Builds 1HZ Rebuild Project (1 Viewer)

[lelandEOD]

Re-Introduction Time!

I recently bought a 1HZ from a mine truck for use in my '73 FJ40. After thinking things over and examining some initial indicators, I've decided to just do a complete rebuild of this 1HZ before installing it in my -40. I'd rather have a known rather than an unknown quality to this engine and I've so far seen a few signs that rebuilding it from top to bottom is probably not a bad idea. The valve stems are pretty wet so I think it's time for a head job. Also, I pulled the timing gears and found some galling on the timing idler gear, thrust washer, and idler shaft.

Oh boy!

 

[Nostradamus]

I'll be tuning in

 

[roscoFJ73]

You might want to think about the injector pump as well. If its down on pressure you wont get full power from the new engine.
Machining the flywheel makes a big difference to clutch feel and longevity.
Some of the aftermarket engine kits are high quality but engine rebuilders told me to use an OEM rear main seal and thermostat, these were people with vast experience.
I remember well the new 1HZ engine feel, the temp gauge was on 3/4 for the first 500klms then slowly dropped off to normal by the time it had done a 1000klns or so.
The engine rebuild company stuck temp sensors on the engine that pop out, but they never did(you void the warranty if they do)
The engine felt quite perky with the 4.11 and 31 in tyres.

 

[lelandEOD]

The teardown

I started this job by just trying to clean up the motor and inspect parts as I went. The truck this engine came from was a Canadian mine truck and it was absolutely coated in a fine alkaline dust. The accessories came off without fuss and I started separating parts into tubs for powdercoating, zinc plating, and steam cleaning.

 

[lelandEOD]

Up until this point, I was not convinced digging into the bottom end (beyond rod bearings) was necessary. My plan was to pull off the IP and injectors for benching, and to strip the block for paint and to have the aluminum parts steam-cleaned.

In order to get the IP and IP case off the block, I removed the idler gear. This is where I first spotted trouble. I checked the thrust bearing clearance before removing the idler gear and it was very tight on a .002" feeler gauge. Once I had it out, I could see some galling on the thrust bearing, the idler and part of the shaft.

 

[lelandEOD]

This discovery pretty much pushed me off the fence with regard to how far I was going to dig into the engine. I also found some oil weeping down around the #6 exhaust valve stem so I think a head rebuild is in order. The engine has 5,000 hours on it so I think it's ready for a wash and rinse.

I found some more unusual wear on the Cam #1 journal. I tried to photograph the wear pattern I found inside the bearing. I assume this is the 'load' side of the bearing.

There is also just the faintest amount of scoring on the #1 cam journal. It's hard to pick up with the camera because of the glare, but it's enough to feel with my fingernail.

I don't know if I can reuse this camshaft. I don't see an undersize bearing offered for the cam. The rest of the journals look ok, although there's also a strange speckled spot on the #6 exhaust lobe. Check this out:

^
I can't tell if this is a casting imperfection or a bit of surface rust from sitting for a long period.

 

[lelandEOD]

Also, the #1 injection nozzle seat is stuck in the cylinder head. Any ideas how to get it out?

 

[lelandEOD]

You might want to think about the injector pump as well. If its down on pressure you wont get full power from the new engine.
Machining the flywheel makes a big difference to clutch feel and longevity.
Some of the aftermarket engine kits are high quality but engine rebuilders told me to use an OEM rear main seal and thermostat, these were people with vast experience.
I remember well the new 1HZ engine feel, the temp gauge was on 3/4 for the first 500klms then slowly dropped off to normal by the time it had done a 1000klns or so.
The engine rebuild company stuck temp sensors on the engine that pop out, but they never did(you void the warranty if they do)
The engine felt quite perky with the 4.11 and 31 in tyres.

I’ll be having both pump and injectors at least benched. With the number of hours on the engine, a rebuild may bea good idea.

 

[mudgudgeon]

You should be able to fish the brass injector o-ring seals out of the head with a hooked pick.

 

[lelandEOD]

You should be able to fish the brass injector o-ring seals out of the head with a hooked pick.

