Cylinder 1 and cylinder 6 low compression and a little blowback plus a rattle

[Rustee]

I had a thread going before about a week ago about my motor when I first bought the jeep. It has a rattling sound near the back (cylinder 6?), also a blown head gasket or cracked 0331 head. I found a TUPY head tat is attached to a block and now I am just trying to figure out if I should just swap the head or swap the block too. There is a little blowback but not enough that it's getting on the air filter. When I take the filter hose off the intake, there is some oil there and appears to be coming out of that PCV valve at the front of the valve cover. Last night I did a compression test and checked out the spark plugs. I took pics. It seems that a couple of the look steamed and some look burnt. The steamed looking ones are where the good compression was which confuses me a little. I think what I need to know now is should I just pull the head at this point and see if the rattle is in there somewhere? Maybe pull the oil pan to for inspection? I also used a stethoscope to try to narrow down the rattling sound and it was definitely louder and clearer when I touched it to the head/valve cover at the back of the engine around cylinder 6. What could be in there making that rattling noise?

1 5-10 PSI
2 155 PSI
3 150 PSI
4 150 PSI
5 137.5 PSI
6 25 PSI

Also I noticed that there was a little smoke coming from what I believe is the oil sending unit right in front of the oil filter. The catalytic converter seemed to have a little smoke coming from the seams too....not sure if that is even abnormal. Oil leaks seem to be coming from around the oil dip stick, oil filter and maybe oil sending unit. Other side of engine leaking from somewhere as well I think.

 

[Gilaguy23]

It sounds like your engine is done. Basically no compression in 2 cylinders, low in a 3rd. I personally doubt its burnt valves and more like just worn out. Even a bad head gasket would not give all the issues you detail. The rattling?? Hard to define on line, but rattling mains or rod bearing(s) are a possibility. I see 2 different brands of spark plug? Although both are a usable part number for the 4.0, Id guess a PO tried a cover up hoping to get all 6 cylinders firing. The smoke from various places is likely crank vapors from blow by and from the cat is probably oil hitting the internals and vaporizing from the heat in them.

 

[Rustee]

It sounds like your engine is done. Basically no compression in 2 cylinders, low in a 3rd. I personally doubt its burnt valves and more like just worn out. Even a bad head gasket would not give all the issues you detail. The rattling?? Hard to define on line, but rattling mains or rod bearing(s) are a possibility. I see 2 different brands of spark plug? Although both are a usable part number for the 4.0, Id guess a PO tried a cover up hoping to get all 6 cylinders firing. The smoke from various places is likely crank vapors from blow by and from the cat is probably oil hitting the internals and vaporizing from the heat in them.

That's kind of been what I was thinking but now also thinking the coil rail could have been causing 1 and 6 not to fire possibly. So I may need to swap that as well. We don't have to take an emmissions test in SC so do you think I should just cut the cat out?

 

[Rustee]

Ticking and rattling in a 4.0L are showing up most commonly as broken piston skirts. It's just down to the degree of failure. The skirts were just a bit thin. These motors in stock form aren't especially prone to rod bearing failures/rod knock. Collapsed lifter issues can occur and will show up as a noisy lifter tick that clears quickly on startup as the lifter pumps up.

And I agree that this motor needs a rebuild. As is, it's done.

Gonna swap it. I've heard enough this morning from responses that I don't even want to deal with fixing it.

 

[Rustee]

I replied early on the other thread and I'd still hold to that recommendation. The noise you describe is coming from a bad piston skirt and the compression numbers say it is very bad.



Honestly I think what you do next depends on what you want to do with the Jeep and whether you plan to hang onto it for a while. I would not swap a long block unless I absolutely knew it was running good before it was pulled. The TUPY head on that block is probably fine, but it's pistons could be just as bad.

These cast iron blocks are pretty tough, but if you keep running your motor you risk breaking a wristpin and opening some new ventilation ports in the side of the block with the steel rod. At that point your block is done. I wouldn't worry about the oil leaks at the moment. You're going to have an opportunity to sort them out.

Based on those plugs, I think you have a cracked head leaking into to valvetrain side. This is a common failure mechanism for the early 0331 non-TUPY heads. Also based on those plugs, 1 and 6 aren't burnt, they'te black from blow by oil burning, and 5 is probably starting to go too. #2 and #3 look pretty normal with the tan color on the insulator. Not steam cleaned. #4 looks somewhere in between.

Honest recommendation for the next step is to get a boroscope down cylinder 1 and 6 to inspect the walls. If they're marred up from piston slap, you're definitely going to need to take that block to the machine shop to get it bored out between 0.030" - 0.060". Luckily they're at BDC together.

Pull the valve cover and inspect the valve train. You probably won't be able to see the crack in the head with the naked eye. When you turn the motor over, does the valvetrain have any obvious issues like a valve not lifting?

Then drop the oil pan. You probably have some piston chunks down there. Inspect the cam from below. Are any lobes wiped out? Does the wear pattern look correct. Uncle Tony's Garage on You Tube has a decent video explaining flat tappet cam wear patterns.

From there, you have some choices.

If it doesn't need to be bored, you can order the piston kit from DeXJs.

