I think I've got a blown head gasket.... - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Engine / Exhaust / Cooling
\ From the radiator, through the case and out
the exhaust. If it has to do with the cooling,
engine or exhaust, discuss it here!

 1Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 05-08-2007, 08:02 PM Thread Starter
Members who have donated towards server costs
 
93VN750's Avatar
 
Join Date: May 2006
Location: Tampa, Florida
Posts: 1,766
iTrader: (2)
 
Send a message via Skype™ to 93VN750
I think I've got a blown head gasket....

I have been trying to get the jetting right and came across an article
that said if the hg is bad and coolant gets into the combustion
chamber that it is impossible to get jetting right.

Well I have no external leaks. All hoses are good, new orings on the
head pipes, new thermostat, and new radiator cap.

I used almost a full overflow bottle of coolant today going to/from
work, 78 miles. Been adding regularly, knowing that it shouldn't be done.

So, will a compression test yield enough information to determine if
either hg is bad?

Then, I can only hope its the front one so I don't have to pull the
engine again.

Jon

93VN750, under re-construction
vn750.com Member # 828

Rick's Stator and R/R
MF AGM Battery
Coastered
Degoated
Shaved & Jetted
Iridium's
MAC Tapered Staggered Pipes
Battery/Temp/Clock Gauge
Stainless Steel Brake Lines
Dunlop D-404's
23,XXX miles and holding pending gasket change (underway!!!)
93VN750 is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 05-08-2007, 09:41 PM
Members who have donated towards server costs
 
Crobins365's Avatar
 
Join Date: Jul 2006
Location: Kennett Square, PA
Posts: 3,505
iTrader: (48)
     
I'm still looking for you, buddy. You have the Vulcan service manual, right? On page 3-7 is a description of how to pressure test the coolant system. That may be a moot point, since you're losing coolant somewhere. But at any rate, it goes on to note that if the pressure drops and you can't find an external leak, look inside. "Droplets in the engine oil indicate internal leakage." So, I guess check that first. Then it goes on to note that you shoudl look at the cylinder head gasket, cylinder gasket (the "lower" one you mentioned in your pm, maybe?), and the cylinder liner o-rings.

C
Crobins365 is offline  
post #3 of 12 (permalink) Old 05-08-2007, 10:07 PM
HAWK
 
Ccspinner's Avatar
 
Join Date: Feb 2006
Location: Chicago land
Posts: 2,576
iTrader: (9)
 
Send a message via Yahoo to Ccspinner
Do you have any smoking from the exhaust?
Is there a sweet smell from the exhaust?
Most of the time leaks like that will only happen when the motor is hot, or at normal operating temp not cold.
Is the oil milky looking?

Chad Falstad "Hawk"
Vroc #17649
2011 HD Ultra Classic "angel"
2001 Nomad 1500 Sold March 2012
2001 VN 750 "Sold June with 2008 with 21,000""Serinity"
Ccspinner is offline  
 
post #4 of 12 (permalink) Old 05-08-2007, 10:08 PM
Stranger Than Fiction
 
cmanningjr's Avatar
 
Join Date: Mar 2006
Location: Alabama
Posts: 151
iTrader: (0)
 
Send a message via MSN to cmanningjr
Seems like, if you are losing that much coolant, if it were a head gasket, you'd see smoke out the exhaust. A compression test may not show a blown head gasket. Try looking for "Milky Oil" or any sign that the water is getting in the block....


Cindy is the resident guru. Give her a min and she'll have a better answer for you.....

'92 Vn750

cmanningjr is offline  
post #5 of 12 (permalink) Old 05-08-2007, 11:48 PM
Members who have donated towards server costs
 
slim's Avatar
 
Join Date: Jan 2006
Location: southern missouri
Posts: 20
iTrader: (0)
 
I would definatly check the oil. You would probably detect slight amount of smoke in the exhaust if it were getting into the cylinder. I would also closly inspect the seep hole for the water pump for residue it could be seeping under pressure and blowing off while moving.
slim is offline  
post #6 of 12 (permalink) Old 05-09-2007, 01:11 AM
 
Join Date: Sep 2006
Posts: 238
iTrader: (2)
 
If the head gasket is leaking into the motor on the intake stroke you will end up with coolant in the oil, if it is leaking on the exhaust stroke it will go out the exhaust.
I would have it pressure tested, if it passes the pressure test then check compression. If it passes the compression test you may have to have a cylinder balance test done. This should be done by a mechanic with the proper air/manifold (psi) guages. This is done by placing the piston at top dead center (compression stroke) with the valves closed. You then inject air pressure into the cylinder thru the spark plug hole and it's monitored by a air/psi gauge with a valve on it to control the amount of air pressure (between 80-120 psi). No need to exceed more pressure than your engine compression produces. Also make sure the motor/piston does not move and open the valves, this will give you a false indication of a bad head gasket. While air is introduced to the cylinder you should not hear any air escaping anywhere. If the motor/piston does not move and the valves remain closed and you hear air escaping thru the intake (carbs) or the exhaust (tail pipes) you have just found a bad head gasket. It's also a good idea to remove the radiator cap. As you introduce air to the cylinder and are listening for escaping air, keep an eye on the coolant in the radiator. Sometimes you won't hear air escaping, but you will see bubbling in the radiator--this also indicates a bad head gasket (air is passing from the cylinder to the coolant system). You may see a few bubbles while first pressurizing the cylinder--if you have a bad head gasket it will not stop bubbling or weven may look like boiling water depending upon how severe the leak is.
When done with one cylinder, rotate the motor to get the other piston top dead center (compression stroke) and repeat.
In summary--any air leaks (make sure piston is TDC and valves are closed) or bubbles in the coolant = bad head gasket.
Hope this helps--good luck and I hope it's not a major issue and your back on the road soon!
Barbwired likes this.
racohoon is offline  
post #7 of 12 (permalink) Old 05-09-2007, 07:08 AM
Members who have donated towards server costs
 
