• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Going Through a Beater XJ 4.0.

Dropped? Ouch, LOL
 
The '88 4.0 is running again! Oil pressure was just under 40psi when the temp was almost to 210. Only a test drive will tell. The new lifters rattled for about 3 seconds on the first startup. I did pump them up by hand and prime the oil pump before startup. They are very quiet now. Just have a heater hose leak, and need to replace the track bar. I can actually hear the leaky muffler now since I welded up the header cracks. Hopefully the welds will hold up. Need to find a super quiet muffler. Broke a lot of the plastic vacuum lines when I pulled the head. All of that needs fixing too.
 
Re: Going Through a Beater XJ 4.0. Test Drives !!!

The '88 XJ 4.0 made it's first run into the hills yesterday. Tons-o-torque. Smooth as silk. Today it made a highway run. Full throttle acceleration was crazy good ! As I climbed towards my destination, it started warming up. Got to the red zone on the gauge pulling a grade. Pulled over into a parking lot, looked her over. The overflow bottle was empty. Full yesterday. No leaks found. Hoses were very firm. It only took 10 minutes to cool down with the stock aux fan running. So off I went up the next grade at 80% throttle. Runs so nice. Temp rose some, but didn't over heat this time.

All of the time in town, way under 210 on the gauge in 60 degree weather. Pulling the grade out of town, warmer, but didn't overheat, until the long slightly uphill highway at 75mph. Then it over heated to the red zone on the gauge, again. Pulled over on a side road. Climbed a burm nose up, and then tail up to try and purge some air in the cooling system. Nope.

Started running warmer on the highway so I slowed down eventually to 55mph. Temp ran about 20 degrees past 210 if I kept it at 55. Any faster and it would get hotter. So 55 it was.

All new cooling system parts. Radiator was rodded out. Why so hot only at highway speed? Acts like a collapsing hose to me. Well?
 
What brand T-stat did you use?

The radiator may still be half full of air. You need to make sure it is full of coolant. Air in the top of the radiator has no way to escape. I always leave the upper rad hose disconnected and elevated when I fill the system. I do the same with the heater hose that goes to the T-Stat housing area on the drivers side and elevate it. that way ALL AIR is purged when filling the coolant bottle.
 
That happened to me the very first time I flushed this jeep. Tried draining it again, and nothing came out !! With an open cooling system, a regular overflow bottle, and a petcock on the thermostat housing, it's easy to make sure it's bled now. I saw your write up about this way of filling the cooling system.
 
Couldn't get a replacement plastic tank for the passenger side of the radiator. So I lucked out and got a 2 core brass radiator with brass tanks at the junkyard. $60. Modine. The tag on it says made in usa. The local rad shop says $100 for boil and rod. He also said that the plastic tank on the passenger side gets the hottest water from the engine so that tank gets thermally beat up sooner. That's why mine died. We'll see if I can fix it to have a spare radiator.
 
You could have bought a brand new 3 row CSF for a few dollars more.

While I am junk yard dog for some stuff, In some cases I prefer a new Chinese part over a used one.

In 12 years I never heard of a 3 row CSF all brass/metal going bad, leaking or having a problem. Not sure where they are made.

Radiators are something I do not screw with fixing, unless it is an obsolete antique one.
 
$60 more for a csf in my case.

Since I have rodded and repaired my first radiator decades ago, I prefer factory known versions because they have a known track record. Good or bad. Brass is almost eternally repairable if it's cared for even a little bit.

Plus the triple core csf may kill any clearance needed for an electric fan in the future.
 
Re: Going Through a Beater XJ 4.0. Larger Fan Clutch Upgrade !!

Let's see how this larger fan clutch helps cooling out here in the desert. It was recommended to me by a guy in Vegas that knows the heat we go through out here south of Vegas.

https://youtu.be/usl4JlacZg4
 
Re: Going Through a Beater XJ 4.0. Torque converter lockup fixed !!

There are 2 brake pedal switches. The switch with the brown connector is for the brakes. The white switch is for the torque converter lock up and cruise control.

The white switch looks like it has threads on it that need adjusting. All I did was push the switch in until it bottomed out on the brake pedal arm. It went click, click. You can use an ohm meter to see if the switch is changing from closed to open or the other way around depending on the year of your jeep. I used the mt2500 scanner as it says weather the brake pedal is being pushed or not.

The torque converter stayed locked up all the way down to 1100 rpm. That will help with fuel economy. It works in 4th (OD) or 3rd gear. Letting all of the way off the throttle or adding a lot of throttle will unlock the torque converter. It will automatically lock up if nothing prevents it from doing so.
 
Interesting info on the switch for the torque converter, Mike. Since you said yours appeared to be out of adjustment, do you think this is an indication that it'd been replaced at some point and not set up correctly, or that it may have "drifted" out of adjustment?
 
Back
Top