If it needs to be bored out, I would seriously consider a Clegg stroker kit. It costs only a few hundred more than the parts you'll already be buying to add the 4.2L crank and 24lb injectors and you'll transform your 190hp 4.0L to something in the 250-280hp range. Either 4.6 stage 1 or 2, but not Stage 3 5.0L because it requires the sides of the block and front of the oil pan be clearanced. You will probably want to have the block deck shaved to get the proper quench, but the cost for this is nominal with the other work being done at this stage. Usually the hydraulic lifters will be fine with this, but the shop can advise if you need to order some shorter than stock. It'll take a while for the shop to tell you what it needs bored and to order the kit, get all the measurements and have it ready for you.

If your cam is good, you can keep it and the lifters (in current order) with the stroker or standard build and it will favor bottom end torque. There is a problem at Comp Cams at this time with the thrust plate style cams for our late 4.0L motors. Most other cams for the 4.0L are for the old cam button style and need some different parts.

You still need to deal with the head. There would be a market for the short block, so don't scrap it.

I appreciate all that info. Not that I would mind having the stroke but at this time it's not really in the budget to do all that is required. Plus I don't have the time right now and need it running asap. I have a TUPY head attached to a block on standby for $100. I'm just gonna swap it out with that for right now.

 

[Gilaguy23]

Heres an idea for you. Being in KY as of 8 months ago I see my share of rusted out 4.0 equipped jeeps ready for the junk yard. There's gotta be a decent priced/good running engine to be had to get you going. The 4.0 is pretty bullet proof and even finding one with 200K on it is a consideration. Just get a guarantee from the recycler its a good runner. Way easier and cheaper then doing a tear down, hoping to find a competent machine shop and costing 3 times as much.

 

[Rustee]

Heres an idea for you. Being in KY as of 8 months ago I see my share of rusted out 4.0 equipped jeeps ready for the junk yard. There's gotta be a decent priced/good running engine to be had to get you going. The 4.0 is pretty bullet proof and even finding one with 200K on it is a consideration. Just get a guarantee from the recycler its a good runner. Way easier and cheaper then doing a tear down, hoping to find a competent machine shop and costing 3 times as much.

I have one on standby with 180k something miles on it with the TUPY head. The guy said he would sell the head and block to me for $100. He also said he would lift the body and swap the engine for $750. Is that a good way to swap the engine out? I guess he's not an engine mechanic but he swaps out frames and motors a lot.

 

[Gilaguy23]

Head and block like in long block? Lift the body on a TJ...NO. remove the radiator and front grill section OK. Why not buy the entire running engine?

 

[Rustee]

Head and block like in long block? Lift the body on a TJ...NO. remove the radiator and front grill section OK. Why not buy the entire running engine?

It's a 4.0 out of a 2002 Wrangler. I have seen a video where they used the cherry picker and just took the fan off without removing the radiator and grill. Is this possible? I may end up just trying to do this myself or have someone come help me. I did tear my last motor apart and re-ring it just by going off the haynes manual....and a little help from the forum lol

 

[Gilaguy23]

RE the Cat. It may be fouled up from oil blow by in the exhaust ,so be prepared to replace it if necessary. I will tell you, you will gain NOTHING in the way of power or MPG removing it provided it isn't already plugged up or falling apart inside. For one, the stink of fumes will gag you. Remove the top or roll up the rear window and I swear you die of carbon monoxide poisoning on a long drive. I dont recall what year you TJ is but you have downstream 02 sensor that will give you a nagging code for the cat no worky right.

 

[Gilaguy23]

Im sure your thinking save a buck and yes thats OK, but it goes something like this. The bitterness of a bad decision will easily outlast the thrill of saving a buck.

 

[Rustee]

Relatively easy with a 2.5L or 2.4L. It's tight with a 4.0L and a risk of damaging the radiator. The plastic tanks aren't super robust. It's really not a big deal to unbolt the grill.

Only time I've seen people lift the body on a TJ is when swapping in a V-8 and even then, not all the time. Or when swapping out a rusted frame.

So today I went to his little shop where he swaps out frames so therefore he has to swap engines too. He actually had a body on the lift and had just done a frame swap. Pretty cool actually. I told him that people didn't seem to be very aware of swapping engines like this and he said well I've had to lift so many bodies that it's just easier for me this way. He also said that the first couple of times he broke some things lol but now he has it down really well. It honestly makes it look so easy to work on these things this way and there wasn't much hanging or look like much to make it happen really. I got the motor from him and he said not to pay yet and choose the best accessories between the two engines and bring the jeep and motor. He never got to hear this motor and we couldn't do a compression test on it there. The frame or body was rotted out or damaged so he got the jeep for whichever of those two that weren't, I forget which one it was. I'm only paying $100 for it and I have the whole thing to work with. We thought it was a 2002 model with 180k something miles because it came from a 2002 jeep but this motor is a 2005-2006 according to the OPDA on it. I took a pic of the casting number in hopes of decoding the year out of it. Hopefully it has less miles than expected, with good compression and nothing bad going on.

 

[Rustee]

RE the Cat. It may be fouled up from oil blow by in the exhaust ,so be prepared to replace it if necessary. I will tell you, you will gain NOTHING in the way of power or MPG removing it provided it isn't already plugged up or falling apart inside. For one, the stink of fumes will gag you. Remove the top or roll up the rear window and I swear you die of carbon monoxide poisoning on a long drive. I dont recall what year you TJ is but you have downstream 02 sensor that will give you a nagging code for the cat no worky right.

It's a 2000 model and I'm sure that oil has been getting dumped through the exhaust. Can I just cut the cat open and take the cones out? What will that mess up?