Question About Cylinder Boring

[Sparky1]

I just updated the thread on the 55C which just doesn't seem to want to leave Florida for Chicago, but I thought I'd ask the question here. According to the owner, we're up to replacing 9 cylinder kits now in addition to those cracked heads. Roger told him the cylinders would have to be bored, but the owner is asking why this has to be done considering the new sleeves. I assume it's to true the block for proper sleeve fitment, but I wasn't sure.

 

[MikeP]

You are correct. The block MAY need to be bored but that would depend on clearance-checking each bore. The DD service manual has a list of several clearance check points for fitting new sleeves so it is possible that on any given engine NO boring is needed at all OR that anything from one to all cylinders need boring to properly fit the new liners.

Boring a cyl that doesn't need it would just be more work/money than necessary.

 

[Sparky1]

Thanks Mike, I thought I was right but wasn't sure. You guys really have taught me a few things huh?

 

[Traveler 45C]

…And those measurements are critical. I think there are 12 points in each cylinder that need to be measured. The kits are ordered referencing those measurements I believe.

 

[Robby]

I know a lot about gas and little about diesal.What holds these sleeves in?Are they press fit?Seems I remember that there are o rings and the head itself hold them in place.Got a lot to learn--Robby

 

[Captcoop]

A sholder at the bottom and the cylinder head at the top. And yes they are pressed in.

 

[captddis]

The engines were already bored .010 over. Because of the heat and maybe poor fit the liners were blue. Will need to go to .020 this time. The liners are pushed in by hand with a good even drag going in and checked for proper contact with the block.

 

[Genesis]

If these are dry liner engines the fit in the bore is CRITICAL.

There are a myriad set of measurements (in the book) that must be done - ALL OF THEM - or you will run into the "blue liner" problem - localized overheating - and a VERY short service life compared to norms. If the work says you need to bore it, then you need to bore it - period.

Do the job right!

 

[Trojan]

You almost never have to bore a cylinder sleeve hole on a DD. The sleeves are bored and honed for the matching piston when you receive them. That's the advantage of having a sleeved block. You have to measure the block bore size in order to properly fit the cylinder liner. The cylinder sleeve has a flange around the sleeves top and a ridge on the bottom. The block is bored to accept this flange. There are seals that seal the cylinder in the bore top and bottom. These are the seals that go bad from an over heat. The cylinder head retains the cylinder in the block. That's about as complicated explanation that I care to go into. If the block bore is bad the block is junk and must come out and be machine bored to get it right. It is very hard to bore a large cylinder hole with a portable boring jig. I have a new engine block on one side and a rebuilt engine block on the other. Don't over complicate a very simple engine. Sleeves are the advantage over a bored block. You can rebuild the motor many times and not require a boring. In a car you can only bore and rebuild a block about 3 times max .20,.40,.60 thousands over.
BILL

 

[Sparky1]

OK, I realize this issue has gotten spread between two threads, but as I now understand it, the mechanic says the engine has to be loosened from it's mount and turned side to side in order to bore the cylinders.

As I said on the other thread, I'm not questioning Roger, but I do wonder why this step is necessary unless there is simply not enough clearance to do it otherwise. That sounds like a pretty tricky proposition to me.

I'm also wondering how this scenario is going to relate to the 12V71N in my boat that's in the process of being rebuilt. My mechanic confirmed that it would be necessary to pull all the sleeves and make measurements to make sure we ordered the correct kits, but I don't recall him saying anything about any boring.

Is this something that's more common in a turbocharged application where there may be more heat?

 

[captddis]

The block is bored to accept the oversize liner, the seals are on 92's not 71's.

 

[captddis]

OK, I realize this issue has gotten spread between two threads, but as I now understand it, the mechanic says the engine has to be loosened from it's mount and turned side to side in order to bore the cylinders.

As I said on the other thread, I'm not questioning Roger, but I do wonder why this step is necessary unless there is simply not enough clearance to do it otherwise. That sounds like a pretty tricky proposition to me.

I'm also wondering how this scenario is going to relate to the 12V71N in my boat that's in the process of being rebuilt. My mechanic confirmed that it would be necessary to pull all the sleeves and make measurements to make sure we ordered the correct kits, but I don't recall him saying anything about any boring.

Is this something that's more common in a turbocharged application where there may be more heat?

I tried to answer in the earlier post. Here goes again. He needs 36 inches above the engine deck for the boring bar, hence rolling the engine. The engines in the 55 are factory rebuilt longblocks that were bored .010 at the factory. A satisfactory fit was unavailable and the engine will need to be bored to the next size liner at .020. If the engine was standard bore then oversize boring probably would not be needed.
Yes there is more heat on a turbo engine especially if the boat has been overpropped and or overheated or in the case of a turbo failure. The cylinder temp will skyrocket. With all that heat metal moves around.


