Hi all,

My parts engine is almost torn down with only the connecting rods and crank still to be removed. Before I remove them I wanted to check w/ you all first on a few points.

After the engine is torn down it will be tanked and the oil and coolant passages cleaned out. The machinist will also check the cylinder liner bore and ball hone the cylinders if appropriate. All in all the block looks to be in excellent condition, the crosshatching in the cylinders is still very clear, the tappets showed literally no wear and the cam lobes only some.

My questions:

1/ The pistons can just be tapped out the top of the engine block? How does one remove the carbon ridge? Running a finger nail across the top of the bore I don't really feel any ridge.

2/ The piston connecting rods use 12 point bolts where they connect to the crank. A 9mm is too small while a 10mm was a bit loose. Are these imperial? Tomorrow I'll scout for a 3/8" 12 point socket. Is there an order they need to be removed in? No order is mentioned in the manual.

3/ Regarding removing the crank, the six hub aligner screws are really on there. Removing them is made more difficult by the crank not being locked. On page 36 of the engine rebuild manual, where it covers removing the crank, step 4 says to "Remove 6 socket head cap screws securing hub aligner to crankshaft, remove hub aligner." I was thinking it wise to have the machinist check the crank for wear and balance but should I bother removing this hub aligner? It isn't necessary to remove the crank from the block. One could stick a piece of wood in the crank galley to lock the crank against assuming that won't somehow damage the crank. That's doubtful as the crank looks extremely robust.
The image of the crank was from earlier in theday, it was flat on the ground when I was wrenching on it. :-)

t

4/ The rebuild manual doesn't mention a specific order that the main bearing bolts need to be released by. Ditto for the big end bolts I mentioned previously.

It's my first tear down and so I've never seen any of this first hand before. Here's a few more images I took while documenting the process. Thank you all for your assistance!

Beowulf wrote:

• The pistons can just be tapped out the top of the engine block? How do you remove the carbon ridge? Using my finger nail I don't really feel any ridge.

If you don't feel a ridge then do as the book says, and just tap them out. Make sure you've got a ring compressor for when the time comes to put them back. That's one of those tools that gets used so rarely you can never find it when you need it but find it a couple of days after you've gone out and bought another.

• The piston connecting rods have 12 point bolts where they connect to the crank. A 9mm is too small while a 10mm was a bit loose. Are these imperial? Tomorrow I'll scout for a 3/8" 12 point socket.

GEMS engine is all Imperial, Thor is a mix of Imperial and Metric, so quite possibly the big end bolts are Imperial.

• Regarding removing the crank, the six hub aligner screws are really on there. Removing them is made more difficult by the crank not being locked. On page 36 of the Engine rebuild manual, where it covers removing the crank, step 4 says to "Remove 6 socket head cap screws securing hub aligner to crankshaft, remove hub aligner." I was thinking it wise to have the machinist check the crank for wear and balance but should I bother removing this hub aligner? It isn't necessary to remove the crank from the block. One could stick a piece of wood in the crank galley to lock the crank against assuming that won't somehow damage the crank. That's doubtful as the crank looks extremely robust.

They will have been put in with Loctite when the engine was assembled so will put up a fight. Choices are to jam a lump of wood in there to stop the crank turning or leave them where they are, as you say, crank can be removed with it still attached.

• The rebuild manual doesn't mention a specific order that the main bearing bolts need to be released by. Ditto for the big end bolts I mentioned previously.

I don't think it matters to be honest. The crank is so stiff you aren't going to bend it. Sit it in place on the bearings, drop the caps on and torque them up (remembering to make sure it still turns after doing each one).

Here's a few more images just because...

I wanted to give a mod the fun of correcting the links so they showed properly.......

the crank has to be removed to be measured for size also if the block to be washed it has to be removed . what is the hub aligner , (harmonic balancer)?,just seen pics all sorted now just give the bolts on the crank a hit with a hammer to loossen also ask about replacing the cam bearings when having work done on the block
yes the bolts are AF its an American motor
as for the lip it will be cleaned up when its bored , its not a case of the hone marks are still their its a case of how round your bores are. i recommend 20thou cut to clean up bores , happy honing:😀

Sorry Gilbert, I saw the broken images too after posting and went back and fixed them. In the meantime I see you also have been by.

Thank you, Mad-as! 20 thousands metric or imperial? Me thinks 20 thousands of an inch would be way too much.

Gilbertd wrote:

Beowulf wrote:

• The pistons can just be tapped out the top of the engine block? How do you remove the carbon ridge? Using my finger nail I don't really feel any ridge.

If you don't feel a ridge then do as the book says, and just tap them out. Make sure you've got a ring compressor for when the time comes to put them back. That's one of those tools that gets used so rarely you can never find it when you need it but find it a couple of days after you've gone out and bought another.

Because the existence of a ridge could damage the rings? And if the old rings are being replaced anyway it wouldn't matter? I'm assuming there's no risk of the bore being scored such that wouldn't be resolved by the later ball hone?

These questions must seem so elementary!

Unless there's a huge ridge, which you would be able to feel anyway, it won't damage the rings. Once out, check the bores for round to make sure they aren't going oval but if you can still see the hone marks, that's pretty unlikely. Same with the crank journals. Check for round and any scratches but again, unlikely to need a grind unless the engine has been really neglected. New piston rings and big end and main bearings should be all you need. When my engine was rebuilt at V8 Developments, they used the original pistons as 4.0 litre pistons are about 4 times the price of 4.6 ones. As Ray said, the rings do the work, the pistons are just something to put the rings on so can be reused as long as they aren't damaged.

Beowulf wrote:

Sorry Gilbert, I saw the broken images too after posting and went back and fixed them. In the meantime I see you also have been by.

Thank you, Mad-as! 20 thousands metric or imperial? Me thinks 20 thousands of an inch would be way too much.

20 thou is 0.5 mm thats 0.25mm from each side . the problem is if they bore at 10thou and it dosent clean up the bore on say no5 cut then they start again and you pay twice because they have done the job twice. you will not be doing this with this motor again so the amount cut out is irrelevant .
oversize pistons generally come in 10 thou 20 thou 40 thou 60 thou oversize. if you just hone out the cylinders it can oversize the bore to much for standard rings ,in other words your motor will be loose and wear out quicker than it should and you could end up with piston slap , this can damage the bore
PS take the stripped down block to your machinist and let him do what he recommends , if he says 10 thou then its 10thou if he can just hone and clean it up then it will be alot cheaper especially if you can reuse your old pistons, don't forget to measure your old pistons as they wear as well and when you put it all together after its been honed the gaps are generally to great
if it was mine it would be a 20 thou cut, no questions . you still have 2 more over sizes to go . at the end of the day its a case of how much you wish to spend .