Topic: Newbie calling... Leaking head gasket.

[Henrik Vik]

My K2 has developed a leak on the left side of the cylinder head. I am in the process of taking out the engine and fixing it while the temperature is preventing me from doing any riding.

My question is this:
Should I order a new head gasket, or just taking the chance that re-torquing the bolts would seal it up?
If I order new gaskets, should I change the bolts to HD bolts while I'm at it? Would that prevent me from needing to re-torque the head after, say a 1000 miles? Or would the use of HD bolts also require re-torquing? I would hate to pull the engine again just to tighten up some nuts .

Thanks for any input

[Gordon]

While you have the engine out you really should go ahead and replace all of the top end gaskets and seals, unless you feel like pulling it out again in a couple of weeks when you realize that it's still leaking. 

[Henrik Vik]

Thanks. That was really my line of thought as well. Just a little put off by the idea of taking the cam out. Never done it before. Lots of work? Would I need to degree the cam again on reinstall? Seems a little intimidating... But if its the way to go, that's how I'll go it.

[Gordon]

An unmodified stock cam sprocket can't be degreed.  It can only be mounted to the cam shaft in one position.  The process of removing and reinstalling the head is not really all that difficult or technical, just follow all the steps to the letter.  When you get to the point of putting the sprocket and chain back on the camshaft look in the engine FAQ for an explanation with pictures of the correct order to put them back on so it all slides together easily. 

[jeepster]

Are you 100% sure it's the head gasket? Could be coming from the valve cover and dripping over the fins.

My K2 has developed a leak on the left side of the cylinder head. I am in the process of taking out the engine and fixing it while the temperature is preventing me from doing any riding.

My question is this:
Should I order a new head gasket, or just taking the chance that re-torquing the bolts would seal it up?
If I order new gaskets, should I change the bolts to HD bolts while I'm at it? Would that prevent me from needing to re-torque the head after, say a 1000 miles? Or would the use of HD bolts also require re-torquing? I would hate to pull the engine again just to tighten up some nuts .

Thanks for any input

[Henrik Vik]

An unmodified stock cam sprocket can't be degreed.  It can only be mounted to the cam shaft in one position.  The process of removing and reinstalling the head is not really all that difficult or technical, just follow all the steps to the letter.  When you get to the point of putting the sprocket and chain back on the camshaft look in the engine FAQ for an explanation with pictures of the correct order to put them back on so it all slides together easily. 

Thanks for this info. I'll go ahead and do it. Would changing the cam chain be a good idea, while I'm at it? How can I see if it is worn?

Are you 100% sure it's the head gasket? Could be coming from the valve cover and dripping over the fins.

I'm pretty sure. Have wiped down excess oil and noticed its protruding through the head and the cylinder. But will change the valve cover gasket at the same time.

Any opinion on the HD bolts? Is it so that they don't need re-torquing as the stock ones does?

[Gordon]

Replacing the chain tensioner parts probably wouldn't be a bad idea if they're the originals.  The roller and chain guide get worn down and also get hard and brittle with age and use.  If they're not completely shot then there's a good chance that the chain itself is still fine, but you can check it by pulling up on it at the top of the sprocket.  It shouldn't lift up much at all.

The head does not need to be retorqued.  Some do it, but many here don't, including myself, and have never had any issues.  I've never used heavy-duty studs so I don't have any opinion on them.  Do a search from the main forum page for retorquing and hd studs and I'm sure you'll come up with several threads on both subjects with plenty of opinions.  While you're at it do a search for using sealant on gaskets.  That's another one of those topics where plenty of people have differing viewpoints, none of which are necessarily right or wrong, and you'll have to decide for yourself which camp you're in. 

[Yoshi823]

There is no gasket on the rocker cover...just use something like Hylomar-good enough for Rolls Royce...good enough for me anyway.

