Topic: MLS Gasket leak after top end build. Repair questions. Solved!!

[albertaboy]

CB 750K5
So I didn't get much more than 3 miles into a shake down run around the neighborhood and I have a head gasket leak. Enough to spatter my boot with oil. Lots of smoke as oil burned off the cooling fins.  I could see oil bubbling at the MLS head gasket. 

Questions I'm hoping to get answers for:
1. I wonder about the compatibility of an MLS gasket with 8 rubber o-rings (thick one) around the metal dowels for the cylinder studs. I've found no definitive answer on the forum. I've read they're not required with an MLS gasket but I had put them in anyways as there was no argument that they would cause a problem.  As my head and cylinder were decked, using a straight edge, I made sure the metal dowels cleared the surface.

2. The next controversy was whether to lube the cylinder stud nuts for torquing. I have HD studs and I torqued the nuts dry.  Fortunately, I have a frame kit and I've striped the top end tonight down to where I'm ready to re torque.  Keep in mind, If I pull the head, will the base gasket be disturbed as,  this engine has been heated up about 4 times now.

3. After I torqued the head the first time, I then waited 24 hrs and re torqued, I proceeded to then break a cam tower bolt and had to remove the head to have a machine shop remove it. Once I replaced it, I torqued and waited 24hrs again to re-torque. Did I ruin the MLS gasket? 

4. On a re-torque, does one loosen all 16 nuts in sequence then re -tighten in sequence or does one loosen just one nut and tighten that nut,  one at a time.

In summary, I need to know if I should remove the 8 thick o-rings,  torque the studs dry or lubed and with what, and can the MLS gasket be reused, and explain the procedure to just simply re-torque.
   
 Thanks for you suggestions as varied as they may be. 

**Edited because guys had asked**
-head and cylinder surfaces milled flat
-cylinder was bored to 836CC or 65 mm
- The MLS gasket used had the large holes to accommodate the dowels and packing o-rings
- On the second try, the MLS gasket still leaked after dowels and o-rings removed and with nuts re-torqued, threads wet with oil .
-Positioning dowels had been ground sufficiently for clearance.

[PeWe]

Which bore do you have? 836?

The MLS gasket I have home (Cycle X 836) has small holes where the 8 o-rings and dowels were placed.
- NO o-rings or dowels to be used with this gasket. Same with Cometic fiber gasket, small holes = no 8 fat o-rings with dowels.

MLS gasket must have very smooth surface. I sanded my head and cylinder with 280-400 grit to remove all scratches. I used the kitchen table where I had a flat board mounted. I did not trust the flatness of the parts so I changed my mind and used Cometic fiber instead.
Last gasket sprayed with head gasket copper spray on both sides, but not around the outer 2-3mm edge of mentioned oil holes, I used the fat o-rings as cover when spraying. I did not want excess spray to be direct hit by oil flow and end up in wrong place.

Yamiya750 sell 836 (65mm) head gsaket with the big holes to be used with the 8 dowels and fat o-rings. This is thicker than Cometic fiber (less compression). I might use this next time. Or the gasket from the site below, very cheap gasket.
This kit has the gasket with bigger holes too: (You can order the gasket as spare)
http://www.ebay.com/itm/69-77-HONDA-CB750K-836cc-65mm-BIGBORE-PISTONS-KIT-W-HEAD-GASKET-CI-CB750KBB-/131286869602?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item1e914ea662

The MLS gasket can be reused several times. There is a thread where people share their experiences.

HD-studs should not be over torqued, they can snap (I know). Max 22.5 ft lbs. Stay under just for sure when your tool might show wrong. Dry studs will cause more friction and less force pressing the parts together. I should have lightly oiled and torque 20-21 max.
The good thing with HD studs is the hardness with much less flex than std. But will snap easier when over torque. Honda std studs show very early when they start to flex.

When re-torque.
Do the nuts one by one, starting from center and going outwards as usual. Release 1/4 turn, direct followed by re-torque to same as last time. I used 2 tools, one for release and the torque wrench for tighten the nut.
Do not forget the 4 6mm bolts under the rubberpucks and the 2 6mm bolts on each side of cam chain tunnel. The last one needed helicoil in my head.
 I re torque these after I have done the nuts

I removed the head without disturbing the base gasket when I was very careful to NOT lift the cylinder. Easy done when I have the frame kit too.

When you have the frame kit..  re-torque again after 300-600 miles. I did, several nuts were loose despite the previous 24 hour procedure.

