[4rnner4life]

2002, 150k, bought in Feb. It's had a HC in coolant issue since I bought it, slight burning of coolant, no coolant in oil, very manageable until just recently. It has overheated twice when left running in park, but no noticeable changes after overheating, and that was months ago. After sitting for 2 weeks it started up and was billowing white smoke so i tore into it and found a cracked head, and what looks like loose foreign body damage to the top of piston #4 and some scratches along the cylinder.

the coolant passages behind the water pump are pretty rusty and the block has some exterior rust. I'm going to pull the rest of the engine and swap in a spare from a 2000 and tear apart the rest of the 2002, see how much trouble I can get myself into.

can a machine shop fix a piston with scratches that deep? seems doubtful. the cylinders will need work too, maybe more than a honing, how much can they take off? i've never cracked an engine open before and was not prepared for this level of damage. I had a plan for a cracked head, but these scratches threw me for a loop.

Any suggestions? I'm planing on completing the swap to get it running, then taking my time with the 2002 engine to make sure it's worth fixing.

I have the FSM for the 2000, and it's pretty close to the 2002, at least as far as the engine goes. theres a few minor differences with the accessories that can be swapped over.

thanks guys, I'd never have the stones to do this without a group like this available!

[nissanh]

With all the issue you got, why not get a low mile engine from a yard? This route will be much cheaper and reliable.

[WallyWest]

Bah, youtube links no work, joke failed.

I agree with nissanh, unless you just really want to rebuild that engine for fun.

[4rnner4life]

yeah, i live in fairbanks ak, so theres not as many engine options, and shipping is generally ignorant. so im exploring my options

[Toyotayoda]

Tearing into an engine is really easy, mark your parts as you remove them making note of placement, it will be down to bare block before you know it. The trick is all that measuring that requires precision tools, and knowing what cause failures, and what failures have done to other parts. Those marks look like something once got into the cylinder, maybe during a tune up, or a valve cover gasket job. One very obvious side affect of overheating is warped cylinder heads, but not so common knowledge is that the piston also swell and can scratch the cylinder walls or even seize midway in the cylinder. The cylinder can also warp, in very extreme cases I've seen blocks warp. Machine shop charges aren't terrible, a few hundred bucks to get the block decked, and cylinders honed, or perhaps bored out, and of course they will clean it up and it will look brand new. Some people just throw a used engine in, but wheres the leaning there, and what are the chances you put in that used motor only to find it's bad. Tear yours down, learn whats bad, if you do get a used unit I suggest pulling the oil pan and replacing the main and rod bearings, they aren't expensive.

[nissanh]

If you plan to rebuild the engine, stay with OEM parts. No aftermarket part can come close to the toyota quality.

[LiquidFlame]

New pistons can be had around $100 each, and Ive seen them oversized as much as .040" if need be. The head could potentially be welded and machined back down, depending on the level of damage.
Im all for tearing apart an engine and rebuilding, but with the level of repairs needed and the cost of our engines, it sounds like it would be cheaper to just swap in a low mileage donor as others have suggested.
Just my .02, good luck either way!

[St Runner]

Looks like that head middle cylinder is also cracked in between the exhaust and intake valves. I would strip off anything of value and toss the rest. The overheating worries me the most about the longevity. An excellent learning tool though!

[alumarine]

What do the cylinder walls look like where the bad piston is?

[69project]

[QUOTE=4rnner4life;2743795]yeah, i live in fairbanks ak, so theres not as many engine options, and shipping is generally ignorant. so im exploring my options[/QUOTE

I would strip the block down, take off all the accessories, bolts etc you need to reuse and then take it and the heads into the machine shop. They will be able to figure out if what you have is reusable. If it is, I would highly consider letting the machine shop do the machine work and re-assemble it for you and give you back a complete long block. Unless you have the special tools of a dial indicator, torques wrenches, ring compressor, etc and a good assembly manual I would let someone who does this part for a living do it. You will have your hands full with the remove and re-install piece of it.

They can give you a fairly decent ball park figure of what you are looking at prior to doing it. To have it all rebuilt is going to be a couple of grand including parts, maybe more since it is Toyota parts and you are in Alaska...

[19963.4lsr5]

When I had the 4.2 for the CJ7 rebuilt the guy only wanted another 300 to assemble it. For 1500 out the door heck yea, I told him go ahead.


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[4rnner4life]

i can feel minor scratches along the #4 cylinder wall, mostly on the lower side where the debris settled.

pulled the other head, when i get my camera i'll put up pics. theres bits of thin Al cracked off the web left over from casting.

on a positive note, pulling the heads before pulling the engine made it super easy to remove exhaust crossover pipe and then access the upper trans to engine bolts

so it seems like both heads are probably bad and everything else is suspect.

I'll take the bad engine into a machine shop to get it checked to see what's salvageable and swap my spare engine in. It would be wonderful if they reassembled it for a reasonable price as well

I have learned more than I ever imagined, most importantly I have learned that I'll probably need reconstructive surgery to get strength and range of motion back in my pointer finger, so frustrating

[thegipper]

Investing a hundred bucks in a Ultra gauge or scan gauge so you can accurately monitor coolant temps is a good lesson to be learned here, especially for those new to this forum. If money is tight, you can even get one of those cheap bluetooth obd2 readers with the torque app to monitor it.

These engines are super sensitive to being overheated. The temp gauge on the dash is essentially worthless.

After reading so many of these stories, I bought an Ultra gauge and set an alarm for the coolant temp (alarm goes off at 215deg).

Hopefully others take this advice, good luck with your rebuild and keep us posted.

[gamefreakgc]

Originally Posted by thegipper

Investing a hundred bucks in a Ultra gauge or scan gauge so you can accurately monitor coolant temps is a good lesson to be learned here, especially for those new to this forum. If money is tight, you can even get one of those cheap bluetooth obd2 readers with the torque app to monitor it.

These engines are super sensitive to being overheated. The temp gauge on the dash is essentially worthless.

After reading so many of these stories, I bought an Ultra gauge and set an alarm for the coolant temp (alarm goes off at 215deg).

Hopefully others take this advice, good luck with your rebuild and keep us posted.

Hoorah for cheap bluetooth readers! $30 and I can see it all. I hit 205 degrees with A/C on in wonderful 110 degree heat, I'm pretty happy with that.

[4rnner4life]

Frustrating thing is I have a scan gauge. I left the truck running for a quick visit when it was -20F outside and ended up staying for 20 minutes. No problem right, except I didn't have the heat on. I'm fairly certain the engine was already toast when when I bought it. Learning all the lessons.