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Discussion Starter #1
Hi Guys,
I am about finishing my TD42 (GQ or GU, they are the same) rebuild.
Before I fit it in the car, I am hand cranking it to make sure that nothing is seized as I had one of the rod resized and brandnew rod bearings).
I found it very hard to crank even without head on, the torque is something around 45NM.
WIth head on, of course, it is mush harder, because the high compression of diesel engines.

Anyone has tested this before?

Cheers,
 

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The old style repco torque wrench is very reliable.
Short of a race not seated there isn't a lot it could be assuming things like ring gaps were done to spec.. I assume you had the crank machined?

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Short of a race not seated there isn't a lot it could be assuming things like ring gaps were done to spec.. I assume you had the crank machined?

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Also not sure on using oil for a rebuild as per the manual.. my experience is only on sr20 rebuilds but assembly lube should have been used I'd think

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There are several things that could cause the engine to bind up, including rings or bearings that are not the correct size to suit the crank/bore size, contamination on or under a bearing shell etc. That said, I've never measured the free spinning torque and only ever done it by feel - perhaps 45nm isn't really tight...is the head on? If not and you're worried about it, then I recommend undoing all the big-ends and push the pistons up the bore so you can see if the crank is binding - it should spin with only minor resistance. If that checks good then check after each big end is fitted so you can tell if one piston/big end is binding excessively.

Assembly lube is a good idea, but I've built many engines just using engine oil with no issues - either way, the type of lube would not cause binding on assembly.
 

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Discussion Starter #11 (Edited)
I have used a micrometer to check the rod bearing clearance, it seems all good, with tolerances of <0.01mm.

I also put the resized rod in position and see if it moves freely on the crankshaft, the result is positive so I didn't check all rods.

Now I am just curious and a little concerned about the heaviness of rotating it by hand, because when the pistons are downwards, it is a lot of lighter than when they are upwards. (I rotate the engine on the stand)

I have successfully rebuilt ZD30 engines using oil as lubricant before, it wasn't so hard to turn by hand.

But I imagine that the pistons are heavier and there are two more pistons, so it could be the case. I have heard 6 cylinders are substantially harder to turn, but never measure the torque before, and that is why I wanted to ask here.

Thank you guys for all the helpful replies. I believe I might not need to setup something to run the engine out of the car for testing purposes.

Or if I do, I might put it on top of some old tyres and install starter and fuel line to start it.
 

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Discussion Starter #12
Short of a race not seated there isn't a lot it could be assuming things like ring gaps were done to spec.. I assume you had the crank machined?

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The crank itself was good condition and only linished and crack tested. Rod is machined.
 

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Discussion Starter #13
Short of a race not seated there isn't a lot it could be assuming things like ring gaps were done to spec.. I assume you had the crank machined?

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one thing about the ring gaps, the first ring gaps are all bigger than specs, with new rings better than old rings which runs still well enough.

Second rings and oil rings are within specs. I am sure that 0.1m gap tolerance should not be an issue.
 

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I always assemble the bottom end without piston rings installed just so I can measure piston deck height. Once the rings are installed it is much harder to stop turning the crank at exact top dead centre for each piston. Without the rings in place and a light film of engine oil on all the parts, the crank can easily be spun by a flick of the wrist as long as everything else is OK.
 

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Discussion Starter #15
I always assemble the bottom end without piston rings installed just so I can measure piston deck height. Once the rings are installed it is much harder to stop turning the crank at exact top dead centre for each piston. Without the rings in place and a light film of engine oil on all the parts, the crank can easily be spun by a flick of the wrist as long as everything else is OK.
Yeah, probably a good idea. It is much like no pistons install. I turn the crank alone easily too. It seems to hard turn is normal, as pistons with rings put a lot of resistance to the rotating.
 

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Discussion Starter #17
OK. It went in. Runs fine, a bit shaky but it is new and cold engine.

Before I put it in, I used some sound insulation on the firewall to reduce heat and noise. Hopefully it will work, but I forgot to punch a hole for the fuel line clip and couldn't put the clip back. :LOL::LOL:
 

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Haha, that too would have been a little easier before installing.
 

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Discussion Starter #20
Start to clean interior too, which is full of dirt and dust. The good thing is, it has minor rust, so I will put more sound insulation on the floor, for too purposes, one is obvious, another is to prevent water from residing on floor so no rust.
 
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