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Discussion Starter · #1 ·
So I'm fairly paranoid now that I've done some serious damage to the patrol After hydro locking it this afternoon. I Was messing around with the injectors today to see what was involved in changing them to the rb25det injectors that I purchased for my turbo conversion, anyway after I Removed #1 injector I sat it on the bench then got sidetracked for a while. Later I returned to put everything back together and I noticed that there was some fuel dripping from to the fuel rail into the injector orifice, of course I didn't think anything of it at the time so I put everything back together and went to move the patrol out of the drive way, turned the key and it started for about half a second and stopped, I though no biggie sometimes it takes 2 goes to catch, turned the key a second time and it locked up straight away, that's when It clicked that the cylinder must have filled up with fuel when I had the injector out. After pumping the fuel out of the cyl she seemed to start and run fine but I'm worried I may have bent a conrod as I've heard stories of people bending rods just by turning the key with a locked cylinder, and I know the tb rods aren't the strongest to begin with. Not to mention I've got a trip to Fraser looming in October so I wouldn't have enough time to start tearing down the engine. I'm after some opinions on the likely hood that I've done some major damage.

Cheers
 

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GHMBC #3
nissan patrol gq lwb,3"lift.
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i think it will be ok.revs weren't high,2nd start didn't really fire on cylinder that locked,runs now.change oil before driving and if it runs without any obvious knocking /vibration it should be fine.the tb rods aren't weak-the 4.5's just don't like boost to much
 

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Discussion Starter · #4 ·
Cheers, really hope that's the case, might do a compression test this afternoon just to be sure, last thing I want Is a slightly bent conrod before I throw the turbo on. Worst case I might get a hold of some Tb42 rods and try and change them over before my Fraser trip. out of curiosity how much work is involved in removing the head and dropping the sump to fit new rods? Can intake and exhaust manifolds be left on? Obviously I'd be up for a head and sump gasket as well as new head bolts and conrod big end bearings, but if there's not to much involved I may end up doing it anyway.
 

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Unlikely its done any damage.
The starter motor doesnt really have enough grunt to bend a conrod.

Its filling the cylinder with water while all other 5 cylinders are producing the grunt that bends things.
I second this.

If you bent a rod, you'd know about it. Even a slight bend is likely to put vibrations through the motor.

I'd just change the oil in case any fuel got past the rings. A compression test is never a bad idea but not necessary as a hydraulic lock up is a sign of a good compression chamber.

Changing the rods is a full engine rebuild job. If you're going to to that much trouble that then I wouldn't take any short cuts. You may as well do a full rebuild.

Honestly, I wouldn't worry too much about it unless there are obvious signs of damage.

I'm curious as to why you want a turbo? What sort of driving are you wanting more power for? If it's 4x4ing then you'll probably make it worse being that its a petrol engine. I'd suggest a supercharger. You'll get better low down torque & smoother boost through the whole rev range. That'd be better for an engine that doesn't cope well with boost.
 

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Discussion Starter · #6 ·
So results from the compression test aren't looking good at 170-180psi across all cylinders except number 1 at 130psi. Purchased a donor tb42 on Monday night for $150 to steal conrods from but after pulling that apart it turns out its #6 conrod was bent leaving me one short. Turning into a bit of a nightmare with only 4 weeks until my trip. Anyone have a spare tb42 conrod they don't want?
 

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GHMBC #3
nissan patrol gq lwb,3"lift.
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i have a tb45 that i would swap for yrs plus $500,am in brisbane.drive it up and can do the motor swap here
 

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You could just open the rocker cover and roll the push rods on bench if you feel its needed. We've had many a hydro locked engines at work and I do the same as what you have done. drain out, start and pray its ok. 9 out 10 there ok due to the starter as pointed out above.
 

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The starter motor has a fair amount of mechanical advantage - if the engine was cranking (which is 100-150 rpm or so) and it then hydrolocked on cylinder 1, even a forged rod could bend. A bit of googling backs this theory up - it's not an uncommon whoopsie, it seems.

One way to check (albeit a bit of work) would be to pull the head off and carefully check deck height with a nice straight edge and feeler gauges. That might give you an indication if the rod is indeed bent (although the compression test seems to indicate this is the case).
 

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Discussion Starter · #12 ·
Managed to source another Tb42 rod to replace the bent one I got from the donor motor so the head will be coming off this weekend, I'll post pictures of what I find. I also went ahead and bought some new big end bearings, new Molly piston rings, New head bolts and a head gasket. All up including the 4.2 rods it will be about a $600 mistake + the time it will take me in labour. ideally if I had enough time I would have just gone forged everything but this should suffice for now.
 
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