Oil leak can occur due:
 to the rubberpucks under the cam towers. they ned to be sealed with avery thin layer against the seat in the head. Not too much, it will flow under the Cam tower where the small holes for oil to cam are located. (inner holes, 1 under each tower)

 if you have replaced the cam tower studs without sealing the threads.

EDIT: It's not fun to find out bad threads in th head after everything is done and tight without leak.
Valve cover bolts threads in head and cam tower stud was moving last time I reached close to max torque. I had to stop at minimum.  Need to fix this soon when I change cam. It's the center bolt on #2 so the head might need to be removed when the frame block the use of a drilling machine. It must be done properly as well, 90 degrees against the head surface.

[Bailgang]

If you can remove the cyl head without pulling the cyl jugs away from its base then then the base gasket should be fine. That's the problem I ran into when I installed a MLS gasket on my 550, the composite head gasket that I had previously installed on it was putting up a bit of a fight and the cyl jugs got pulled up just a bit from the base in the process. It didn't separate much so I thought I could get away with it but that was all it took to tear the base gasket and I had a leak there at the base shortly after getting it all together. I can't comment on your o-ring issue because mine was a 550 but I was able to re-use the MLS gasket twice until I got my base gasket issue sorted out.

[flybox1]

AB - you might also check out this thread when you reassemble:
http://forums.sohc4.net/index.php?topic=107040.0

+100

1. I omitted the dowell rubbers
2. no lube.  If you do, this changes your torque values.
3. you're ok.
4. torque in stages. I waited 8-10 hours between.  Loosen in reverse order of torque sequence, and then begin the retorque sequence again.

[PeWe]

4. torque in stages.

+10

About torque.. oil under nuts make a big difference. Friction will otherwise cause lower torque.
Real torque specification should be fine from stud supplier APE and Kibblewhite.
Which lubrication and torque range... It is not that clear. I used motor oil. I know from my job that Molycote 1000 is much more slippery and need less torque to reach same forces on the bolts keeping the parts together.

My guess is lightly oiled, 18-20 ft lbs.

[albertaboy]

PeWe  Yes, 836cc and I'm sure the MLS gasket is from Cycle x. (I had MRieck ship it with my order).
Cal- Yes, I had used all tips in BrandEn's post. I took the rubber o-rings as optional.
flybox1 and Bailgang, thanks for the tips and confirmation.

Thanks everyone for your suggestions.  I will carefully pull the head and try not to disturb the base gasket.... and remove those o-rings.  Last night I tightened the #1 nut and found it started to turn at about 15 lbs.

I suspect my preferred torque wrench is off. It is a used Stanley Proto that came with a Nist certificate of calibration that was only 30 days old when I got it. I unfortunately dropped it, despite trying to be so careful to not bang it around. I went ahead and used it anyways. But I've only used it on this engine.

I have a cheap ($100) clicker wrench that's brand new. It's for sure to be off.  So without learning to test calibration, I can't imagine trusting it.

I also have a beam style torque wrench.  I snugged it into my vice and I hung 24.49 lbs off of the handle and the pointer read 30 lbs.  The weight I used were two 12.5 lb weight lifting plates that I verified their weight on a commercial scale that I have.  Assuming the weight scale is correct.

I think I'll stick with the Stanley Proto again. .....   

[Dunk]

Can't comment on MLS head gaskets but I used a MLS coated base gasket and after maybe 100-200 miles it started weeping oil out the front. Normal fiber with metal fire ring head gasket is not leaking. I used HD studs torqued to 20 ft/lbs (too chicked for 22 with all the snapped studs I've read about here) with oil on the threads. Always oil threads for head bolts or studs. Dry and they will reach torque before reaching proper clamping force and will also be less consistent from one nut to the next.

I checked torque the next evening, but did not back any off. Did not understand the proper method of retorque which I believe is slightly loosen and retorque each nut one at a time in torque sequence.

In any event after my experience with the coated steel base gasket I'll be sticking with standard gaskets coated in gasket snot, which has always worked leak free for me in the past.

In your case I suspect orings may have caused a problem since your leak sounds quite large. You're talking the large rubber dowel orings? If the gasket did not have the larger holes to accommodate them I'd put my money on that being the primary cause of your gasket failure.

[flybox1]

vesrah gasket set, HD studs, permatex copper spray, torqued twice, in stages. no leaks....