It’s stuck in there with carbon pretty good. I’ll have to get the head off before I figure out how to get it out. I most likely have to soak it in something for a while.

Also, question for you guys who rebuilt 1HZ‘s. I will have the head off today but I don’t see a way to keep the block on the engine stand in order to remove the main bearing cap. There don’t appear to be enough bolt holes on the cylinder block to support the block when I remove the bearing cap. Do I have to put the assembly on a table to get the crank out or am I missing something?

 

[1HaytchZed]

How complicated is it to remove the injectors? I wanted to remove them and get them bench tested by a local diesel shop. I am experiencing some white smoke under load or moderate++ acceleration.

 

[lelandEOD]

How complicated is it to remove the injectors? I wanted to remove them and get them bench tested by a local diesel shop. I am experiencing some white smoke under load or moderate++ acceleration.

Not complicated at all. You just remove the injector lines, uniformly loosen the leakage lines and remove them. Then use a deep socket to sequentially remove the injectors. I don't know if the injector seats are supposed to stick to the injector or if it's common for them to stick in the head.

This is my first diesel rebuild so I'm learning as I go.

On with the teardown. I got the cylinder head removed and found one small surprise. It looks like something got battered around the combustion chamber for a while on #1: Check out the piston damage:

The head looks unscathed ok so I'm not sure what failed...

All six of my pre-cups are cracked in two or three places. Cha-Ching! $$$$ There goes $600.

Also, it looks like the exhaust valve on #6 has been leaking for a while... notice the carbon buildup.

 

[lelandEOD]

Also, here's a question for the 1HZ/IHDT-guru crowd... the Pre-cup and valves on #4 are a slightly different color than the other five cylinders... any idea what this might suggest?

Now it's on to the bottom end... I can't wait to see what surprises are lurking.


I first marked the big ends with a hand punch to keep everything in order:

 

[1HaytchZed]

Are BEBs on the 1HZ susceptible to failing as a common failure mode like the 1HDTs? Should BEBs also be replaced for a "new to you" 1HZ?

 

[lelandEOD]

Are BEBs on the 1HZ susceptible to failing as a common failure mode like the 1HDTs? Should BEBs also be replaced for a "new to you" 1HZ?

I'm no authority on either engine but I can tell you there's no way I won't be replacing every bearing in the bottom end.

 

[1HaytchZed]

I'm no authority on either engine but I can tell you there's no way I won't be replacing every bearing in the bottom end.

Right I understand your perspective, I would too in your shoes, but was asking in general for baselining a 1HZ for a "new" owner. Hopefully someone with BEB and 1HZ knowledge can chime in.

 

[lelandEOD]

Right I understand your perspective, I would too in your shoes, but was asking in general for baselining a 1HZ for a "new" owner. Hopefully someone with BEB and 1HZ knowledge can chime in.

That was the advice I was given; rod bearings and timing belt.

 

[roscoFJ73]

the Pre-cup and valves on #4 are a slightly different color than the other five cylinders... any idea what this might suggest?

I would guess its an injector spraying differently.

 

[roscoFJ73]

Are BEBs on the 1HZ susceptible to failing as a common failure mode like the 1HDTs? Should BEBs also be replaced for a "new to you" 1HZ?

I replaced the BEB on a 1HZ that had 200000klms on it and they were like brand new. But this wasn't a mine engine.
What leleandEOD is finding is pretty normal for a mine motor. Lots of high rpm, sometimes new parts slammed onto worn out parts, but if it wasn't a 1HZ it probably would have died long ago.

 

[lelandEOD]

The pistons are out and at least the cylinder walls seem to be in ok shape; I can see crosshatching in all six holes. No broken rings and, other than the buggered up #1 piston top, the other pistons look ok as well.

The rod bearings, however, are another story... Yikes. It looks like #1 and #6 must have spun some foreign matter at some point (maybe bits of the idler gear shaft?) because both bearings have grooves worn into the bearing surface. I can't see any damage to the crank journals but I won't know for sure until I have it checked over.