Frustrated - head gasket leak early after top end rebuild

That's great news SecaMaverick! Sounds like your on-track to have an 'almost new' XJ that will be reliable for a long time, and you've found some new friends with some awesome tools!

My experience with different machine shops has almost always been the same. If you act like a jerk and push work on them they will gladly charge you a pretty penny, but if you are polite, do the hard part for them (removing the parts and bring it to them), and establish a relationship with them-they are often VERY accommodating. They like to work on these old mills as much as we do.

I think he's already had the last two on your list done Rick as he's already taken the head to this shop. Re-facing seats is def a shop job, but I would lap my own valves as it is EASY. Seals are a pain IMHO-shop job for sure. For $12 how can you go wrong.

 

I hadn't considered getting all the seats refaced as Rick suggests, as only one valve guide is questionable (IMHO) -- but they haven't verified that for me yet. I'm dropping it off with them after work today. I'll ask them their opinion once they get a good look.

I am a little confused about your statement (MercuryMan) about seals being a pain, though. When I replaced them two years ago, they were one of the easiest things to replace. I pulled them off the valve guides with pliers, and pushed them all the way on with heavy finger pressure. Is that not to be expected?

And yes, TASxj, I'm a rotary enthusiast. I rebuilt the motor in my '79 Rx7 back in '96, and although I sold it 10,000 miles later, I'll have another one of these days. Love 'em.

 

I bought my 83 back in 03 for $367.00, I promised the little old lady from Pasadena that I would never sell. You should get another before everyone thinks they are a "classic" and cost to much.

THeres something about that dorito the goes round and round thats hard to kick. Its like a bad addiction.

 

Sorry my bad - Seals aren't hard I meant the guides-hence the $12 dollar comment.

 

You're probably right about the "cost too much" comment, but I think it's already started in my area. I saw three way-overpriced examples for sale this past summer, and they weren't in desirable shape.

And no problem, MercuryMan -- I thought that's what you probably meant, but I was still a little worried that my whole problem might have boiled down to me not pressing the valve seals on completely.

 

Na, off can be hard-the seals were stubborn on a 750 Suzuki I rebuilt with a buddy. But it had sat a long time and they were brittle and dry. I just put a little A-lube on the new ones and pushed them on.

The guides are probably doable but I was paranoid about doing the drifting and getting them 'precisely' in place. I've seen seats cut but it's a multi-step process and I believe from what I watched-it's a bit of an 'art' that I don't possess.

 

Re: Frustrated - head gasket leak early after top end rebuil

Well, I let the motor set until now, mostly due to cold weather and lack of time. But I got the valves back together on the machine-shop freshened head, and the new rings are on the pistons (all ring end gaps and clearances measure within spec).

New problem: when I went to put the pistons on the conn rods, now I notice that connecting rod #2 has a detectable amount (1/32" or more) of slop side-to-side that I can move it if I grab the top of the connecting rod and wiggle. None of the other connecting rods are loose like that.

I don't feel looseness if I try to "lift" the rod from the motor, only if I cock it side-to-side.

I guess I'm asking since I have no experience with crank bearing issues, but how urgent of an issue is this? Should I button it up and ride, or is this a "split the case now and rebuild or else you're risking your life" kind of a thing?

 

The Pistons "Float" on the Wrist Pin.
Some side-to-side End-play is normal.
Once the Piston is installed within the Cylinder the Float ceases.

 

Re: Frustrated - head gasket leak early after top end rebuil

Just to clarify, Rick -- the con rod slop is where the large end is attached to the crankshaft. The pistons weren't even on yet when I grabbed the connecting rod and wiggled it side to side.

 

There'll always be a small amount of play as you describe in a plain bearing engine, since the "bearings" are actually supported on a high-pressure film of oil in use and have to have oil clearance between them and the crankpin. I'd be more worried about the ones that don't have any play tbh, perhaps would be worth checking again?

