Hi everyone. What do you think of this? Do top end only or what? Read on.

I got a 2000 stock 4Runner w/ V6 3.4 liter 5VZ-FE engine and auto tranny, all with 225k miles. Actually the engine is a pick n pull replacement due to major problems 100k miles ago, and at that time I replaced water pump, oil pump and every seal possible at the time without taking apart engine except we did take off oil pan for pump and all seals there. And now the head leaked exteriorly just last month at the head gasket. So I fixed it with coolant trick, but I know that's only temporary fix. So thinkin' of rebuilding just top end, head work, valves, all gaskets on top, etc., not go into bottom end. Runs great with acceptable range compression. Can't afford to buy any replacement 4runner right now. We'll probly keep this another 100k miles. Head work at machine shop will cost me about $600 base price, and head gasket complete set probly about $150 or so. I'll do all the grease monkey work.

So do you agree with my plans? I don't "think" I can afford a bottom end total work. And the tranny will just have to last till I need a pick n pull for it, like I say it's running fine for now but I don't trust the existing head gasket. Any knowledgeable comments appreciated. Thanks.

Dave

 

How often do you change the oil, and does it need any added in that interval? It's hard to tell about the oil pressure, but ever get any oil light on at idle when the engine is hot? Good compression currently (presumably on the cylinders that aren't leaking) is a great sign.

Other than that, when you take the heads off, you can inspect the bores (or take the plugs out and use a borescope). I will say that my wife's '96 needed headgaskets at a bit over 300K (it had an earlier revision gasket style) and the bores looked GREAT when we got a look at them. Crosshatching over almost all the bores, just some very small shiny triangles at the top of the bore on the 'throw' side (the rod tosses the piston a bit in the direction of the crank rotation). Certainly good for another 200K miles.

Unless it's been really neglected in the past, odds are really good that you won't need to touch the bottom end at all.

 

Thanks Jomoka. Yes, it's had great care since I've had this engine, replace oil every 5k miles, no smoking, seems adequate oil pressure, zero oil consumption. Only thing is I don't know anything about the engine's care for it's first 100 k since this was a pick n pull. But it was running when it got in a wreck so assuming it's a good engine. Yes I'll be inspecting bore well when I replace heads. Thanks.

 

You can get a pretty good idea of how well it was maintained before you got it by how clean or dirty it is under the valve covers. They all get dirty with 200K+ miles, but sludgy buildup means someone stretched the oil changes a lot in the past.

But really, I'd have to figure that the odds are really low you'll really need to do anything other than do the HG's and replace every other gasket on up from there.

 

Thanks!!!

 

I haven’t split my 5VZ open, but I can speak from my experiences with my 22RE. Top end work does NOT require messing with the bottom end.

I replaced my head gasket without touching the bottom end.

I replaced the timing set without touching the bottom.

I replaced the cam without touching the bottom.

Each time I would inspect the cylinder walls to see if they still had hood crosshatching. I never ran head or block sealer through the system so I never worried about cleaning out the passageways.

The only time I pulled the bottom apart was when #2 piston decided to eat some of a ring. That scored the cylinder wall, pitted the piston crown, and fragged the valve seats. So I had it over bored and went from a 2.4L to a 2.6L and threw an LCE head with oversized stainless valves and decked the block. She was a lot more fun after that.