I feel scummy for making my first post a question, but it seems I can't avoid it. I've been hunting around for info regarding the thermostat housing on my 3VZ, and it all seems to pertain specifically to replacements/known issues/etc. - which makes perfect sense.

My question: Is the t-stat housing a known problem point on the 3VZ?

I just bought the truck (92 xtra cab, 4x4, 5spd, 3.0) and am tearing into it to give it some much needed love. Among those points is replacing the thermostat. Obviously prime time to replace the housing as well. I'm not leaking coolant, overheating, anything of the sort that I can tell. I know some engines (VW VR6) have notoriously garbage thermostat housings, and the advice is generally "if you're doing work anywhere near it, replace it before it breaks." Want to know if I should pick up a thermostat housing while I'm ordering everything else.

Work the truck needs: Power steering pump, rear main seal, clutch, valve cover gaskets, oxygen sensor.

Work that's uncertain/close enough/looking like it will need attention in the near future, so I'm doing it now: New radiator, timing belt/idler/tensioner, throwout bearing, camshaft plugs/seals, new wires and plugs, PCV, front crank seal, water pump, thermostat, distributor cap/rotor, fuel filter, air filter, accessory belts. Obviously also checking everything else I can along the way and fixing/replacing as necessary. (Is there an easy way to just *check* valve clearance? I've read a few threads on adjusting, and screw that..)

If you've got any advice for other things I should look at/consider/just do it while I'm torn down this far, I'd appreciate the input!

Answer to the first question, no. No reason to replace it whatsoever.

Valve clearance question, it's as easy as it gets as is. And yes, you must adjust if necessary. If not you might as well do no other work on it. It's as important as anything else.

Thanks for the reply!

I'll definitely adjust, if it's needed. Just hoping it's a bit easier to check than tearing everything apart to the full extent of adjusting.

If ya got the valve covers off, you are there.

At worst, the purchase of a 30 or 40 dollar tool (if you're not into improvisation),
and a few pucks.

Found this thread upon further hunting: https://www.yotatech.com/forums/f128...t-tech-226997/

Having not had this engine apart yet, the how-to's I've read made the valve project sound much more complicated somehow. Seeing a thread with pictures prompted me to Google some pictures of the 3VZ-E - and suddenly the valve job looks like any valve job I've ever done. Not sure why it was described as being so daunting, maybe I'll figure it out when I get in there.

I don't know why either. Because that part in and of itself isn't very difficult at all. Especially if you done it on another engine with shims for adjustment I'd imagine. The thing that freaks most people out is removing the plenum. Or rather reinstalling it and getting all the various lines/hoses plugged back in where they're supposed to be.

There's really only one thing about this engine that's a total PITA regardless of how you do it, or even how many times you've done it. That's dealing with the exhaust crossover. Best way is to install a 3" body lift first. Other than that, it's a complete nightmare.

My first bike used shims for the valves, and had the valve cover trapped between the cam gear and frame in such a way it was nearly impossible to get apart without gouging the rim of the aluminum valve cover by dragging it across the steel cam gear. I feel like a complete PITA design must be a prerequisite to using a shim-under-bucket design on the valves haha.

I'll already be in well past the vacuum lines, so definitely time to go at the valves. And I'm no longer limited to one vehicle, so ordering new shims doesn't mean tearing it down, figure out what I need, reassemble it to get to the dealership and order them, then tear it back down to replace them when they come in

Thanks for your input.