Timing Reinstall - Crankshaft Won't Turn by Hand

[Extrageration]

Hi everyone,

Completely new to the forum and hoping someone here might be able to help me.

My wife was driving the 2012 LR4 when it overheated. She pulled over immediately, but the damage was done. Failed head gaskets, confirmed by two reputable LR shops.
Same old story...Repair costs were prohibitive so it's either sell/part out or take on the challenge and fix it myself. The truck only has 85k miles on it, so I decided it was worth the work.
For someone that has never taken on a project of this size, I've found this to be a ton of fun and has really strengthened my bond with the truck.

Threads here have been incredibly helpful and the job has gone as smooth as can be, until time to reassemble the timing. Once everything was together, the crankshaft simply wouldn't turn by hand. Now, I was NOT going to put too much force on it and I've been very slow and easy when trying...was NOT going to force it. Something is awry.

When the chains and camshafts are out, the crankshaft turns by hand as expected. Nice and easy. No odd or unexpected sounds.
Reassemble all of the timing components, and it doesn't want to move.

At some point, I think I got the crankshaft out of TDC (almost certainly). I spent time finding TDC again, reassembled timing, same outcome.

Is there an obvious step here that I missed? Am I simply not getting to TCD and that's causing the problem? Or, are there other, more concerning possibilities here?

Appreciate any advice or help.

MJ

 

[Shoshone]

I have engine overhaul experience, but not with the RR 5.0, so take anything I say with that in mind. Did the engine fail by sudden loss of coolant ? How? Were the heads checked for stuck valves, warpage, cracks, etc? When the camshafts were installed, did you rotate each and check that they turned freely and all valves opened can closed properly? Could the cam shafts lock up after the head was torqued? I assume this is not supercharged.

There are also chains that drive the oil pump. No problems there?

If you are unsure of cam and crank timing, could a valve be hitting a piston? You are wise not to force anything.

Good luck! I am going to change guides and tensioners as preventive maintenance so tell us what you find.

 

[Extrageration]

Originally, the truck overheated due to the dreaded coolant crossover pipe failure. That was addressed at LR specialist shop without additional concerns. The next overheat event occurred within two months with exhaust bubbling up and overflowing through the overflow tank. Likely a lingering result of the first overheating event.
The heads were taken to a reputable machine shop for a full cleaning, testing, etc.

Timing chains, tensioners, etc. were all done at the same trusted independent LR shop about 10k miles ago, so all "new" parts there. I did not remove the chain on the oil pump as it did not seem necessary for the head gasket job.

I rotated the cams for the purposes of setting the timing, using the timing tools/camlocks. But, I did not rotate them a full 360 degrees. The service manual indicates not to "over-rotate the camshafts." Not sure why not. Logically, it sounds like a good idea. Any potential issues or damage if I do so?

 

[greiswig]

I'm having a hard time following what happened to this engine and when, but some random thoughts:

- HOW did you find TDC again? Are you sure you aren't seeing a different mark? Any way to check and verify that #1 actually IS at top of travel?
- you say that there is no reason to remove the head gaskets because there was no issue there, but likely there was: that's how exhaust ended up in your coolant. I'm not clear on what happened next, or what the machine shop did to the heads.
- when there is valve interference, there is a distinctly different feel to it when you are trying to turn the crank; a "suddenness" to the stopping. If it's just tight springs or compression, the feeling is mushier.
- have you turned the cams with the heads installed, but without the chains? You should be able to do this with the crank at 90 or 270 degrees, I believe, without interference, because all pistons would be halfway down the cylinders. Double check to make sure it's ok to do this, but I'm wondering if there is something about the way the heads are installed that is restricting movement.

 

[Extrageration]

I see your point. Part of this was definitely confusing as I wrote it. Edited it a bit in hopes to clarify.

I did remove the heads which were cleaned, tested, and decked. They were reinstalled with new head gaskets.
The interference is not what I would call mushy. I would describe it as more "sudden."

My attempt to find TDC was very unscientific, as I am completely new at this. I placed a rod through the spark plug hole in #1 while turning the crank and watching for the position at which the piston would be at its highest point. This is not a very accurate approach I'm sure. Guidance on a more accurate approach is appreciated.

I'm open to rotating the cams with the chains off to test for interference, but I don't know if there are any potential issues with this approach. The service guide does provide a warning not to "over-rotate the cams."

Not in a hurry here, so I'm going to do some more research and take my time. As it is, I probably need to take a weekend off from this project if I wanna stay married.

 

[evoluzione]

This is a four cycle engine which means that it takes two crank revolutions for a complete cycle. You have 50-50 odds on being in the right position. My guess is that you are off by one revolution (in relation to the cams). You also need to make sure you are using the correct cylinder as “cylinder 1”.

Regards,

Ken

 

[ftillier]

Isn't there a tool to lock the crankshaft at TDC? Takes all the guesswork out.

 

[greiswig]

There’s typically a mark on the crank pulley. And on the cam sprockets.

i wanted to clarify something someone said above: your crankshaft can’t really be one revolution off of TDC. IOW, 0 degrees BTDC on the crank is identical to +/- 360 degrees on the crank. So if the timing is off at true TDC, the cams are where your attention should be.

 

[ktm525]

This is a four cycle engine which means that it takes two crank revolutions for a complete cycle. You have 50-50 odds on being in the right position. My guess is that you are off by one revolution (in relation to the cams). You also need to make sure you are using the correct cylinder as “cylinder 1”.

Regards,

Ken

I agree you are likely at TDC with your method if you are using the correct cylinder but the question now is which part of the cycle are you in on that cylinder. You said you had two overheats. Did the shop mess up the repair after the first one?

 

[greiswig]

I placed a rod through the spark plug hole in #1 while turning the crank and watching for the position at which the piston would be at its highest point. This is not a very accurate approach I'm sure. Guidance on a more accurate approach is appreciated.

Rotation of the crank produces a sine wave at the piston, not a triangle wave. So capturing TDC this way is likely to leave you off by some degrees because you're trying to discern movement at the flattest part of a sine wave. It can be used to help you find the mark on the crank pulley, or the keyway on the crank, but it's possible that you are off far enough to cause interference.

And, as others said, it's probably a good idea to double-check that you're actually working in what JLR thinks of as cylinder #1.