Pops Yoshimura  used to use spray on copper grease on head gaskets, but I have used a thin smear of Copaslip either side of graphite headgaskets and NEVER had it go again.

You'll need a manual...I have always used the Haynes here in the UK but the Clymer is good as well.

[Gordon]

There is no gasket on the rocker cover...

Yes there is a gasket for the valve cover. 

[Yoshi823]

I seem to remember a seal that sits in it's own groove in the rocker cover....

[Gordon]

I seem to remember a seal that sits in it's own groove in the rocker cover....

Wow.  Are you kidding me with that?  Even if it were an o-ring, an o-ring is still a type of gasket.  Regardless, that's still incorrect.  The 750 has a paper gasket between the valve cover and cylinder head.  I'm trying to make sure this guy has good information to go off of.  Why are you trying to confuse things?     

[Yoshi823]

 

Sorry all.......I feel such an idiotplonker...I have the Honda 550 manual out in front of me after answering someone else's question...and I was soooo fixated on the 550 that my head was in the wrong gear.

Of course there is a paper gasket on the 750 cam cover...I had my 750 engine apart often enough.

So apologies all around. I'll learn to put away the manuals before starting to read other posts in future.

[MötleyRöx]

I was soooo fixated on the 550 that my head was in the wrong gear.

I think your head was actually in the wrong book. 

[Deltarider]

Quote from: jeepster on Today at 12:32:24 pm
Are you 100% sure it's the head gasket? Could be coming from the valve cover and dripping over the fins.

I'm pretty sure. Have wiped down excess oil and noticed its protruding through the head and the cylinder. But will change the valve cover gasket at the same time.

Most "head leaks" origin from the O-rings around the oil passages.

[Yoshi823]

I think that it was because starxz only talked about his K2 that it didn't click that it was the 750. It was only when I retraced the post and looked at the picture that I realised what a plonker I am (readers in the USA might want to You-Tube 'Only Fools and Horses' this one).

[Henrik Vik]

Quote from: jeepster on Today at 12:32:24 pm
Are you 100% sure it's the head gasket? Could be coming from the valve cover and dripping over the fins.

I'm pretty sure. Have wiped down excess oil and noticed its protruding through the head and the cylinder. But will change the valve cover gasket at the same time.

Most "head leaks" origin from the O-rings around the oil passages.

I'll go ahead and buy a full gasket set. Will then change all the O-rings I can see. And every other seal I come by as well
I'll probably buy the Cyclex set. Seems to be the only complete set I have come by. Thought about buying their gasket sealer as well, called 3 bond. Don't know anything about it except from what it says on their site.

Sorry all.......I feel such an idiotplonker...I have the Honda 550 manual out in front of me after answering someone else's question...and I was soooo fixated on the 550 that my head was in the wrong gear.

Of course there is a paper gasket on the 750 cam cover...I had my 750 engine apart often enough.

So apologies all around. I'll learn to put away the manuals before starting to read other posts in future.

No worries I'm just appreciating that people are trying to help

[Henrik Vik]

Right. Just done some more reading in some other posts. More specifically this one: http://forums.sohc4.net/index.php?topic=28789.0. Hondaman states this:

Pat: you'll likely find that you want to replace the cylinder base gasket, because removing the head also disturbs this seal just enough to make it start leaking later, anyway. 

I did it many times the wrong way in racing, just to get through the next race, but it nearly always leaked unless replaced.

So I need to pull the cylinder off as well?

[MFHP]

Quote from: jeepster on Today at 12:32:24 pm
Are you 100% sure it's the head gasket? Could be coming from the valve cover and dripping over the fins.

I'm pretty sure. Have wiped down excess oil and noticed its protruding through the head and the cylinder. But will change the valve cover gasket at the same time.

Most "head leaks" origin from the O-rings around the oil passages.

Most engines I found leaking from the rubber nickels right beneath the cam towers. These are most likely to be hardened with age and slightly shrunk. They close the stud access holes in the head.