[albertaboy]

Hey
I appreciate everyone's help.   In the mean time, I found a local distributor of CDI wrenches, a division of Snap-on that had a 3/8 drive 5-50lb clicker wrench for $120.00  Why not, I need another wrench right?    It is NIST calibrated certified right in the box. If this is still made in China, I suspect made with more strict tolerances and quality of parts at least. I wanted more peace of mind that I had something more accurate. Now.... careful not to drop it. *** Edit- turns out, the wrench is made in the USA***

Regarding torquing the cylinder stud nuts dry or lubed. My HD studs and HD nuts came from Cycle X- I bought them directly a year or better ago.  I just realized I've never heard what Cycle X had to say about the topic.  So, I just telephoned Cycle X and Ken said to torque with high temp grease.  Just thought I would add to the debate but at least the information comes from a well known source.  Thoughts?

[iron_worker]

I've also had trouble with leaks with the MLS gasket ... twice now. My leaks haven't been that bad but just enough for me to get some drops on my side covers when I'm going down the high. Just enough to piss me off. ha

Things I may have screwed up:

1) Only went to 18ft*lb because I had a questionable repaired thread for my studs...got skeered.
2) My Princess Auto special torque wrench may not be accurate.
3) I didn't use any lube for the threads. This would significantly reduce the amount of actual clamping force I'm getting.
4) I also had to pull my head off because of a stripped cam tower bolt (sounds like our experiences are similar lol)

Some things I did right:

1) Had the head and cylinders machined ... both times
2) Didn't use any rubber "packing" as per Ken's orders at CycleX. (Only need the o-rings on the two center studs on the pressure feed galleries.)
3) Torqued in stages.
4) Waited 24hr and retorqued. (one loosened all the way and then fully retorqued, go around like that in sequence)

Looking back I'm thinking between only going to 18ft*lb dry torque is probably my main issue. I'll be going back in to try again eventually but probably not this winter. The leak isn't bad enough to really cause much trouble ... just annoying.

IW

[albertaboy]

I've also had trouble with leaks with the MLS gasket ... twice now. My leaks haven't been that bad but just enough for me to get some drops on my side covers when I'm going down the high. Just enough to piss me off. ha

Things I may have screwed up:

1) Only went to 18ft*lb because I had a questionable repaired thread for my studs...got skeered.
2) My Princess Auto special torque wrench may not be accurate.
3) I didn't use any lube for the threads. This would significantly reduce the amount of actual clamping force I'm getting.
4) I also had to pull my head off because of a stripped cam tower bolt (sounds like our experiences are similar lol)

Some things I did right:

1) Had the head and cylinders machined ... both times
2) Didn't use any rubber "packing" as per Ken's orders at CycleX. (Only need the o-rings on the two center studs on the pressure feed galleries.)
3) Torqued in stages.
4) Waited 24hr and retorqued. (one loosened all the way and then fully retorqued, go around like that in sequence)

Looking back I'm thinking between only going to 18ft*lb dry torque is probably my main issue. I'll be going back in to try again eventually but probably not this winter. The leak isn't bad enough to really cause much trouble ... just annoying.

IW

IW,
Good to hear from you and thanks for you tips.
Is there a proper orientation for the MLS gasket, up or down??  The grooves in mine appear more prominent on one side vrs the other?

[albertaboy]

I've also had trouble with leaks with the MLS gasket ... twice now. My leaks haven't been that bad but just enough for me to get some drops on my side covers when I'm going down the high. Just enough to piss me off. ha

Things I may have screwed up:

1) Only went to 18ft*lb because I had a questionable repaired thread for my studs...got skeered.
2) My Princess Auto special torque wrench may not be accurate.
3) I didn't use any lube for the threads. This would significantly reduce the amount of actual clamping force I'm getting.
4) I also had to pull my head off because of a stripped cam tower bolt (sounds like our experiences are similar lol)

Some things I did right:

1) Had the head and cylinders machined ... both times
2) Didn't use any rubber "packing" as per Ken's orders at CycleX. (Only need the o-rings on the two center studs on the pressure feed galleries.)
3) Torqued in stages.
4) Waited 24hr and retorqued. (one loosened all the way and then fully retorqued, go around like that in sequence)

Looking back I'm thinking between only going to 18ft*lb dry torque is probably my main issue. I'll be going back in to try again eventually but probably not this winter. The leak isn't bad enough to really cause much trouble ... just annoying.

IW

IW,
Good to hear from you and thanks for you tips.
Is there a proper orientation for the MLS gasket, up or down??  The grooves in mine appear more prominent on one side vrs the other?

I searched via google thinking other engine building arenas would have discussed this. Very little said so i decided it don't matter which way is up.  Some advocate spraying the gasket with copper spray despite cometic saying it doesn't need to be.  It's all a coin toss It seems.

