REBUILT 12ht break in procedure? (1 Viewer)

[Trubo Dislel]

The more I learn and research the more I realize how much I don't know.
Anyone have experience in breaking in a rebuilt 12HT? Apparently its more complicated than I thought and I could not find any info in the manual or online for 12HT
Brand new injectors, rings, pistons, bearings, reground crank, new camshaft & lifters and recoed head. Cylinders are ok needs new crosshatch for new rings
Then I learnt that flat tappet engines are the worse to break in. I've done my fair share of research and YT videos on this flat tappet configuration.
I know that the lobes needs taper, lifters needs crown, valve springs needs a lighten, needs special breaking in oil, RPM to 2K for like half an hour.
Well the problem is all these info I've got are for v8 petrol chevy blokes on Youtube and might not apply to an old Toyota diesel.
Also a close up of the flat tappet crown surface I'm working with. I don't know if this will spin or not. Really do not want to break a 12ht.

Any help and tips appreciated thanks...

 

[3_puppies]

maybe check in the diesel section

Diesel Tech / 24 volts

BJ/HJ diesels (3B, 13BT, 1KZ, 1HZ, 1PZ, etc) and other diesel conversions (ie: Isuzu, Hino, 4BT, 6BT, etc)

forum.ih8mud.com

 

[Spike Strip]

I don't know of any special procedures for the 12HT, but as a general process, don't use a break-in additive - use an oil specially blended for engine break in (running-in?) Break in the engine, then straight away change oil to a proper flat-tappet diesel oil.

Amsoil and Penrite come to mind. Lucas and Driven have good ones, if available to you.

I'd ask in a local forum what others have used.

Good luck

 

[FJBen]

When I rebuilt my 13bt the machine shop guy (does a ton of diesel engines/gensets etc).

Said start it, check for leaks quick. Then go on a drive. Pull a trailer even. Get a good load on her, vary the RPM, don’t lug it. Don’t idle it or baby it.

Drive it like you normally would watching all the gauges and such.

Hills are somewhere you can load it or get weight in as well will help set the rings.

 

[AussieHJCruza]

X2, start, check for leaks, get good quality oil pressure and coolant temp gauges, hitch up a trailer and load her up. Don't lug it hard and don't rev to the governor in every gear, but also don't do constant RPM, pull through all the gears and vary the RPM. IMHO (famous last words) the whole flat tappet cam thing is overblown by internet mechanics. Make sure it has the proper oil (at least 1000ppm of zinc)

 

[Trubo Dislel]

Unfortunately I wont have the luxury of driving the engine after its all buttoned up. I am doing an entire vehicle restoration so I will still need to work on the electrics, body, chassis and drivelines after finishing the engine.

Unless this is really critical for general diesel break in procedure to drive it and put load on it? Otherwise I can only break it in on a stand. I am planning to have the oil splash guard out and inner valve springs out during break in so oil can get up into the cam and less valve springs wont be too harsh on the new cam assembly. I hope this is unnecessary.

I'm eye balling Penrite's 10 Tenths running in oil online.

 

[AussieHJCruza]

Unfortunately I wont have the luxury of driving the engine after its all buttoned up. I am doing an entire vehicle restoration so I will still need to work on the electrics, body, chassis and drivelines after finishing the engine.

Unless this is really critical for general diesel break in procedure to drive it and put load on it? Otherwise I can only break it in on a stand. I am planning to have the oil splash guard out and inner valve springs out during break in so oil can get up into the cam and less valve springs wont be too harsh on the new cam assembly. I hope this is unnecessary.

I'm eye balling Penrite's 10 Tenths running in oil online.

IMHO run it as little as possible on a stand. Especially a diesel, run it with no load as little as possible. You get 1 chance to wear the rings into the new bore and it won't happen with no load.
It's critical for any engine to be under load to break in, either on an engine dyno or in the vehicle.
Likewise with running without inner valve springs, wouldn't recommend as you want the lifters to break into the cam in the way they will be running during the engine's life which won't be without the inner valve springs.

Penrite's 10 tenths 15W40 would be a good choice I'd say.

 

[dogfishlake]

The scary cam break in is very real on petrol flat tapped v8 engines that have much higher revs and higher spring pressure.
The start it and drive with a load on it will be best because you get the working load you need for ring seating, and being a 12ht, your RPM's will be right where they should be for cam break in. There is no additional load on the cam no matter how hard the engine is working as long as you aren't revving too high.

Man, I totally get the concern breaking in such a rare engine, but I think it will be great

 

[Spike Strip]

I seem to recall a YT series of videos with Roothy/ Terrain Tamer where he rebuilt a 12HT and then taped the breaki-in.

 

[TheBussman]

wait till the truck is ready to drive before breaking it in. it needs load to seat the rings. Driven is the only oil know of that makes diesel specific break in oil. your break in oil probably wont be in there long enough to need the diesel oil detergents/dispersents but it's also not much more then the other break in oils on the market.

 

[Trubo Dislel]

I appreciate and will take all of this advice in great consideration. I will leave the springs in and might as well the oil pan splash plate in, though I don't know If I should slap a new set off springs in, I don't have much spare funds for this.

I recently got my crankshaft back from the machine shop and measured the clearance and I'm getting 0.09mm with the new oversize bearings , which is far outside standard spec but just right under maximum of 0.1mm. I had instructed the machining guys to get it in standard spec with the 0.25mm oversized bearings but what a disappointment. I don't know if this is ok to run for as long as the 12ht lasts. I will run 15w50 if that's the case

I'm pretty sure I wasted a load of money on the crankshaft to get it in standard clearance since before all the machining I was getting 0.1mm clearance anyways with a new set of Daido metal shells.