Builds 1-HDT rebuild - late 2019 start

Joined
Jun 15, 2016
Messages
312
Location
Denver
Im planning on personally rebuilding my 1-HDT next winter. This will be the second engine I have rebuilt, ever. I know this will be a large and costly undertaking, so I want to get a head start on gathering any parts, tools, and collective knowledge that might help me, while starting a thread to document progress. I'll be updating the following.

Here is my reasoning for a rebuild:
  • Below-spec compression on #3, low-end compression on others
  • Slobbers oil through breather
  • Double check BEBs were actually replaced, and/or 100k km refresh
  • Fix ring or head blowby
  • Opportunity to get ahead of anything starting to rust in engine compartment
  • Opportunity to replace all the hoses
  • Opportunity to rebuild horribly leaky PS system
  • Opportunity to buy more tools
  • Get it all over with at once
  • Possible rugrats on horizon, may be now or never
  • Something for me to do, and a learning opportunity
  • Afterwards, I will know EVERYTHING about this truck

What I've already done:
  • New turbo
  • New injectors
  • Rebuilt IP
  • Fresh timing belt and water pump

Other plans (budget providing):
  • New manual tranny (h151f): Auto tranny is sticky until warm, and suffers on mountain passes. Current engine smoky when in drive at idle, but clean when in neutral. Hoping rebuild will solve that, but if not, a manual tranny should help.
    • Sticking with upgraded auto tranny
  • Rebuild TC with higher high and lower low gearing. Higher gears should help with h151 5th. TC currently has loud but undiagnosed rattle.
    • Fix rattle, look in to lower lo possibility

(Really) high-level plan of attack:
  • Pore over manuals
  • Create budget to ignore
  • Purchase tools
  • Remove TC
  • Remove tranny
  • Remove engine, TC and tranny as one unit
  • Block and head pulled apart, measured and sent to machinist
  • Purchase rebuild parts
  • Purchase tranny and TC parts, if budget allows
  • Clean, clean, clean.
  • Paint stuff
  • Rebuild TC
  • Install wholesale valve body and tc (rebuild whole tranny if in budget)
  • Rebuild engine
  • Install engine, TC and tranny
  • Tig weld stainless exhaust
  • Make necessary tunnel/crossmember changes for stickshift
  • Install stickshift
  • Install TC
  • Drive in to sunset

Tools to buy (incomplete list, some may change depending on level of machinist involvement):
  • Tranny jack
  • Press (or borrow a friend's) - not necessary?
  • Calipers
  • Inside calipers
  • Dial indicator with bosch fittings for IP timing
  • Plastigauge
  • Engine stand of sufficient capacity
  • Assembly lube
  • Ring grinder
  • Aviation sealant
  • Piston ring lube
  • Number punches
  • Liquid teflon
  • Loads of beer
Random wishlist items

Random Build Notes
Things to ask machinist:
  • Are you using a torque plate?
  • Rebuild head? Work with shims before?
  • Magnaflux for cracks?

Removal
1HDT engine removal

Questions outstanding (need more research):
  • Can pistons from later model 1-HDTs be used? Are there any other modifications to make for this to work?
    • Use pistons for correct year.
  • Are there any other parts that can be swapped for greater longevity?
  • What gear ratios should be used in the TC?

Anyone out there perform a 1-HDT rebuild? Any advice? Things you wish you knew? Tools specific to the 1-HDT you wish you had?
 
Last edited:
Joined
Dec 17, 2007
Messages
4,231
Location
Sydney, Australia
I rebuilt a HD-T.

First thing, after you ignore your budget, double it :doh:

They are a simple engine to rebuild.

Engine stand will need to be capable of holding up a big block iron V8. EVERYTHING about these engines is heavy. If you're doing a rebuild late 2019, hit the gym now, you might still have time to bulk up.

There's no lash to set for injection pump drive gears. Gears are installed with match marks aligned, timing is done by rotating the IP.
Be careful about the sequence of how you install the IP. it's possible to install them wrong and induce a side load on the IP shaft and kill the shaft seal which can lead to diesel entering the sump.

If you're doing the whole thing, port match the head and manifolds, and deshroud the valves.

Pistons, and injectors and IP should all match the same year. There was changes throughout the years.

If you're planning a turbo upgrade, also plan for a large intercooler, EGT and boost gauges

Before removing the engine crack the crank bolt loose using the starter motor, 32mm socket, 3/4" breaker bar resting on the frame rail, and bump the starter.
Trust me, cracking this puppy with the engine on a stand ain't gonna happen.

After rebuild, be prepared to run it in hard, don't baby it. Really common for people rebuild these, wrap them in cotton wool, then wonder why they chew oil because the rings have never bedded in and the bores have glazed
 
Joined
Dec 17, 2007
Messages
4,231
Location
Sydney, Australia
Specific tools that would be helpful

Valve shim removal tool for compressing valve springs / shim buckets for changing shims

A 12 point star socket for head bolts (can't remember the proper name)

Dial gauge and injector pump timing tool adapter

A good set of picks for removing injector seals / O rings
 
Joined
Aug 13, 2015
Messages
216
Location
Calgary
What year is your 1HDT? What’s the part number of your IP and also of the new injectors you bought?

Did you get a stock replacement turbo or upgrade to something else?
 
Joined
Jun 15, 2016
Messages
312
Location
Denver
@mudgudgeon Thank you for the advice. I'll start hitting the gym now! Lucky for me it looks like I already have most of what I need tool-wise.

@zipdoa Its a 1990. I need to dig for those part numbers. Turbo is the smaller of the Wink models (and more than Ill ever need).
 

