Socket clearance for re-assembly for just one connecting rod bolt not enough

[havoc_squad]

I'm having an issue with just ONE connecting rod cap inlet, the clearance hole when the bolt is put only finger tight won't allow my 12 point socket in without pushing the rod cap at that end out of alignment.

Which then I can barely feel a crack/line.

All other holes on the connecting rod caps are wonderful, no problems at all.

I've turned down the socket a couple of times, which has helped for the clearance but I'm still running into a small ridge at the cap side.

The other side is butter smooth with no irregularities.

Do I need to take the rod cap to a machinist and bring my 12 point socket with me to fix the clearance issue?

 

[jakedaawg]

Sure you don't have the cap mixed up? They are not interchangeable or reversible.

 

[havoc_squad]

Nope, no mistake upon assembling.

I put labels on the cylinder heads before taking the rod caps off. One at a time, the caps went into permenant markered plastic totes. I made sure things were labeled and organized, no mixing up.

All the connecting rods align perfectly, except for this one and only one side of the connecting rod.

If I placed it on the wrong connecting rod, the other end of the rod would have not aligned perfectly. The dot on the cap is facing the correct direction on all connecting rod caps as well.


As I explained, core problem IS the friction of the socket moving into the slot. You cannot torque down that connecting rod because it will move and I will be having a bad day of bearing/crankshaft damage if I ignore this.

The only options I can think of are:

1. Buy the BRP/OMC one and hope its thin enough to work.

2. Pay a machine shop to enlarge the bolt head recess enough to be the same as the others.

3. Buy a parts motor and get a good connecting rod out of that

4. Buy a new one (Get robbed financially)

5. Buy a used one (Get one connected to a good used piston with warranty?)

 

[jakedaawg]

I've never had an issue but my sockets are all old and thin. What motor are you working on?

 

[racerone]

??---How were you able to take it apart with that same socket ?

 

[F_R]

The sockets that I have that never failed me are Snap-On and Craftsman. Of course we know where Craftsman went.

 

[havoc_squad]

??---How were you able to take it apart with that same socket ?

Teardown summary of the problematic connecting rod:

I turned the socket down with medium grit sandpaper until the socket fit on the bolt head hole without force. Snug fit but not binding.

I untightened it just enough to release the torque with an appropriate hand tool on the suspect spot one. At that time, resistance/friction increased against the side of the socket and I had to wiggle out the socket by hand to stop and do the other side.

I did the same with the other rod bolt to only break the torque which had zero problems with clearance issues.


Once I did that, came back to the suspect one. The same amount of resistance was felt for the next part of the rod cap against the socket.

I cannot remember if I turned my socket down some more or not to aid in it fitting, but I did NOT do any pounding or attempts by force (No hammering or other common dumb practices).

I believe I wiggled the socket by hand in place due to tight fit and continued the equal un-tightening of the rod bolts.


What about some forum discussions made by OMC rebuilders talking about certain connecting rods that under most situations were just fine, that were no good because they couldn't get them to line up?

 

[racerone]

Use a dremel and grind a wee bit of the rod to give the required clearance.

 

[havoc_squad]

While I was previously thinking about the steps yesterday on disassembly for the previous post.

I pulled the connecting rod away from the crankshaft with the bearings removed and loosely fit the cap on to check it for fitment.

What I noticed is the good side I can move and get it to align perfectly, on the inside and outside of that side of the rod.

The problematic side seems like the rod cap is about a couple of thousandths of an inch past the edge when the good side of the rod is perfectly aligned. I can run my finger outside the rod from the top down and not get resistance, but when going bottom up, I feel it.

I'm concerned that without some fixture to move the rod cap into alignment, there's no way to fix the bearing surface issue caused by that offset.

I'm sure this is one of those situations where outboard machine shops earn their money they charge on knowing the go/no-go situations.


I would say my follow-up question before I pull the head and attempt any dremel work on that rod head hole recess is:

How do you handle connecting rod caps with one side perfectly aligned while the other side hangs over a couple of thousands of an inch?

 

[F_R]

I'll catch heck for saying it, but tap-tap with a hammer.

 

[racerone]

F_R----Don't worry about what people say.------Tap , tap with a wee hammer is the correct procedure !!

 

[havoc_squad]

F_R----Don't worry about what people say.------Tap , tap with a wee hammer is the correct procedure !!

Just to repeat to make sure I understand the answer given:

When rod cap and bearings are installed on crankshaft finger tight, make sure good side is properly aligned and won't move (maybe a small amount of torque), then tap the connecting rod cap on the bad side to motivate it to move inside until it's aligned.

Then attempt to snug the problematic side now aligned with a socket wrench to hold the alignment in place.

Snug up the other side, checking for alignment on both sides holding.

If it stays, torque it down in stages to OEM manual spec and be glad the miracle happened.


If this is not the steps, what means/method/process should it be?

