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Cracked cylinder head, help me decide what to fix

Trevlaw

Sketchy Machinist
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Jan 8, 2021
Messages
549
Location
Corvallis, OR
My TJ is a 2002 4.0 with 160k on the clock. Unfortunately I must have an earlier 02 as I have the 0331 head, not the TUPY casting. Over the last several months I've been chasing some misfire, cam and crank codes. Ended up replacing the cam and crank sensors with NOS Mopar sensors and that seemed to clear up those codes. Though lately I've been getting seemingly random P0301's and nothing else, and over the past several tanks of gas my mileage has dropped considerably, about 130 miles per tank vs the 180-200 I've gotten since I've owned it over the last 7 years.

It's had a very slow coolant loss for a little while, fixed some coolant leaks and thought I was good. Pulled plugs and did a compression and leak down test.

Compression test
Dry Wet (~3/4 Tbsp Motor Oil)
#1 115 115
#2 130 130
#3 140 140
#4 130 140-145
#5 135 145
#6 130 150

Leak Down Test
#1 60% Air heard from dipstick and radiator cap
#2 40% Air heard from dipstick and radiator cap
#3 30% Dipstick only
#4 33% Dipstick only
#5 30% Dipstick only
#6 27% Dipstick only

So I think that confirms I've got either a cracked head or head gasket issue between # 1 and 2. I had a bad fan clutch over last summer, and there was a day when it was 115* outside, couldn't keep the motor from hitting 220-230, got stuck on the highway and it just wanted to get hotter the slower I went. Anyways, that probably didn't help me out, but the Jeep is my DD, so if I'm gonna have to pull the head off I don't really want to dick around with dragging a possibly cracked head to a machine shop.

I'm curious what everyone things about a replacement Clearwater head? I've seen decent reviews of them on here, but some older posts on other forums and reviews they have don't seem too hot, but there's not any TUPY heads for sale local to me to have cleaned up. I figure the least I need to do is a head gasket and head swap and that would get me up and running like normal again.

But, in my research I've also discovered that apparently Chrysler has a TSB or something a long time ago about the 98 - 02 IIRC 4.0's having poor quality pistons or something along those lines, leading to them being more prone to piston skirt failure.

So, I figure with the head off that could be a good opportunity to replace pistons and rings assuming my cylinders aren't worn too bad, I do have a bore gauge I would be able to inspect them with. I'd probably do rod and main bearings at that point too, but I've done those before on an older 4.2 in the vehicle and didn't have any issues, so that wouldn't be too big of a deal. Then I'd basically have new everything except for the block, crank, cam and cam bearings.

It's a slippery slope though, and an expensive one too, but I'd really hate to just do a new head, have a skirt break in the next couple years and scrap my block, especially since right now I at least have the convenience of still being able to drive it while I gather parts and get a plan worked out.

There's not much of this work I don't feel comfortable doing, I'm just not setup for any of the machine work that could be involved, so that would get contracted out, but all of the disassembly, inspection and reassembly will be done by me and with my work schedule I have 4 days off every week to get it done.

What say the group, any ideas on what I should or shouldn't replace and any ideas on where to get a new or reman head?
 
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Trevlaw

Trevlaw

Sketchy Machinist
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549
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Corvallis, OR
I love finding excuses to recommend rebuilding engines into strokers but honestly, I'd swap on a TUPY head and just drive it.
Yeah, I seem to love finding excuses to spend money. Any idea on other places to find a TUPY head? Seems the Clearwater head is a new "reinforced" casting. Just concerned about the quality of their castings and the work they do. Not having any luck finding anything locally, just older Cherokee and YJ motors.

I may have a lead on a new unused Edelbrock 50169 for $800, not that I'm looking for performance really, but I'd trust the quality a bit more and could shave a few pounds. Would just need to figure out how to adapt my newer factory exhaust manifolds to it
 

Jamesval035

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Nov 18, 2018
Messages
602
Location
Cameron, nc
I replaced my cracked head with a Clearwater back in 2014. Unfortunately what your concerned about happened with a broken piston skirt in 2017 and ended up rebuilding with the same Clearwater head. Have not had one issue with the head.
I think a tupy head would probably be difficult to find and take some time to do so.
 
