97grand4.0

I get that, but after reading alot I concluded you can avoid twisting them if you just alternate a couple turns each when loosening or tightening.

dave1123

Okay, I was just telling you how I did mine. Whatever works. I can remember spending hours and hours in my life adjusting solid lifters and hydraulics are a LOT easier. The bridges are what keep the rockers centered on the valve tips so I wanted to make sure I didn't twist them at all. That's better then SBCs where the pushrods keep the rockers straight.

Just for information, do you know how much travel the lifter plungers have on the 4.0? I can't find in specs anywhere. I'd like to know where the plunger is designed to ride in normal operation. I saw a video about the 4.7 where some guy put .060" spacers under the anchors to help keep the rockers from coming off. If there's that much room, why does the 4.0 have this much problem staying quiet?

dave1123

Rear axle works fine, but I think it did something to the T/case as well. The shifter works fine and all the selections work normally EXCEPT when I put it in 2wd, it's still in part time 4wd. I'm currently driving it in full time and it's okay, but it's still driving the front axle which I don't need until the snow comes. I know from past experience it only makes a small difference in fuel mileage, like 1 or 2, but it's just the principle of the thing. Why put wear on the axle CVs when I don't need to? Anybody know if the shift fork is bent or something? Maybe it broke the teeth off the slider or something? It's a 242 and I'm not going to pull it apart until I have the parts to fix it then and there. It'll get a new chain, bearings, and seals when it does come apart.

97grand4.0

Hm got me swinging on that one. Worst comes to worse take the front shaft out until you get it figured out. Not so good to be driving on dry pavement in 4w. I never hada T case apart but am thinking something is either jammed or stuck or broke from your events with the rear pumpkin. Would be good if you could manipulate the shifter enough to sort of unstick it.
Not to hijack this thread too badly, but I changed just the #1 cylinder rockers pivots bridge and 1 pushrod. I picked up a few parts just to compare. Sadly I wasn't able to get many good measurements, but the pivots as you said did show no wear right to .oo1. So when I close looked at the pushrods, at least 2 of them anyway, instead of being ball shaped at the rocker end they were sort of conical...even tho they were the same length. Thinking that and the bottom of the rocker are the wear points I changed the aforementioned parts and started it. No tick! So now thinking Ill do them all. These are preliminary results, Im gonna let it sit cold and recheck. Even the new rockers, you could slide from side to side a bit, but not after I ran it for a second or two. Just not the sturdiest design. However, fingers crossed, it seemed better for sure. One thing I dont have is an oiling problem, they are awash in it.
Another thing I noticed was the old rockers spun across the valve quite readily when loosening them, they were off a bit, and the new ones seemed to go on straight and stay there with careful alternating torque to the 2 bolts.

dave1123

This is very interesting! I wouldn't have thought the pushrods would have been worn so much. I once bought a set of racing pushrods for my 350 Chevy and they were made by welding ball bearings to a tube with an EDM hole burnt thru them.

SO... it seems the rockers and pushrods are the culprit! Who would have guessed?

Yes, my 242 took a shot when the rear locked up. Makes me remember a Muncie 4-speed that shattered when a rearend locked up on the dragstrip. A good thing it wasn't mine! There was gear oil and pieces all over the track. It was an end-of-day grudge match so they closed the track early.

97grand4.0

Well, it's not conclusive, mind you I only did one cylinder, but it's enough to convince me to change them all, just gonna save some bux and order off ebay rather than cough up almost 200 from napa. That is a gamble worth taking vs. a valve job and lifter replacement that may not eliminate the problem!
I still have noise just not as much, it definitely changed for the better so I eliminated some of the noise and from what my ear tells me the most offensive and longest lasting ticker seemed to be gone. Also the engine was quiet by the time I got out of the driveway vs having to drive half a mile or more. Google 'pushrod wear' and click on Images.. and there is much about the pushrod end of the rocker and the deforming of the ball at the end of the pushrod. Also if you see unusual marks on the side of the pushrod, like it's hitting the head where it goes through, but it looks like it isn't, this is likely because it really IS hitting the casting as they can flex under load.
With 200k on the clock it isn't hard to see this could be a issue. I never had an engine or car last that long so it's hard to be very critical of the design.
Also I tightened them with the valves closed, that way one is not trying to open with the other closed as you tighten the bridge. Like I say they stayed right on center of the valve. So a couple things going on there.
Also the sealed power rockers had a oval opening for the bridge where the oe had a squarish opening, and the sealed power rockers were thinner steel with a lower profile approaching the valve end.


