P1436 Revisited

No, there is no way to get inside. Plus, from under the car, it's darned difficult to get any kind of lubricant to where it can do any particular good.

There is NO aftermarket alternative. It's repair or replace from Toyota. So, on to repair...

The RIGHT way to solve the problem involves removing the entire assembly from the car. A good summer's day project. It's one vacuum hose, disconnect O2 sensor #2 (under the passenger side carpet, the mating connector is near the center console; pull it through the rubber chassis boot) two bolts (holding cat converter to engine), and disconnect resonator from the muffler (behind the left rear tyre) and wiggle it out of its rubber mounts (lubricating these is helpful). Once it's out, you can work the butterfly valve around, so that it moves freely. Due to its high operating temperature, most lubricants will be driven off (I'm not sure about the ZEP mentioned above), so it should be convinced to move freely whilst dry.

On my 2001 for this project, to get really free travel, I had to work the valve full travel, back and forth, several hundred times (I attached a small vise-grip plier to the actuator to give me extra leverage) while applying Liquid Wrench to get rid of debris at the top pivot point/bearing. The lower pivot point is internal to the valve, and not really accessible. I did bang the lower pivot point a few times with a ball peen hammer, on the theory that it would loosen any debris at that lower point, and reduce friction there.

If the car sits, particularly in US north winters, with snow, road salt and debris... both the butterfly valve shaft and the upper bearing point can corrode and bind to each other, giving rise to the fault when the valve can't move, or can't move fast or far enough.

So far, my repair has lasted two years. No P1436 faults.

This same vehicle was giving P0440 faults (Evap system failure). The usual suggestion is "replace the fuel cap". Well... while you're there, look at the mouth of the fuel fill pipe. The Gen1 fuel fill pipe is prone to rust (at least in the US north) and if there's enough rust, the gas cap can't seal. So I block the fuel inlet with a paper towel, and CAREFULLY use a dremel tool and bronze brush to clean as much of the corrosion off the fuel fill pipe as possible (plus remove any crusty stuff on the rubber gasket portion of the fuel fill cap).

THEN put a few layers of clear nail polish over the metal gasket-facing parts of the fuel fill pipe. The theory is, the nail polish will fill in any divots in the metal from the scraping/brushing, and make for a better gasket seal. The nail polish lasts about a year, then needs renewal. So far, this has prevented any recurrence of the P0440.

Hope this is helpful...

 

Here is a helpful revisit of this revisit, updated to 2023.
My recommendation, as long as the cats aren't clogged and there aren't any leaks from corrosion, is to simply disconnect the vacuum line to the valve at it's source up under the hood, then stick the valve assemble on the exhaust in the opened position. Very easy.
Then get yourself a Honda Goldwing 1500 cruise control vacuum valve, part# 36625-MN5-000, and insert it onto the HCAC vacuum source up under the hood.
Where that is located, you can easily and cleanly bolt it to the plastic panel on the engine coolant reservoir tank.
It'll look really pro so there's nothing to raise concerns at inspection.

It'll cost your no more than a whopping $35 - $40 in parts, and your codes p1436 and P1437 will not come up again.

I did this to my 2003 Gen1 over 3 years ago. No codes or other issues, and always passes inspection in a breeze.

This fix is also fantastic for non-HCAC aftermarket cat installations on the Gen1 also.

 

I'll add that I have a couple of OEM exhaust systems for anyone in those CA-compliant states that need such. Kinda have to cut the assembly in half to ship economically, right in front of the resonator. So, if you're going to do that anyway, and weld them back together, might as well just weld to your existing resonator and muffler and pay less shipping. LMK, I'm not asking much over cat value to cover my labor. But, there's not a crystal meth excise tax added on either. Just trying to save these cars.

If you don't know, the prices on these cars hit bottom and are now going up. I sold a couple for around $3000-$3200 three years ago. KBB and NADA have them worth more today, and I'm asking more for the cherries I have

If you don't live in one of those CA-compliant states, the solution Bruce describes works great. I have two cars with cheapo cats and Goldwing parts. But, if you think these will be collector cars one day, you might want these OEM parts.

 

I have seen Zep Groovy anti-seize lubricant discussed in these pages, but can't find it locally.
A high-temperature anti-seize lubricant is Permatex 81343, which may be more easily available.

 

I have share my experience and honestly great success on this subject quite a many times. It Works.

Sooner or later all Gen1, as I very enthusiastically own, are going to have to accept that Toyota no longer manufactures these parts. When somebody finds a new one, it is only because there still is a dwindling backstock that is nearly gone.
It is inevitable that gen2 or aftermarket parts are going g to have to be used and adapted to the Gen1.
Maybe, by grace, somebody will actually manufacture an aftermarket Gen1 cat system, but none do at this time.

Adapting Gen2 aftermarket cats without getting p1436 and p1437 codes is very do-able, and not at all expensive.

Install an OEM or aftermarket Cat section.

Get a Honda GL1500 motorcycle cruise control vacuum pot.

Install the vacuum pot under the hood to the vacuum line that went to the OEM HCAC unit on the Gen1 cat system.

With some simple modification of the vacuum pot bracket it can be mounted very professional looking on the upright plastic panel of the engine coolant tank.

Sometimes, and it is common, that gen2 aftermarket cats send too much exhaust flow past the O2 sensor position, and that can set off Bank 1 Sensor 2 codes.
A simple straight O2 sensor spacer solved that issue permanently on my '03 Gen1.

Since some people criticized that I was tricking a high emissions problem using the spacer.
I had a scientist friend who had a particulates measurement device do a sniffer test of my exhaust per required CARB procedures, and low and behold I was putting out emissions that were well below CARB required standards.

I recommend doing away with that Toyota engineers bad idea for a solution HCAC unit, and go with this much simpler and less likely to develope problems solution that I am using.

Toyota eliminated the HCAC unit, when the Gen2 was released, for some obviously good reasons.