Builds 1990 LJ78 in Montana (2 Viewers)

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Well, I have finally gotten around to creating a thread about my Prado. The purpose of this thread will be to outline the mods and fixes I perform.
I bought the Prado in Vancouver, BC in early December, and drove it ~600mi home to Whitefish, MT the next day. It ran and drove great with the exception of a nagging problem with the torque converter not wanting to stay locked up. I intend to do what is necessary to fix the common issues with these to make it a reliable vehicle, but to leave it at that.
-New gauges: oil pressure, water temperature, boost, egt
-New, larger radiator fan
-Water-to-air intercooler
-EGR delete
-Transmission cooler
-New straight-pipe exhaust

Here it is doing its first proper work
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And its first recreation
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The first thing I did was install a mechanical oil pressure gauge, since the stock unit was not working properly. This required some custom work, because the gauge did not come with any metric adaptors to screw into the sending unit hole. I ended up cutting the end off the old sending unit and drilling and tapping the back to fit the standard adaptor that came with the gauge.
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This ended up working really well, and I now know that my oil pressure is perfect.
 
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The next thing on the docket was to replace the turbo, which was leaking a significant amount of oil, both on the inside and the outside.

I also bought a 6"x6"x2" intercooler core to make a custom W2A intercooler that sits on top of the valve cover between the turbo and the intake manifold. That will be going to the fabricator today.
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Four new Bosch glow plugs from Australia are waiting to go in; the old ones are shot.
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Joined
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My boost gauge and transmission cooler arrived today. They will probably get installed this weekend when I install the intercooler and replace the lockup solenoid in the transmission.
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How should I go about testing the ECU coolant temp. sensor? I understand that this could be the cause of my TQ lockup issue. I read a troubleshooting procedure that involved disconnecting the electrical connection to the transmission and running through the gears manually to see if the problem was mechanical or electrical, but my understanding is that TQ lockup is solely electrical, and thus would not work at all under those circumstances.
 

GTSSportCoupe

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How should I go about testing the ECU coolant temp. sensor? I understand that this could be the cause of my TQ lockup issue. I read a troubleshooting procedure that involved disconnecting the electrical connection to the transmission and running through the gears manually to see if the problem was mechanical or electrical, but my understanding is that TQ lockup is solely electrical, and thus would not work at all under those circumstances.

The temp sensor is under the intake manifold in the block. It crosses to a north american temp sensor. I wouldn't bother trying to test it, just replace it instead. I don't think it's that expensive. Replaced mine a few years back.

In terms of testing, I'd use a voltmeter to monitor the electric signal that goes to the torque converter lock-up solenoid. Then you can see if the problem is the signal, or in the transmission.

Someone mentioned in another post that if they pulled their brake pedal up, then their torque converter locked up properly. I think this is because there is a switch there that indicates when you are braking. This would normally take the transmission out of lockup. If this switch is adjusted wrong, the computer might think you are braking when you really are not.

Just ideas....
 
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Thanks for the reply. I have tried the brake pedal thing; if I tap the brakes, I can feel the TQ unlock and then re-lock, but holding it up after it has unlocked by itself doesn't seem to do anything. I will try replacing the sensor, and if that doesn't do it I will probably end up replacing the lockup solenoid.
The issue seems to happen most when everything is all warmed up (after 20-30 minutes of driving), so it seems likely that it has to do with the temp sensor or something inside the trans, which would indicate the solenoid.
 
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More parts arrived today: water temperature gauge, pyrometer, intercooler water pump.
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Just finished installing a gauge cluster for my new gauges. It replaces the frankly useless altimeter and the cool but not very useful inside/outside thermometer. I made it out of some sheet aluminum left over from my intercooler. Now I just need to get them hooked up.
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I also had the exhaust system replaced with a 3 inch straight-pipe. I never would have guessed that a 2lte could sound that good. (Video is on the way.)
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Another item checked off the list: EGR delete. It took about 4 hours to remove and block off the EGR system and the throttle plates. Everything is gone but the exhaust pipes, and those are blocked off.

Here are the items I removed:

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After getting rid of those, I had to disconnect the pipe that goes into the intake manifold to get at the rest of the electrical and vacuum controls, at the bottom of the picture.
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Here is what it looks like when it is out:
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I didn't end up removing the large "UFO" and the exhaust pipes because I didn't have material handy to make block off plates, so I cut a solid gasket out of some scrap ducting, gooped it up with RTV, and installed it on the pipe going to the intake.
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While I had it all torn apart, I replaced my glow plugs and removed both throttle plates. It starts way easier now, and there is a very noticeable increase in low rpm power. I was happy to find that there has been no sludge buildup in the intake in the ~25,000kms since the PO replaced the head.
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While I had it all torn apart, I replaced my glow plugs and removed both throttle plates. It starts way easier now, and there is a very noticeable increase in low rpm power. I was happy to find that there has been no sludge buildup in the intake in the ~25,000kms since the PO replaced the head.
View attachment 1227410
How in the world did you get those screws out of the throttle plate?
 
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How in the world did you get those screws out of the throttle plate?

The screws in the little plate came out without much trouble, but the big ones stripped out, so I drilled them out with the biggest bit that would not mess up the shaft, and then ran a tap through to clean out what was left. I had to remove the throttle body so I didn't get metal filings down the intake. Even after all that it required some gentle persuasion to get the plate out, but I was careful not to mess up the TPS while I was at it. It was definitely worth the trouble.
 
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Awesome to see another water to air system in the works... keep up the good work.

Thanks! I went and picked up my intercooler a couple of days ago, the only thing left is a heat exchanger and a reservoir. The intercooler is designed to fit in the space over the valve cover between the turbo and intake manifold. It won't be the most efficient one out there, but it should do the job.
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GTSSportCoupe

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Thanks! I went and picked up my intercooler a couple of days ago, the only thing left is a heat exchanger and a reservoir. The intercooler is designed to fit in the space over the valve cover between the turbo and intake manifold. It won't be the most efficient one out there, but it should do the job.
View attachment 1228815

Very nice!! I love the work you are doing!
 
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COOLING FAN UPGRADE - TAKE 2

A couple of weeks ago I decided to upgrade my radiator fan to improve cooling. I had read that the 3.0 V6 fan works really well, but couldn't find any in my area, so I resorted to the Isuzu Trooper fan, which has the same hub and bolt pattern. However, once I got the fan home and compared it to my stock fan, it became apparent that the Isuzu fan is made to rotate the opposite direction (this is due to the fan belt routing on a V6 Trooper).
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So I decided to install the fan backwards. I had to modify the shroud a little, but it ended up fitting really nice. Lots of air blew out now when the fan was on.
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This was the first time I could actually hear the fan while driving. However, after a couple of days of driving there was no noticeable difference in cooling, so I held a piece of paper in front of the radiator, and the paper blew forward. I reversed the fan, installing it as it would have been in the Trooper, but it was even worse, so I got on ebay and bought a new Toyota ring fan for a V6. Since installing that there has been a vast improvement in cooling. I still need to fix up a more adequate shroud, since I had to butcher the one I made for the Isuzu fan.
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Joined
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Last weekend I make a roof rack mount for a hi-lift jack. I considered mounting the jack on the back of the vehicle, but couldn't get it to fit anywhere without interference with the doors, ladder, or spare tire.
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The finished product:
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I am pleased with the results, but it has added several new rattles to the Prado.
 

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