they are ok. What can cause a motor to have such a good leak down and such a bad compression? Me and the shop are seriously lost. Anybody has any info to help me out? I don't now what else to do. All the help is greatly appreciate it. Thank everyone in advance 👍🏻👍🏻👍🏻👍🏻👍🏻

 

You'll know when you pull it all apart.

Then you can put it back together again but properly.

 

Well, you know which test is right since it is running on two cylinders.

 

What would happen if all 4 rockers fell off on one cylinder?
Why would they do that?
Reground cams and no shims.

Not that you're going to loose 4 rockers but has anyone looked?

 

My engine has 5 min of run time on it. I just put it back in the car to break it in. I toon it to a very reputable shop here in California but they were as puzzled as I am. Another weird thing is, before I took it to the shop I bled the lifters and did a compression test and I got 120 across the board. Once the lifters fill up with oil that's when I start losing compression. Any thoughts? I need to get my car back up running this is very flustrating. Thanks in advance

 

what kind of lifters?

 

Oem

 

So you had good compression, but then after running the engine the lifters expanded and now you have little to no compression on two cylinders. Sounds like something doesn't fit quite right between the cam and valve seat.

Maybe re-do the compression tests and triple check that you are at TDC on the compression stroke for each cylinder's test, putting your thumb gently over the sparkplug hole you should hear the air hiss as it gets pushed out around your thumb while rotating the crank to TDC.

If it still has bad compression, time to pull the valve cover and start checking clearances.

 

Has anyone looked under the valve cover?

 

I would say the best bet would be to pull the head.

 

Yes the valve cover was removed and everything was inspected. The cams were also removed and inspected. The shop could not tell what the problem was. Again this a " well known Evo shop" in California. I called few shops and I was told that it could either be bad lifters or the valve hight was not set properly. I did an engine built and also replaced the valve and guides. But again what's puzzling is that I get really good compression when the lifters are bled 120 on all 4 cylinders. I will try some more diognostics to see what The exact problem is. I'm just trying to avoid pulling the head but if I have to that would be the last resort.

 

This is what happened to me when my car ran on 2 cylinders. My driver side spark plug wires before the coil pack plugs had gotten brittle from age and 1 of the wires broke under the factor wire protection sheath. I fixed it up properly and it's been working great 4cyl since.

This wouldn't answer your lack of compersion...but thought I'd share.

 

Let us know what you find. My guess would be some blunder at the machine shop or faulty parts. Maybe measure the installed height of the valves.

 

The fact that you get good compression when the lifters are smaller, and no compression when they are full length means there's obviously something not fitting right. Something is too long.

Either the lifters are too big, the valves are too long, or your cams are improperly timed. You need to pull the head and start checking clearances.

 

sounds like the valves are too long to the seats have been cut too much.