Ok to remove head nuts without removing cams [Head Gasket Leaking]

[D0wn5h1ft]

I replaced the head gasket on the '79 I picked up a couple month ago as part of it's restoration. Now it's leaking out of the back side of cylinder #1 or #2 and I want to retorque down the head. Obviously when I replaced the head gasket the first time part of the process is remove the cams, etc. but I am wondering if there's anything wrong with skipping that step and just taking off the cam nuts, lubing them like it indicates in the manual and putting them back down to get better readings on my torque wrench (so it's not the torque + the resistance on the threads). I won't be moving the heads at all just properly loosening the nuts (in order of course and in a two step process like it says), lubing them with high temp lubricant (graphite or whatever I find at the store), and tightening them back in the appropriate order.

I would love to be able to skip the steps of removing the cams again if at all possible.

[IanDMacDonald]

I'm trying to visualize all of the parts at play here loosening those cylinder head nuts. Because the valves, etc., are part of the head, I cannot see any damage done. I'd think the only thing at play would be tension on the cam chain. I mean, the head does not really lift if at all loosening the nuts. However, I'm curious to know if it's really a torque issue and instead a bad gasket. How do you plan on fixing the leak? A simple torque? In the time it took to get all of these responses, you could simply remove the cams, stay organized and methodical, and save yourself any grief if something messes up.

[D0wn5h1ft]

True but I know I got it the timing right when I put it back together and I really don't feel like rolling the dice again by taking the cams out. It wasn't the worst thing I've had to do but it was enough of a pain that I don't want to do it again. Also, the battery is charging so I was hoping I'd have my answer by the time it was done . I don't think the gasket was bad since it was the one I got from you but who knows? I think the more likely culprit is that the head nuts are putting up a fight and therefore my torque numbers are off. Ideally, what I should have done if I wasn't so stubborn is when I had the heads off taking a die to the threads of the head/cylinder bolts and replacing/retapping the head nuts to ensure that they would go back together nicely.

All I know is that I'm going to respect the torque values this time because I'll be a monkey's uncle if I break off another bolt in that d**n engine.

I think you're right about loosening the head nuts, though. If I'm not moving the heads it shouldn't be a problem at all. I'm going to see if I get any "No, don't do that"s here in the next few hours otherwise I'm just going to go ahead and do it.

[IanDMacDonald]

No! What you should do is be patient and wait Gabe! U want to find out what impatience gets you? Read some of my threads. It's after 7p, and it's getting late. Get your cookies and milk and wait for everybody to see the thread before you jump on anything. If everyone says no biggie, go ahead, then at-least you learned that it's okay to do.

[mack]

Leak

Are you sure that it's leaking at the back of the cylinder head. Leaks at the cam chain tensioner tend to blow back and appear as a leak in the spot you've indicated. Post a picture of both the CCT and the area you see the oil.

[D0wn5h1ft]

It's not leaking oil, you can see little puff of vaporized gas coming out of the seam between the cylinder case and head. Also, that's not my engine it's just an example of where I'm talking about.

[Stoners420time]

not sure

Is it your carb holder poss.? But all the bike's and car's I've worked on I think that you will be ok , yet I'm a young 43 so I'm gonna keep posted here to read more feed back

[CaptonZap]

I can't find a specific statement in the Clymer manual, but most specs call for clean dry/ lightly oiled threads. Lubing them with extreme pressure lubricant's would allow more stretch for a given torque than the bolt could stand without stretching or breaking. The Yamaha manual for the XJ states that all torque values are for clean dry threads, unless otherwise stated. There is no lube called for on the head bolts
The pros use stretch measurement instead of nut torque, since that is ultimately what you are trying to achieve, but with the average home shop equipment, that is problematic. Use the manuals specified torque setting, noting the reduced value for the two lower nuts.
If your threads were booger ed, naturally you should run a chasing die down them.
Puffing gas doesn't sound encouraging, but give it a go, you may luck out.
Good luck, CZ

[skids]

Very good comments. Tension can not be directly measured with a torque wrench! If this release of pressure at the head gasket was noticed right away, the gasket may still be OK.

[D0wn5h1ft]

Very good comments. Tension can not be directly measured with a torque wrench! If this release of pressure at the head gasket was noticed right away, the gasket may still be OK.

The bike hasn't fired up as of yet. I'm not getting good enough compression, due to the leak, on the #1 cylinder for it to start. Wore out a battery trying to get it started but I'm going to wait until tomorrow to pull the head nuts and torque them back down again and hopefully get a good fit this time.

[natemoen]

Why not just loosen and retorque the head?

[trbig]

I don't see any problem with it, but I would loosen the holding screw for your cam chain tensioner so it can move if it needs to, but the most important thing is to make sure you loosen those little 12mm nuts on the bottom side of the head on the front and back BEFORE you loosen the top nuts.

Just make sure when you torque it again that you do it in order like the manual states, starting in the center and working your way out. Don't forget to re-torque again after it has gotten to operating temps the first time, then cools.

[GLoweVA]

It's not leaking oil, you can see little puff of vaporized gas coming out of the seam between the cylinder case and head. Also, that's not my engine it's just an example of where I'm talking about.

If you're getting "puffs" then that's the cylinder pressure leaking past the 'seal' on the gasket.
I had one fail on me:



I was getting puffing too and lost compression in #1 cylinder. Unfortunately I rode her home and ended up burning a hole in #2. (and 4 as well)

You may be able to get by with retorqueing the head nuts, but if you still get the puffing after that, sorry to say, but the heads got to come off.

[D0wn5h1ft]

I just replaced the head gasket so I can't imagine that the head gasket is damaged, only that the head needs to be re-torqued because it didn't make it down properly the first time. I'm goin to give it a shot and see what happens

[Outster3]

My take on the matter

Hi, it's a while since I posted.
I've rebuilt 3 of these motors along with transmission rebuild.
1 thing I can tell you that I've seen is that you can have an uneven surface on your head(s). You may thing it's flat and even with a straightedge will appear to be true, it may not be. It's important to obtain a virgin surface before assembly.
Torgue all head bolts in a correct order and the correct spec.
The manual for these bikes are only good for certain bits of information otherwise they are worthless in my opinion. If you want a good running bike for years to come, math is something you need to become good with. People may disagree with me. But math is what will make fuel/ ratios correct, engines not leak , timing to be correct, gravity fed fuel correct , back pressure amounts correct and finally a bike to ride true.

You can have an oil leak no matter what you do because in the early years of Japanese engine design they were bad about having porous engine blocks that were soft and unable to be punished . They had there eyes set on being fast on the short track to prove something.

I have worked on and rebuilt hundreds of bikes for myself and others. From American made Indians, heritage , Harley to jap specials . Crotch rockets and cruisers. I don't claim to be an expert but I've toyed and tried enough with in inline 4s to be able to resolve just about any issue I've encountered.