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Trevlaw

Trevlaw

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Joined
Jan 8, 2021
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549
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Corvallis, OR
I replaced my cracked head with a Clearwater back in 2014. Unfortunately what your concerned about happened with a broken piston skirt in 2017 and ended up rebuilding with the same Clearwater head. Have not had one issue with the head.
I think a tupy head would probably be difficult to find and take some time to do so.
I replaced my cracked 01 head with a clearwater head two years ago. Head was excellent quality and no problems since.
Well that's good to hear about the heads at least. Do either of you guys remember if the head you purchased was the brand new one they currently offer? It seems like they may have used to also offer remans. Curious if their current offering that they say is reinforced might be a TUPY, or if the TUPY is completely out of production. Planning on calling tomorrow to see what they can tell me

Leaning towards just doing the head swap and seeing how long the rest of the motor holds up.
 

SkylinesSuck

TJ Expert
Joined
Mar 28, 2020
Messages
3,030
Location
Northern VA
I have always heard Clearwater was the go to for a TUPY head. I have no first hand experience as my head is the older casting which is btw easily swappable with your current head but would require the use of an aftermarket header or at least older style factory manifold (older heads have bigger exhaust ports). The same would be true with that Edelbrock head which they don't make anymore. If you ever have any performance plans for the motor in the future, I'd jump on that thing like a fat kid on a cupcake.
 
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Trevlaw

Trevlaw

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Corvallis, OR
I have always heard Clearwater was the go to for a TUPY head. I have no first hand experience as my head is the older casting which is btw easily swappable with your current head but would require the use of an aftermarket header or at least older style factory manifold (older heads have bigger exhaust ports). The same would be true with that Edelbrock head which they don't make anymore. If you ever have any performance plans for the motor in the future, I'd jump on that thing like a fat kid on a cupcake.
Yeah, I'm waiting for the guy to respond on the Edelbrock, if he'll ship it, I'll definitely go with that one. Might have found a TUPY or two I could get shipped for $250, hoping they're both TUPY's and I can get one of them cleaned up.
 
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Trevlaw

Trevlaw

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Joined
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Messages
549
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Corvallis, OR
Sounds like I'm second in line for the edelbrock head, I'd imagine the first guy is probably going to get it since he's local to the seller.

Not having a ton of luck finding a head, might have a TUPY I could grab for $180 + like $120 to ship it, then whatever machine work costs to get it fixed up.

Also found a full 2004 WJ 4.0 with 132k on the clock from a local wrecking yard. It's supposedly still in vehicle, I can go check it out before they pull it, I could probably see it run and I guess they do a compression test before pulling. it's $1,050 including the core charge. I'd imagine it should have the TUPY head on it, it's 30k miles less than mine, and it seems like the WJ motors are one of the easier swaps for a 2000+ TJ.

Does anyone have experience swapping a WJ motor into a 2000+ TJ? Any weird hangups or problems with the two interchanging, or is it basically plug and play?
 

jeepguy03

TJ Addict
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Joined
Jul 23, 2020
Messages
1,252
Location
Connecticut
I'd go with the Clearwater, then you have a brand new top end compared to whatever you find at the junkyard. I installed a brand new Clearwater head on a friend's 2001 XJ at around 90k miles when he bought it. The Jeep ran great until he totaled it around 230k.
 

NskLJ

TJ Enthusiast
Joined
Oct 19, 2021
Messages
452
Location
Long Beach
My TJ is a 2002 4.0 with 160k on the clock. Unfortunately I must have an earlier 02 as I have the 0331 head, not the TUPY casting. Over the last several months I've been chasing some misfire, cam and crank codes. Ended up replacing the cam and crank sensors with NOS Mopar sensors and that seemed to clear up those codes. Though lately I've been getting seemingly random P0301's and nothing else, and over the past several tanks of gas my mileage has dropped considerably, about 130 miles per tank vs the 180-200 I've gotten since I've owned it over the last 7 years.

It's had a very slow coolant loss for a little while, fixed some coolant leaks and thought I was good. Pulled plugs and did a compression and leak down test.