If you're unsure at all I'd advise taking the bottom end to your friendly machine shop and get their opinion since they seem to be enthusiasts & very helpful.

 

End float of 1mm or less is normal and preferable. Radial play along the rod or up and down play would need to be fixed.

It's good to hear that your back to wrenching-almost there and in time for warm weather. I've been in relative hibernation on my projects too for exactly the same reasons. Can't wait for more time so I can get back to busting by knuckles! I'm rebuilding a truck engine, tidying up several issues on the Virago, repairing the gel coat and interior on a boat, and upgrading the 550. All hopefully before July!!

 

Re: Frustrated - head gasket leak early after top end rebuil

Thanks guys. The end float isn't all that much (I'll be measuring actual here shortly), and I was just surprised that my manuals didn't really say anything about checking that (that I could see) during a top-end rebuild. There's definitely no up-and-down play, so I'm pretty satisfied to just button it up and get on with things.

Speaking of warmer weather, I'm wondering where it is. Here it is April 20 in Ohio, and I was bundled up against the snowflakes during my son's soccer game this morning! That's just wrong.

Sounds like you need more things to do, MercuryMan! :wink:

 

I would go to an Auto Parts Store and get a Strip of PlastiGuage.

You lay the Strip across the Crank Journal and tighten the Big End to secs.
Torquing the Connecting Rod squishes the PlastiGuage Strip from Round to Flat.
The PlastiGuage will be stuck to the Bearing or Journal when you remove the Rod to inspect the Measurement.

There is a Scale on the PlastiGuage envelope that measures the degree to which the PlastiGuage Strip was flattened.
The Width of flatness corresponds to a Measurement of the Close Tolerance Between the Journal and Bearing.

You compare the Measurement to the Factory Specs.
You will then know if the tolerance is too Tight or ... in your case ... too loose.

The Test will provide you with the Accurate Information needed to determine if the Standard Bearing is OK ... or you need to:
• Replace the Bearings
• Use a set of Oversized Bearings.

This YouTube Video show the process measuring an Engines MAIN Bearings.
The process is the same for Big Ends.

https://www.youtube.com/watch?v=rXp1vVtsp7s

 

Re: Frustrated - head gasket leak early after top end rebuil

Rick,
Not sure if I'm misunderstanding you or if you're misunderstanding me. My connecting rods are not removed from the crank, the engine has been in the frame the whole time, and I only have the top end apart. I have no way of checking bearing clearance (do I?) unless I actually pull the motor out of the frame, flip it over, remove the pan, and remove the connecting rods by unbolting them from the underside.

I do not have noticeable bearing slop up and down - only side to side, sliding along the bearing. And it's not much, but the others have none I can feel.

Now for a second important question. The 2 o-rings that go on the right oil galleries (under the cylinders) are different colors in my gasket kit: orange and black. Is that a mistake, or does the orange go on the front (exhaust side) or back (intake side) specifically?

 

I think he misunderstood where you were in terms of engine completeness... And I also *think* that the orange o ring will be Viton whereas the black will be rubber. Although I have no idea which would go where...

 

The Yamaha Motors Parts Diagram site lists those O-rings as:

Dowel Pin Gasket. (2)

They are the same.

 

Wow, where does the time go. Since the last few posts to me in this thread (almost 5 years ago!), I finished up the top-end rebuild, met my (now) wife, got married, sent my son to boarding school, bought an FJR1300, watched my son graduate, yadda-yadda. And I replaced the XJ's crankshaft end seals (which were also leaking slightly), and have ridden it for several thousand leak-free miles. Obviously, some of those things are more important in the scheme of things than others.

I guess since I found this old post I neglected, I wanted to give it some closure for posterity, and state that the extra head work I had the machine shop(s) do, in conjunction with replacing the top-end parts/gaskets again (and using the gasket seal spray SPARINGLY) has seemed to give me the results I was hoping for.

Thanks to all who participated in helping get me to that successful end.