Do they sell refurbished 242's?

97grand4.0

I am so STOKED! That WAS the problem. Been driving it all morning, SO much better!! Next Ill change them all and get rid of the little stragglers!! Seems more powerful, quieter, smoother, ...just...wow

dave1123

Well, NOW you've got ME stoked! I've done a LOT of work with Chevy small blocks, but never with an engine with 200K miles on it. I've seen gauled pushrods, but usually just one and it was bent also. I've seen step-worn valve end tips on rockers and adjusting nuts that had to be replaced because they wouldn't hold an adjustment.

JUST MAYBE we've hit on something to improve the life and health of a 4.0! Wouldn't THAT be a kick? Mine rattles a lot and constantly now so I'm assuming all the pushrods and rockers could stand to be replaced. Tell you what, you do yours and then I'll do mine, then we'll do a write-up for the forum.

Once I get my 242 straighten out. Reman, Transfer Case Express, $795 exchange. Did you know they used the 242 in the Hummer H1?

97grand4.0

Yeah mine has had the cold start rattle since Ive owned it, about 5 years I think. I think this will work for cold start rattle where it quiets down completely warm, but not for other stuff. I was sure I had the dreaded cracked piston skirt. Im down to just a light chatter for a minute or two on start up, where it was "here comes the diesel jeep again". When you said the pivots were a super hard grade and the rockers were just stamped steel that got me really thinking..

dave1123

The rockers are HEAT TREATED stamped steel. I figure probably 50 or 55 Rockwell C. As an old toolmaker's rule of thumb, if you can scratch it with a file, it's under 60 RC. If it makes the file smooth, it's above 60 RC. I may get feedback on this, but the Rockwell C scale uses diamond as 100 RC.

My 242 shifts fine thru all the ranges and functions as usually, except 2wd. When you put it in 2wd, the front axle chirps and skips like it's still in 4 part time. Even slamming it into 2wd doesn't make any difference. It's probably a bent shift fork not allowing a clean engagement. It probably got kicked out of 2wd went the axle blew. In the last 100+miles since getting it back and driving in 4 full time, my mileage went from 15.9 to 14.3. That's as shown on the VIC. That's also including doing papers twice. My route includes several dead ends and many cul-de-sacs + 300 stops&starts.

I'll probably wait on fixing it until I pay down my credit card some. First purchase is going to be new tires. Anybody have any experience with Firestone Winterforce with dry road wear?

Bugout4x4

Hey Dave... I have been following your unfortunate event here and hope you don't mind me dropping in to mention something that has not been brought up yet in all this. I know you are on top of these vehicles and might have already checked, But is it possible that the torque from it locking up may have moved the drivetrain around enough to affected the TC shifter linkage? Bent something or changed the adjustment? Have you tried loosening the linkage and manually putting it in 2 wheel from underneath to see if it engages all the way without the linkage controlling it? Just a curious thought since I didn't see it mentioned and really hoping it might be this simple and you don't have to shell out a bunch for a TC.

dave1123

My WJ shifts by cable and everything works fine except when you put it in 2wd, then it's actually still in 4 PT. No, I haven't disconnected the cable and tried it, but might soon. Thanks for the thought. Things were kind of fuzzy that night, but I think the shifter was in 4 PT when I stopped. That's why I think it popped out when the axle locked.

Bugout4x4

Thank you for the reply Sir. I hope it turns out that the cable is just restricting it from going full throw. When you mentioned it was kind of like it was in between 4 pt and 2 wd I had flashbacks of the days when chevy three speeds would get stuck in 2nd and 3rd at the same time. I remember panicking a couple times and physically bending linkage with the shifter by my own hand trying to get it out of one or the other. But in your case here, the lock up may have moved it enough to bend the cable housing bracket or cause the TC lever clamp to slip on the shaft? I'm not sure how they are arranged on yours for sure but I can just imagine the forces put on the drivetrain when it locked up, it's a wonder it didn't twist the driveline. Please update, got my fingers crossed...

dave1123

Uncross your fingers because it's gonna be awhile. I've got other fish to fry presently.