Compression test
Dry Wet (~3/4 Tbsp Motor Oil)
#1 115 115
#2 130 130
#3 140 140
#4 130 140-145
#5 135 145
#6 130 150

Leak Down Test
#1 60% Air heard from dipstick and radiator cap
#2 40% Air heard from dipstick and radiator cap
#3 30% Dipstick only
#4 33% Dipstick only
#5 30% Dipstick only
#6 27% Dipstick only

So I think that confirms I've got either a cracked head or head gasket issue between # 1 and 2. I had a bad fan clutch over last summer, and there was a day when it was 115* outside, couldn't keep the motor from hitting 220-230, got stuck on the highway and it just wanted to get hotter the slower I went. Anyways, that probably didn't help me out, but the Jeep is my DD, so if I'm gonna have to pull the head off I don't really want to dick around with dragging a possibly cracked head to a machine shop.

I'm curious what everyone things about a replacement Clearwater head? I've seen decent reviews of them on here, but some older posts on other forums and reviews they have don't seem too hot, but there's not any TUPY heads for sale local to me to have cleaned up. I figure the least I need to do is a head gasket and head swap and that would get me up and running like normal again.

But, in my research I've also discovered that apparently Chrysler has a TSB or something a long time ago about the 98 - 02 IIRC 4.0's having poor quality pistons or something along those lines, leading to them being more prone to piston skirt failure.

So, I figure with the head off that could be a good opportunity to replace pistons and rings assuming my cylinders aren't worn too bad, I do have a bore gauge I would be able to inspect them with. I'd probably do rod and main bearings at that point too, but I've done those before on an older 4.2 in the vehicle and didn't have any issues, so that wouldn't be too big of a deal. Then I'd basically have new everything except for the block, crank, cam and cam bearings.

It's a slippery slope though, and an expensive one too, but I'd really hate to just do a new head, have a skirt break in the next couple years and scrap my block, especially since right now I at least have the convenience of still being able to drive it while I gather parts and get a plan worked out.

There's not much of this work I don't feel comfortable doing, I'm just not setup for any of the machine work that could be involved, so that would get contracted out, but all of the disassembly, inspection and reassembly will be done by me and with my work schedule I have 4 days off every week to get it done.

What say the group, any ideas on what I should or shouldn't replace and any ideas on where to get a new or reman head?
Being you DD, have you thought of installing a cyl head and then building a short block in the next couple months and put the new head on when you swap the engines?
 

SkylinesSuck

TJ Expert
Joined
Mar 28, 2020
Messages
3,030
Location
Northern VA
I think the later model 4.0s were different castings in the WJs vs TJs and aren't compatible, but don't quote me on that. I will restate that early model heads are compatible with the exception of needing an aftermarket header. It's an option.
 

williambmac

TJ Expert
Supporting Member
Joined
May 5, 2019
Messages
3,193
Location
Fucktard state of NJ
Sounds like I'm second in line for the edelbrock head, I'd imagine the first guy is probably going to get it since he's local to the seller.

Not having a ton of luck finding a head, might have a TUPY I could grab for $180 + like $120 to ship it, then whatever machine work costs to get it fixed up.

Also found a full 2004 WJ 4.0 with 132k on the clock from a local wrecking yard. It's supposedly still in vehicle, I can go check it out before they pull it, I could probably see it run and I guess they do a compression test before pulling. it's $1,050 including the core charge. I'd imagine it should have the TUPY head on it, it's 30k miles less than mine, and it seems like the WJ motors are one of the easier swaps for a 2000+ TJ.

Does anyone have experience swapping a WJ motor into a 2000+ TJ? Any weird hangups or problems with the two interchanging, or is it basically plug and play?
Yes, I do. The WJ will bolt right into your Jeep. I've done a few of them.
Stay away from that edelbrock head. I will do nothing for a stock 4.0, and your exhaust manifolds will not work with it.

Also clearwater cylinder heads are GTG. They are brand new hd castings.
 

SkylinesSuck

TJ Expert
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Mar 28, 2020
Messages
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Northern VA
Good to know on the WJ motor swap. At least I prefaced that with "I probably don't know what I'm talking about" or something to that affect 😆
 
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Trevlaw

Trevlaw

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549
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Corvallis, OR
Yes, I do. The WJ will bolt right into your Jeep. I've done a few of them.
Stay away from that edelbrock head. I will do nothing for a stock 4.0, and your exhaust manifolds will not work with it.

