My lifter on the passenger side nearest the firewall is quite loud. It has a constant tapping up to about 3500 RPM then is taps about 90% of the time and misses 10%, like it wants to just barely start smoothing out.

I pulled the valve cover and find .025 gap between the rocker and valve stem. The engine was a crate rebuild 50,000 miles ago. I'm not sure why the .025 slop. I'm thinking either a wore down cam lobe, or ware on the bottom of the lifter??

Any ideas?

I suppose I need to pull the manifold and pull the lifter out? Before I do that I thought I'd see what you guys think?

 

You might be able to get the lifter out with a magnet if it's not too gummed up.
Eric

 

Few things to consider. You may have a worn cam lobe which isn't so bad because it means you get to replace it with a bigger one. The easiest thing to check is the pushrod. Roll it on top of your kitchen counter and see if it is perfectly straight. If its not straight the fix is cheap. FE's have been known to bend a pushrod every once in a while and the only thing you would need to pull is the valve cover and rocker shaft. Make sure you loosen the shaft evenly so you don't bend it.

 

Hey I looked at some of the other posts and found Ratsmoker recommended using a quart of Marvel's Mystery Oil to loosen up the varnish. I dumped it right into the lifter gallery and within minutes the lifter smoothed out. Thanks.

Now I got another problem, every revolution I here...CH..CH..Ch..Ch..CH..CH..like compression air leaking. And under thrittle pressure it feels like it is firing at the wrong time on a cylinder so it runs very rough.

I pulled off spark plug to number 4 cylinder (the same one that the lifter was not pumping on) and the engine smoothed out and quit making the leaking noise. It seems I may have a blown head gasket. The compression to this one was about 90 psi while the rest on that side are 123 to 139.

Any other explanations???

Prior to pulling the rockers and examinint the rods, and prior to the mystery oil, this was not occurring???

 

Which valve was loose?? Intake or exhaust??
You may have a burnt valve...


Steve & the Rockette
'63 F100
'68 F100
'72 Capri 2L
'73 Capri 2.6L V6
'73 MG B GT 2.6L V6(Ford)
'98 Contour SVT 2.5L V6 (Mods)
'01 ZX2 (No Mods yet)

 

The last lifter toward the back, the exhaust for cylinder number 4. I understand why a burnt or chipped valve would cause the low compression and also the Ch Ch Ch Ch sound. But I can't figure out why it would make it run soooo bad driving down the road, and run soo much better when I disconnect that spark plug entirely. Any ideas why??

 

I'd bet that if you check the leakdown on the exhaust valve lifter that was making the noise before, you'd find that it is pumped up and holding the valve open a smidge. You removed the rocker arm shaft and checked the pushrods for straigtness, didn't you? That allowed the lifter spring to push the lifter piston to the top of its travel, given that the lifters are not varnished up and stuck. Hopefully, you did NOT mix up the pushrods, and DID put them back where they came from because someone in the past might have had to fit a non-stock length push rod.
Any way, you should be able to use a hand-held piece of wood to push down on the cam side of the rocker arm as the engine is idling, and make each valve clatter as you bleed the lifter down, and then quiet down as the lifter fills back up with oil, just apply steady pressure. If you cannot make a lifter bleed down and clack, then you have a stuck lifter. You can get them out without removing the intake if you have a good strong magnet-on-a-stick and can work the lifter up and down in its bore til it goes past the varnish build-up on the side of the lifter. The lifters used were prone to sticking as they did not flow much oil as they were worked, only that little amount that could be replaced as the valve train wore in.
If you replaced the lifter or pushrod, you may now have a valve that is moving where it should, but has not moved for years, by increasing the lift to normal. The valve stem could be gummed up where it is now operating.
As far as running smooth at idle, I one time started the engine with all the driver side spark plugs disconnnected (by accident), and the engine ran very smooth. Surprised me! The same engine was able to be stalled by hand if you pushed on the valve train just right, and the details escape my old brain cells right now. I remember! When pushing on the cam side of the rocker arms, you can make the engine stall if you push real hard on a stuck lifter. Running poor at speed could be caused by the engine blowing back thru the intake valve if it is not seating. You should also note the flow of oil out of the rocker arms and down the top of the rocker arm to the top of the valve. If you do not have oil flow, most likely the groove in the rocker arm is worn away. Either cut a new groove if you don't have money, or replace the arm. But, I'll bet the bottom of the rocker arm shaft is so galled that you'll be loathe to put a new rocker on that old shaft. The whole assembly can be taken apart and cleaned, but you have to replace the caps at the end of the rocker shaft. I used a coat hanger in an electric drill back in 1965 when my dad's T-bird dropped its coolant 1 block from home and I was accused of hot-rodding. (Freeze plug rusted out-hmmm. Had problems with the radiator freezing up also-Hmmm. maybe my dad should have invested in some antifreeze. Could have helped the freeze plugs last longer..
Good memories.
tom

 

Tomw,

Thanks for all the ideas. Yes I do normally keep track of all the push rod locations and normally fit them back exactly as they go. However, I got two engines apart and plan to sell the old one in this truck so I swapped rockers and push rods when I had it opened cause the rockers are so much newer on this one making the noise.

But, obviously something I did changed. You said the rough running under throddle pressure may be backfiring through the intake valve. That seems to make a lot of sense. It sounds just like that. Like backfiring at the wrong time when valves are open. At first I thought it was a messed up distributor cap because that's what it acted like.

It must be something like that. You talked about playing around with the rockers when the engine is running. I used to do that on my old 4 cylinders. Can I do that with 390's without oil dumping all over??

 

[updated:LAST EDITED ON 22-Feb-02 AT 08:14 AM (EST)] If you look at the inside of a set of old rocker covers, you can see where the oil is splattered from the rocker arms. It only splatters at higher RPM. At idle, it just kind of drools out of the oil hold on the rocker arm, and drizzles down the arm to the top of the valve stem. Keep the RPMs down, and you will have no mess, given that the return holes are clean. You might need to make a cardboard catcher to get the oil that drops off the valves, as they are canted such that vertical would be on the exhaust manifold. Either way, it is minimal.
ALSO note if the pushrods are turning. If they are, then the lifter/cam lobe surfaces are OK. If the pushrods are not turning then there are 2 possibilities: 1)lifters stuck with no pressure relief to alllow the lifter/pushrod to turn (check at each cylinders TDC for a little clearance) or 2)cam lobe/lifter base fit is not as it should be, which is at an angle, not square on. The lifter does not hit the full surface of the cam lobe, but rather hits the shoulder.

my 2 centavos
tom