1993 Toyota 4Runner - Repairs worth it?

toyota
4runner
#1

I’ve got a 93 4Runner with the 3VZE that has 210k miles on the clock. It needs intake and exhaust valve stem seals (requires pulling heads) and valve lash adjustment. I’m capable of doing the repairs myself and have all of the special service tools available

I’m going for 300k miles because I don’t have the money for a new (or used) car right now. Is it worth doing these repairs to get me to my goal before getting rid of the truck? The motor was rebuilt at 94k miles by the previous owner.

#2

It depends on what kind of condition the rest of the truck is in, but I’d generally say go for it.

Who told you you have to pull the heads to do this? The dealer? Usually the official manual calls for pulling the heads because if you don’t the valve will fall into the cylinder while you’re working on it. However, on most cars crafty mechanics can work around this, most commonly by putting compressed air in the cylinder, which keeps the valves in place while they remove the retainer. One of the posters on this (and other) forums has a nifty trick involving nylon rope, too. Perhaps there’s something on this truck I’m unaware of that makes it so you actually do have to pull the heads, but it might be worth calling around-- you might be able to get this done much cheaper.

#3

They recommend pulling the heads because of the head gasket issues these engines have. I can do the lifter adjustment with the heads on because I don’t have to remove the cams. But removing the cams to do the seals can cause the heads to warp and put stress on the head gasket (so I’ve heard).
The truck is in great shape otherwise. No rust, but it has its share of scratches and dents.

#4

I’d do the valve check/adjustment (required) and forget about the seals. If you pull the heads, you might as well do a valve job too.

#5

Toyota had a recall which called for the installation of an improved head gasket on these motors. I’d guess depending on when the PO rebuilt the motor that you’ve got them and the improved head gaskets may not be as prone to warping, though I have a hard time imagining how removing the cam would cause this anyways.

If it were me, I’d just go ahead and do it without pulling the head and keep an eye on things afterwards. After all, the worst thing that can happen is you have to change the head gaskets, which pretty much just entails removing the heads!

#6

the po actually had the engine rebuilt by toyota because of the recall. he did not want to take any chances further down the road. I know it needs seals because it smokes really bad on cold starts (after 6+ hrs of sitting overnight) and I’ve taken a boroscope down the intake and seen oil seeping from the valve stems. I figured that I would do the valve lash because the valvetrain has gotten noisier after the last 10k miles or so

#7

not to complicate your task but how can removing the cams cause the head to warp? are the bolts that hold the cams in their saddles common with the bolts that hold the heads to the block?

Keep in mind that replacing valve stem seals may not solve your (you don’t explain if your sympton is oil comsumption or visible smoke) oil issue.

Any chance you can just live with the sympton? Is it causing the plugs to become oil fouled? or is the trail of smoke behind you excessive?

I have have had many negative consequences when doing top-end work on high mileage engines, sometimes it would have been best to just leave it alone or do a complete job,just my humble opinion

Saw your borescope observation, you may have valve guide,valve stem problems that seals wont help.

wonder why the seals let go so early and drastically? only about 110k since overhaul and now you have this problem, any idea how complete the work done at 94k was? (did it involve cylinder head recondition?)

#8

I wouldn’t do the seals without changing the head gaskets. I think removing some of the head bolts to pull the cams and then replacing them is just asking for trouble.