Also clearwater cylinder heads are GTG. They are brand new hd castings.
Thats good to hear. Went and checked out that WJ engine. Oil looked good, and it started up with a jump pack without any issues, idled and rev'd it a little bit and everything seemed smooth, no knocks or ticks at all. I did pop the oil cap and could see TUPY on the head inside.

Junk yard said it'd be $1,050 for the motor, I'd pay and then they'd pull it and do a compression test. Said if I wasn't happy with the compression I could try another motor or just get a refund.

Bob at Clearwater said his heads are an even better casting than the 0331 and the 0331 TUPY, said the TUPY is also a piece of shit. So that threw me off a little bit, but he's got them new, in stock and ready to ship.

So I'd be about $900 all in for a Clearwater head and other parts, and just run my motor till something else breaks.

Or $1,050 to swap in the WJ motor with the TUPY head and I also believe that year should have the better Pistons. I'd also get to keep my motor as a spare, would need a different head of course, and be able to swap it in if I have problems down the road. Could also rebuild it over time as a new stock build and swap it back in later.

Not sure which route I want to go, kind of leaning towards the WJ motor and if the compression sucks, get a refund and order a Clearwater head.
 

williambmac

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Fucktard state of NJ
Thats good to hear. Went and checked out that WJ engine. Oil looked good, and it started up with a jump pack without any issues, idled and rev'd it a little bit and everything seemed smooth, no knocks or ticks at all. I did pop the oil cap and could see TUPY on the head inside.

Junk yard said it'd be $1,050 for the motor, I'd pay and then they'd pull it and do a compression test. Said if I wasn't happy with the compression I could try another motor or just get a refund.

Bob at Clearwater said his heads are an even better casting than the 0331 and the 0331 TUPY, said the TUPY is also a piece of shit. So that threw me off a little bit, but he's got them new, in stock and ready to ship.

So I'd be about $900 all in for a Clearwater head and other parts, and just run my motor till something else breaks.

Or $1,050 to swap in the WJ motor with the TUPY head and I also believe that year should have the better Pistons. I'd also get to keep my motor as a spare, would need a different head of course, and be able to swap it in if I have problems down the road. Could also rebuild it over time as a new stock build and swap it back in later.

Not sure which route I want to go, kind of leaning towards the WJ motor and if the compression sucks, get a refund and order a Clearwater head.
I don't know why he said the TUPY head sucks. Yes, his castings are new and thicker.

How many miles on the WJ motor? I would want the compression test before I hand over any cash.

I picked up a 4.0 last summer for 400.00 from a private seller.
 
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Trevlaw

Trevlaw

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I don't know why he said the TUPY head sucks. Yes, his castings are new and thicker.

How many miles on the WJ motor? I would want the compression test before I hand over any cash.

I picked up a 4.0 last summer for 400.00 from a private seller.
130k on the WJ, 160k on mine. Not the best deal, but I searched from Redding, CA to Seattle yesterday and there's nothing for sale that is compatible with my 02, just lots of 90's motors. I'm hesitant about handing over that much as well, but I spoke to the general manager and he was clear about being able to get a refund if I wasn't happy with compression, more of a deposit I guess since they still have to pull the motor from the rig.
 

SkylinesSuck

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Messages
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Sweet! Now I get to say my tag line;

Buy the new motor, swap it in, rebuild the current motor as a stroker spare on the stand slowly over time. You'll have a spare upgrade waiting for you when the WJ motor pops and you can take your time building it. Done and done. You're welcome 😁
 
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Trevlaw

Trevlaw

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Sweet! Now I get to say my tag line;

Buy the new motor, swap it in, rebuild the current motor as a stroker spare on the stand slowly over time. You'll have a spare upgrade waiting for you when the WJ motor pops and you can take your time building it. Done and done. You're welcome 😁
That's kind of my line of thinking too, except for the stroker part. Might do a stock rebuild though. Was hoping my 4.0 would last longer as I'm close to firing up the 4.8 LS swap in my J10 and I have plans for an LS in the TJ later on