1HZ Crank Failure

[beaterchevy]

Looking for some advice from the Diesel guru's here - sorry for the long story, hoping the details will help.

I have a 60 series with ~1994 1HZ/H55f transplant - supposedly approx 200,000km. I've owned it for only about 6 months.

Turbo'd about 1 month ago - fairly conservative tune, 7-8psi max boost, max EGT on a long hill 1150F pre-turbo. Cruises on the highway at ~7 psi boost, 600F EGT / 110km/hr.

Engine has always ran super smooth and quiet, stars up with barely a turn of the motor and doesn't really require the glowplugs to start. No noticeable black smoke, etc of any kind - appeared to be a solid motor.

Over the last few weeks I've noticed that the oil pressure was slow to build on startup, but not slow enough to trip the low oil pressure switch - and once it came up it was normal and stayed up. Didn't think much of it.

Last Friday I go to leave work and notice significant oil mess on the front of the engine and apparent leaking from the front main seal. Dip stick level had decreased from full to about half way on the marks. Fired it up and everything sounded fine but you could see significant run-out on the crank dampener/pulley.

Thought maybe a bad dampener had taken out the seal, tried to get it home so I could start looking into it and made it about 5 km down the highway before oil pressure started to fall and engine started to knock/thunk - pulled over immediately and shut the truck off. Probably ran for less than a minute between the dropping oil pressure and start of the noises until I shut it off.

Towed to shop, dropped pan - crankshaft is cracked (not separated, just cracked - about 1mm wide and 2" long) in the fillet just behind the #1 rod throw. No debris in the oil pan, nothing caught in the strainer - only some light brass/metal particles in the bottom of the pan - looks like bearing material.

Dropped the #1 connecting rod bearings and they are worn, but not totally destroyed. No evidence of bearings spinning.

PO had the Injection Pump rebuilt before I bought it - uncertain of the reason or how bad things were running before the pump was done. Best theory we've got right now is that the IP was bad previously, perhaps causing misfire or overfuel in the #1 cylinder - causing damage to the crank. Additional load from the turbo caused crack to propagate to the point where it is now. I'd expect that the failure surface will look like a typical fatigue failure but won't know until we can pull the crank.

Looking for some advice and comments as to what the potential root cause of the crank failure could be and what should be done to inspect and repair this motor.

I've gotten a good used crank, but am considering the options of just replacing the crank along with the main bearings, con rod bearings.

Or should I be pulling the head and doing more or less a full rebuild on the engine? This of course could spiral into a whole pile of money and work.

Or should I abandon the motor and just try to find a replacement?

Obviously don't want to be doing this again in the future, but at the same time I don't want to tear any deeper into the motor than necessary to keep the costs and the timeframe at the shop to a minimum.

Any practical advice is appreciated here. Thanks for your input.

 

[ozcrusier]

I would take a punt and just replace the crank and bearings and see how it goes. I guess the workshop wants to do a complete rebuild and give you 12 months warranty with a 8 grand bill. Its a tough call on what way to go but I would rebuild for turbo before buying another second hand engine.

 

[Hulsty]

My mate had a similar problem, wore out the crank thrust bearing and started wearing into the crank, damaging the crank, knock knock no oil pressure. Swapped in a new motor. Possibly cause was a heavy clutch and a hard life.

 

[roscoFJ73]

They are tough engines but many used 1HZs have seen life in the mines . Many of them have been rebuilt using parts from other dead engines.
I suspect you have one of these or the klms are much higher than stated with the seller only repeating what he was told.
Rebuild kits are not expensive, but I would just repair the bottom end if you have good compression.

I have had 2 1HZ in HZJ75 ,both with approx 250000klms and the cranks are like new with very good oil pressure.


Is your 60 a white one?

 

[beaterchevy]

Thanks for the responses guys.

Yes, the 60 is white.

Oil pressure has been good since I've owned it never done a compression check but I'm assuming good condition based on how easy it starts and how clean it (was) running.

My research has indicated this was not a mine truck, but was a combo pulled from a JDM import - but as with anything like this, no way to really tell.

What's the chances that the #1 conrod or piston have been damaged by the crank failure? Any way to get an idea of this without pulling the head and pulling the piston out?

 

[ozcrusier]

Strange place for a crank to fail.
If all the bearings look OK I would measure her up and order the right bearings and button her up. I believe your ear for engine noise saved number 1 conrod from punching a hole in the engine block.

 

[Tapage]

I would do the bottom end and go from there .. if you are aware that head job could be in your future and you are ok with it ..

 

[roscoFJ73]

View attachment 1061673



Yes, the 60 is white.
?

There was an owner on here a few years back with the handle of HZJ60guy. He spent a bit of dough doing up a white 60 with a 1HZ conversion and had some engine problems not long after it was finished. I think he ran out cash and sold it. Pretty sure he was from Vancouver.

 

[Jan-78FJ40]

You have to pull the engine anyway at this point, unless you want to leave the cracked crank in there (which would be a bad idea, as it is certainly out of balance with a crack that wide). You also have to disassemble most of it to get the crank out. Might as well pull the head and look at the piston and cylinder surface.

 

[beaterchevy]

Yes, this is HZJ60guy's old truck, i'm the second owner since he had it built. I was not able to find any issues relating to the 1HZ in it in the archives here - does anyone remember anything specific about motor troubles on this rig?

Most of what I can find is in regards to it being a giant over height truck, which is now been corrected more or less - but nothing in regards to engine troubles. As always there is a mess of problems from the PO's, but I was not expecting the engine to be one of them.

The PO had a maintenance log book in which he recorded a number of rough running (stumbling, misfire, white/blue smoke) clogged fuel filters, and eventually IP failure (what the failure mode was was not recorded). Once the IP pump was rebuilt it appears in the log, and from my driving on this) that everything was running smooth - no smoke, quiet, no leaks, etc.

Thanks for the advice on all of this.

Also see conflicting storied on re-use of the head/main/rod bolts - FSM gives measurements to inspect the bolts by, but seems general web story is all bolts need to be replaced. Any comments on this?

 

[OGBeno]

Saving grace out of all of this is that at least new parts are available for the 1HZ in the US.

Good luck with the rebuild.

 

[BC40]

Had to replace the crank in a 1hdt because of cracks in half the journals, none of them open like yours, but NFG regardless. Reason we openned it in the first place Had low oil pressure hot. Someone had replaced the rod bearings when it was imported, but the main bearings were also bad. Since you can't inspect/replace the mains without seperating the bottom of the block nobody had checked why oil pressure was low. We went the good used crank and rebuild route. There have been a number of bad cranks in 1hdts that I've heard of, which is the same crank as a 1hz, so maybe your just that lucky. The bolts are not that expensive, but it certainly adds up. For the consequences of one failing, we spent the $50 for new rod bolts, but even those were within specs. The rest we reused

 

[ozcrusier]

If your concerned on number 1 just pull that slug and check if its been kissing the valves or head. I would pull all the slugs and give it a hone with new rings.