how best to reattach the spark plug gaskets to the head

[batever]

Hi, I'm looking to hear from someone who has actually done this task or at least who has talked to someone who has done it(no theory). A few of my spark plug gaskets got knocked loose while I was doing my valve lash adjustment. One of them is totally knocked off the head, a couple of them are breaking free but are still partially stuck to the head. I'll probably leave those couple alone because they are still in the right position on the head and once the valve cover is retorqued they will probably seal fine. (somebody correct me if I'm wrong).

It looks like the seals had no rtv or sealant originally, probably the new rubber ones just seat on the head and stick there I'm guessing. But now they've been broken free by my wrenching. (next time i'll use and offset 10mm wrench for the valve lash and that will avoid the whole issue--i was using a straight-handled 10mm and kept knocking into the spark plug gaskets as I was doing the job)

I'm planning on reseating/repositioning the one that broke completely free. How to best go about it? I am thinking, clean the seating surface and the gasket with brake cleaner on a rag, put a very thin layer of either red permatex (650F intermittent) RTV on the bottomn of the seals, or hondabond, seat it in the valve cover, then install the valve cover.

Does this sound like the right way to go? and which would be better, red RTV or hondabond, or something different.?


Thanks in advance for your help.

[C91BLX7]

If you are talking about sparkplug tube seals, just replace them, they should stay on the valve cover.

[batever]

yeah, I guess they are the upper sparkplug tube seals.

I don't want to buy a whole new set. When I took my valve cover off the seals were seated on the head, not on the valve cover.

so should I 1) take them all off the head, then maybe use some rtv to put them in the valve cover seating area?

2) or leave the ones that are on the head where they are, and put the loosened one into the valve cover seating area with rtv

3) least desirable from my point of view but of course I'll do it if necessary,buy a whole new set of them. If I do that, do I use RTV or just place them in the seating groove in the valve cover and torque the cover on.

It doesn't look like they ever had any kind of sealant on them. I'll go look at the valve cover again now, though.

thanks.

[Boost_Lee]

which seals are you talking about?

If you are just doing a valve adjustment, then you are prolly referring to the upper spark-plug round looking seals. They seal the valve cover to the top of the spark tubes. Those should be placed in the valve cover itself, then just make sure the mating surface is clean and you can use a tad it of rtv if you wish, although i dont think its that important. I believe they sell these individually at the dealer if you need only one, but you should be able to remove them from the top of the tube holes without damaging them.

If you are referring to the lower tube seals, then you gotta put on your rocker assembly again to do the valve adjustment

[batever]

No, it is the ones on top, no rocker arm removal required.

3 of them are still sticking to the head, one is completely free.

So pull them all off the head, seat them all in their valve cover seating grooves, and torque the valve cover on?

that makes sense to me. I might put a tiny dab of RTV in those seating grooves if the seals look like they might fall out during installation, but from what I'm hearing unless I need to hold them in place, I won't use any RTV.

[Losiracer2]

No, it is the ones on top, no rocker arm removal required.

3 of them are still sticking to the head, one is completely free.

So pull them all off the head, seat them all in their valve cover seating grooves, and torque the valve cover on?

that makes sense to me. I might put a tiny dab of RTV in those seating grooves if the seals look like they might fall out during installation, but from what I'm hearing unless I need to hold them in place, I won't use any RTV.

yeah its REALLY no big deal. just push them in those channels in the VC. When you removed the VC they were prob. on the machined surface of the rocker assembly right? well that's just b/c they probably formed a seal on there. What you can do to prevent that is take those gaskets, when you plug them back in the channels of the VC, put a drop or two of oil around the exposed part of them and they shouldn't do that anymore.

[Boost_Lee]

yep^

i never worry about those gaskets leaking

[batever]

thanks for your help. now I see what to do.

they were stuck on to the head so good I thought that's how they were supposed to be!

This is my first timing belt change I have done and I adjusted the valves too.

BTW, another question:

when my camshaft is perfectly aligned at TDC on cyl #1, i can never get the crankshaft exactly exactly exactly in line. The crankshaft timing belt pulley is always either 1/2 tooth shy of north or 1/2 tooth past north.

I don't feel any interference and can't conceive of how to get them to line up perfectly perfectly after tensioning. At this point, I'm assuming that's ok because I've done it like 8 times now, shifting the belt back and forth. I'm assuming there's a small amount of tolerance in there for the timing.

There appears to be no interference, as I've rotated the engine through all 4 cyls multiple times and all I feel is what I think is compression and release (although without sparkplugs in, how can that be? the air would go out the sparkplug holes. What is the resistance and release that I'm feeling?)

[Losiracer2]

thanks for your help. now I see what to do.

they were stuck on to the head so good I thought that's how they were supposed to be!

This is my first timing belt change I have done and I adjusted the valves too.

BTW, another question:

when my camshaft is perfectly aligned at TDC on cyl #1, i can never get the crankshaft exactly exactly exactly in line. The crankshaft timing belt pulley is always either 1/2 tooth shy of north or 1/2 tooth past north.

