Hi evertrol.yone,
My beauty has 230's miles and have some minor issues that I want to fix, exploring if I can update the car at same time.
I don't need advise like "buy another one" or similar. Actually is my third car, so is more like a hobby.

Transmission has been rebuild and goes fine and smooth, but I have a minor problem with the transfer case. When inserting reverse, makes clunks and cranks. Guys from the transmission confirms is the transfer case.
So I have the option of buying the 1999 transfer case, I believe that this one has limited slip diff, while mine does not as it has trac control. Could be possible? Like plug and play? Does anybody knows the part number?

What about doing the same with the rear diff and change actual one for a limited slip diff from first series?
I do off road with the car and for sand is better this trans option than trac control, that stops the car.

Rebuilding engine. It takes oil, like a litter every 600 miles while cruising at 85 MPH. Not a big deal but I am thinking in rebuilding the engine. Doing this, any possibility to make it 3.3 or 3.5 liters? Does anybody knows if there is a kit to do this?
I do not want to SWAP engines I believe that I will need to change all CPU's and maybe trans. No so much sense.

Thanks for feedback,

 

Vehicle "projects" are fun, but imho only if the person/owner does the wrenching.

The most important part is just because it can be done does not mean it is the right thing to do. Ex: Limited slip diff. To me it makes sense for RWD. RX does come in AWD, but still the power split is such that the rears are followers and not the main source of traction. Since you were explicit in stating that no one should tell you to buy another vehicle, so I will only say is make sure the expected results are achievable.

Be aware of return/warranty when you purchase and install used equipment. Mechanics charge the labor but when they purchase used equipment then they 'should' give you warranty and free labor in case of issues.

For oil consumption, please use a catch can in the PCV path or check compression & leak down test. What I am stating is, make sure the issue is diagnosed properly before you venture into rebuild. Another case of 'want/desire to do' is predicating 'what should be done'.

From one tinkerer to another ... first gen is getting old and plastic parts, hoses etc are getting brittle. Touch only things that need to be touched. Invest in factory service manual(s). Do not expect to recover any $$$($) you spend on the vehicle.

Salim

 

Thanks Salim,

The car is with me since the first day, so 23 years now. I have the service manuals with me. I do practically all maintenance by myself. Of course rebuild the engine is a big job. I did it in a Fiat 127...but it was like a Lego game comparing to RX.
Just wondering if the change of the transfer case with limited skip diff will make sense or not, as the transfer case is making problems... since 120 's miles ago. :-) and still goes.
Thanks for the suggestion of do a compression and leak test. I will. PCV has been replaced but maybe I need to check all path, hoses...
As is the third car at home, if I have it parked for some days, not big deal. But I love the car, and to go for skiing, is just the best, that's why I want to solve the wild consumption issue.

 

I don't see why the viscous coupler t-case won't fit, the CV axles and most of the internals are the same between the two cars so it's probably worth a shot. It even looks like the 2001-2003 Highlander or 2007-2009 RX350 one would fit too. As for the oil burning, try the 2006-2007 3MZ-FE rear valve cover and if that doesn't work some Berryman B12 down the spark plug holes to maybe unstick the rings. If those two didn't help I'd then be a little concerned.


Viscous coupler



Non viscous coupler

 

There is a long discussion on the valve cover. Check it out. Personally I would prioritize the power plant and use that as proceed to go or put everything else on hold based on that.

Salim

 

Some of your points:

1) Diff: based o@MattRX has kindly shown, it’s no problem. But, it won’t disable your TC system. And if you do go down this road, RE: your sand comment, look into seeing how easy the TC system can be defeated. I have a same vintage Volvo XC, with both TRACS and an LSD rear diff in addition to the AWD system. I found the TRACS a real drag in snow and offroad, and was able to very easily install a switch to defeat it. Best of both worlds - TC system for rain and unexpected road issues, then just flip it off for play time.

2) Be aware w/the VC center diff in the rear, it can be damaged easily w/mismatched tire diameters on either side. Watch carefully about that if a spare used or tire sizes changed or even tires changed.

3) For consumption, and if you do suspect rings, 1st go through the known issues with the 1mz as mentioned. Then, before tearing things down, run the new Valvoline Restore & Protect a while. It is a remarkable new cleaning oil and may address sticking rings or clogged drain holes if that is your issue. There is enough real-world user experience to believe their (very credible) claims.