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Discussion Starter · #1 ·
Howdy ya'll. My wife and I recently drove our old 91 YJ from Michigan to Moab and back and had a sweet adventure. The old 4 liter started acting up with 400 miles to go (on the way back). We made it home with the engine making some awful racket (sounded like valves or lifters). The engine has about 140,000 miles on it but doesn't leak or burn oil. Anyways, I inspected the valves, springs, pushrods, and rockers and found nothing wrong. So I pulled the head and removed the lifters. All 12 were stuck in the up position (the springs inside the lifters were therefore not functional). It was able to free up one of the lifters and get some spring action working. Obviously. I could just replace all 12 lifters but I find it very hard to believe that they could all go bad at once. The rest of the valvetrain looks like new. Has anybody else seen this type if thing happen? I'd appreciate anyone's idears. Thanks!
 

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What kind of oil are you running? Detergent or non-detergent.

What kind of filter are you running?

How long do you go between oil changes.

If all 12 stuck at the same time, it would seem oil related. If you are using a good detergent oil, a good filter and doing regular oil changes, my guess would be that the oil filter bypass is stuck open or you are getting a lot of something in the oil from blowby or by other means.
 

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Discussion Starter · #3 ·
Howdy Taz. I run 5 quarts of Valvoline 10W40 and 1 quart of ATF with an AC Delco filter. I usually go 5000 miles between changes. In his case, I had the Jeep in pieces for months to repair a broken frame and rusted body. I changed the oil just before the trip. It probably had about 4200 miles on it when the problem started. The Jeep has a 3-speed auto, so it revs high on the freeway. It was running at about 3100 RPM for hours before the racket began. I started using 1 quart ATF a few years ago because I was told it would keep the engine clean. Everything looks really clean under the valve cover. You could be right about the oil. Maybe ATF in the oil isn't such a great idea....

Broncoloco
 

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[ QUOTE ]
I started using 1 quart ATF a few years ago because I was told it would keep the engine clean.

[/ QUOTE ]
It did and it deposited the sludge in the lifters.
 

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Sounds like Taz is on the right path. Lack of oil to the lifters could be the major cause along with a failing oil pump, blocked screen, with any oil flow problem you may also have an overheat problem. Check for oil pressure also oil flow .
 

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Discussion Starter · #6 ·
It does seem like the lifters would be a good place to accumulate sludge, indeed. It just seems unusual that they'd all get stuck at once. I was thinking that they could have been oil-deprived, but the rockers and pushrods all look good amd I'd expect them to be damaged if they were oil-deprived. I guess I need to run the engine with the valve cover off and verify that I'm getting good flow up through the pushrods. That should be a good and messy experiment! I'm guessing I should replace the pushrods along with the lifters (at a minimum). Do you think that'll be enough? Thanks.
 

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I can’t say from here but if I already had the head off and knew that I had a lifer problem, I wouldn’t put it back without having the valves ground and reseated.

Obviously, change the oil but look closely at what comes out. Run the old oil through a piece of cloth or a paper towel. See how much junk you trap. If you get quite a bit, I’d drop the pan and clean out any deposits.

Personal preference, I don’t like Valvoline, I use Kendall and I realy don’t like 10w40, I use 10w30.

As a side note, if what we suspect is true and the lifters were stuck, they were not at the fully pumped up position or they would have kept the valves off of the seats and the engine wouldn’t have run.
 

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Re: How can all 12 valve lifters get stuck at once

Skip the ATF. That's a maladaptation of an older SBC technique to quiet lifters. It's a thinning agent ..nothing more. There are no detergents of any merit in a combustion environment that aren't trumped BIG TIME in engine oil.

I don't have any insight into your lifter issue ..but your 10w-40 was probably a 30 weight and then sheared even more just due to the higher level of viscosity index improvers employed to make the 10w-40 spread. If you look at HDEO for diesels ..they're 15w-40. That's because that's the best they can do in conventional oil and make it shear stable.

It's the same for 5w-30 oils. If you run them long enough (like factory recommended intervals) ..they're 20 weights. That's why you see a "PREFERRED" after 10w-30 in the jeep owners manual. That's why Ford knew that it could use 5w-20 oils ..because millions of people have been without issue ..the only problem was making a 5w-20 oil that could start out as a 5w-20 oil and remain a 5w-20 oil and not shorten the oil change interval and cause undue maintenance expense.

If you have sludge anywhere ..it's typically everywhere (mainly no higher flow surfaces).
 

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Re: How can all 12 valve lifters get stuck at once

[ QUOTE ]
All 12 were stuck in the up position (the springs inside the lifters were therefore not functional).

[/ QUOTE ]

I'm missing ssomething here. This sounds like the normal condition to me. As soon as you let the pressure off the lifters the internal spring will expand them, drawing oil in. If you try to push the plunger down it will seem to be locked, but will slowly go down as the oil seeps out.

There's a leakdown test and a device to perform it. It uses a weight and lever to apply a force to the plunger, and an indicator to show how far it moves. It's been way too long since I've tested lifters, but the force is considerable, and in a healthy lifter it takes a long time to go down.

My guess is that the extended time at high RPM thinned the oil so that the lifters leaked down too fast. It wouldn't surprise me if after an oil change the engine would be back to normal. Maybe it would only take a cool down.

Now that you're as far as you are, you have other problems. Did you keep the lifters in order so that they can go back on the same lobes? If not you might as well pitch them. After 150K miles they're worn in to their own lobes, and won't last long if you switch them.

And in other bad news, new lifters usually don't last long on a worn cam. New lifters aren't flat on the bottom; they're slightly convex. New cam lobes aren't cylindrical; they're slightly conical. That combination puts the area of maximum pressure slightly off center on the lifter face. When the lobe turns under it, the lifter spins, which equalizes the wear over the lifter face.

After 150K miles the lifters and cam lobes have gotten comfortable in their wear patterns. Changing either component will likely wipe out both. If you can't put the old lifters back where they were, it's time for new lifters and a new camshaft.
 

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Discussion Starter · #10 ·
Re: How can all 12 valve lifters get stuck at once

Thanks for all the input, guys. As far as the stuck position of the lifters goes: they're all stuck at the height resulting from the free height of the spring. The lifter's "cap" still had the ability to travel a few milimeters up through hydraulic pumping. The lifter "cap" is the part which interfaces directly with the pushrod. However, the inner "cup" of the lifter (which the "cap" fits into) would not travel downward inside the outer cup to compress the spring (the spring is between the two "cups"). This renedered the springs useless resulting in zero compliance within the lifters.

Maybe I'll just rebuild the whole engine. Anybody know a good source for 4.0 Liter rebuild parts? I'm not gonna run ATF in oil no more. Thanks!
 

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Re: How can all 12 valve lifters get stuck at once

OK. That helps. If it won't expand to its limit it could be varnish in the upper part of the lifter bore that hasn't been used forever.

To make the lifter go down when it's full of oil should take a lot of force and a lot of time. The '78 FSM doesn't specify a force to be used in the test, just the test tool to be used (J-5790), but my guess is that it applies 50 to 100 pounds. It does say that a good lifter will take 20 to 110 seconds to leak down 0.125".
 
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