12HT lifespan how many K's are they good for

[lokka]

Like the heading says id like to hear about how many K's have been put on 12ht's is 450K too much or is it only just run in im lookin at a few all with good history and all around this mark id just like to hear what others have seen em do ...

[flyology]

I rebuilt mine at 450k...... all was good inside, still had hone marks in the bore but..... the factory pistons were stuffed. not worn out, but the top ring groove was damaged with the groove opened up so the top ring was sloppy.

Apparently this is a common problem with 12-HT's, the aftermarket replacement pistons I bought had steel inserts in the piston for the top ring groove.

Depending what your engine is like (if you have one) they are not that expensive to rebuild if you can do some of the work yourself. My bill from the machine shop was around 2K, that was for a crank linish (didn't need to be ground) reco head, bore and hone to .5mm oversize, resize rods, fit new little end bushes, fit cam bearings hot tank etc.

My pistons rings bearings thrusts (rebuild kit) was around $1100.00, and was all quality parts, I have heard you can get kits or ebay but the quality is questionable.

I have also heard dont use anything except a factory toyota head gasket (at around 200.00 ouch!!) but is a lot more of a head ache if you need to replace it.

the rebuild on my injector pump set me back 1700 (full reco) and turbo was 1100.00 (I needed a new exhaust housing as mine was cracked, that was 600 alone second hand, dont think you can get them new and no one makes an aftermarket housing.

I do know a bloke who has over 600K on his 12-HT and it is still going strong as far as I know, he services it regularly and changes the oil ever 5k, plus uses fully synthetic mobil one.

Hope this assists, I think 450K is getting up there, depends on how many more k's you want to do before a rebuild.....

[lokka]

Thanks for the reply ive read most of your posts about your truck theres plenty of good tech there thanks for being so informative ....

I havent purchased the rig as yet but this info may make me lean towards the higher buy price of one with a recoed engin cheers

[DR Frankenstine]

The problem is you may spend 5K more on a suposedly better unit and still have to spend money on that. The second hand market is an unknown, For that matter so is the new.

[lokka]

The problem is you may spend 5K more on a suposedly better unit and still have to spend money on that. The second hand market is an unknown, For that matter so is the new.

Yep this is true its all in the gamble of buying second hand it allcomesdown to service history with these things tho no matter how well ya look after them they can and do still break ...

Old man has an 80 with a 1hdft and its done unknown K's as the motor was fitted as a second hand runner to the truck he brought hes had it about 10years and has allways looked after it its only done about 100K in this time and looks like it needs a top end reco due to a miss and oil usage seems like a valve problem ....

Its just the luck of the draw

[Wozza244]

Mine had 370 on it wen i got it, i flogged it pretty hard, had to show up a few 80 and 100 series

The day it broke it had 483,000 on it, it started fine, no miss no abnormal smoke no nothing and then ya wouldnt credit it i was just cruising at 70 and i saw alot of smoke behind me, ALL COMING FROM THE BREATHER PIPE
It still ran no worries, still had heaps of punch, but yeah ya couldnt drive it round like that, the EPA would spew.

Thats when i sold it in parts.

[Shaun05]

I'm currently rebuilding a 12HT that had about 400K on the clock. It looked like a real heap of shit from the outside. The guy I bought it off had given it a really hard time. I thought I would find it to be worn out and in pretty bad shape but when I cracked it open, to my suprise everything so far has measured up within factory specs! Even the injection pump was in top condition.

I'll let you know what the crank is like when i finally get around to measureing it up.