Head bolt washer diameter

[scottryana]

Since head gaskets fail on the 1FZ daily, there must be about 10 of them being worked on right now. Would any of you be able to accurately measure the OEM head bolt washer diameter?

Thanks!
Ryan Scott

 

[aae42]

mine will be opened up tomorrow, i can see if i can bother the mech to check

 

[scottryana]

That would be great if no one else has theirs pulled apart! I am going to guess they are around 22mm, I was just looking at the ARP stuff and their washer is 19mm, looks like the Supra community is having issues with the ARP washers digging into the head and causing head gasket problems.

Supra Head pics

Stock washer

ARP washer

Head issue

 

[mtnzorro]

my head and all the washers are up at the machine shop, which i'll be dropping by tomorrow; so i can check as well (if no one gets this answered sooner). i've also already ordered the supra arp stud kit, making this is all very timely.

i'm a 1 banana mechanic, so forgive my ignorance, but assuming the supra kit washers are smaller, would the "fix" to this be to simply use the OEM washers?

 

[scottryana]

Mtnzorro,

Yes that is exactly what the Supra guys are doing. They are using their stock washers. Both are the same thickness. At some point in late 2014 people think that ARP changed their washer diameters, some people that have bought Supra kits have the larger washers and some don't so you might not have anything to worry about. I just wanted to check it out.

 

[mtnzorro]

Thanks. Good to know!

 

[mtnzorro]

23.5 mm for the oem washer. I'll get a measurement on the supra ARP kit one once mine arrives.

 

[scottryana]

Great thanks! So ours are even a little bigger than the Supra washers which are 22.15mm. So if people have the kits with the old ARP Supra washers I would suggest not using them for sure.

 

[Rwhat]

I just installed mine. The diameter was about the same. However the thickness was different. IIRC

 

[bryson]

Sounds like you have your answer, but here is what I figured out when I did studs last year:

https://forum.ih8mud.com/threads/arp-head-stud-kit-for-the-1fz-fe.798885/

I am basically running a Supra kit with larger diameter washers - 7/8"/22.225mm - in my 1FZ. No forced induction or other goodies, but so far so good.

 

[inkpot]

I get 3.01 mm thick

 

[blkprj80]

Stock measured at 23.5mm as above.
Opel washer was 20.6 OD.
Both are 3mm thick, with stock maybe a hair thicker like 3.02mm

I used the Opel washers. I hope they hold up.

 

[scottryana]

On a stock engine I am sure you will probably be fine. Just looking at things that happen with boost. And not so much power but cylinder pressure. The 1FZ has a lot more piston area so the PSI in the cylinder needed to create a lot of load on those washers isn't all that high.

For anyone going forward in the future I would use the larger stock washers.