98 TJ engine swap: automatic to manual transmission

Jms76 said:
I’ll give this a shot, in your opinion with the 170k miles, is there any chance of making this into a reliable engine? Meaning, all the stuff I’d do to this is just a band-aid until the engine fails? My goal is to make this into a reliable and nice vehicle my kids can drive. And can go down the highway without blowing up or needing a tow truck.

Given that perspective, would it just be best to order a new rebuilt engine, put new clutch in during install and move on?

More research I do, any fix in this would just be a patch until it fails or has another issue.

Whether I get a fully rebuilt or the used jasper engine, seems like a pretty straight forward install.
Click to expand...
I’m going to do a few more diagnostics this week.

When you do the compression test, is it best to do it with engine cold or warmed up?

Also my plan was to pull all the plugs and disconnect the injector wires then perform the test. Do you need to remove the air filter?

Spec wise, thinking cylinders should be around 150 psi and within 10% of one another?

Any other thoughts or suggestions?
 
Do it warm, and the rest of your plan sounds good. No need to mess with the filter but wedge the throttle body open. I think last time I did mine it was like 135'ish, but even numbers across the cylinders of more important than the actual numbers.
 
SkylinesSuck said:
Do it warm, and the rest of your plan sounds good. No need to mess with the filter but wedge the throttle body open. I think last time I did mine it was like 135'ish, but even numbers across the cylinders of more important than the actual numbers.
Click to expand...
Yea, I do recall having to keep the TB open when I did this before. What do you think is a concerning variance between cylinders. Is 10% too much? What would you expect to see if a cylinder has an issue? Say all 130-135, except 1. How much lower ballpark would you expect a cylinder with issue register?
 
I think I've heard that 10% number in several places before as well fwiw, but I'm not certain. I did a compression test one time on a different kind of I6 and had 115-125 across the board except one which was 92. Pulled the motor apart and find a cracked ring land.
 
Performed compression test, cylinders 5 & 6 pretty low as compared to others. Also inspected with borescope and found scuffing in 5 and what appears to be some vertical wrist pin marks down cylinder wall on 6.

Also, an probably most important, stuck a wood dowel down cylinder 6 plug hole and was able to push the piston left and make the same tink/clank noise when it is running.

9D786FCA-42D1-481B-B474-2EF9D63E606B.jpeg


B24C2B69-D6B4-4142-B9A6-94C037DAF130.jpeg


4387CECD-BD2B-40BB-894F-203357B3F5BC.jpeg
 
Last edited:
  • Sad
Reactions: SkylinesSuck
At least your found it. Now to figure out your plan of attack to get a new motor in there. Are you still thinking about that motor from the XJ? You could swap that in and rebuild the one you have now at your leisure. And this wouldn't be a thread with me talking about motor stuff without suggesting you rebuild it as a stroker 😁
 
  • Like
Reactions: NashvilleTJ
Will probably keep the core and build into maybe a stroker engine. Good project and learning experience. I’ll see how this replacement goes. Replacing the clutch, flywheel, water pump, engine mounts, pulleys, belt, etc. while having it apart.
 
  • Like
Reactions: SkylinesSuck
Couple of questions regarding the engine swap?

1. I’m using a new flywheel, is there any need for a shim? Don’t think so, but wasn’t sure unless you had the existing flywheel machined down.

2. The replacement engine I ordered says cam has no thrust plate. From the research I did, that makes sense, but seems there should be a button in the timing cover. My existing timing cover has a dimple in it, but not sure if there is something behind it to keep cam from walking too much forward. Couldn’t find a part or wear item that I should replace in the timing cover other than the chain guide, gasket, and harmonic balancer seal.

3. The transmission and cylinder dowel pins? Just buy new or is there some magic of getting them out and reusing? Found the following 2 part numbers, J4005148, J3172318 respectively, these look like the replacements.

Any other pointers? Watched a bunch of videos on rebuilds, found little things like not to torque timing cover until you get it centered on the harmonic balancer.
 
I have never heard of anybody shimming a flywheel. Also, Jeep flywheels should never be machined. They have a slightly convex shape and that would ruin them.

There are two styles of cams. The early style used a spring loaded button that rides on a nipple on the inside of the timing cover. Later style used a cam retaining plate. I am unfamiliar with the later other than knowing aftermarket cam options are very limited for it.

No idea on the dowel pins for the tranny. What are the other ones you are asking about?

I've never heard of not torquing the timing cover until it's centered on the harmonic balancer. I don't think there is any room for adjustment, but I'm interested if you have a link.
 
SkylinesSuck said:
I have never heard of anybody shimming a flywheel. Also, Jeep flywheels should never be machined. They have a slightly convex shape and that would ruin them.

