[jakevaj]

Just found out yesterday that my motor has zero compression at cylinder 5, but all the other cyclinders are fine. That explains why my car is running rough and seems out of balance. I have a 289, bored .030 over, comp cams, roller rockers, performer intake, holley carb, holley mechanical fuel pump, mallory unilite distributor, hooker hedders, march serpentine belt system, ford racing world class T-5 tranny, and front and rear wilwood disc brakes.

What does zero compression mean...burnt/cracked valves, bad head, and or bad piston rings? What are some of your experiences in similar case?

[tripleblack]

I'm surprised you have NO, ZERO compression. This would indicate the rings are completely gone, or that the valves are stuck open on the compression stroke (easy to spot if you pull the valve cover off).

Its unlikely the other end of the motor (piston seized and rod broken in half) is at fault, since the noise of that rod slamming around in there would be clearly heard.

I'd start by pulling the valve cover and checking out the valves for that cylinder. If they seem OK, you have probably lost your rings on that cylinder. Odds are you've scarred up that cylinder wall pretty good, too.

You won't know the extent of damage (assuming its not a valve job situation) until you pull the heads.

Best of luck!

[jakevaj]

There are no noticible noise at all to indicate that something is broken. I pulled the spark plug and it is wet with fuel and no residue of oil in the cylinder chamber or on the plug. The only way to be sure is to pull the valve cover and head for examination. Is there an easy way to test the cylinder to see if the piston and rings are good? How easy is it to do a leak down test and what does it involve? I don't want to spend too much time taking everything apart to find out that the piston is toast and will need a complete overhaul. I'd rather just take out the whole motor and put in a new one.

[mustangaretuff]

sounds to me that a valve is stuck. If the intake or exhaust valve are stuck open then the motor can't build compression.

[tripleblack]

As I said, IF its a stuck valve, you can easily tell this by removing a valve cover. Watch the valves on that cylinder as you turn over the motor (disconnect the coil cable to prevent the car from actually starting up). If they function normally, it is probably NOT a stuck valve.

What were the compression readings for the other cylinders? If they vary a lot, the motor needs an overhaul regardless of what's up with #5.

[jakevaj]

They are reading +140 psi. I just hope it's the valves. Anyone know of a good machine shop or engine retailers in the Sacramento, CA. area or within a 100 mile radius?

[restomod]

Do a leak down test. It will tell you exactly where the leak is. It only takes a few minutes to do one cylinder.

[jakevaj]

With cylinder 5 dead...and the car running crappy, is it safe to drive it to a shop within 15 miles one way? Will it do any more damage to the motor or tranny? The motor shakes below 1500 rpm and above 2000 rpm?

[Doc]

Keep it simple to start with. Check those valves. Don't worry about that shop trip till you are sure yo uhave to go there. If you don't see anything visible with the valves, andthe adjustment on the rockers is correct then start thinking of taking it to the shop. I fyou want to rebuild the motor in the car then I suggest you call a wrecker to come pick it up for you and drop it off at the shop of your choice. You can do more damage to the cylinder in question by driving it that way, and damage to other pieces in the bottom end from the vibration factors at the rpms you are quoting.

289's are getting harder and harder to find by the day. If you want to keep the car original then I suggest the wrecker and a rebuild of the motor that is int he car.

If you do find you need an overhaul, and want another 289 for a builder core I have one that will be coming up for sale very shortly. Engine is good for an overhaul, but was shoddily rebuilt by the previous owner. Nothing is hurt, but I woudl overhaul this one anyway.

Doc

[jakevaj]

I found out what went wrong. I have roller rockers on my heads and they didn't clear the baffle on the valve cover. The exhaust valve rocker was hitting against the screw that was holding down the baffle...this kept the valves from closing all the way. This happened because I had put in new valve cover gaskets and they were thinner than the old ones. I bought new 3 3/4" tall valve covers and now the engine is in normal operation. Thanks for your comments.

[Knightnsd]

I know they make a spacer for this, (think people who have to have a specific valve cover use them), if you are that close to the valve covers. Problem is that the spacers have a gasket above and below so you have 2 potential leaks. You may want to look at new valave covers if you are that close. I know I have cut that baffle away before to clear my rollers but try and avoid that.

[jakevaj]

I bought new valve covers...taller than the ones that were giving me problems. Everything is good now.