Milling the heads during head gasket job 1GR-FE 4.0 V6

[Warwicke36]

I just wanted to make this post to help inform anyone who has to do head gaskets that milling the heads in my case was a non issue. I read horror stories of timing issues when searching about milling heads on the 4.0 liter motors. In my case the machine shop milled the heads .008" ... the manual states not to mill the heads and instead replace them if they are warped over .0039"

From the manual
"Maximum warpage: 0.10 mm (0.0039 in.)
If warpage is greater than maximum, replace the cylinder head."

So when the machine shop said they machined them .008" I was worried. I DID replace the timing chains with new OEM ones to combat any compounding issues with chain stretch and milled heads. My guides looked great and I think the chains were totally fine but I didn't want to risk it.

I hope this post helps anyone who is thinking about or in the middle of this process. Because when I googled milling heads 1GR-FE all I got was gloom and doom with no resolution.

 

[triethylborane]

I just wanted to make this post to help inform anyone who has to do head gaskets that milling the heads in my case was a non issue. I read horror stories of timing issues when searching about milling heads on the 4.0 liter motors. In my case the machine shop milled the heads .008" ... the manual states not to mill the heads and instead replace them if they are warped over .0039"

From the manual
"Maximum warpage: 0.10 mm (0.0039 in.)
If warpage is greater than maximum, replace the cylinder head."

So when the machine shop said they machined them .008" I was worried. I DID replace the timing chains with new OEM ones to combat any compounding issues with chain stretch and milled heads. My guides looked great and I think the chains were totally fine but I didn't want to risk it.

I hope this post helps anyone who is thinking about or in the middle of this process. Because when I googled milling heads 1GR-FE all I got was gloom and doom with no resolution.

Machining the heads should not present an issue if it is only taken down to the stated tolerance in the manual, even though Toyota is couching it as a warpage (then replace). The timing chain is something to check and determine if stretch is present, this is can be an issue on simplex timing chains, but Toyota probably went with a simplex chain for rotating mass reduction and dimensional reasons. The tensioners and guides are more critical IMHO as they are the main points where the chain can "lengthen" and cause a problem.

Interesting post, Im looking at overhauling my 1GR for a project, so appreciate the notes.

 

[MikeinNH67]

I'm curious as to how many miles you have on your engine. Thanks.

 

[Warwicke36]

I'm curious as to how many miles you have on your engine. Thanks.

203k now.... I'd estimate 195k at beginning of failure, but that's a guess. I bought this thing on a whim at 191k... It cost me a song, but I fell in love. Wouldn't be surprised at all if it had failed prior to purchase. The leak was so small even when I did the replacement, its possible it way this way for a while.

 

[importman]

Mine were milled .004 when I did my head gaskets. So far no problems to report.