Freelander 2 (LR2) Freelander 2 diesel starting on 3 cylinders, now running properly, after cylinder head change.

Juzza6720 said:

My mate has autodata and has just sent me a pic, It's not great quality though. It says this for main bearings.
1) 10 Nm
2) Slacken off 180 degrees
3) 23 Nm
4) 46 degrees.
View attachment 217008

Hope this helps.

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Thanks, that's perfect. It's the big ends torque I need, but that seems to be what this is saying.
Use new bolts.

Stage 1: tighten to 10Nm.
Stage 2: slacken off 180°.
Stage 3: tighten to 23Nm.
Stage 4: tighten a further 46°.

I think that's what I need, and sounds about right for this size of bolt.

Cheers.

Wow that's complicated !
What ever happened to tight and some...............

andyfreelandy said:

Wow that's complicated !
What ever happened to tight and some...............

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Or PF Tight?

andyfreelandy said:

Wow that's complicated !
What ever happened to tight and some...............

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Torque To Yield (TTY) more commonly known as stretch bolts need to be tightening to exactly the correct amount, which is why I was after the information.

These TTY bolts are normally a one time use, as they undergo a material change when being tightened.

Basically the torque + the angular puts the bolt in a prestressed state, which is only available at very specific points as it's tightened.

So it's absolutely essential that the correct procedure is followed, if the fixing isn't going to fail in the future, which for a big end bolt would be disastrous.

Alibro said:

Or PF Tight?

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That's no good, as the bolts are £25 a pair with the shipping, so exact procedure only is needed.

I guess the small torque used, backed oft then back on for more torque, mates the bolt head to the mating surface to ensure the correct start point for the final angular turn. They know how the bolt stretches and the twist depth of the thread when it turns. Some clever thinking behind this to get the perfect bolt hold, factored against the stretch. Nice.

Hippo said:

I guess the small torque used, backed oft then back on for more torque, mates the bolt head to the mating surface to ensure the correct start point for the final angular turn.

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It's likely a 'skuff' pre torque to flatten out the surfaces, which as you say will simply provide the correct datum point to start the tightening sequence.

Hippo said:

They know how the bolt stretches and the twist depth of the thread when it turns. Some clever thinking behind this to get the perfect bolt hold, factored against the stretch

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It's an exact science in metallurgy, which has become pretty standard for critical bolts in high stress situations.

Nodge68 said:

That's no good, as the bolts are £25 a pair with the shipping, so exact procedure only is needed.

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Like me dear old dad used to say.
"If a job is worth doing, it's worth doing well."
I shoulda (I did really ) known better than to come out with a crack like that to the Nodgester.

Alibro said:

Like me dear old dad used to say.
"If a job is worth doing, it's worth doing well."
I shoulda (I did really ) known better than to come out with a crack like that to the Nodgester.

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It's all a bit of fun Ali!.
However I am OCD where engine repairs are concerned.
Unfortunately there's no second chances with stretch bolts, simply because the science is so exact.

Nodge68 said:

It's all a bit of fun Ali!.
However I am OCD where engine repairs are concerned.
Unfortunately there's no second chances with stretch bolts, simply because the science is so exact.

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I changed the head gasket on two K series cars but had a very different experience when tightening the head gasket bolts. The first was an MLS HG and the tightening sequence went without a hitch. The second was a an Elastomer Polymer one and I struggled to get the last turn recommended.
I suspect it needed more crushing down than the MLS one but it made me wary.

Alibro said:

I changed the head gasket on two K series cars but had a very different experience when tightening the head gasket bolts. The first was an MLS HG and the tightening sequence went without a hitch. The second was a an Elastomer Polymer one and I struggled to get the last turn recommended.
I suspect it needed more crushing down than the MLS one but it made me wary.

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The bolts used in the K4 are strong, and need a long lever to pull them round to the correct rotation. The amount of torque needed does vary between the early 9.9 and later 10.9 bolts, the latter being seriously tuff to rotate to the correct amount.

These con rod cap bolts aren't anything like the K bolts, only having and needing a modern clamping force.

I'm more concerned that my torque wrench might not be accurate enough for this job, so I'm thinking of getting one of those digital torque boxes, which have an accuracy of 2%.

Following this thread with interest Nodge.

Are you going to have the head skimmed just to double check the surface before refitting the valves?

LUKBENPHI said:

Following this thread with interest Nodge.

Are you going to have the head skimmed just to double check the surface before refitting the valves?

