The Stovebolt Site Forums The Shop Area Engine Shop Push rod worn off on 61 235

Hey everyone...

The other day on the way to work my 235 started to have a back-fire like one cyl. just died. I came straight home (about a mile) and parked it. Upon checking things out, I found that the #6 exhaust push rod was off to the front of the rocker and that the "cup" on the top was warn off to the side.

My question is this: What could cause this? I am thinking that maybe it was mis-adjusted? The valve train always seemed a bit noisy to me, but I am not that knowlegable on these old stovebolts. It certainly wasn't extremely noisy. Also, the #6 plug has always seemed to be more black and sooty than the rest. Does this indicate that it was too tight or loose?

Any input would be of great intrest. P.S. I had to drill a 5/8" hole in the lip of the cab above the valve cover to get the push rod out of the engine, but it worked!

Joe

It sounds like you've run MANY miles with that rocker arm out of adjustment. The constant pounding of the pushrod on the sloppy rocker has worn both of them to the point they finally disconnected. Valve adjustment at every tune-up is just a fact of life with solid lifters, and even hydraulics need the occasional check and readjustment. You might have been able to remove/install the pushrod without altering the cab if you'd removed the rocker shaft assembly first. I'd reccomend a thorough inspection of all the pushrod/rocker relationships, and replacement of any parts that are showing wear. Then, adjust the valves every time you change spark plugs.
Jerry

Thanks Jerry,

I have only had the truck for a few months, and the engine was supposed to have been rebuilt about 5 years ago. I would guess that the valves have never been adjusted since then.

I did remove the rocker before trying to remove the push rod, but the push rod is so long that it hits on the firewall where it curves out toward the front of the truck. Thus the hole. I am sure I could have put a jack under the engine and took off the motor mounts and let the front of the engine down far enough to remove it, but the hole seemed easier!

I will be looking at all the adjustments and resetting all the valves before buttoning it back up.

My wife has an 86 cj7 with the 258, when I am done with the adjustments, should it sound similar to the engine in the jeep?


Thanks again for your help,

Joe

You are always going to have some rocker arm/valve noise with solid lifters. If you can't hear them, they are probably too tight. Later stuff like your cj has hydraulics so you shouldn't hear much unless it has a lot of wear.
Fred

"61"- - - -as in "1961" I assume? That's the next-to-last year of production for a 235, assuming it's got an original engine in it. All the car engines from the late 50's, and, I believe, the late-model truck 235's had hydraulic lifters. Hydraulics are supposed to be virtually silent when they're adjusted properly, but lots of factors can influence the noise level, including how much wear all the parts have.

If you use the search function here for "valve adjustment", you'll find lots of advice on adjusting valves, both mechanical and hydraulic, and at least some of it is correct. There's more misinformation out there about adjusting hydraulic lifters than possibly any other topic up for discussion among stovebolters. I prefer using the "companion cylinder" method of adjustment, with the warmed-up engine stopped, then rotated by hand until each cylinder is in position to be adjusted. I've never found an effective way of doing an engine-running adjustment on hydraulic lifters, but then, I've only been doing it 49 years!
Jerry

Truck 235 and 261 are solid lifter. Specs for stock cam (1960 manaual) are .006" intake, .018" exhaust, adjusted hot.

Thanks guys for all the input.

One last question, just for discussions sake.

The push rod has a ball on the bottom end and a cup on the top. The only hydraulic lifters I am familiar with are in the chevy v-8's which have a hole in the center to push oil up through the push rod to oil the rockers. The push rods in my 235 do not have a hole through them. Does this mean the lifters are solid?

I should have my new push rod tomorrow morning, and I will have at it then.

Thanks again,

Joe

Joe,

No pushrods for this engine are hollow. The upper end gets oil from another source. Your lifter can be solid or hydraulic depending on which engine you have...usually a car engine would have hydraulic lifters and a truck would have solids, but not always.

Stuart

Interesting - I had exactly the same issue when I got my late 235 first - same cylinder.
Turned out I needed new hydraulic lifters.

Ah, the recurring mystery and confusion about hydraulic lifters.....

Late 235 blocks are all drilled to use solid OR hydraulic lifters, which look almost identical.
There is no oil supplied through the push rods.
Hydraulics 'pump up' with oil from the block gallery, not from the top, which has little pressure and just enough for the rockers.

I had hydraulics on my daily late 235 for 12 years now and hardly ever have to adjust them.
- Easiest and surest way to adjust hydraulics is at idle with the engine hot.
Tighten until the clicking just disappears and then go 1/8 or 1/4 more turn. As long as the pushrods are spinning - you are in good shape, as that means that the lifters are spinning, which is a very good thing.

The shop manual suggests to tighten them 1-1/2 turns, but that's way too much as it prevents the pushrods from spinning, which means lifter\cam lobe wear - not so good. Let alone your valves never fully close !!!

Before worrying about lifters, check your cam to know if it needs solid or hydraulic lifters first.
235/261 cams have small casting lumps on the rear of the cam, between the 3rd and 2nd to the rearmost cam lobes.
2 or 4 raised "lumps" identify it as a hydraulic cam, 1 or 3 lumps as a mechanical lifter cam.

Also make sure you are at least aware of the lack of zinc in oils sold after 2006.
There is plenty info on this forum and all over the web.
If you break in new lifters, use the same method as breaking in a new cam/lifters. 15 minutes at 2000 rpm should do.

You might also check for an oiling issue. If no oil to the rockers, they wear quickly. Disassemble a couple of the rockers from the rocker tube and see if there is any abnormal wear on the shaft, ie, out of round rocker bore, excess clearance for the rocker. Just a thought, as I've had this happen on a 57 235 causing erratic lifter clearance.
dg

Hey everyone,

I have been on vacation for a week and didn't have time to post the outcome of my project.

I put in the new pushrod and adjusted up the valve. The new pushrod is spinning and looks and sounds fine.

New problem: the #1 and #2 intake valve rockers were not oiling. After removal and inspection, and after talking to my engine expert, I called his rocker rebuilder for help. It seems that I may have some incorrect rockers. The suspect rocker arms have a groove on the inside that I believe should line up with the oiling hole in the bottom of the rocker shaft (which it doesn't). The oil hole in the rocker doesn't line up with the groove like it does on the #1 exhaust rocker either. The rocker rebuilder suggested making a groove across the inside of the rocker, from the existing groove over to the hole in the top of the rocker. Then another one at the bottom of the rocker over to the oiling hole in the shaft.

I did all this, and they now oil the same as all others.

Question: Has anyone seen what these rockers should look like? I didn't have the time to take more apart to look at the rockers that were working.

Thanks for your input.

Joe