12HT serial number (1 Viewer)

[cruiserpilot]

I‘d just ask someone but it I had no idea these engines have a serial number. So
where is it located? Does it have build dates then when I do find it?

 

[OGBeno]

If it is a factory installed 12H-T, it will have a serial number and a date code stamped into the block.

The serial number will be on the left hand side of the cylinder block back by the #6 cylinder wall down low (near oil pan).

 

[cruiserpilot]

Thank you. A friend just messaged me. Wish I’d known that when I had the turbo out. Think it’s
possible to see it with everything installed? Will the serial number have pertinent info about year
of manufacture?

 

[relaxedcruiser]

Hi Cruiserpilot,
the engine number is easy visible - but since I build a 3 inch knee behind the turbo I don't have that heatshield anymore. (seems to be very fine) Shouldn't be in the way anyway by the looks.
Unfortunately there is not much information at all about the engine number. I searched a while ago and it seems to be a big mystery.
The pic shows the rear end of the lifter cover.
Would love to know which year my engine is as its not the original one. I still can't understand why the po painted the block red instead of the lovely blue.....
Hope that helps - and let me know if you can find further information.

 

[seapotato]

There's also a number stamped into the flange for the oil pan, only visible with the pan off. Near the back I think. Mine was 222. Indicates which of the three "standard" sized bearings are in it.

Mine had a matching 2 on the bearings. Wasn't particularly useful info to me. I just ordered bearings that were the same as what I had as a standard set. The varying sizes are a toyota only thing.

Biggest thing is the change that happened in 87 or so, before that the mains and beb's are the same as a 2h, after that the beb's have no oil hole, and the tab is on the opposite side.

Mine is an 89, so I went through a fair bit of this while trying to get a parts seller to grasp that the 2H bearings wouldn't fit.

 

[OGBeno]

Hi Cruiserpilot,
the engine number is easy visible - but since I build a 3 inch knee behind the turbo I don't have that heatshield anymore. (seems to be very fine) Shouldn't be in the way anyway by the looks.
Unfortunately there is not much information at all about the engine number. I searched a while ago and it seems to be a big mystery.
The pic shows the rear end of the lifter cover.
Would love to know which year my engine is as its not the original one. I still can't understand why the po painted the block red instead of the lovely blue.....
Hope that helps - and let me know if you can find further information.

View attachment 2871833

It’s just a serial number of its position on the manufacturing line. Nothing mysterious about it.

 

[cruiserpilot]

What @seapotato said helps. Thanks. I’ll have to call you in the spring when I get my engine
rebuild parts list finalized. It’s in the details, and when I take the engine out to redo it I don’t want
to be scrambling. I’ve got a seep at rear of oil pan so I might find that number sooner than I needed.
@OGBeno thanks, but my hopes of knowing what year of engine I have will have to wait until I see that bearing indicator stamp. Was hoping it would tell, c’est la vie.
Its a donor engine of unknown year.

 

[OGBeno]

What @seapotato said helps. Thanks. I’ll have to call you in the spring when I get my engine
rebuild parts list finalized. It’s in the details, and when I take the engine out to redo it I don’t want
to be scrambling. I’ve got a seep at rear of oil pan so I might find that number sooner than I needed.
@OGBeno thanks, but my hopes of knowing what year of engine I have will have to wait until I see that bearing indicator stamp. Was hoping it would tell, c’est la vie.
Its a donor engine of unknown year.

It's cast into the block. It's a numerical code system.

1st digit will be the year (in the below example, 8= 2018)
next 2 digits will be the month (05= May)
Last 2 digits will be the day (12= 12th day of May... in 2018 that was a Saturday)

The casting dates will be, generally speaking, within 1-2 weeks of the engine assembly itself. The 1HZ below was actually assembled on 5/21/2018 while the castings were done about 10 days earlier.

Looks like this:

 

[FJBen]

The only mention I find of engine serial number is on my original delivery card from the dealer. It shows the engine number and the VIN for the vehicle. Not sure if they do that anymore.

 

[OGBeno]

The only mention I find of engine serial number is on my original delivery card from the dealer. It shows the engine number and the VIN for the vehicle. Not sure if they do that anymore.

It's done internally now.

 

[seapotato]

What @seapotato said helps. Thanks. I’ll have to call you in the spring when I get my engine
rebuild parts list finalized. It’s in the details, and when I take the engine out to redo it I don’t want
to be scrambling. I’ve got a seep at rear of oil pan so I might find that number sooner than I needed.
@OGBeno thanks, but my hopes of knowing what year of engine I have will have to wait until I see that bearing indicator stamp. Was hoping it would tell, c’est la vie.
Its a donor engine of unknown year.

Pop a big end cap off and you'll know right away. It's a pretty drastic obvious difference between the two eras.


After that it gets down to sizing if you have machining done etc.

I took a billion pics when I had mine apart, I can share the album with you if you want so you can eyeball the bits and pieces.

 

[cruiserpilot]

It's cast into the block. It's a numerical code system.

1st digit will be the year (in the below example, 8= 2018)
next 2 digits will be the month (05= May)
Last 2 digits will be the day (12= 12th day of May... in 2018 that was a Saturday)

The casting dates will be, generally speaking, within 1-2 weeks of the engine assembly itself. The 1HZ below was actually assembled on 5/21/2018 while the castings were done about 10 days earlier.

So this casting is separate from the serial number? I’ll look for both now.

 

[OGBeno]

So this casting is separate from the serial number? I’ll look for both now.

Yes. I stated as such above.

 

[REDREEFER]

Good info guys, thanks. I’m just getting into doing a rebuild on my 2nd 12HT and have always been curious of the date code As I know that the serial numbers and stampings on the oil pan mating surface do not apply to the date so based off your info @OGBeno I think these numbers cast into the block might be what we’re looking for?
problem is they are not grouped together like the HZ. One is 8.6.27 and the other is 7.8.22. Wasn’t able to find any other #’s
thoughts on that?
the 68030 number is the same on both.

 

[Ophir]

Pop a big end cap off and you'll know right away. It's a pretty drastic obvious difference between the two eras.


After that it gets down to sizing if you have machining done etc.

I took a billion pics when I had mine apart, I can share the album with you if you want so you can eyeball the bits and pieces.

@seapotato I would love to see your album as well --- my 12h-t rebuild is coming.

 

[seapotato]

@seapotato I would love to see your album as well --- my 12h-t rebuild is coming.

Sure. It's a Google photos thing, so you might have to pm me with an email address.

I probably posted most of them in my thread.
Kinda long and meandering, but the 12ht stuff starts around page 10.
Hopefully you find something useful amongst the bs

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