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I've measured the head for distortion and it's within tolerance, so no, I'm not skimming it. I've got 4 new valves on order, so will fit these when they arrive.

I might find another head at some point in the future, so I have a good spare, just in case of future issues. But I'm not expecting any future issues really.

I'm also waiting on some new rings for the replacement piston, so I can start on the bottom end repair.

Nodge68 said:

I've measured the head for distortion and it's within tolerance, so no, I'm not skimming it. I've got 4 new valves on order, so will fit these when they arrive.

I might find another head at some point in the future, so I have a good spare, just in case of future issues. But I'm not expecting any future issues really.

I'm also waiting on some new rings for the replacement piston, so I can start on the bottom end repair.

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Good plan then, may be worth searching for smashed up 2.2 mondeos as a cheaper source of parts as they also use th dw12

LUKBENPHI said:

Good plan then, may be worth searching for smashed up 2.2 mondeos as a cheaper source of parts as they also use th dw12

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I missed one on ebay a few weeks ago, but hadn't got my head off at the time, so didn't want to spend out unnecessarily. I should have placed a bid, as it sold for just £100+ £15 shipping, and was complete. Some people sell just the head, missing the cam housing top cover, but the 2 parts are machined as a pair, so need to be kept together.
I'll get a suitable replacement at some point though, just in case.

Ok. So I've now received a good pile of parts for the repair to the engine.

I'm in two minds if I should change the piston rings on the replacement piston I got? I did order a set, which were very cheap at just £2.40 for the one piston. However on arrival I see the replacement rings are made in China. Now I do by a lot of electronics stuff from China, most of it is ok. However I'm now in a quandary as to whether I risk fitting Chinese piston rings, or if I simply fit the piston as I received it. The rings on the piston are fine, and actually haven't fully bedded in yet, as only 60% of the ring surface has been in contact with the previous bore.

So what is the general consensus on this issue?
I will be doing the piston replacement tomorrow (weather depending) , so answers before then would be good.

I've also received all the valves to sort the head. However these will take a while to lap in, as although the seats looked ok with the naked eye, I can see that only parts of the seats actually touch the valves, when I used engineers blue to mark the contact areas.

In the old days, I'd use a valve seat cutter for this. However modern valve seats are really hard, so need grinding in to the correct profile. I've some ideas as to how to get the valves to lap in correctly, but if those ideas fail to give an acceptable seal, I'll have no alternative but to find a second hand head.

If the rings were made in china and supplied through the parts network from a propper supplier like lrseries or johncradock or main dealer, then I would trust them and consider fitting if needed. They will have gone through quality control and sold as pukka.

It sounds like they're direct from china. Like ebay or similar? If so then that would be a concern as they may be production rejects sold on the cheap as a side line. 2.4 sovs is a bit cheap I think.

If yer replacement piston has little wear and the rings are functioning ok with little wear then I would re-use them instead of the cheap ones. Its survived the use its had without problems so hopefully it will continue to do so. The piston holes will have been cut to a high tolerance so yours and the original engine it lived in should be near enough the same dimensions. Even after some use I would eggspect them to be equal wear.

Hippo said:

It sounds like they're direct from china. Like ebay or similar? If so then that would be a concern as they may be production rejects sold on the cheap as a side line. 2.4 sovs is a bit cheap I think.

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The rings in question came from an LR parts supplier that I use quite a lot.

The rings are marked All Makes, and to be honest, I've not had many good experiences with all makes.

Hippo said:

If yer replacement piston has little wear and the rings are functioning ok with little wear then I would re-use them instead of the cheap ones. Its survived the use its had without problems so hopefully it will continue to do so. The piston holes will have been cut to a high tolerance so yours and the original engine it lived in should be near enough the same dimensions. Even after some use I would eggspect them to be equal wear

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30 years ago, I'd not have considered using second hand pistons in an engine. However production tolerances are now so tight, that used components from engines are basically interchangeable. The replacement piston has absolutely no wear on it at all, like I said, even the rings aren't fully bedded in yet. I ordered the new rings because they were so cheap, and I was ordering from the supplier anyway, so added them on.

I am now concerned that the Chinese All Makes rings might be worse than using the partially worn rings that came on the piston.

Can't remember using all kesma myself but have seen stuff with their name on when looking around the web. They're not a brand that sticks out as a problem. As said before if it were mine I would go with the rings supplied with the piston.

When I took my v6 apart it was like new inside compared to what i was eggspecting.