Known problems with 3.4l?

[Hardizzy]

You can check for the Strawberry Milkshake by disconnecting the transmission cooler line on the bottom of the radiator (there are two, use the low pressure one on the driver side), have an assistant start the vehicle and take a sample. These engines are also known to leak oil from the valve covers; an involved job, but not impossible. Also, go with DENSO plugs with two prongs/double platinum (something about the way the spark is delivered or something like that, I forget why). Other than that; they are powerful, easy to fix, parts are plentiful and reasonably priced

A much easier way to tell if you've got the milkshake is to remove the radiator cap and shine a light. Another tell-tale is to feel the radiator hose. The transmission oil once mixed with the coolant softens the hose. Yet another easy way is to simply look in the coolant overfill.

I live in the Northeast, so the leaky valve covers have the added benefit of rust proofing. Couldn't care less about those gaskets.

 

[Bad Luck]

Or check the fluid on the transmission dipstick

 

[ZIPF1]

Let's revive this thread a few years later and another 100k miles. Any new longterm trouble with 3.4 besides routine maint items? I know there was at one time a head gasket recall on early third gens. Any other year engines suffer rod failure or only 2000 model year? Highest mileage I've seen is 377,000. Any insight on carbon buildup on heads or valves needing adjustment.

I would love to hear from those who have the 90 series Prado. I am about to purchase one 3400 V6 GX with 280000km. I’ll share pics when I can figure out how to do this

 

[Flinch]

Great engine, pretty bulletproof and legendary. Stay on top of coolant changes, some say a new radiator/lines every 150-200K, timing belt/water pump/tensioners every 90-100K. Valve cover gaskets leak but that happens in any engine and the replacement is worth it. I Seafoam the fuel every oil change and switched my 2002 LTD to high-mileage full synthetic. Not a single leak. Just replaced the fan belts and the new ones still squeak, makes me see red every time I start her, but if that's my only problem in a 14 y/o car then I'm golden. Good luck, take your time and find the right T4R for you.

My water pump made it to about the 200k mile mark before developing the slightest seal problem forcing me to top off every 3 weeks until I could get i replaced - I was impressed. I am steadfast on annual coolant changeouts, and when I do that I ONLY use distilled water for mixing antifreeze [using Toyota spec].