1HDT HDJ81 Misfire

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ubguessin said:
Does anyone have a connection that could get me a rebuilt head for this motor?
Click to expand...

The next question is why do you think rebuilding the head will help?
If an injector will not go full depth , its either an obstruction or the thread is damaged, but you would be able to see the problem. But your mechanic can not see it.

And how much is the protrusion, has anyone accurately measured the depth in the injector hole?
 
roscoFJ73 said:
The next question is why do you think rebuilding the head will help?
If an injector will not go full depth , its either an obstruction or the thread is damaged, but you would be able to see the problem. But your mechanic can not see it.

And how much is the protrusion, has anyone accurately measured the depth in the injector hole?
Click to expand...

Thinking the same
 
X3, you won't see any more of the injector hole with the head off than the head on. My bet is although it can't be seen, there is something stuck in there, old washer or something
 
Are the 1HD T injector tubes slightly tapered? I keep saying they have a thread but thats wrong.
 
I want a new head because the guys at OC broke off the tapped hole that holds the injector down with the V clamp and I dont partiularly trust it to hold long term.
 
roscoFJ73 said:
Are the 1HD T injector tubes slightly tapered? I keep saying they have a thread but thats wrong.
Click to expand...

There is no visible taper and I think the only contact between injector and head is the seat and rubber o ring. They're held in only by a clamp that bolts to the head at relatively low torque. Hard seal via the crush washer plus a rubber o ring further up the shaft, which I can only imagine is to keep moister/junk out of the cavity.

What does the damaged thread for the clamp look like and what was the fix the mechanics used? There are a lot of clever solutions machinists have come up with to fix similar issues and you can probably do it yourself or at least at a low cost.
 
Thinking about it more, a poor repair job there maybe the cause of the injector protrusion, since that fastener is the only mechanism used to properly seat the injector. That could be a definite cause of all the problems you're describing.
 
dcruiser666 said:
Thinking about it more, a poor repair job there maybe the cause of the injector protrusion, since that fastener is the only mechanism used to properly seat the injector. That could be a definite cause of all the problems you're describing.
Click to expand...
The thing is, the repair is on the #1 or #2 cylinder, my issues are coming from #5
 
ubguessin said:
I want a new head because the guys at OC broke off the tapped hole that holds the injector down with the V clamp and I dont partiularly trust it to hold long term.
Click to expand...
I would drill and retap or helicoil if needed. My turbo FZJ80 had plenty of km with a helicoiled rear shock mount on the rear axle, helicoil loctited in and the bolt torqued to spec with no problems. I wouldn't junk the head because of a broken bolt, it can be properly repaired
 
I would have no hesitation running the head with a helicoil repair for the injector.

It's fairly common for a crush washer to get stuck in the head and get overlooked when changing injectors. They can be hard to see, and hard to dislodge.
Get et yourself a hooked tool and go fishing for a washer in the injector hole.
The 1hdt injectors are clamped into the head, not threaded, so there's no thread to damage in the bottom of the hole. No need to be shy with a hooked tool.
 
mudgudgeon said:
I would have no hesitation running the head with a helicoil repair for the injector.

It's fairly common for a crush washer to get stuck in the head and get overlooked when changing injectors. They can be hard to see, and hard to dislodge.
Get et yourself a hooked tool and go fishing for a washer in the injector hole.
The 1hdt injectors are clamped into the head, not threaded, so there's no thread to damage in the bottom of the hole. No need to be shy with a hooked tool.
Click to expand...
#5 injector hole has 3 Copper washers!! All the others appear to have 2!! Mechanic said they are stuck pretty solind in there having to chip them out.
 
I've used a slide hammer rigged up to a pick before, that worked pretty good. Once you get them to break loose, then can work them around with a pick easily.
 
ubguessin said:
#5 injector hole has 3 Copper washers!! All the others appear to have 2!! Mechanic said they are stuck pretty solind in there having to chip them out.
Click to expand...

NOW we're getting somewhere! Great news, as weird as that sounds, lol!
 
mudgudgeon said:
They all need to come out. Install fresh ones when the injectors go back in.
Click to expand...

That's a good suggestion, you should know what's in each of those holes before moving forward after this discovery.
 
IanB said:
That's a good suggestion, you should know what's in each of those holes before moving forward after this discovery.
Click to expand...

yes, and it this point, trust absolutely nothing the previous mechanic touched. Recheck and baseline anything they touched as much as possible as you proceed with fixing your problems.
if something they touched could potentially be a cause for your issue, treat it with suspicion until you can rule it out.

I think you're dealing with something simple that has been overlooked or misunderstood.

trouble shoot the basics, start with and eliminate the cheap low hanging fruit before opening the engine and removing the head.

work on one potential problem at a time. be certain you understand the outcome before moving on to the next one.

eg, get injector install sorted, then test drive.
if that's made a difference to the miss, move on to tuning the fuel pump settings. recheck timing with the correct tool. if this isn't 100% correct, consider checking the pump timing gears were aligned correctly.
if all good, tune boost and fuel settings. this is simple enough, but is quite a process in its own right.

you can tune this yourself if so inclined.
if you do it as a novice tuner, expect to tune, test, retune, test, repeat multiple times. there's good info on here about the tuning process.
you might just be amazed at the results

compression test was good. was a leak down test done too? if both these are good, there should be no reason to remove the head base on what you have told us.
 
Also just be 100% sure the mechanic doesn't break the stuck washers into pieces allowing bits to fall into the combustion chamber. I would want to be there to watch this
 
Haven't tried it but a really long extractor like this could be ideal for the job.

Screenshot_20200604-135938.png
 
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