Weighing my options

Jakebrake

Jakebrake

Member
Joined
Oct 7, 2020
Messages
33
Location
Philly burbs
well, i was going to take my yj wheeling... was.

looks like the head gasket blew. (antifreeze surging out of overflow tank, overheating). i let it cool off, and left it parked until the mrs and i got back from the wheeling trip (her jl performs like a trooper). popped the radiator cap, permatex present. checked oil, and, permatex present. no bueno.

engine is an 89 4.2...figure parts are gonna be an issue. plus, it's pretty much an underpowered slob. originally was a 4 banger, someone converted to a 4.2 carbureted. i believe it's a 905 trans.


i called my mechanic, and, asked him to call his salvage yards looking for a decent 4.0 liter. still haven't heard from him. (shop is always busy)

now i wonder, am i better suited with a 4.0, a 4.0 liter head, or, fixing the 4.2?

(granted, i really want to stuff a 383 stroker in it, with a th400, but, i haven't developed the ability to print money, so, there's that)

i figure someone here has done one, if not, all of the above, and, has hit every pitfall imaginable.
 
My opinion, for cost, is to pull the head, recondition whatever it needs, and replace the head gasket. That's assuming the block is doing fine and you're happy with the carburetor.

The 4.0 option gets you fuel injection, but there is a bunch of extra stuff required to support it (fuel pump, computer, wiring harness). Mopar used to sell a kit to convert the Carburetor 4.2 to Electronic Fuel Injection (EFI), but I just checked and it is no longer available.

I have the 4.2 with that Mopar conversion and have had no problem finding parts. I also had a head gasket blow and replaced it in short order. To that end, I have a parts list with everything in that EFI conversion kit for the Manual Transmission (AX-15), so theoretically, you could purchase the kit in parts. I believe that list also contains the additional Automatic Transmission parts needed but were omitted from the box mine came in.

Your decision is as much emotional as it is practical, What shape is the rest of the Jeep in? Are you happy enough with it to invest in a new engine? Personally, I think it is way more cost effective to maintain the heck out of the Jeep than to buy a new one.
 
Gary747 said:
My opinion, for cost, is to pull the head, recondition whatever it needs, and replace the head gasket. That's assuming the block is doing fine and you're happy with the carburetor.

The 4.0 option gets you fuel injection, but there is a bunch of extra stuff required to support it (fuel pump, computer, wiring harness). Mopar used to sell a kit to convert the Carburetor 4.2 to Electronic Fuel Injection (EFI), but I just checked and it is no longer available.

I have the 4.2 with that Mopar conversion and have had no problem finding parts. I also had a head gasket blow and replaced it in short order. To that end, I have a parts list with everything in that EFI conversion kit for the Manual Transmission (AX-15), so theoretically, you could purchase the kit in parts. I believe that list also contains the additional Automatic Transmission parts needed but were omitted from the box mine came in.

Your decision is as much emotional as it is practical, What shape is the rest of the Jeep in? Are you happy enough with it to invest in a new engine? Personally, I think it is way more cost effective to maintain the heck out of the Jeep than to buy a new one.
Click to expand...
Whereas cost is something of an factor, I also have to look at Parts availability to a degree. I know the four liter is torqueier than the 4.2. That's part of my issue. The carburetor, that I can replace with something a little more modern. My big thing, is am I going to be picking up that much more torque going with a 4 liter? Also, I know carburetors have a tendency to get sort of womkey when you start going on very steep inclines. This is basically going to be an off-road use vehicle. Granited, it had does have to get me to the off-road park under its own power.
 
well, the good lord was kind enough to help me solve this dilemma. the bottom end is pretty much clapped out. the blow by was particularly heavy. tried the old school bypass trick, and viola~ the blowby was 3 feet. rings are pretty much wasted. 4 liter it is. and, a new radiator, just to deal with all of the permatex that found it's way into it.
 
yeah....plot thickened....4.0 carbed yard motor near me....may as well find a virgin in las vegas...resisted urge to put in 383 stroker. getting rebuilt 4.2. hoping to have it back in time for the weekend. (not going to happen...i just like to hope) so i can wheel with it.
 
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