Is this a sign of a failed head gasket?

[93Bandit]

On my 77 GS750, the exterior "seam" between the head and the cylinder block where the head gasket is, is dark with oil all the way around the engine. Is this a sign of a potential head gasket failure? I haven't been able to do a compression test yet and I'm not sure I'll be able to for some time. I'm in-between houses right now and don't really have a good place to work on my bikes. I intend to do a compression test once I'm able, but I thought I'd ask you guys what you think to help prepare myself.

 

[Nessism]

Yup. That looks like a gasket leak to me. Regarding a compression check, be sure to adjust the valves first and hold the throttle wide open with a hot engine.

 

[93Bandit]

If the general consensus is that the head gasket has failed, then I will probably skip the compression test and tear the motor down for gaskets. While I'm in there, I hope to install some 850 pistons and jugs if I have them by the time I get that deep into the bike build.

 

[Rich82GS750TZ]

To be more sure, you could clean it up, dry it well, then spray foot powder all around the valve cover gasket area, tach drive inlet, cam chain tensioner , and head gasket. Fire it up and see what gets wet where. Only cost you a can of foot powder spray if you don’t already have one.

 

[1978GS750E]

A compression test might take 15 minutes???? Why not do it and see the numbers before tearing into the engine?

 

[93Bandit]

If the general consensus is that the head gasket has failed, then I will probably skip the compression test and tear the motor down for gaskets. While I'm in there, I hope to install some 850 pistons and jugs if I have them by the time I get that deep into the bike build.

I forgot to mention the bike doesn't run. Needs the carbs cleaned.

 

[Cipher]

If the general consensus is that the head gasket has failed, then I will probably skip the compression test and tear the motor down for gaskets. While I'm in there, I hope to install some 850 pistons and jugs if I have them by the time I get that deep into the bike build.

I forgot to mention the bike doesn't run. Needs the carbs cleaned.

do the check
why friviously dismantle the top end without numbers?
aspire harder

 

[Nessism]

do the check
why friviously dismantle the top end without numbers?
aspire harder

If the head gasket is leaking the top end must come apart.

 

[Cipher]

If the head gasket is leaking the top end must come apart.

obviously but why not do the check
to measure is to have more than a zesty sig line

 

[1978GS750E]

Agreed Nessism. But wouldn't you want to get it running to see what else might be wrong in the engine or tranny before tearing into it? Or maybe it was running at some point, who knows?

 

[Nessism]

I'd split the whole engine. Parts are cheap enough to not worry too much about what you would find.

 

[uk gs nut]

Why not try a cylinder head re torque ?. It might help.

 

[Brendan W]

Torque check would be first on my list too. When mine failed it was between 1&2 on the front side. Large parts of the join were bone dry and I was losing a litre every 400 miles, boots wet.
Get the tank off and have a look at the valve cover gasket in between the cams and the chain tunnel area. A leak here can get out the front and run around the headgasket.

 

[Buffalo Bill]

Torque check would be first on my list too. When mine failed it was between 1&2 on the front side. Large parts of the join were bone dry and I was losing a litre every 400 miles, boots wet.
Get the tank off and have a look at the valve cover gasket in between the cams and the chain tunnel area. A leak here can get out the front and run around the headgasket.

Right, probably oil seeping from the timing chain cavity. The GS is 40 years ago engine tech, the gaskets seep.
But if your plan is to rebuild it anyway?moot point.

 

[93Bandit]

do the check
why friviously dismantle the top end without numbers?
aspire harder

If you had read my second post, you would have noticed that I'd like to do 850 piston/jug swap. That being the case, the engine will need to be torn down regardless. At this point, low compression due to a head gasket is moot.

obviously but why not do the check
to measure is to have more than a zesty sig line

Twice now you've attacked me in referencing my signature. Feel free to exit the thread at any time unless you have something positive to say. I appreciate any and all constructive criticism, however I believe you're being childish.

Agreed Nessism. But wouldn't you want to get it running to see what else might be wrong in the engine or tranny before tearing into it? Or maybe it was running at some point, who knows?

PO said it ran not too long ago. I put a battery in it and it almost fired but it's out of fuel. Also, I'm sure the carbs need a thorough cleaning. I have no reason to believe the engine has mechanic issues.

Torque check would be first on my list too. When mine failed it was between 1&2 on the front side. Large parts of the join were bone dry and I was losing a litre every 400 miles, boots wet.
Get the tank off and have a look at the valve cover gasket in between the cams and the chain tunnel area. A leak here can get out the front and run around the headgasket.

This was my second thought, I wondered if a leak at the chain tensioner caused the leak so I looked, but that portion of the head is actually drier than the rest of the engine. Its oily all the way around the engine, even the front. I'm betting on a failed head gasket.

 

[93Bandit]

I'd split the whole engine. Parts are cheap enough to not worry too much about what you would find.

That'll what'll I'll do.

 

[Big T]

Just as a side note, a compression test is not always a good indicator of a bad head gasket on these motors.

The compression sealing rings can be fine, but the 40 year old seals around the oil passages can go bad, allowing the oil to ooze out, while the motor still operates perfectly.

 

[Cipher]

If you had read my second post, you would have noticed that I'd like to do 850 piston/jug swap. That being the case, the engine will need to be torn down regardless. At this point, low compression due to a head gasket is moot.



Twice now you've attacked me in referencing my signature. Feel free to exit the thread at any time unless you have something positive to say. I appreciate any and all constructive criticism, however I believe you're being childish.



PO said it ran not too long ago. I put a battery in it and it almost fired but it's out of fuel. Also, I'm sure the carbs need a thorough cleaning. I have no reason to believe the engine has mechanic issues.



This was my second thought, I wondered if a leak at the chain tensioner caused the leak so I looked, but that portion of the head is actually drier than the rest of the engine. Its oily all the way around the engine, even the front. I'm betting on a failed head gasket.

Had you read Nessism's sig line you'd know I was making fun of him not you.
But hey go ahead ignore sound advice and seek only approbation of your preconceived notions.

 

[Nessism]

What difference would a compression test make on an engine that needs to come apart?

 

[Guest]

wow its like its february around here or somethin'.