Topic: Gasket sealants

[techy5025]

Guys,

I dismantled my engine today from the valve cover down
to the upper case.  I noticed that the head to cylinder and
cylinder to upper case gaskets seemed to only have sealant
on the top surface....had to scrape it off. The valve cover
gasket didn't seem to have any sealant on either side. Oil
was leaking out the head gasket...common I hear. 

I wonder if Honda only sealed one side?  The engine has never
been apart as far as I know.  So in putting it back together,
where should I put the gasket sealant...both sides or ? 

Also, what type of sealant is best from you that have had good
results?  There also seems to be a fair amount of carbon on the top
of the pistons and in the head valve cavities.....I assume it would be
wise to remove it to keep the compression ratio the same?

Jim

[bryanj]

NO SEALANT on the head gasket!!! Clean grease on all paper gaskets(NOT HEAD) and maybe on the "o" rings to hold them in. Genuine honda gaskets come with some sort of"sticky" on the gasket round the oil feed galleries and cam chain tunnel but aftermarket dont

[JHansen]

why no sealant on the head gaskets?

for sealing up my engine cases and such, had good luck with Hondabond, available at most Honda dealers

[techy5025]

Thanks for the replies.  I gather that the sealant will help stop leaks...used
sparingly...at the risk of breaking loose and jamming an oil passage.  I assume
that this would apply to any oil passage that is after the oil filter...which should
catch floaters.  Loose stuff in the case seal would probably be caught by the
filter I guess.

Is the head gasket the major worry....how about the valve cover and cylinder
base cover gaskets? 

Jim

[Lumbee]

...I think your head gasket is the main worry...I'm never seen one leak from the base gasket, and the valve cover seems to always get the stained/wet look with out ever really leaking.  I'm on my 3rd rebuild (3 diff. motors) now, and am batting 50% on leaking head gaskets, so I'm debating wether or not to use any sealer on this 3rd motor.  I did not use any sealant on the first 2.  I almost perfer a slight weap and the peace of mind of knowing I don't have any sealant residue in the motor over a sealed motor and possibly doing damage by getting debris in the motor.

You make a good point as it seems they did come from the factory with some sealant on the head gasket (on the bottom side).  The motor I'm tearing into now is a 77 750F w/only 15K miles, so I'm assuming I'm the first to tear into it.  I only has sealant on the area surrounding the cam chain tunnel, which is odd as I hear alot of folks recommend putting sealant around the oil pasages.

[dusterdude]

man,all this head gasket stuff makes me want to leave my engine alone.good grief.

[techy5025]

Well reading back over the "gasket sealant" threads, Terry seems to be the only one who
has personal experience with sealant killing an engine.

The "engineer" in me always wants to hear proof as the the "root cause" of failures.  I've
chased too many failures that were at first misdiagnosed.  In our case we don't have a large
budget so we have to go with the common experience.

Having been appraised of the dangers of too much of the stuff, I think I will go with a
carefully placed "thin" layer of the Yamabond 4 and hope for no leaks....and no seizures! 

Jim

[scondon]

I finally got a "no-leak" engine put together. Thiiiiiiiiin layer of Yamabond 4 around the 8 oil return holes. I even put a smidge on the sides of each knockpin gasket(75-78 750 engines?). More generously applied to the underside of the 6 "pucks" under the cam towers

   I think, more than anything else, that the APE Heavy Duty Cylinder studs kept this motor leak free as I have used sealant in the past and still got a leaky engine. Keep sealant far,far away from the oil feeds at the rear of the engine or fried cam and towers may result (from one who knows )

[Sam Green Racing]

Is that big motor up and running again Sean ?

Sam.

[scondon]

Is that big motor up and running again Sean ?

Sam.

 Yes indeed It's passed the 1,000 mile mark since putting it back together and not a "wet spot" to be seen. The only things collecting on the fins is rain,dirt and bugs

[Lumbee]

...the bike that has the leaky gasket is my daily rider.  I put a thousand miles on the bike a couple months back and the head didn't seem to leak on that trip.  However when I came back to my daily grind its leaking again.  I only live 5 miles from work which is a quck shot down the interstate.  In addition I go to the gym every day at lunch which is about a mile from work.  My theory is the motor isn't getting very hot on these short runs, and thus the weeping head.  Whereas on a long trip the motor gets hot and thus expands to tighten things up...

[edit] did I just say thus twice???

[Sam Green Racing]

No but you put 2 ands in front of your thus, looks like the 1st and should have been a hot.

