What Can Cause 0 Compression

[me612]

OK well first I'll give a little info on the car. 1991 Talon AWD, 110k miles. Mods are 50trim, stock longblock, typical supporting mods.

Yesterday I received my 3g lifters in the mail, so I put them in. I also changed the timing belt when I did this. I've done a dozen timing belt jobs before, so I'm 99.9% sure I did it right (I say 99.9 because obvoiusly something is wrong here so maybe somewhere somehow I did something wrong). I compressed the lifters before installing them also. Now basically I get this all together, and I pull the MPI fuse, let it rev for a little to get oil pumped through everything. Put it back in, go to start it, and nope. If I floored the pedal, it would start but wouldn't stay running. I decide to do a compression test (I was 150 across the board a month ago) now I'm at 150-0-0-150. I was told a leak down test won't work with absolutely 0 compression. You have to have atleast a little. I don't know, I decided to go back and check my timing belt again. It is still lined up perfectly. I figured maybe something happened somehow and I bent a valve. I took the head off, and everything looks to be fine. No valves "look" bent, the pistons look great (you can tell I just did the MCCC Cleaning!). Headgasket looked fine, I'm really confused. I'm bringing the head in to get pressure tested since it's out, but I'm wondering what else this could have been. What all can cause absolutely 0 comression? Not even 50psi of pressure, just flat zero. What could I have overlooked here?

 

[femmeDSM]

0 Compression almost always means bent valves. Coupled with the fact that you just installed a timing belt.....I'd say that's your best bet, even if they "looked" okay...

In fact, at the moment, I can't think of anything other than bent valves that can cause 0psi.

You should still be able to perform a leakdown test with 0 compression. That air has got to be going somewhere. 0 psi vs 50psi wouldn't make a difference in whether a leakdown test could narrow it down. At least not that I've been aware of.

 

[RoasT BeeF]

Ive been in the same position as you and when I pulled the head all the valves looked fine. After taking it to the machine shop it did turn out that some of the valves were bent. They are probably bent, just not enough for you to notice.

 

[me612]

Well I will be bringing the head in on monday since everything is closed. I agree with you since Timing was done as well. But the thing is that I triple checked this damn belt. I put it on, then once I was ready to start putting the rest of the pulleys on, I checked it again, still good. Now this happened, I took it apart, checked, and they were still lined up perfect. I don't know, we'll see what they say about the head. To look at the positive side, it's a good time to upgrade my valve springs!

 

[steve]

I compressed the lifters before installing them also.

How did you do this?

Steve

 

[Old Mitsu Tech]

You might make sure that your valve train is operating as it should. If you didn't bend valves and usually if you bend valves, you get all 4 cylinders as they are exact copies of one another. Perhaps a lifter holding the valves open a little? It is the change that I'm concerned about. Check your lifters and if possible, rent or borrow a bore scope with a mirror and look at the valves inside the head. Just don't crank the engine over with the bore scope in the cylinder or that costs around 250 for the scope.

Good Luck

 

[91dsmcrazy]

sounds like a bent valve. i had a valve burn out and did the same. but iam goin with a bent valve. did the vales also seat back in place? just a guest

 

[me612]

Steve, the lifters were compressed by inserting a small pick inside the lifters, and pressing on whatever it is in there that causes it to be able to be compressed, and holding them upsided down, pushing them in and out and getting most the oil out of them. Then inserting them into the head.

Old Mistu Tech, the head is already off the car. The valves look fine. No different then cylinders 1 and 4 valves, and those cylinders had 150 compression.

Again maybe they are bent, because obviously just because they "look good", doesn't mean that they are. But I gues I just think that for me to pick up dead 0 compression, that they'd be bent more then that. The head pressure test will tell me more!!

 

[me612]

Just so you guys can see kinda what I see, here is a pic of the valves in the 2 cylinders that had 0 compression.

 

[luvmygst]

Would bad lifters not opening the intake valves cause 0 compresion, since you just changed the lifters, mabey? Like has been stated previously usually all of the cylinders bend the valves not just 2 of them.

 

[me612]

Exactly what I think, I don't see how I have 2 cylinders with NO compression, and 2 with PERFECT compression. About the lifters, I guess I had thought that if they didn't open, then I'd still get compression, but maybe you are right, if it's the intake ones not opening, then it'd not be sucking in any air to compress. Makes me think...

 

[steve]

We seen adjusters that were pumped up keep the valves from closing and ding the pistons but I'm pretty sure than even collapsed the rocker and cam cause the valve to open some.

Steve

 

[Old Mitsu Tech]

No ding marks on the valves. Do the pistons show any shiny spots where the valves would hit? If not, then it's got to be the lifters holding the valves open during the compression stroke.