 

[racerone]

Done it that way for about 50 years and you can not argue with that !

 

[havoc_squad]

Information update, after several attempts across multiple days to tap with a flat machine hammer it into alignment carefully and regularly taking the cap and bearing off to check it, some of the clearance was taken up but I couldn't get the last couple of thousandths.

Long story short, the surface of the cap that was extruding was the side where a chip of the inner bearing surface on the connecting rod chipped on a most recent attempt.

Now, the rod is junk and I need to source a used or new connecting rod and buy new Wiseco piston pin circlip.

It's always something delaying progress...

Anyways, the bearings look okay with no visible signs of distortion or markings, however should I go ahead and get new ones now for this connecting rod?

What is the best strategy for sourcing the rods? Would getting several rods sold as a lot on EBay with free return policy be the best game plan?

I am guessing that the engine head gaskets are single use only once torqued and have to be replaced correct?

 

[TrueNorthist]

An observation, if I may, with absolutely no negative judgement implied to the OP.

Language and proper terminology. (Nomenclature)

It is a very helpful thing to give clear, unambiguous and easily understood descriptions, using correct terminology, of the procedures being related when seeking guidance from other technicians, even in person. Un- tightened is a perfect example of a confusing term. (Loosened is correct, among others...)

Also, what is a flat machine hammer? Im not sure if in my 45 years slinging mechanics hand tools for money if I've ever seen one. Maybe I have, but the only way to know for sure while sitting here in my pajamas is if it is identified using the correct term, or a pretty picture.

And some things, such as warped and/or bent bearing caps should be physically brought before a qualified technician so the steps for resolving it can be demonstrated, or at the very least corrected before installation. In fact, I kept a couple heat-damaged caps in a drawer and would swap them for the caps removed from a project, so the apprentice would encounter it during reassembly.

First fail: failing to seek advice on discovering misalignment. Second fail: completing assembly and proceeding to finishing steps. Third and return to class fail: trying to start the engine. (Prevented completely by substituting other critical components, if only to save the engine for the next apprentice)

The advice given above by our resident wise owls above is indeed correct (careful tap, tap with a small ball-peen hammer and a soft brass drift, etc) but if it's a first time attempt by a novice it's 50/50 without first hand direction. Guaranteed to fail if the descriptions proffered are vague, confusing or inaccurate. Sometimes it's best to pay a professional.

 

[havoc_squad]

Yes, I am aware I reached the limitations of my knowledge and skills involving a connecting rod that refuses to align by hand.

That is why I listed the questions above to make the best informed decision given the circumstances I find myself in.

After speaking to an established/known outboard machine shop over the phone that is within 2 hours drive and providing them the details, they mentioned a new connecting rod or a used one verified as good by any general engine machine shop would work.

So based on the data I gave them and "assuming" all other steps were being handled correctly in assembly by me, the machine shop rep said I should not need to take it in for them to inspect/investigate.

My questions I have:

1. What data can be used to determine if the connecting rod crank journal bearing set needs to be replaced if nothing visible appears to be at fault? I ask this because I am reviewing the situation after this setback and trying to avoid making this a money-pit of complications.

2. Where can I find the data for the tolerances or steps to check connecting rod part # 0392591 and any signs to look out for that are not obvious if I chose to get used ones with free return policy if defective. (Obvious items: Cracks, pitting/corrosion on bearing surfaces) if I buy used ones?

I don't see any measurements in the OEM service manual for the tolerances for the connecting rod wrist pin hole diameter, nor for the diameter for the connecting rod diameter where the crank journal bearings sit on.

I'm not opposed if I must to fork out $200 in a new connecting rod for this expensive complication, but I want to make 100% sure this is the best course of action given the options and risks.

3. What about the question I raised about the head gaskets, are they one time use/fit only? The reason I ask is because I have to pull that piston & connecting rod out and replace the connecting rod and piston wrist pin circlip. I don't want to waste money if not necessary, just need to make sure of yes or no.

 

[racerone]

Your location ?

 

[havoc_squad]

In the region/area where Oklahoma, Missouri, and Arkansas meet in the US.

If I need to be more specific, I'll PM that information.

 

[racerone]

Sorry ---Too far away to take advantages of boxes full of spare rods.

 

[havoc_squad]

I found an online US retailer called SouthCentral Outboards in the US selling used reconditioned connecting rods. They had the part number for the connecting rod used for my model of engine.

If it wasn't an issue with forum rules regarding competitors, I would post the link.

Comes with a 30 day warranty of the product:

Steps they listed that are done to each:

End caps perfectly matched
Micro-polished for inspection
Glass-beaded and handwashed
Rust-free guarantee
Corrosion-inhibited & Torqued prior to storage

Yes, there's a risk with used parts in general, however I think this is the best option for used at $25 plus shipping.


If this direction goes bust after inspection, I'll buy a new one if I must.