[Sam Green Racing]

Is that big motor up and running again Sean ?

Sam.

 Yes indeed It's passed the 1,000 mile mark since putting it back together and not a "wet spot" to be seen. The only things collecting on the fins is rain,dirt and bugs

Must be nearly time to put it on a dyno .
You know it makes sence, I'm dieing to know what it makes.

Sam.

[scondon]

...the bike that has the leaky gasket is my daily rider.  I put a thousand miles on the bike a couple months back and the head didn't seem to leak on that trip.  However when I came back to my daily grind its leaking again.  I only live 5 miles from work which is a quck shot down the interstate.  In addition I go to the gym every day at lunch which is about a mile from work.  My theory is the motor isn't getting very hot on these short runs, and thus the weeping head.  Whereas on a long trip the motor gets and and thus expands to tighten things up...

[edit] did I just say thus twice???

 Also, the oil pumps at a greater pressure until it gets hot. Usually about 10-15 minutes of riding for me.

Must be nearly time to put it on a dyno .
You know it makes sence, I'm dieing to know what it makes.

Sam.

 I might have the other bike up and running before this one sees a dyno. I've been chasing ghosts between carbs and ignition, can't quite figure why it's not getting all the power it should. With everything clean and new it goes "too fast", then after daily riding it settles back to about 80-90% of potential. I changed EVERYTHING when I put this bike together so there's much for me to learn in troubleshooting it.

 BTW Sam, when ARE ya gonna get yours finished?

[Sam Green Racing]

That's a sore point at the moment Sean.
We got held up waiting for one thing and another, then the guy that Chris wants to build the motor for him has to much work on.
So after me bailing him out to the tune of $1700.00 to keep him on track for this season, he seems to be content to sit and wait even if he misses out the whole year.
To say i am pissed off is an understatement.

Sam.

[Lumbee]

sam...corrected...

...good point on the oil pressure Scon...

[scondon]

That's a sore point at the moment Sean.
We got held up waiting for one thing and another, then the guy that Chris wants to build the motor for him has to much work on.
So after me bailing him out to the tune of $1700.00 to keep him on track for this season, he seems to be content to sit and wait even if he misses out the whole year.
To say i am pissed pff is an understatement.

Sam.

 Damn, now I'm pissed too   Send it to me, I'll get it done for ya. Should only cost a few thousand pounds to ship, right?

[Sam Green Racing]

I would have carried on helping him and brought Mike over for a working holliday, as it is he wants this guy over here do it.

I think for the rest of this year and in future i'll be spending my money on my own pleasures.

Sam.

[Sam Green Racing]

sam...corrected...

Just having fun Mark.

[MRieck]

I would have carried on helping him and brought Mike over for a working holliday, as it is he wants this guy over here do it.

I think for the rest of this year and in future i'll be spending my money on my own pleasures.

Sam.

My oldest son and I were prepared to go at your command sir. It will be another time as I'd like to meet many of the folks who have helped me and vice versa. A fine bunch here that's for sure. Sean...I want to here about that "real" head I did for you.

[Sam Green Racing]

I more or less told him that, thats what pissed me off, that and the financial help I had given him waisted.

Sam.

[scondon]

Sean...I want to here about that "real" head I did for you.

  You'll be happy to know that work has begun on the project. 7 weeks of rain and a nasty 10 day cold has kept me from making any progress, but I'm currently getting the front end, brakes, and rearset controls sorted out. Most of the parts have been gathered and I plan on having the bike stripped down by the end of the month. Hoping to be having fuel flowing through that head all summer long  

  This bike will definitely get on a dyno.

[Sam Green Racing]

How many bikes have you got ?

I thought the one that was leaking was the 836 that Mike ported for you.

Do I take it you'r building another one ?

Sam.

[scondon]

How many bikes have you got ?

I thought the one that was leaking was the 836 that Mike ported for you.

Do I take it you'r building another one ?

Sam.

  You bet The first one was a stock '78, beefed up, but still a daily rider. This next one is starting life as a '78 but will be a hodgepodge of parts from different bikes. The engine will be much the same as the last with the exception of a "better than new" head with the "works"(oversize valves,stage 2? porting, and springs/retainers that can withstand higher rpms). Keihin CR carbs and "Crazy Monty Campbell" X-pipe exhaust to finish things off. I expect this thing to breath fire

[Sam Green Racing]

So the black one in your avatar is not the 836.

Sam