DEAD...this ain't good

[blue65coupe]

No compression on cylinder #5.  "0", nada, zilch   Checked 3 others and had 150.  My question:  Is there any reason to pull the heads and check the valves or is this more than likely an engine pull?  I've got an idea, just want to double check.

[6t6red]

If you haven't already done this.  Take valve cover off and check for some obvious valve sticking open.

[silverblueBP]

Fer someone that doesn't "drive" his car, you sure do have a lot of problems  :pick


Like Paul says, pull the VC and look first. Pull the motor after you rule everything else out. I'm pretty sure......this time....that you don't need to rebuild the.....






Carb.

[silverblueBP]

and are you absofreekinlutely it was at TDC with both valves completely closed?


edit, just realized I was thinking leak down test  :yikes  :dumas

[cmayna]

Duane,
We all hope it is a valve issue.  Let us know what you find.   

Question: Were you a bad little boy when you were in school?   Is this payback time for you from your 3rd grade teacher Ms Humpalot who caught you looking down her........well you know.

[blue65coupe]

Thanks guys.  I'm on the same track but wanted to get some ideas before I waste anymore time doing carb rebuild crap.  I'm hoping like heck it's a valve issue and not a wiped out cam lobe.  Why?  I do not feel like pulling the freakin' engine.  If it was a ring/cylinder I should have some compression so I'm guessing a valve is the culprit.  Maybe even a rocker.  I'm gonna try to pull the covers tonight.......................way over my head and take a nap.  Will let you know what I find.  Thanks.

Craig, no comment.

Mark, check the MB pics.

[tarafied1]

it does seem like a valve to be Zero, but a real quick check would be squirt some oil in the spark plug hole and check again. If it goes up any you effectively sealed the rings, if it doesn't effect it it's the valve(s). Pretty hard to get zero with a ring problem but a burnt valve can be zero. A burnt piston could be zero too but you would be blowing the dipstick out of the tube!

[silverblueBP]

Mark, check the MB pics.

Are we talking about the 90??

[blue65coupe]

No Mark, I'm talking about my "messages".  From first appearance it seems the intake valve on #5 is open.  I don't know if I'll have enough time tonight but tomorrow I'm gonna check the retaining nut on the rocker and then the valve.  Somebody tell me if my steps are wrong.

1-get pushrod for exhaust starting upwards
2-check nut on intake side, if good proceed, if not adjust (tighten to spec)
3-remove rocker from intake
4-tap valve lightly with soft hammer

correct me if I'm wrong on steps 1 and 2.  I'm basically checking to see if the rocker nut has backed itself off a little.

[daveSanborn]

First off..... if a cam lobe was "wiped out", it would provide no lift.  No lift = no open valve.  It's doubtful that your camshaft is part of the problem.

Do you have an engine repair manual?  It will give specific guidance for valve adjustment....


I'm not sure what you're talking about in step #3..... why would you want to remove the rocker?

Same for step #4..... what will tapping the valve with a hammer accomplish?  It's retained by the valve lock and shouldn't be going anywhere.


Let's go back to the beginning....

With the compression gauge installed in the #5 spark plug hole, what happens when you crank the engine over (as if to start the engine)?

Are ALL of the other cylinders recording 150 ???

If all of the other cylinders are a consistent 150 except for #5, and the #5 rockers are cycling when  you crank the engine over, it likely is a valve issue... as in a burnt valve.


Would it be easier for you just to drop the car off at my place?

[blue65coupe]

Probably so Dave.  If it's stuck open, couldn't tapping it free it up?  How do I know without pulling the head whether it's burnt or stuck? 

[daveSanborn]

With the valve cover off and an old towel laying along the outside edge of the cylinder head (to prevent oil from squirting onto the exhaust manifold), crank the engine as if to start it and watch the rockers carefully.  Are they lifting and falling as the others around them?

If it were me.....

I'd play around with this for a while and then pull the intake/head.


Just make sure that your gauge is working properly and there is actually a real problem.

[cmayna]

Duane, Let's see some pics

[blue65coupe]

There's nothing noticeable per se with the valve cover off.  The rocker had a little play in it.  I'm gonna try and loosen it, slap the vc back on and see what happens.  If the problem is still there I guess I'll start removing stuff.  That's gonna suck.

[silverblueBP]

Since the VC is off, re-check the compression. You will see what's going on at the same time.

[blue65coupe]

VC off, compression "0", pushrods and rockers are all functional.  Tapping the valve didn't work so it looks like it's shot.  Going to start the disassembly tonight and having a more knowledgable helper Sat. morning to pull the intake/heads and inspect as we pull to make sure I don't miss something "extra".  This absofreekinglutely (thanks for the word Mark) sucks.

Since they're coming off, I wonder if new aluminum heads would make me feel any better?

[gotstang]

Damn, that sucks! Have you considered pulling the motor? I'd hate to be doing all that work in the car, and you can pull the motor in ~4 hours on a bad day and everything would be mucho easier.

[lethal289]

No, I think he needs a new gas tank first. 





That sucks Duane.  It looks like you have all the luck.

[johnpro]

VC off, compression "0", pushrods and rockers are all functional.  Tapping the valve didn't work so it looks like it's shot.  Going to start the disassembly tonight and having a more knowledgable helper Sat. morning to pull the intake/heads and inspect as we pull to make sure I don't miss something "extra".  This absofreekinglutely (thanks for the word Mark) sucks.

Since they're coming off, I wonder if new aluminum heads would make me feel any better?

I wouldn't pull those heads until you know where the compression leak is, or at least have an educated guess.  It will really suck to pull the heads, get a valve job or buy new ones, and reassemble the whole thing, only to find out you have a broken ring and get to start over.

Do a leak down test, or at least put compressed air into that cylinder and listen to where it's leaking.  Once you pull the heads, you can no longer do any more troubleshooting.

[silverblueBP]

+1 what John said, the leak down test will tell you where it's at. You can buy a tester fairly cheap if you don't have one and if you don't have one, you SHOULD have one.

[blue65coupe]

That's one thing we're gonna do.  I'm doubting this (not ruling out) considering the compression over 5 checks has registered a complete "0".  That ring would have to be virtually gone.  However, we're gonna do it anyway.  I got everything apart last night down to the intake and heads.  If I haven't mentioned it, this sucks.

[blue65coupe]

Air is blowing straight back through the intake.

[silverblueBP]

So it's just the intake where you hear the air? No air out the exhaust or in the dipstick? If not, sounds like the intake valve is blow'd up.

[blue65coupe]

Yep.  I'll find out for sure in the morning.  I never "heard" anything so I'm assuming/hoping it's just burnt.  (Keeping fingers crossed) 

[cmayna]

Sounds like I should come over and fire up a fatty for you.  Maybe the herbal gods would show a little remorse towards you.......

Seriously Duane,
I hope you don't have to pull the engine.