s10xtremist

I just bought an '01 with 160K miles on it's 4.0. It had a dead miss on cylinder #4. I'll spare you the preliminary diagnostic steps, but I ended up removing the valve cover, but not before doing a compression test. The compression test showed all cylinders except #4 to be almost identical. #4 wouldn't even register on the gauge. Upon removing the valve cover, I found the pushrod on the #4 intake side to be out from under the rocker and just kinda laying to the side. The rocker fulcrum bolt was tight just like all the others. As best as I could tell from looking down the hole with a flashlight, the lifter looked ok. I threw it all back together and fired it up with the valve cover off. The engine seemed to idle perfectly and I could barely tell it was even running because it was so smooth. I checked the compression on #4 and it acted nearly-identically to the other 5 cylinders. I did notice a crack letting coolant in and it was running down into the exhaust pushrod tunnel. It looked to be the ubiquitous 331 failure.

Here's as much back story as I have: A kid drove the Jeep throughout college. He parked it when he bought a new Civic. He said there was a period where it sat for about 6 months. He decided to start it and run it ever so often to engage the 4WD to keep it all working. He says he's not very mechanically inclined and didn't seem to be when I was looking at it. The radiator, thermostat and heater hoses look to have been replaced within the past year or so, if not sooner. He said it just started having a rough idle one day. I don't know if he drove it much like that or not. Based on my findings and his input, my theory is this:

Radiator cracks and Jeep runs warm or hot. Kid takes it to a shop that replaces the rad, thermostat and hoses. The already-weak head is cracked from it being ran hot and/or overheating, but this goes undetected. Kid drives it for a short while after having it at the shop and it runs warm or hot again. Tired of messing with it, he parks it and buys a Civic. Jeep sits for about 6 months and he fires it up one day. Since it sat for so long, the oil drained from the lifters and, just buy chance, the #4 intake pushrod is thrown before the lifter could pump up. Since he's now moving out of state and the Jeep has "so many problems", he decides to offload it as-is for cheap.

Of course, the crack could have happened before and caused the overheating or it was a result of the overheating. I'll never know and it's pretty much irrelevant at this time. I just wanted to add the back story in case it had any significant clues as to how that pushrod fell out. I know I at least need a head. My concern is what could happen to have allowed the pushrod to have so much slack that it popped out, and what should I do to repair it? It really seems at this point that I could put it back together and run it if it weren't for the crack in the head. I'm thinking I just need new lifters and a new (upgraded casting) head, and a damned good engine flush while it's disassembled. I'm trying to get my hands on a borescope so I can inspect the cam lobes. Or maybe I'll just wait until I have the head off and lifters out.

dans98xj

since the head has to be replaced any way I would change out all of the lifters wile you were in there. There should be no way for the push rod to fall out once it is assembled between the rocker arm and lifter. Sounds like the spring in the lifter may have collapsed, or the plunger inside the lifter could have collapsed. Once the head is off changing out the lifters is a pretty easy job.

s10xtremist

So, the lifter collapsing can actually allow enough room for the rod to fall out of place? I really hope this is the case. Otherwise, the only other way I can see that much slack would be from a worn cam lobe. But, for the short time I ran it, all the rockers seemed to be moving the same amount.

Any advisories against getting a low-mile TUPY head from a salvage yard and having it cleaned/checked/etc.? As much of a HP junkie as I am, I'm all for OEM parts and reliability with this thing. I really don't wanna start a snowball of "while I'm in here I may as well...". I fell into that with a 6 liter build for my S10. Things got out of control and I sold the built 6.0 to buy this XJ.

dans98xj

there should be no problem with pulling a head from a JY. I would definitely have it checked and gone over with a fine tooth comb. If you saw coolant running into the oil passages wile you had it running you might be better off looking for a replacement engine instead of just a head, if the PO was running it with coolant leaking into the oil then let it sit for 6 months there could be considerable scoring on the bearings or even rust and other damage that has not reared its ugly head yet. I would hate for you to put a head on it run it then blow the bottom end.

s10xtremist

Good point. Sad and painful, but true.

Firestorm500

IF you can find a good TUPY-head 4.0 in the SY, get the whole engine.

You're going to need it.

s10xtremist

I'm keeping my eyes out for an '02+ Grand Cherokee motor, but I'm gonna have to do what I can afford at them moment. A head is under $50 at the SYs, but I'd have about $300 invested once it's cleaned, magnafluxed, decked, resealed, etc. I can get a whole pullout for about $375. If I get a pullout that I feel comfortable with, I'd probably just swap in the whole thing after replacing the little things- valve cover and oil pan gaskets, etc.

Firestorm500

You're not helping yourself by buying another 0331 head. It may be the reason the Jeep is in the salvage yard.

You wouldn't be spending much more, if any more, if you buy an brand-new aftermarket head and bolt it on.

quneur

More likely scenario; The kid was trying to fix an overheating problem. He either changed the head gasket first or replaced hoses, thermostat, radiator, etc. Either way, when he replaced the head gasket, he didn't put in the push rod properly. There are oil galleys (galleries?) next to the lifters and if the rod is placed at an angle will miss the lifter and fall into the galley.

