I have decided to complete a 3.4 swap on my 94 runner 3.0. However, until then I am going to complete a head gasket replacement on the current engine. (Only waiting on the 3.4 due to facing medical retirement and possibly going back to Oklahoma) I have read a lot on this forum the past few weeks. I know that I will/ should replace the knock sensor along with harness, plenum gasket, PCV and grommet. I am just not sure what else. I will be purchasing an entire gasket set, head bolts, timing belt and pulleys. I would like to do as much as possible while I have this thing torn apart. What are things that I should/you would replace. Also, does anyone have any lessons learned from this project? I appreciate all of the help guys. I love the 4runner I purchased, but finding this group and seeing how many guys are out there that are crazy about this rig makes it that much better.

 

Just food for thought, why throw all this time and effort into an engine you are going to replace? Unless you have to wait for the long drawn out process and the HG needs to be replaced then I get it.

Sorry no words of wisdom just curious as I argue with myself if a 3.4 swap would be enough or I should just save and do a 1UZ swap in a few years time instead.

Goodluck!

 

A 1UZ swap sounds awesome. I wouldn't need it as this will be my daily for a few years and then just my hunting/camping rig after that. It is not in dire need of replacement. I definitely need to change out the valve cover gaskets, need an oil pan gasket (hoping its that and not the main seal) and I have some tapping going on in my engine. It has 157K and I am pretty sure that it will need a timing belt soon. I am waiting for the knock sensor to go as it looks a little shady in that area from the previous owner. And for a few hundred bucks I will be able to put some new gaskets on, add some head bolts and most importantly learn the inside of my engine which I need to do prior to trusting it to do any long journeys. I am currently in VA and it will be about a 20 hr drive back home if I end up getting retired next year.

 

Inspect all the rubber (you can see 90% of it right now). The molded hoses (like those from the resonator/air cleaner to the top of the plenum) are a dealer only item, so if you're going to replace them you might want to get them in advance. The intake hose (resonator to throttle body) can easily crack, and that is available after market.

Replacing the head gasket is a big step from just the timing belt and valve cover gaskets. I'm not sure I would do that as a "maintenance" item. Remember that you don't know what you're going to find until you start taking stuff apart. You might find that what seemed to be a perfectly good bolt actually was screwed into a loose helicoil, and when the helicoil backs out with the bolt you've got an issue. Or, many people manage to break off the top of an otherwise working TVV (in the back of the engine) because they get very brittle over time. This isn't enough to say "don't do it," you just need to expect the unexpected.

I would use spray degreaser and carefully clean your entire engine. Then run it for a few minutes and look for oil leaks. Gravity is not your friend; a leak anywhere (valve cover) works its way down to the pan and the main seal. Your pan may not even be leaking!

 

You brought up some very good points. I wasn't even thinking about helicoils and what not or even the reality that I could possibly jack up an otherwise perfectly aluminum block. It is definitely making me think. In your personal opinion do you think that a timing belt kit and valve cover gasket along with plenum gasket and continue regular maintenance would be the best thing for it or for me in my situation since I plan on building a 3.4 next summer?

 

The degreaser and oil leak check is a good point. I thought my OPG was leaking horribly, checked everything...the oil filter I bought from napa kept vibrating loose apparently and the valve covers are weeping slightly but it all collevted where the oil pan meets the block and down so it looked really bad around the gasket.

I took it to Toyota and had them check it while it was in for something else, found out it was the filter. I have never had one come loose before/after that one filter. I check regularly now especially after washboard roads.

I could have pulled that entire OP off etc for no reason...learned my lesson