2006 4Runner 2UZ, 297K Miles. Should I replace head gaskets?

[TRD48176]

Hello everyone, this is my first post and I'm looking for you thoughts
Recently purchased '06 4Runner with 2UZ and 297K miles. E/G and Trans work fine, A/C is cold. I've pulled the engine to detail the engine compartment and replace the timing belt. But was curious if anyone had any thoughts on replacing the head gaskets? Years ago when I worked in Toyota Dealerships, the head gasket was a maintenance item at about 90K ~ 100K miles on Camry's and Corolla's. But the maintenance schedule for my Runner stops at 120K miles for service with no indication for Head Gasket R&R. I know, if it ain't broke don't fix it.
Any thoughts? Thanks

 

[Rspring]

Interesting! At 297k and 14 years of life in Michigan, I would have thought there would be much more pressing issues. My two cents: While it is out, look hard for any signs of bad HGs like external coolant or exhaust leaks from the block / head intersection. Look for inside-out rust in the exhaust. Then conduct a cylinder pressure and leakdown test. If no issues, leave them alone.
After that:
- Pull the valve covers and re-torque the heads.
- While doing the timing belt, inspect the cam seals.
- replace all cam seals as necessary
- replace cam timing sensors
- replace o2 sensors.
- clean the intake and MAF
- REPLACE rear main seal
- Inspect radiator and replace at a hint of damage or degradation
- replace upper and lower radiator hoses
- replace spark plugs and coil packs
- inspect and replace oil pan gasket if necessary
- use highest quality synthetic lubricants in everything as you put it back together. Stick with Toyota coolant and filters (or Wix filters).
With the engine out, you have room to look at other wear items like the inner axle boots, with just a bit better access. Inspect and replace as necessary. If you want to change springs and struts, and/or UCAs, they are a little easier now too.

Now look at the transmission. Definitely service it while it is so easy to drop and get all the fluid changed. Input seal ok?

Drive it another 300K miles, but if you are doing it in Michigan, anticipate corrosion will be a bigger threat than anything in the long block of your 2UZ.

 

[TRD48176]

Thanks for the feedback. Yes, I would agree, 14 years of Michigan winters, I was expecting much worse. The vehicle was purchased in S.E. MI and serviced for the majority of its life at the local dealer. The frame has typical surface rust but no perforation. Front upper and lower control arms are out already. P/S rack will be removed, inspected and or rebuilt or replaced. Front CV shafts will be inspected and addressed accordingly.
I’ve not removed the Exh. Manifolds yet, There is a slight exhaust leak, and I’ve read online the Catalyst hanging off the end of the manifold is not the best design and prone to cracking.
All of your suggestion sound good and I’ll be sure to check all of the items you mentioned.
Other than some minor sheet metal corrosion, the Runner is in good shape. I plan to get it cleaned up, install a TRD Pro suspension, and some other bits and pieces, and travel to Ouray, CO next July, and OEX West in Flagstaff.
Thanks again for your suggestions.
Bob

 

[MountaineerLC]

The 2UZ is pretty much bomb proof as long as you change the oil and take care of the timing belt and cooling system. Lots of high mileage Cruisers over in the 100 forum and no one is messing with head gaskets. In fact, I don't know that I've read of a HG failure on a 2UZ that wasn't overheated.

 

[daddywagon]

Hmm engine pulled + leaky ex manifolds means it’s the opportune time Doug Thorley headers.

 

[Cruiser Vic]

I would recommend transmission front pump seal. It's the seal that the torque converter sits in.

 

[thatcabledude]

No