Edit: he probably didn't know about the 331 head crack and just replaced the gasket hoping to fix the problem.

s10xtremist

I figured I'd be fine with a TUPY head, no? Can you suggest an aftermarket head? I was referred to Alabama Cylinder Head, but I'm not finding anything except old forum posts where they went out of business. Maybe the guy that referred me to them hasn't bought heads in a few years. The other popular name I see is Clearwater. Is their head worth the extra $150 (and more if that doesn't include shipping)? I realize it's new, but is the casting even more improved over the TUPY? Are there any other, preferably closer dealers for the same new head that Clearwater sells?

I don't think he did any of the work on it. He seemed very mechanically DEclined (he sold this Jeep after buying a Civic). Regardless, the head is cracked and I'm gonna replace the lifters as a precaution. I'll look around with a borescope when I get the head off. What kinda baffles me is that the oil looks fine. Dirty, but fine. No milkshake/mayo appearance. I ran it for a good 20 mins while I checked out the A/C, temp and oil gauge readings, etc. before I bought it. Then I took it for a couple donuts in the field next to my house when I got it off the trailer while my friend moved the WJ outta the shop for me to park this XJ. Maybe the coolant leak is just too small at the moment and it's burning off more than mixing? Or maybe the crack JUST developed (doubtful, but possible)?

s10xtremist

I guess I should post some pics. Really, I should start a build thread to document it's transformation. But I'll post a couple here just 'cuz. The amount I paid for it was in expectations that the motor was toast. I think I got a plenty fair deal.

Unmolested stockness:








Not bad for $2,200?

extrashaky

Yes. The TUPY 0331 heads fixed the casting flaw that causes the original 0331 to crack.

Clearwater is popular because it's easy. For $450 you get a brand new head ready to be bolted right in without needing to be checked or worked over by a machine shop. If you get a used head, at a minimum you'll need it checked, and you'll pay more if it needs any work.

But if you're talking about pulling an entire engine and can get one with a TUPY head, all that becomes moot.

That is not a reliable test for coolant in the oil. Years ago when water got into oil, it would emulsify, causing the milkshake appearance. You could see pretty easily when you had water in your oil as a result. But not any more.

Over the years SAE requirements for oil detergent packages have become more stringent, and as a result the detergents have gotten better. When an engine cools, moisture in the air inside it will condense on the inner surfaces. That moisture stays in the engine until you start it back up and get it hot enough to burn it off. This is one reason the cooling system uses a thermostat to get the engine up to running temp as quickly as possible, to burn off that moisture so that it can't do as much damage.

While it's warming up and that moisture is in the engine, the detergent in the oil bonds with the moisture to reduce the amount of damage done during warm-up. Detergent molecules chemically bond with oil on one end and water on the other until the engine is hot enough to burn it away. That doesn't completely eliminate damage or wear, but chemically bonded water does less damage than free water droplets dispersed in oil.

As SAE requirements have become more stringent, the oil is able to chemically bond more water. But the down side of that is that the oil doesn't emulsify and turn milky like it used to when detergents weren't as good. The water is still there and doing damage. You just can't see it as easily. Since the detergents are intended for small amounts of condensation and not a coolant leak, damage is still happening. I was using Mobil 1 synthetic in my 2000, and although my oil level rose (from coolant leaking into it), the oil itself looked pretty much the same to me. A mechanic I know said it looked a little lighter brown than it should, but damned if I could see it.

So you can no longer look at the oil and be sure there's no water in it. Instead, you have to have it tested. You can send off a sample to a lab like Blackstone for $25. They'll send you the test kit for free. I actually send samples off for analysis for all my vehicles at every oil change, because I like being able to see how the engine is wearing. If I had been doing that before my head crack, I would have caught it early enough to save the block and just swap the head.

s10xtremist

^^^
Wow. Exactly the education on this matter that I needed. Thank you! For $25, it's worth it to test the oil to know if I should keep this engine or divert my efforts elsewhere. I can get a complete pullout engine for a little more than the cost of having a salvage head purchased and then reman'ed. The local machine shop charges $250 to reman these heads and the head is about $50 from the salvage yard. A pullout is about $380 out the door. I'll keep looking for a good new head supplier as well as a good salvage yard head and complete pullout in case my Blackstone results are unfavorable. Again, thank you for the details and education. I'm happy to have learned something new about engine oils and I'll be sure to pass this on to my buddy that thought the same as I.

s10xtremist

So... I FINALLY got my Blackstone sample kit in today. I originally ordered it on the 8th and it went out on the 10th, but I never received it. After a week, I called and they said they'd send me another if I still haven't gotten it within a week. Well, I had to order another kit this past Monday. I'm gonna pay for rush shipping to have it to them for Monday morning. I need the results by the end of next week because my local salvage yard is having a 50%-off sale the weekend before Labor Day and I'd love to get a complete pullout for $150 out the door. Really, if I find an engine in great shape with good miles, I'll probably pull it and not even bother with re-heading mine. I'm gonna check the '02+ Grand Cherokees.


For tonight's progress, I started tearing down the top end to pull the head. All that's left is the exhaust manifold bolts under the intake- save the best for last, right? Anyway, I noticed this white ring on all of the pushrods:



It's a white greasy substance and it looks like a water line the way it's on all of them. It's slimy and rubs off. Does the oil level actually get that high inside the valve cover when the engine's running?

Bustedback

An engine from a 99 and newer Grand Cherokee won't be a direct swap into an XJ. The 99 and newer WJ and TJ 4.0 block is different.