I don't feel any interference and can't conceive of how to get them to line up perfectly perfectly after tensioning. At this point, I'm assuming that's ok because I've done it like 8 times now, shifting the belt back and forth. I'm assuming there's a small amount of tolerance in there for the timing.

There appears to be no interference, as I've rotated the engine through all 4 cyls multiple times and all I feel is what I think is compression and release (although without sparkplugs in, how can that be? the air would go out the sparkplug holes. What is the resistance and release that I'm feeling?)

Yeah I had your same exact problem, but my cam gear was about 3 teeth off and my engine wouldn't fire up. So it does have some leeway to it. But don't go more than 3 teeth off, otherwise you'd prob. get piston to valve contact. The key is to have the T belt tension loose, then move the crank about 3 teeth CCW on the cam gear and then tighten the tensioner bolt up. That's how Hondafan81 explained it to me, iirc.

As for the resistance, that's normal, even w/ the plugs out, there is going to be some friction between the piston and sleeves when it moves back and forth.

[batever]

why do I feel tension and release when rotating the crankshaft by hand

As for the resistance, that's normal, even w/ the plugs out, there is going to be some friction between the piston and sleeves when it moves back and forth.

OK, friction I understand but this isn't friction--this is a cyclical tension and release: I don't understand why it feels like at every 90 degrees of the cranskhaft there's a buildup, then a RELEASE of tension.

I'm not super worried, as it has always felt like that, even when I first took the covers off and rotated the engine to see how it felt and watch everything move before I disassembled the belts etc.

I'm just curious what that buildup and release is. I always thought it was compression, but then I realized, "the spark plug holes are open so that can't be it!"

One thing I am thinking about is that maybe at some point in the piston's travel, either at the bottom of the cylinder, at the middle, or near TDC, there is less mechanical advantage for the crankshaft so it is harder to turn, then when the direction of the piston changes and it moves a little below TDC it starts to get easier again.. I'm guessing it's when the piston is at the bottom of the cylinder that there is least mechanical advantage for the crankshaft, for a number of reasons.

Actually, while I was rewriting this post I looked at my computer screen background image, which is of a DOHC 4 cylinder engine (probably not a Honda though):

http://en.wikipedia.org/wiki/Image:E...ovingparts.jpg

here's a smaller image,not as much fun to look at but it's animated (however, its crankshaft doesn't move clockwise like honda's do)

http://en.wikipedia.org/wiki/Image:Cshaft.gif


In this diagram, it looks like the #2 and #3 (pair A) pistons move up and down at the same time, while the #1 and #4 (pair B) cylinders are offset what I am guessing is 180 degrees averaged from the #2 and #3 pistons. The pair B pistons are slightly offset from one another and I am guessing they perfectly balance one another on either side of bottom or tod dead center. When pair A is at TDC, pair B is at BDC. (don't know if my Honda SOHC is exactly the same, but it can't be that different).

In pair A at TDC, the #2 and #3 pistons, one of them has to be on the compression stroke and one has to be on the exhaust stroke. But they move together, and at both the top and the bottom of their stroke there is a "dead point" where the crankshaft has no mechanical advantage whatsoever. It's at this point where momentum and the action of the firing cylinder must work to keep the piston moving.

I'm guessing what I'm feeling when I spin the crankshaft is the resistance at these "dead points." then the release is when finally there's enough torque/leverage to move the piston more easily. At operating speeds the dead point wouldn't be a such factor because of the momentum of the crankshaft I'm guessing. But at hand cranking speed it's very noticeable.

I'll have to take note as to when exactly the tension builds up by looking at the camshaft pulley position next time I rotate the engine by hand. To work on this theory.

On this engine diagram, when pistons 2 and 3 are at tdc, numbers 1 and 4 are at or very nearly at bottom dead center. ( one and 4 are slightly offset from one another by about ten degrees, as well. I guess this smooths out the crankshaft motion).

Each 90 degrees of crankshaft rotation moves a piston that is at tdc all the way to bottom dead center, and vice versa. So you would feel the heavy resistance as all the pistons approach and go slightly beyond their bottom dead centers and their top dead centers, then relatively free movement until they are all again at a bottom or top dead center. All of the pistons in this engine diagram are at their dead centers pretty much close to the same time.


It feels like "turn turn turn--freely, for most of the 90 degrees of crankshaft travel--then it tightens up for maybe 10 or 20 degrees of travel, then releases. Again, I'll have to pay better attention for where exactly in the cycle the tension feel and the release feel is.

Ok, i think that's it! What do you think?

Does anyone else want to chime in?

[Losiracer2]

But I don't understand why it feels like at every 90 degrees of the cranskhaft there's a buildup, then a RELEASE of tension.

I'm not super worried, as it has always felt like that, even when I first took the covers off and rotated the engine to see how it felt and watch everything move before I disassembled the belts etc.

I'm just curious what that buildup and release is. I always thought it was compression, but the spark plug holes are open so that can't be it.

One thing I am thinking about is that maybe at some point in the piston's travel, either at the bottom of the cylinder, at the middle, or near TDC, there is less mechanical advantage for the crankshaft so it is harder to turn, then when the direction of the piston changes and it moves a little below TDC it starts to get easier again..