SHREDwagon

SILVER Star
Joined
Jan 16, 2010
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1,300
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Rocky Mountains, Canada
Anyone out there perform a 1-HDT rebuild? Any advice? Things you wish you knew? Tools specific to the 1-HDT you wish you had?
I did, 6 years and 100k kms ago.

Would add sourcing rebuild kit, replacing all seals in said kit with OEM, testing head, truing crank, oversize pistons & rings (?), and definitely replace the harmonic damper. Also a good time to install a block heater. I would budget $6k US if your head and crank test fine. You will be 1 to 2 months ahead swapping in a low mileage replacement.

Forget TC gears. Install a 3" exhaust and tune. Then intercooler. Then turbo.

H151 swap is big bucks.

GL
 
Last edited:
Joined
Jul 5, 2013
Messages
481
Location
San Diego
On the engine stand, I would recommend building a cradle that sits on the ground. These engines are super heavy, when I was doing mine, I started with the stand and it was super skecthy and dangerous, not worth the risk. I used the stand after i stripped the block down to work on the bottom end, after that i flipped over set it on a cradle and did the rest from there. Most stands you buy will not have the arms that line up with the block holes so you will need to modify those to fit. Also make sure to get a really good torque wrench, that you know is calibrated and accurate.
 

db3

SILVER Star
 
 
Joined
Nov 27, 2004
Messages
191
Location
SF East Bay Area, CA
Your engine stand needs to be a heavy duty unit. Mine was a typical HF unit, which I didn't trust with the weight of the 1HZ. I borrowed a stand from Georg, @orangefj45, which worked well. The one thing I recommend is to use your maintenance hoist to rotate it. Much safer!

1903749
 
Joined
Jun 15, 2016
Messages
312
Location
Denver
@db3 @Loober Hoping to borrow a decent stand. If that falls through, I have my eyes set on this one: Amazon.com: OEMTOOLS 24846 1250 Lb. Rotating Engine Stand: Automotive

That should be roughly 2x the weight of a complete 1hdt.

@SHREDwagon I debate on whether or not to make the a442f the way I want it (Wholesale parts on a rebuild) vs. just going for the 151. I'm guessing Im in for a huge hit to the bank account either way. TC gears would only be done to reduce the rpms doing 80mph on the 151. Lower low range is a 'nice to have' but probably one of the first things I'd be willing to drop off the list.

Exhaust, aftermarket turbo and intercooler are currently installed and Im happy with them. Too much low-rpm smoke to get a tune to stretch them anywhere close to the limit. Maybe decent compression will help.
 
Joined
Aug 13, 2015
Messages
216
Location
Calgary
FWIW - I regretted rebuilding my 1HDT. Way too expensive, would've been much cheaper to part out the motor and get a complete 1HDFT. Or part the truck and get one that already has a manual transmission.
 
Joined
Dec 17, 2007
Messages
4,231
Location
Sydney, Australia
FWIW - I regretted rebuilding my 1HDT. Way too expensive, would've been much cheaper to part out the motor and get a complete 1HDFT. Or part the truck and get one that already has a manual transmission.

Have you put figures to those options?

I spent $2k on parts to rebuild a HD-T (no machining done).
I later sold the same engine as a running rebuilder, condition unknown, and requiring IP rebuild or replacement for $2500. (full disclosure, IP issue caused the engine to runaway, RPM exceeding redline by a metric s***-tonne)
At the time used Japanese import HD-T were $7.5 - 8k, HD-FT were $8.5 - 10k AUD.

I could have done a full strip down / rebuild, send everything in for machining, head rebuild etc for well under the cost of a used replacement.
 
Joined
Dec 17, 2007
Messages
4,231
Location
Sydney, Australia
TC gears would only be done to reduce the rpms doing 80mph on the 151. Lower low range is a 'nice to have' but probably one of the first things
Just a heads up, if you run steep rocky trails and 35's or bigger, the tall 1st gear in a H151 really gives the clutch a hard time crawling rocky sections, plus turbo may not be on boost for really slow speed stuff meaning a double whammy. Tall gearing, and low compression/low bottom end torque until the turbo is on song.

Here's my hdj81, about 10years ago. HD-T, H151, 4.1 diff gears, 3x locked, 35's, tuned up with stock turbo, 3" exhaust.


Fairly steep, not super technical. Down to just above idle, but still enough momentum to stay on boost, and be able to punch it for more power when needed.
Much slower, or more technical and it starts to struggle.
My preference would be for a H150.
 
Joined
Sep 30, 2014
Messages
368
Before removing the engine crack the crank bolt loose using the starter motor, 32mm socket, 3/4" breaker bar resting on the frame rail, and bump the starter.
Trust me, cracking this puppy with the engine on a stand ain't gonna happen.
It is a good idea, but you can easily remove the bolt on an engine stand by making up a cheap tool to hold the balancer using the 6 bolts. Eg cut out a plate with a hole big enough in the middle for the big socket, drill 6 holes so you can bolt the plate to the balancer and just weld a bit of scrap steel tubing that’s long enough to reach the ground. You can use the same tool for tightening however you’ll need to remove the vacuum pump for clearance.

My preference would be for a H150.
Agreed, the H150 is identical to the 151 just with a lower first gear.
 
Joined
Jun 15, 2016
Messages
312
Location
Denver
Nothing serious happening yet. I have a big trip in late october I need to keep it together for, but then the gloves are off.

Decided to keep the auto tranny, but am trying to get my hands on a wholesale valve body. If there's any benefit to getting a new torque converter I might do that too, but need to be sold on the idea.

Picked up a chassis manual and printed out the 1hdt engine manual. Will probably start opening up the wallet for any tools needed come October. Sounds like I need to wait for any actual engine components until I can get it apart and inspect.
 
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