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Transmission issues after engine swap.*Solved*

7K views 9 replies 3 participants last post by  Guts 
#1 ·
I have a 2000 WJ 4.7.
I blew the motor, literally sent the pistons into the oil pan.

Anyway, I installed a new (to me) 4.7.
During the install, I had to remove the torque converter with the motor as the engine was locked up.
My girlfriend set the torque converter down and didnt realize it leaks out tranny fluid.
Probably unrelated but i filled it back up to the brim and reinstalled it on the input shaft.
I noticed a hose has gotten wedged into the bellhousing. In between the torque converter and the flywheel.
I was able to remove most of it. No idea where this hose came from. It was a tiny hose and shapped as a U. anyway probably unrelated.
Bolted everything down fine


Engine starts fine. it sounds amazing. my buddy who was helping me drove it around the shop a few times.
However, it didnt have an alternator on it yet so I towed it back home using a tow strap and my other WJ.
My girlfriend was in the pulling vehicle and we came up to a traffic light, I was trying to stop but was on a steep incline. So i started my WJ and put her into second then first to help slow down the vehicles.

Turn it back off. Got home, started it back up to pull it into a parking spot. It felt like it was a manual and I had my foot halfway on the clutch. I have to give it high revs to get her to move. Parked it.

Came out the next day, wont move. Started it up, checked trans fluid, full as ****. Took off the trans cooler line to radiator to remove some, and nothing was coming out. Pulled it out manually through dipstick, the fluid is a brownish color but didnt smell burnt.

I've never had transmission problems with this jeep before. NO gear works. When I shift into a gear. The RPMs raise slightly as if its trying to move.

I probably gave way more information than needed but i figured giving you all the details of what may have contributed would be helpful.

I spent $1,000 on the jeep itself.
and $1,800 on the motor, $250 on the tools and $300 on misc shit. I'm tired of dumping money into this thing so hopefully it will be an easy fix.
I also have to get a new power steering pump, alternator, valve cover gasket.

Should I abandon ship or stick it out?
 
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#2 ·
Most people don't give anywhere near enough information or intentionally leave stuff out. The only extra information you gave, I don't think the vacuum line has anything to do with your trouble.

Unfortunately, it is likely you damaged the transmission while towing your WJ. Depending on what transfer case your Jeep has, there are certain procedures you need to follow to flat tow (all wheels on the ground) a Jeep. Automatic transmissions like power input from the engine to pump fluid, lubrication, through the transmission. If you just turn the output shaft (towing with the engine turned off) you can damage bearings or clutch packs. Towing it as you did, on a rope, it is best to leave the engine running at an idle and in neutral, to allow you power steering and power brakes.

If it wasn't damaged from towing, what type of transmission fluid (ATF) did you use to fill the torque converter? Using any form of dextron will kill a Jeep's transmission. Barely wanting to move under power is the symptom. Overfilling a transmission can damage it, but in your case it's not likely it was damaged by overfilling. It is also possible the torque converter wasn't purged of air but that is also unlikely.

A running WJ with a V8 can be worth about $2,500+/-. A WJ with a bad transmission is worth $1200-1,800. A rebuilt transmission can be expensive, however, a new motor and transmission gives new Life and value to your vehicle...
 
#4 ·
ATF+4 is the right stuff. Damage from the wrong fluid is a costly repair. You may still have damaged the transmission by towing it. How far did you tow your Jeep?

The symptoms also indicate it could be the the torque converter. That is less expensive than a transmission, but not quick job to replace it.

The transmission will read overfilled with your Jeep not running or a bad torque converter. The correct reading is when the vehicle is running because the fluid gets pumped into the transmission.
 
#5 ·
Right. But I had the vehicle running, with the trans cooler line off the radiator, and nothing was coming out. And I towed it the following miles

The day the engine seized it was towed 39 miles
a month later, it was towed another 40 miles.
The next day, it was towed 40 miles again. On this last tow, thats when I started it and down shifted to help stop. It shifted amazing and quickly. I shut it off and put back into neutral once i stopped.
 
#8 ·
I do not think your transmission was actually overfilled. I don't think it was prudent to drain any fluid. If your transmission was operating correctly, low fluid level would cause the exact same symptoms your transmission has now (not pumping fluid through the cooler, slipping, fading and barely wanting to move under power). No, low fluid level may not be the issue, but you would never know if the issue had been corrected. An overfilled transmission is not likely to have been damaged with so few miles actually driven. Towing it overfilled would not caused damage.

Towing your jeep on a rope 40 miles without it running is long enough to damage your transmission. Three times that is very likely to cause damage. Starting your Jeep and immediately dropping it through the gears is another very likely cause.

Another cause for transmission issues when swapping motors, it is easy to crush or plug a transmission line. This would have the same symptoms.

A clogged filter would also have all the same symptoms.

I'm thinking about just purchasing a new (to me) transmission. Specifically this one

$250 for a working transmission with a one year warranty sounds to good to be true. Remember, you get what you pay for. I'm not saying this won't work for you. I am not a transmission expert, but I have a lot of experience with breaking transmissions, I have destroyed over 2 dozen transmissions. Going cheap on transmission repairs rarely pans out.
 
#9 ·
Okay so just to update, I pulled the Trans pan. heavily coated in shavings. Fluid smells burnt and extremely dark. So the verdict I'm sure we can all agree on: Don't tow your jeeps without removing the driveshaft or flatbed tow it.
Thanks everyone for their advice and help.
 
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