Determining 18 or 20mm dowel pin size on a 2006 6.0L???

asburyslim · May 24, 2012

I have a 2006 6.0L with 183K on the clock. I bought it with 180K and have already had the typical massive head / gasket / fuel in coolant failure that we all have nightmares about.

I have a truck at a local diesel mechanic's shop right now (so I can't go look at it myself) and I'm trying to order parts. I'm doing the bulletproof EGR and oil coolers, power steering cooler relocation kit, ARP head studs, and new or reconditioned heads depending on whether I can find a machine shop locally that can do hardened valve seats for me.

My problem right now is that I can't figure out whether this truck has the 18mm or the 20mm head dowel pin size to order the correct head gasket kit, etc. The truck is a 2006 model year with an assembly date on the door jam of 12/2005. I have the casting numbers off of the heads, but I don't have the engine serial number. This seems to be right in the cutoff timing for when they "commonized" these engines.

Does anyone have a trick that I can use with any of the above information to determine the correct parts to order?

colo_dually · May 24, 2012

Howdy, and welcome to the ORG.

The switch to the 20mm dowels was late Jan '06, worse case have the shop measure them for you. Most Ford joints will have both on hand, maybe a quick overnight delay. I'll wager you have the 18mm dowels.

asburyslim · May 24, 2012

Thanks for the reply. I've got the truck with a mechanic that doesn't usually do any sort of aftermarket parts in his repairs so he told me to order the parts I wanted. I was considering aftermarket head gaskets but the word on the street about black onyx isn't good so I'm just going to let the mechanic go with stock gaskets and figure out the right part himself I guess. The heads aren't even off yet so I don't know exactly what I'm dealing with.

Again, thanks for the help.

a2elvis · May 24, 2012

If it's an 05 build date then it will most likely be 18mm. Use Ford OE head gaskets you wont be sorry. Just make sure the head work is done or built by a reputable machine shop.

You may want to contact John@ Domestic Diesel in Chino I think he has a good machine shop that he uses for the 6.0L head work.

Onefaststang · May 25, 2012

The oem ford gaskets come with both size dowel pins.

m-chan68 · May 28, 2012

If your truck has a "yellow circle" type dipstick, along with four "UFO shaped" nuts that secure the FICM to the FICM bracket, you have a late-build 2006 engine which uses 20mm engine block dowels which mandates Ford gasket part number 6C3Z-6051-AA.

If your truck has a black "TEE handle" type dipstick, along with an upper metal bracket that secures the FICM and air intake to the lower front FICM bracket, as well as another upper bracket at the back side of the engine, chances are you have an engine that uses 18mm dowels in the block that requires the more expensive 4C3Z-6051-EB part number.

skuzzitude · Aug 28, 2012

Commonized engines started on January 11, 2006 with a serial number of 6,723,722 and above. Any truck with a build date of 2005 makes it IMPOSSIBLE to be commonized since engiens weren't build then. See my signature... engine was built 2 days before truck assembly...... mine is a commonized (just barely)

Tommyboy7777 · May 21, 2013

My trucks build date is january 10 2006,so am I 18mm or 20 mm dowels?

jtaylor75 · May 22, 2013

FWIW i have an 06 Truck that had the yellow oil dipstick and UFO shaped FICM bolts. So I figured I would buy the 20mm head gaskets. Long story short, I had 18mm block and heads. I bought the truck used so i dont know the complete history. Maybe someone put a long block in it a while ago.

mustangmike6996 · May 28, 2013

the cheapest im finding the 18mm gaskets are 135 a side with head bolts and stand pipe. I already have studs, are there any places priced cheaper? Is there a resale market for just head bolts?

fgpantaleo1 · Apr 7, 2024

You can buy just the OEM head gaskets without the head bolts and I’ve use Scotty‘S racing for the machine work on the heads ln Springhill, Florida, on old Shady Hill Road

Determining 18 or 20mm dowel pin size on a 2006 6.0L???

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