I have been asked to rebuild a 95 4Runner that was over heated twice in a week. The radiator blew and the driver kept driving till it stopped.

I opened up the engine and found #4 piston with a hole in it, water and oil mixed throughout the engine, piston fragments in the pan, scaring above the ring line in #4 cylinder, slight grooving on the main and rod bearings, heads are warped about 0.015".

My question is, how much can the heads be resurfaced before causing issues with head gasket sealing, piston to valve clearance, any other issues, power loss, etc. Also, how many times can the block be bored? It has 0.5mm over pistons in it already.

Going to the machine shop tomorrow to see what he says. But he has never been helpful before.

 

 

that is one of those questions hard to answer without some good measurements .and being up close and in person .

Will the heads be trued up by .025 ?? Sure they are not cracked as well.

Is the block straight or does that need work as well ??

It was the bearings that were scored not the crank ??

How did the cams make out with the coolant and oil mix??.

It might be more cost effective to just build a old tired engine instead of this one or just throw a used one in.

since it seems not well taken care of.

 

In my estimation, the heads could be trued up with 0.025,

The block is not warped.
The bearings and crank both have minor grooves in them but the plastic gage shows 0.0035 clearance which is out of spec.
The cams look good.

The engine looks to have very little miles on it since a recent rebuild. The owner got the vehicle from his boss that took it as trade from someone else. The radiator blew and in the process blew the head gaskets. The daughter continued to drive it till it stopped.

The question is not what should I do, it is, can the heads be surfaced safely and can the block be bored more than 0.020"?

 

The heads need to be checked for cracks between the valves first, All cyl's
or your wasting money.
V6 heads are notorious doing that when over heated.

 

You say the machinist has never been helpful before? Seriously find a new machine shop.

 

Spacer gasket is available in a 0.020" over. Rings and pistons .02 .03 .04. Rod bearings at 10 20 30 and 40...

 

Call time of death on that engine. I don't know if you'll be doing the rebuild on the clock or if you are a friend but I see this one coming back to you in some form or fashion. You said it yourself, it looks like it hasn't been long since it's last rebuild. You need to find out what happened to the radiator. What do you mean by "blew"? Just one scenario would be, the radiator has been bad for a year and this same type of failure happened 6 months ago leading to the previous engine rebuild. That would tell me two things. One, the previous rebuilder didn't take the time to investigate what caused the engine to crater and used that same attention to detail in his rebuild. Two, that engine already crashed once due to an overheat. With about a 30% chance that a head gasket failure causes a minor crack, two catastrophic head gasket failures probably bumps that up to about a 90% chance that there is some kind of fracture in either the head or the block this time. I don't doubt that you can make the short block work but those heads have to go and that block needs surfaced and magnafluxed to rule out a crack. Doubt the local machine shop offers that.

I'm voting long block or used engine in this repair. No question about it.