I'll have to take note as to when exactly the tension builds up by looking at the camshaft pulley position next time I rotate the engine by hand. To work on this theory.

It feels like "turn turn turn--freely, for most of the 90 degrees of crankshaft travel--then it tightens up for maybe 10 degrees of travel, then releases. Again, I'll have to pay better attention for where exactly in the cycle the tension feel and the release feel is.

It's one thing I'd like to understand better.

well also consider that every 90* rotation, A cylinder is at TDC, 1-3-4-2. So the piston stops at the top and then goes back down. That could be causing the resistance. I really don't know the exact specifics of all the parts but I can visualize it and it makes some kinda sense to me. But again, that shouldn't be anything to worry about, b/c remember, when the A/F mixture ignites, that combustion pushes the pistons down and rotates everything, and also remember that oil is being squirted, when all this is going down, so I would think friction would be less during the period when the engine is actually running. But that's about as far as I'm gonna go lol, I'm already WAY off topic from your original post. If you want to know why then I'd prob. start a new thread in the tech. section or just research about it.

[evil_demon_01]

Rocker gear causes the resistance - The valve springs are trying to resist being compressed by the cam lobes. Its very normal
Btw sparkplug tube seals are very cheap - even from the dealer, Just replace them and the rocker cover gasket as well.

[batever]

Ok, Losiracer2 you beat me to the punch while I was reediting my huge theory above (check it out if you have the time--it's neat and it's got some cool links too).

Yes, the 90 degrees of crankshaft travel between piston dead centers that you pointed out was what I was thinking too. except, now that I've researched it, i'll point out that you wrote that every 90 degrees of crankshaft travel one piston is at TDC, which was a very helpful point that turns out to be basically right--but which could be corrected to say "every 90 degrees of crankshaft travel, two pistons are at (or very close to) TDC. (while at the very same time the other two pistons are either at, or very near, Bottom Dead Center).

I feel happy to have learned that much, so thank you.

Then, evil_demon_01 pointed out that most of the resistance is from the springs resisting the motion of the rocker arms against the valves during valve opening. Which now that he says it is so obvious i'm like "d'oh" I can't believe I overlooked that! Those springs are super strong, I can't even move them with my bare hands. They would count for a lot more resistance than just the dead center issue with the pistons. Actually, I remember reading at one point that compressing those springs uses up a very significant amount of the available energy of an internal combustion engine.

So, now that you pointed it out, evil_demon_01, I'm realizing that the dead center part of the piston travel actually occurs in the "free movement" part of the crankshaft motion, while the resistance I feel when rotating the crankshaft is actually the resistance by the valve springs to the rocker arms.

It's true that this thread has gone way off topic but these things happen--and it's interesting stuff.

Thanks for your input, guys. I appreciate it. (and if you've got time, check out my little exploratory mini-essay three posts above with the engine diagrams and animation link--I had fun writing it. Like everything, it's obvious stuff once you know it, but thinking it through for the first time and also with your help is fun. And then I discover that, as usual, I'm wrong or only partly right and need to revise my understanding!)

[evil_demon_01]

Ok, Losiracer2 you beat me to the punch while I was reediting my huge theory above (check it out if you have the time--it's neat and it's got some cool links too).

Yes, the 90 degrees of crankshaft travel between piston dead centers that you pointed out was what I was thinking too. except, now that I've researched it, i'll point out that you wrote that every 90 degrees of crankshaft travel one piston is at TDC, which was a very helpful point that turns out to be basically right--but which could be corrected to say "every 90 degrees of crankshaft travel, two pistons are at (or very close to) TDC. (while at the very same time the other two pistons are either at, or very near, Bottom Dead Center).

I feel happy to have learned that much, so thank you.

Then, evil_demon_01 pointed out that most of the resistance is from the springs resisting the motion of the rocker arms against the valves during valve opening. Which now that he says it is so obvious i'm like "d'oh" I can't believe I overlooked that! Those springs are super strong, I can't even move them with my bare hands. They would count for a lot more resistance than just the dead center issue with the pistons. Actually, I remember reading at one point that compressing those springs uses up a very significant amount of the available energy of an internal combustion engine.

So, now that you pointed it out, evil_demon_01, I'm realizing that the dead center part of the piston travel actually occurs in the "free movement" part of the crankshaft motion, while the resistance I feel when rotating the crankshaft is actually the resistance by the valve springs to the rocker arms.

It's true that this thread has gone way off topic but these things happen--and it's interesting stuff.

Thanks for your input, guys. I appreciate it. (and if you've got time, check out my little exploratory mini-essay three posts above with the engine diagrams and animation link--I had fun writing it. Like everything, it's obvious stuff once you know it, but thinking it through for the first time and also with your help is fun. And then I discover that, as usual, I'm wrong or only partly right and need to revise my understanding!)

Anyway we can help, we will
This can be seen when you have the cambelt off and everything is lined up (#1 at TDC) If you rock the cam back and forth, You can feel it "snap" back and forth as you go each side of TDC, due to the tension of the springs.