The Stovebolt Site Forums The Shop Area Engine Shop Checking bleed down on lifters

'56 235 with hydraulic lifters running 20w50 oil. While hot I pulled my valve cover and put a one foot long lever on each rocker while at TDC, and by hand I put steady pressure down on the push rod end of the rocker arm. Each one took about 5 seconds, ten seconds tops, to collapse the lifter down. I'm thinking that is a bit too quick. Check balls leaking by somewhat or maybe too much clearance between plunger and lifter body? Anybody have a guideline or rule of thumb for this type or lifter test?
Thanks, Lem

I think the proper term for that condition is "worn out"! Good lifters should take a lot longer than that to bleed down.
Jerry

Ok, what really puzzles me is that #6 exhaust and #5 intake rockers were a little loose. I had just recently adjusted the valves to 1 1/2 turns past no slop. So that indicates to me that the plungers were stuck down inside the lifter body. How can they be sticking when they are worn so much. I have had all the lifters out recently and thoroughly cleaned them, all the plunger springs looked to be ok, none were broke or collapsed.

I don't think you can see wear on a hydraulic lifter with the naked eye. Back in the 50's when they were first becoming common instructors used to demonstrate the precision fit by by holding the plunger tightly in their hand for a couple minutes while the body remained at room temp; the plunger would not fit back into the body until it cooled to room temp also.

Wear or no wear, what would cause the plungers to not return up into position? I'm sure after years of use they didn't wear to a tighter clearance.

Binding, if the bore is worn with a taper, the plunger can bind up on the side. It could be as it all rotates, it has one spot something doesn't fit right.

The normal clearance for lifter parts is about 2/10,000" (0.0002") That's a strand of hair cut into 10 equal slices. A little wear can let the plunger get cocked in the bore and get into a bind, plus the leakdown rate increases. Automatic transmission valve body parts can do the same thing, with no measureable wear. Ford AOD's are chronic for that problem, with their aluminum valves running in a steel valve body.
Jerry

The engine is only 60 years old, I don't see why anything should be worn out! Haha

Why did you do a leak down test?

Engine noise?

Driveability issue?

Jeffrey

It has a small tick at idle. I can live with that, but when I drive at higher speeds, 60-65 mph with 3:50 gear, for about five minutes or so it will develope an extremely loud tick. It as awful. I have to slow way down or pull over for a bit so it will go away. I can do high speeds for a short distance, no problem. But extended high speeds/rpm's will result in the loud tick. So I have to go 50-55 to avoid the issue, and that isn't always good with traffic.

Have tried it will thinner oil? and what does the oil pressure due at higher speeds?

Is the oil pump pickup screen clean? Can you duplicate the condition in the driveway?

I originally had 10w30 and it had the same issue. I have the 20w50 in to attempt to remedy the issue but no luck. Oil pressure is a steady 25-30 at high speeds and 8-10 at idle while fully warm.

Sure sounds like you are on the right path looking at lifters. I suspect as you do that they are worn and bleeding down too soon at higher rpms. Low speeds they seem to keep up.

You probably know what you have to do now, change them out.

Joe

Yes, it looks like I need new lifters. But just popping new lifters in is risky. I should get the cam re-ground to do it properly.

In my opinion, it's not really to much of a risk on a 235. Lifter and cam interface has become a huge can of worms and really doesn't need to be. Valve spring pressure and lobe design are what kills cams. A radical lobe, Extreme Energy, for example, slams the valves open then drops them to get maximum degrees of open time in a limited amount of time. These quick ramps create extreme amounts of load on the cam and lifters. On the other hand, a stock 235 cam has very little lift so the lifter just rides up gentle ramps with very little load on the cam. Then you have to consider valve spring pressures. Most racing springs have 300 to 500 lbs of pressure when valves are fully open, now your typical 235 when new had 140 lbs of pressure when fully open. Combine the easy ramps and low spring pressure, there is very little load on the cam. On top of all that, rpm also has role to play.

Just replace the lifters and run the engine just as you would if it had a new camshaft. Use some break-in oil or add some zinc additive, once broke in, drive as you normally would and change oil when you see fit. Use the oil of your choice, and just for good measure, add 1/2 a bottle of additive, then next change add the other half. Third oil change you can go without if you choose. I quit adding it to my 250 8 years ago and now run off the shelf 5W20 oil.

Joe

Before you make the decision about changing or regrinding the cam, set up a dial indicator where it can bear on the outer edge of the lifters (not the pushrod seat), and measure the lift of each lobe. If they're all within a few thousandths of each other, go with lifters only. If there's a noticeable difference in lift between lobes, better swap cams.
Jerry

Great food for thought. Thanks for the helpful info. Really appreciate it. I have some thinking to do.

So I think I am going to just try some NOS lifters with the existing cam. Currently the engine has 20w50 in it, with maybe 500 miles on it. Can I add zinc additive to this 20w50 oil for break in, or should I dump it in favor of something else. If so, what is recommended for a break in oil? Thanks, Lem

20w50 is too thick for a rebuilt engine w/500 miles or less. Try a 10w30 or a straight 30w. Brad Penn is a good break in oil that is already formulated w/enough ZDDP to break in a flat tappet cam/lifter combination.

There's plenty of debate on continuing to run a ZDDP additive after break in, some say yes, some say not needed. You'll find oil generates a lot of discourse LOL

Dave

I should have worded it better. The engine has thousands upon thousands of miles on it. The oil that is in it has about 500 miles on it. I'm just going to put NOS lifters in this old engine. My question is this: is the 500 mile old 20w50 oil adequate for breaking in the NOS lifters if I add a zinc additive?

I would say yes.

The only way lifters and cam contact area get oil is from throw off of the crank and rods. In my opinion, 20-50 is way to thick and doesn't get splashed around like thinner oils do.

Back when I drag racing, I seen 20-50 oil twist off more then one distributor drive and wear out distributor gears, and on top of that, the car ran faster and quicker with 10-30 oil.


Joe

Also thicker oil never makes up for worn away metal.

I had a 79 Ford years ago, 302. Engine was near the end of it's life and the car was about 15 years old.

Point was the engine started drinking oil. So I went from 10 30 to 10 40, then 20 50. Oil consumption went down.

However spark plug consumption went up. The plugs were getting so fouled up from running thicker oil and the OEM plug was the hottest heat range plug available.

It got tiresome real fast dealing with plugs fouling. And a lot easier adding a quart of 10 30 every 5 to 7 days.