In the 58, you will probably be able to use standard liners. they come in sizes 1 thru 5, the block should be stamped with the current size liner installed. look on the deck under beneath the liner. Probably 2 or 3 now. Adam will have to fit the liners to the block and a couple different sizes are usually used. Dave

 

[Sparky1]

Sorry I missed this in the earlier comment, but thanks for the clarification Dave. I'll pass that on to the owner. He has total confidence in Roger but was curious since he's a diesel retard like me. I would have figured there were engine hatches above that would allow the proper access, but I guess maybe the outboard side is the problem.

Adam did mention the numbers of 1 through 5 as to which kits we would need for my engine, but he didn't say anything about what sizes were in there now. I'm assuming he'll know about the sizes being stamped, but I'll mention it to him just to make sure.

 

[Trojan]

There is no difference in the cylinders between a natural and a turbo motor. Also cylinder exhaust temperatures are supposed to be maintained the same. That's the reason some people use pyrometers as load increases so does the cylinder heat. The turbo increases the HP. by raising the cylinder compression stuffing more air and fuel into the same hole as a natural. The root blowers add the air quanity and the turbo stuffs the root full. It is surprising at how low the air pressure is from a turbo. Quanity is more important than pressure. I don't remember the boost pressure on a DD but most boosts run around 6 - 10 psi. depending on the motor and it's use. Don't get me wrong blower and turbo pressure is critical. But with one you get the other. My DD books are on the boat so I can only go by memory. Which also needs a tune up now and then. For an example, the old Offenhausers could run 14 psi before detonation and the replacement Eagle engine by Ford could only run 12 psi before detonation. A sizeable amount of HP was lost. Ford did not have a better idea. But Offy blocks are a thing of the past. No one has been able to make a motor as good as the Offy.

By the way portable big bore machines suck. The quality of the bore is totally dependent on the quality of the machine. As in size makes a difference, along with the experience of the person operating the boring head. Something of this size is better left to the stationary mills outside the boat in a real shop.

BILL

 

[Brian Degulis]

Randy now that you've gotten a taste of how involved this stuff can get are you re thinking doing all 12 kits in your boat?


Brian

 

[Genesis]

I would NOT bore an engine in the boat. No way.

The fit of the liner to the block on a dry liner engine is CRITICAL. If contact is not 100% with the block you WILL get localized overheating and service life will be extremely poor, with failure at or before 1,000 hours. This, by the way, is the usual reason that rebuilds on these engines fail and is why the 92-series engines are easier to in-frame with successful results - they are wet liner and these issues do not come up.

I know my view on this is likely to be in the minority but my view is that if "by the book" you are out of spec once you pull the liners and take the necessary measurements (indicating the need to bore) the block needs to come out of the boat. Ditto if your examination of the old liners reveals discoloration (the infamous "blue liner" problem) or the liners refuse to come out without extreme measures, especially if the engine has been previously in-framed - both indicate a rebuild done with the block out-of-spec the last time it was apart and localized severe overheating. If this problem is not corrected you will have another short-time failure. The equipment available for in-frame use simply isn't as rigid or precise as that available in a shop and in this application precision is THE determinant of success.

This becomes a major problem in a MY or similar boat where "reasonable" engine removal access was not provided at original build, but that doesn't change the facts. A shop overhaul is easier to perform and will take few labor hours for a quality job which helps to mitigate (but probably does not offset, particularly in a MY) the R&R expense.

 

[MikeP]

Re MYs and engine removal...In a 53 "classic" MY the engines can be removed straight up and out of the eng room. Hatt provided screwed-down "hatches" in the salon for this purpose. When I pulled up all the carpeting on our 53 in '05 I saw the hatches and unscrewed one of them to find that I was looking right at the engine with an opening large enough to pull it. Unfortunately, on the ED version or, from what I understand, any 58, the wall between the pilothouse and the salon/saloon lies over that area and blocks access to the hatch (if it was still installed - I don't know). I have no idea how other Hatt MYs were set up to accommodate engine removal.

 

[Sparky1]

Randy now that you've gotten a taste of how involved this stuff can get are you re thinking doing all 12 kits in your boat?


Brian

There was never any question that I'd do all 12 once my mechanic told me about the surface rust. Now had this been done right the first time with somebody who knew what the hell they were doing, I would probably have opted to replace just the one hole with the cracked liner given the very low number of hours on the engine. Then again, if they screwed up that one kit, there were probably others just waiting to fail. Given what I know now, I would never replace just one kit.

 

[Brian Degulis]

Ok I'm not following this that close. I didn't know you discovered problems in the other cylinders.


Brian

 

[krush]

Shoot, if you are just going to run at hull speed, put some bubble gum on it and run it. It'll probably last longer than you think hehehe. Hell, you got 11 other cylinders to rely on.