How common? - 3rz cylinder head cracks between exhaust valves & spark plugs

Hi all. Just looking for some input on the head for my 3rz valve job project that's turning into more than I anticipated (not surprising!).

On my original head, the machine shop alerted me to a crack between the cylinder 3 exhaust valve & spark plug (where my valve tightened up, requiring a valve job). The machine shop recommended a new head or a used head that can be rebuilt ("cracks never get smaller, only bigger"). The local Toyota salvage yard has heads they certify as rebuild-able (i.e. if they are warped or cracked, bring it back for another) so I went there and swapped my head for a used one. Unfortunately, the first two I got had cracks similar or worse than mine (found out after I take them home & do some cleaning). Is there a decent chance that I'll ever find a rebuildable head at the salvage yard, or do almost all 3rz heads crack between the exhaust valves & spark plug threads? My other option is to just buy an aftermarket head (new OEM is a bit too pricey).

Thanks!

 

its pretty difficult to crack an aluminum head on account of aluminum being so soft and flexible. im kinda surprised you found so many in a row. honestly though, you should change the yard you're trying to get them from. keep trying to find a good head or buy one off ebay where they will refund you fully if there's something wrong with the head.

 

From what I understand, it's relatively common. I blew a head gasket @ 185k and tore the truck down do discover I cracked the head across the valves on multiple cylinders. I went ahead and replaced the motor with a JDM motor.

 

Thanks both for your insight. I'll keep going back to the salvage yard until I find a good one or they get fed up with me and offer a refund. I'm assuming a head with even the slightest crack should be avoided? For reference, the crack in my original head (from a single exhaust valve to the spark plug threads) was only visible after it was completely cleaned and with a bright light shown on it. (ie no nearly the severity as shown in OLIVER2010 pic).

 

right, no cracks at all whatsoever!

 

Well good news...exchanged the head for another one Friday and it checks out so far...was a good start to the weekend.

 

How did that jdm engine work out? I am in the same boat as you with almost exactly the same mileage @ 179,000 and the engine is pushing all the coolant out of the overflow bottle and it's leaking into the combustion chamber as well. I have to add About 2 liters every 60 miles. The jdm engines seem a lot different than my 8 port 3rz. Different cool packs, power steering pump and oil dip sticks seem to be in different locations. And an extra steel line wrapped around the front of the valve cover that my engine doesn't have. Is your jdm engine strong?

 

My JDM motor has been good to me thus far. I’ve only put a couple thousand miles on it though. I’m not sure about the coil pack situation as my motor had the distributor in the head. I believe the pipe you’re refering to is just a coolant line. On stuff like that i removed the JDM stuff and just reused my own.

Here are some of the differences I ran into:

1. Oil pan was different, it had a sensor in It as well as being a 2wd pan (pick up tube & pan will need to be swapped if
4wd).

2. Power steering pump was some kind of weird sealed system. Just unbolt the pump and reuse your old one.

3. The harmonic balancer is different. You will need a longer A/C belt.

4. Motor mounts, you will need new ones or resuse your old ones.

5. Dip stick tube, the block should be predrilled from the factory with an aluminum “plug” rtved in. Take off the oil pan and drive the plug from the inside out. Reuse the plug & rtv where the tube was.

6. Some of the coolant piping is different, i just used my old stuff.

7. There is a sensor in the intake manifold (air temp..? Idk) that will not be used if keeping U.S. harness & ECU (like me)

8. EGR plug will not be used (if using U.S. & U.S. ECU), JDM Motors don’t have EGR

9. Exhaust manifold was different, i believe it was because it was a 2wd motor. It was taller than the 4wd manifold.

10. Vacuum lines aren’t exactly routed the same between the U.S. & JDM. Best thing to do is take a bunch of pics and number the lines and where they went and try to reroute them to the JDM motor. If i remember correctly some lines won’t have a home.

11. ECU & harness are different, U.S. ECU is 3 port and JDM is 4 port.

That is everything i recall that was different. There might’ve been some other petty stuff. All in all it wasn’t a bad swap. My JDM motor ended up having a bummed injector from the beginning so i just reused one old one. I didn’t use the JDM ecu or harness because i didn’t feel like running all that wiring and also some of the plugs were damaged during shipping. Let me know if you have anymore questions.

 

I think my 2000 has the cracks too. I was loosing coolant and getting random misfire codes. The previous owner had spent a lot of money changing plugs, wires, coils, knock sensors, rad. Nothing worked. I put a $6 bottle of rad stop leak liquid glass in there and it is fixed now. Runs perfectly and no codes or coolant loss. With 200,000+ miles I'm not spending money for new heads.

 

my 2000 3.4L also develop a crack on cylinder 3. Replaced with a JDM motor.