[Simpson]

My K2 has developed a leak on the left side of the cylinder head. I am in the process of taking out the engine and fixing it while the temperature is preventing me from doing any riding.

Hello starxz,
I have the identical issue you are experiencing.
This is my current state.


Very good compression, all tensioners look perfect, internal engine over all looks great

The question I ask myself is now:
-Do I retorque the studs and re-assemble
-Do I pull apart top end and replace all gaskets, seals and rings...

Due to overall health I might just re-torque studs.
Haven't made up my mind yet.

Seems to me if I loosen the studs, I would most certainly have to pull the entire top end apart to replace all gaskets.

[Gordon]

So I need to pull the cylinder off as well?

I always do.  It's much easier to do it while you already have the engine out anyway than to have to pull it out again later just to replace the base gasket. 

Doing all of the top end work at once also gives you a good opportunity to really get the engine nice and clean before putting the bike back together.

[ofreen]

Due to overall health I might just re-torque studs.
Haven't made up my mind yet.

Seems to me if I loosen the studs, I would most certainly have to pull the entire top end apart to replace all gaskets.

When you do the retorque, there's no need to loosen all nuts at once.  One at a time, back off each one 1/4 turn, then torque.  Typically when you loosen it, the nut will crack or pop suddenly and be loose.  When you retorque, the nut will turn farther. 

As I've mentioned before on the forum, my '75 750F was weeping at the head and base gaskets at around 53,000 miles.  I retorqued the head and the weeping stopped.  At 82,000 miles, I retorqued again when I had the engine out to replace the cam holder seals, though there were no leaks at that time.  I did it because the opportunity was there.  Still no leaks, now at 121,000 miles.

As others have mentioned, it the head comes off, replace the base gasket.  Pretty much a certainty the base gasket will weep if you don't.

[Duke McDukiedook]

I gotta ask, is it leaking a lot or just seeping a bit? These 750's were notorious about leaking from the word go. I would hate to see you pull the engine for a minor leak, but if it is a gusher, by all means pull and tear away.

Mine seeped from the day I bought it but not enough to lose a lot of oil or get my pants dirty so until it comes time to do something major I can wait.

[Simpson]

I gotta ask, is it leaking a lot or just seeping a bit? These 750's were notorious about leaking from the word go. I would hate to see you pull the engine for a minor leak, but if it is a gusher, by all means pull and tear away.

Mine seeped from the day I bought it but not enough to lose a lot of oil or get my pants dirty so until it comes time to do something major I can wait.

Mine leaks enough that when I come back from a ride there are oil streaks on the air filter covers. Blows back into the bike from the wind. Happened suddenly at the end of the summer.

[Simpson]

When you do the retorque, there's no need to loosen all nuts at once.  One at a time, back off each one 1/4 turn, then torque.  Typically when you loosen it, the nut will crack or pop suddenly and be loose.  When you retorque, the nut will turn farther. 

As I've mentioned before on the forum, my '75 750F was weeping at the head and base gaskets at around 53,000 miles.  I retorqued the head and the weeping stopped.  At 82,000 miles, I retorqued again when I had the engine out to replace the cam holder seals, though there were no leaks at that time.  I did it because the opportunity was there.  Still no leaks, now at 121,000 miles.

As others have mentioned, it the head comes off, replace the base gasket.  Pretty much a certainty the base gasket will weep if you don't.

I like your thought process. Thanks for posting.

[Henrik Vik]

I gotta ask, is it leaking a lot or just seeping a bit? These 750's were notorious about leaking from the word go. I would hate to see you pull the engine for a minor leak, but if it is a gusher, by all means pull and tear away.

Mine seeped from the day I bought it but not enough to lose a lot of oil or get my pants dirty so until it comes time to do something major I can wait.

Mine i just seeping a bit. After a couple of trips, you can see that the fins are wet with oil, but there are no runs.