Honda CX 500 Forum banner
1 - 12 of 12 Posts

·
Registered
82' cx500c custom
Joined
·
14 Posts
Discussion Starter · #1 ·
Rode the bike about a mile down to the mailboxes and noticed a power loss and a boggy idle. Ran home on the bike and noticed coolant leaking out of the head cover gasket. I'm assuming it's a blown head gasket but have yet to tear into the top end. Anyone have any advice of things to watch out for that isn't covered in the service manual when replacing the head gasket?
 

·
Registered
CX500EC Eurosport 1982
Joined
·
61 Posts
When you clean up the engine case end, block up the coolant jacket with some old rags or blue garage roll and then when you pull it out do it swiftly and pull it away from the exposed cylinder so that any crud is flung away from the piston/cyl. Cover the push rod channel while doing this too.
 

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,475 Posts
By "head cover" you mean the valve cover, right?
Unless something is very wrong there should not be coolant in the valve cover (not to mention that the rubber seals should keep anything that is in there in). Your first step should be making absolutely sure where the leak is.
 

·
Registered
82' cx500c custom
Joined
·
14 Posts
Discussion Starter · #4 ·
By "head cover" you mean the valve cover, right?
Unless something is very wrong there should not be coolant in the valve cover (not to mention that the rubber seals should keep anything that is in there in). Your first step should be making absolutely sure where the leak is.
Yes the valve cover. Honda parts nation website was just calling it a head cover. Im going to examine the water pump housing and rule out any drip down. I'll post some pictures tomorrow of the coolant drip location.
When I purchased this bike I was excited to get my hands dirty along the way.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
11,198 Posts
Check the connections around the thermostat, too.
 
  • Like
Reactions: Molten Stenberg

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,475 Posts
I can see them calling head covers (they are often called rocker covers too) but I wanted to make sure we were talking about the same thing.

The water pump is at the rear of the engine. The thermostat housing is above the engine between the cylinders with a pipe running each way to joints on each cylinder head.\

As Randall said, check check around the thermostat housing. If there is a leak at either end of the pipe, the thermostat housing or even where the rad hose attaches to the thermostat housing it could easily run around the cover and drip off at any point, looking like it is leaking from the cover seal.
 

·
Registered
Joined
·
309 Posts
I'm with the others that it's extremely unlikely to be coolant leaking from the valve covers/gaskets. That being said, taking the valve covers off is super easy, so you could pull off them to confirm there is no coolant in that area. then continue searching for the actual source.
 
  • Like
Reactions: Molten Stenberg

·
Registered
82' cx500c custom
Joined
·
14 Posts
Discussion Starter · #8 ·
I can see them calling head covers (they are often called rocker covers too) but I wanted to make sure we were talking about the same thing.

The water pump is at the rear of the engine. The thermostat housing is above the engine between the cylinders with a pipe running each way to joints on each cylinder head.\

As Randall said, check check around the thermostat housing. If there is a leak at either end of the pipe, the thermostat housing or even where the rad hose attaches to the thermostat housing it could easily run around the cover and drip off at any point, looking like it is leaking from the cover seal.
Well after further inspection and some deep breaths I found the coolant culprit, very easy to see when not in tunnel vision mode (see image). I'm still wondering about the sudden power loss and boggy idle. Any thoughts if this issue correlates with the coolant leak?
Thanks for lending your experience!
 

Attachments

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,475 Posts
The power loss & bogging is probably unrelated. Unless the coolant was getting onto the spark plug wire and the wire's insulation has developed tiny cracks or one of the boots on the spark plug cap are leaky.
 

·
Super Moderator
'84 CX650E that is evolving into a GL500
Joined
·
17,475 Posts
An o-ring on either end of each of the pipes and one between each joint (elbow) and the head it mates to, another between the top & bottom of the thermostat housing and one on that seals the temperature gauge sender to the housing. That makes a total of 8.

Looking closer at those pics, it looks like the leak might be between the joint and the head but it could be leaking higher up and running down the back of the joint and around the bottom of it. You need to look up underneath with a flashlight to make sure it isn't coming from somewhere else. You don't want to replace all of those o-rings and then find out the problem was a loose rad hose clamp.....
 

·
Registered
82' cx500c custom
Joined
·
14 Posts
Discussion Starter · #12 · (Edited)
An o-ring on either end of each of the pipes and one between each joint (elbow) and the head it mates to, another between the top & bottom of the thermostat housing and one on that seals the temperature gauge sender to the housing. That makes a total of 8.

Looking closer at those pics, it looks like the leak might be between the joint and the head but it could be leaking higher up and running down the back of the joint and around the bottom of it. You need to look up underneath with a flashlight to make sure it isn't coming from somewhere else. You don't want to replace all of those o-rings and then find out the problem was a loose rad hose clamp.....
The clamps were all secure. There was quite a bit of movement on the piping that comes out of the thermostat housing (image1). I pulled the elbow which connects the head to the thermostat and noticed some sort of sealant on the o ring. It looked cracked and like it had failed(image2). I cleaned all connections and ordered the oem o rings. The right side looks dry as a bone.
Now to find out where the idle/power loss gremlins are hiding. Carbs are pulled and getting ready to clean them with the help of Larry's guide.
 

Attachments

1 - 12 of 12 Posts
Top