You may have to go back to the old lifters if they won't let the valve close all the way.

Anyway, Good luck

 

[me612]

You should still be able to perform a leakdown test with 0 compression. That air has got to be going somewhere. 0 psi vs 50psi wouldn't make a difference in whether a leakdown test could narrow it down. At least not that I've been aware of.

Ya 's I thought I could do it still, but a friend of mine told me i couldn't, not with 0 compression. I figured even if it was 0, I'd still hear some air moving somewhere. But I don't know, I've never done one. I was going to buy a tester but couldn't find anywhere locally that sold one. I even tried hooking up my air compressor to my Compression Tester hose, but I found that wasn't going to work. I wish I could have done that test so I could have heard where the air was going.

 

[me612]

I don't see any dings on the pistons at all. If the lifters are holding anything open, why would it do it only on 2 cylinders, and not on the other 2? Hopefully the pressure test will yield some answers!

 

[femmeDSM]

Ya 's I thought I could do it still, but a friend of mine told me i couldn't, not with 0 compression. I figured even if it was 0, I'd still hear some air moving somewhere. But I don't know, I've never done one. I was going to buy a tester but couldn't find anywhere locally that sold one. I even tried hooking up my air compressor to my Compression Tester hose, but I found that wasn't going to work. I wish I could have done that test so I could have heard where the air was going.

Did you try following this Tech Article?
I've never needed to do one myself, either, but maybe this will work. I'm sure a shop near you could do a leakdown test if you can't figure out the problem

 

[me612]

No I didn't see that article, but that is exactly what I tried to do, but the little valve on the hose was stopping any air from traveling that direction out the fitting. I don't think mine is removable neither, but I'll have to look. Ya if I get everything back together, and the problem is still there, I'll have to try that again. And if I can't get it to work, then I'll have a shop do the test for me.

 

[19Eclipse90]

I don't see any dings on the pistons at all. If the lifters are holding anything open, why would it do it only on 2 cylinders, and not on the other 2? Hopefully the pressure test will yield some answers!

It would only do it on two cylinders because each valve as you know has it's own lifter. The scenario here would be that one or more of the lifters in cylinders 2 and 3 are not working correctly whereas the lifters in cylinders 1 and 4 are. That is strange though for brand new lifters. WTF
With that information, I'll have to lean towards bent valves. Of course try the old lifters again to make sure and keep from spending the big bucks first.

 

[Morphius]

Did you chase the threads on all the holes for the head bolts? A must. You could be hitting the required torque too soon and not getting correct compression of the head gasket. I've had this happen twice. Once on my friends car and another on a project car we sold. I'd recommend it before you put the head back on.

Given you are 100% sure you timmed it right, I'd suspect it's the lifters. Try rebleeding those on the two suspect cylinders. I've had this happen a couple of times. In my case on one car, it was doing it on all four. We had bled all the lifters and installed them prior to head installation and all four read 0 compression. Then we rebled them again and two more worked. Repeated procedure again for last two cylinders. Pain in the butt.

 

[me612]

I don't see how this would be a head stud problem. Nothing in that area was touched during my lifter install. Those were installed probably 4k miles ago, and I've had no problems related to them, and have had good compression.

As far as bleeding the lifters, I will rebleed them before I put the head back in. That's the only thing I can think of is that maybe I didn't get enough oil out of them when I compressed them.

Either way I'm still going to get the head tested, and go from there. Thanks for the tips everyone.

 

[steve]

The 3S manual has you prime the adjusters using diesel fuel rather than motor oil.
It bleeds down on it's own if the adjuster is still pumped up. That's how I did them for both the Stealth and the GSX when I installed the 3G lash adjusters.

Steve

 

[me612]

Steve, when you say primed, are you saying you submerged them in the diesel fuel, then pumped the lifter a few times to get some in there, and then that's it and installed it just like that? And then the lifters bleed themselves if they are too pumped up?

 

[steve]

Yep, stand them up in a can full of clean diesel and stick a wire down inside to open the check valve and pump the wire 4 or 5 times until all the bubbles stop before installing in the head.

Finding the check valve is the hardest part. If the wire doesn't move when you pres down you don't have it on the check valve.

Steve

 

[me612]

So now, then they will be full, and I thought the lifters should be empty for the most part when you install them, so they don't hold valves open that shouldn't be open.

 

[steve]

I wouldn't suggest doing that with motor oil for the obvious reason but the diesel seems to bleed out from the normal pressure of the rockers while still lubing them during startup.

The FSM also has leakdown tests for a adjusterd using diesel. I forget tho much pressure is applied but they shorten 1mm in 4 to 20 seconds.

Steve