There are two styles of cams. The early style used a spring loaded button that rides on a nipple on the inside of the timing cover. Later style used a cam retaining plate. I am unfamiliar with the later other than knowing aftermarket cam options are very limited for it.

No idea on the dowel pins for the tranny. What are the other ones you are asking about?

I've never heard of not torquing the timing cover until it's centered on the harmonic balancer. I don't think there is any room for adjustment, but I'm interested if you have a link.
Click to expand...
Received the new engine.

Couple of follow up items.

As far as the flywheel machining goes, saw a video where someone had it machined on a Jeep 4.0. Agree that probably it is not a good practice and may cost you more than a new flywheel. I did find the shim that can be used. I’ve included the info as a reference.

The reman engine came with the intake/exhaust alignment dowels installed on the head.

The engine also included the two bushing (I called them dowels) in the block where it mounts to the transmission. They are located on the lowest and widest mounting location. I know this sounds stupid, but I’d say they are located on the wings of the block. They are not solid, more of a bushing that the bolt goes through. Seems like they help get the transmission aligned to the engine.

I’ll take a picture and post.

Lastly, regarding the harmonic balancer used to align the timing cover. Originally picked up on that from a video, but also found it in the Haynes manual. Included the paragraph.

Do you have a recommendation on oil and whether or not to use a zinc additive?

Lots of opinion, seems like you want to use conventional oil at least initially.

1B299EA2-F33D-40B5-AD38-00CB12F03FF6.jpeg


80C01D49-3E17-402F-9328-D99B60A902CD.jpeg


6B925A56-57BA-47B9-9684-DA43E308132B.jpeg


6B3F8669-792D-429D-8FB0-9DBF630936BD.jpeg
 
  • Like
Reactions: SkylinesSuck
Interesting. Never seen some of that before.

For oil, I personally ran Comp Cams break in oil that I ordered along with the cam. It's got gobs of zddp and since the cam is the main thing you are worried about reference oil on break in, I figured I would use their stuff so if it died, they couldn't blame the oil I chose. For normal running after break in, I use Valvoline VR1 as it has elevated zddp levels. I don't like additives. Feels kinda like shooting in the dark to me.
 
I'm not a fan of Lucas in general mostly due to their marketing practices, but I honestly don't know much at all about their products. Regardless, break in should consist of firing the motor and running it at around 2000-25000rpm for 20 min while varying the rpm a bit. This is strictly for the benefit of the flat tappet cam. Then change your break in oil. I'm not saying you can't put the same kinda oil back in it, but change it. Then go do what most consider the typical engine break in where you give it the beans a bit and let it engine break to slow. This is for the benefit of seating the rings.
 
SkylinesSuck said:
I'm not a fan of Lucas in general mostly due to their marketing practices, but I honestly don't know much at all about their products. Regardless, break in should consist of firing the motor and running it at around 2000-25000rpm for 20 min while varying the rpm a bit. This is strictly for the benefit of the flat tappet cam. Then change your break in oil. I'm not saying you can't put the same kinda oil back in it, but change it. Then go do what most consider the typical engine break in where you give it the beans a bit and let it engine break to slow. This is for the benefit of seating the rings.
Click to expand...
Found this oil testing information. Looks like the Lucas rates well for break-in. I’ll be sure to follow the break-in rpm and time requirements.

2D52B001-50AD-4DE2-A950-4C873F90E6E5.jpeg
 
  • Like
Reactions: SkylinesSuck
In process of preparing the new engine due install, two questions:
1. The old engine has a main bearing girdle, the new one does not. Wasn’t expecting to have to swap that over. In looking a pics on-line, seems some engines have it, others do not. Was only expecting to swap the oil pump pick up and pan on bottom end.

Assume that it should be swapped over to new engine?

2. Installing a one piece felpro rubber oil plan gasket. On the rear main cap, there is a groove in it. The gasket spans the groove. Just want to be sure that I should not compress the gasket into the groove. It can be done, but don’t think it should be. Tried to find a few pics online, but couldn’t tell.
 
The girdle will swap over no problem. I believe the gasket goes into the groove but I'm not certain off the top of my head. I'll see if I can look through some old pics and figure it out.
 
Yea, I’ve struggled to find pic or instructions on placement. If I tuck into the groove, seems gasket has too much extra material, plus pan feels like it will seal better out of the groove. You really need to compress this to get it in. Kind of strange, but better to figure out ahead of time.

Are there any more bottom end parts to swap over that I’d be missing. Pan, oil pick-up and girdle. That is all I see, but would like to confirm.
 
Top Bottom
Back