[iron_worker]

I thought the gasket could only fit one way one with all the holes lining up?

IW

[70CB750]

I thought the gasket could only fit one way one with all the holes lining up?

IW

Yeah, only one way.

[iron_worker]

That may explain your substantial leak. Mine leaks but it's a very slow leak... not even enough get any on the ground.

IW

[albertaboy]

I thought the gasket could only fit one way one with all the holes lining up?

IW

Yeah, only one way.

That may explain your substantial leak. Mine leaks but it's a very slow leak... not even enough get any on the ground.

IW

I know there's only one way front to back (intake or ex), but (IIRC) I was able to flip mine over and choose which side  Of course I am sitting a work now so late afternoon tomorrow is the earliest I can get back there to check it out.  Been discussing with MRieck also, and he's confirmed there's only one correct way up and that putting the intake side towards the exhaust is impossible.

[iron_worker]

I think even flipping it that way there is only one way it can go.

IW

[albertaboy]

I think even flipping it that way there is only one way it can go.

IW

You are correct. MRieck stated so also in an email, and I've just come the garage to see for myself. It will go on but when you seat it all the way, the front and back cam tunnel bolt holes only line up one way.  At least I know that putting it upside down wasn't my problem.
Pewe pointed out that the o rings have to left out due to the hole size over the studs. Turns out there are two MLS gaskets, one with larger holes to accommodate the dowels and o-rings. I had the gasket with large holes.   
Now, I am left uncertain what caused my leak. Maybe as I torqued the nuts dry I didnt get enough pressure.  I am going to remove the dowels and o-rings anyways. Going to torque with a bit of oil and use the most accurate wrench I could afford.  I will use Hondabond around the oil return holes and ..... cross my fingers.

[iron_worker]

I used the o-rings on the two pressure feed studs (inner ones at the rear) but did not use the "packing" (cylindrical rubber pieces) on the oil returns. I'm thinking if I had torqued to the full 20ft*lb and used lube mine probably would stop leaking completely... hopefully.

IW

[BPellerine]

a guy down here who works as a mech had the same probs you guys are having and put up with the leak for a long time then he found his t wrench was out ,retorqed and all was well.bill

[albertaboy]

I took an extra step and sprayed mine with copper coat. Apparently not necessary but also can't hurt either. Day one torque complete and now awaiting till tomorrow to re torque and put it all back together.
We got snow here today but not enough to stick. If the temps warm up enough for a ride, I should be able to report by Thursday. I don't know why I live here.

[HondaMan]

My 2 cents: I ALWAYS oil the studs/nuts for anything that needs measured torque. If they are a little corroded, I wire brush the "male" threads and then use grease instead.

That's one of those things they taught us during the Apollo Program when I was in school. (Remember Moon Shots?) 

On these fancy gaskets that must crush a lot to make the seals, the correct torque is much more needed than on the old paper-fiber ones with goo smeared all across their faces. Those old-style ones sealed themselves shut after the 2nd time the engine reached temp. Those of you out there who worked on the old CL/CB72 and CA95 probably remember that: run it at least twice before giving it back to the customer, so it will be dry...

[PeWe]

Yes, I remember a head gasket with glue surfaces when my engine was 736cc. I think it was Honda original gasket. Lots of work to clean and scratch head and cylinder next time when open the head that was rather stucked together.

[albertaboy]

I used the o-rings on the two pressure feed studs (inner ones at the rear) but did not use the "packing" (cylindrical rubber pieces) on the oil returns. I'm thinking if I had torqued to the full 20ft*lb and used lube mine probably would stop leaking completely... hopefully.

IW

Good point, just to be clear for anyone reading this, I continue to use the two rear o-rings and the two long dowels up front on each side.

[albertaboy]

My 2 cents: I ALWAYS oil the studs/nuts for anything that needs measured torque. If they are a little corroded, I wire brush the "male" threads and then use grease instead.

That's one of those things they taught us during the Apollo Program when I was in school. (Remember Moon Shots?) 

On these fancy gaskets that must crush a lot to make the seals, the correct torque is much more needed than on the old paper-fiber ones with goo smeared all across their faces. Those old-style ones sealed themselves shut after the 2nd time the engine reached temp. Those of you out there who worked on the old CL/CB72 and CA95 probably remember that: run it at least twice before giving it back to the customer, so it will be dry...

I have oiled this time. Thanks for the confirmation. There is often conflicting advice in any forum. Seems like one just cant read enough and more than one argument seems convincing....
Im about to head out, do a second torque, put her back together and hope it stops snowing so I can go for a ride.