Crobins365's Avatar
 
Join Date: Jul 2006
Location: Kennett Square, PA
Posts: 3,505
iTrader: (48)
     
Thumbs up

Quote:
Originally Posted by racohoon View Post
If the head gasket is leaking into the motor on the intake stroke you will end up with coolant in the oil, if it is leaking on the exhaust stroke it will go out the exhaust.
I would have it pressure tested, if it passes the pressure test then check compression. If it passes the compression test you may have to have a cylinder balance test done. This should be done by a mechanic with the proper air/manifold (psi) guages. This is done by placing the piston at top dead center (compression stroke) with the valves closed. You then inject air pressure into the cylinder thru the spark plug hole and it's monitored by a air/psi gauge with a valve on it to control the amount of air pressure (between 80-120 psi). No need to exceed more pressure than your engine compression produces. Also make sure the motor/piston does not move and open the valves, this will give you a false indication of a bad head gasket. While air is introduced to the cylinder you should not hear any air escaping anywhere. If the motor/piston does not move and the valves remain closed and you hear air escaping thru the intake (carbs) or the exhaust (tail pipes) you have just found a bad head gasket. It's also a good idea to remove the radiator cap. As you introduce air to the cylinder and are listening for escaping air, keep an eye on the coolant in the radiator. Sometimes you won't hear air escaping, but you will see bubbling in the radiator--this also indicates a bad head gasket (air is passing from the cylinder to the coolant system). You may see a few bubbles while first pressurizing the cylinder--if you have a bad head gasket it will not stop bubbling or weven may look like boiling water depending upon how severe the leak is.
When done with one cylinder, rotate the motor to get the other piston top dead center (compression stroke) and repeat.
In summary--any air leaks (make sure piston is TDC and valves are closed) or bubbles in the coolant = bad head gasket.
Hope this helps--good luck and I hope it's not a major issue and your back on the road soon!
Very nice write-up, Racohoon! Even if we all end up taking our bikes to the shop to have this done, this is really, really helpful in understanding what's going on.

C
Crobins365 is offline  
post #8 of 12 (permalink) Old 05-11-2007, 02:29 PM Thread Starter
Members who have donated towards server costs
 
93VN750's Avatar
 
Join Date: May 2006
Location: Tampa, Florida
Posts: 1,766
iTrader: (2)
 
Send a message via Skype™ to 93VN750
Quote:
Originally Posted by racohoon View Post
If the head gasket is leaking into the motor on the intake stroke you will end up with coolant in the oil, if it is leaking on the exhaust stroke it will go out the exhaust.
I would have it pressure tested, if it passes the pressure test then check compression. If it passes the compression test you may have to have a cylinder balance test done. This should be done by a mechanic with the proper air/manifold (psi) guages. This is done by placing the piston at top dead center (compression stroke) with the valves closed. You then inject air pressure into the cylinder thru the spark plug hole and it's monitored by a air/psi gauge with a valve on it to control the amount of air pressure (between 80-120 psi). No need to exceed more pressure than your engine compression produces. Also make sure the motor/piston does not move and open the valves, this will give you a false indication of a bad head gasket. While air is introduced to the cylinder you should not hear any air escaping anywhere. If the motor/piston does not move and the valves remain closed and you hear air escaping thru the intake (carbs) or the exhaust (tail pipes) you have just found a bad head gasket. It's also a good idea to remove the radiator cap. As you introduce air to the cylinder and are listening for escaping air, keep an eye on the coolant in the radiator. Sometimes you won't hear air escaping, but you will see bubbling in the radiator--this also indicates a bad head gasket (air is passing from the cylinder to the coolant system). You may see a few bubbles while first pressurizing the cylinder--if you have a bad head gasket it will not stop bubbling or weven may look like boiling water depending upon how severe the leak is.
When done with one cylinder, rotate the motor to get the other piston top dead center (compression stroke) and repeat.
In summary--any air leaks (make sure piston is TDC and valves are closed) or bubbles in the coolant = bad head gasket.
Hope this helps--good luck and I hope it's not a major issue and your back on the road soon!
That's really helpful, but one question. When doing the pressurized cylinder test, would the air forced into the combustion chamber through a spark plug hole go through the piston ring gaps anyway? They are not a 100% seal.

Jon

93VN750, under re-construction
vn750.com Member # 828

Rick's Stator and R/R
MF AGM Battery
Coastered
Degoated
Shaved & Jetted
Iridium's
MAC Tapered Staggered Pipes
Battery/Temp/Clock Gauge
Stainless Steel Brake Lines
Dunlop D-404's
23,XXX miles and holding pending gasket change (underway!!!)
93VN750 is offline  
post #9 of 12 (permalink) Old 05-11-2007, 03:04 PM
Members who have donated towards server costs
 
fergy's Avatar
 
Join Date: Mar 2006
Location: Kyle, Texas
Posts: 4,054
iTrader: (3)
   
I think as long as your rings are good and the cyl walls are not scored, the pressure would bleed off very slowly, giving time for the "real" leak to show up. I'm no expert here, but it's what I've read...

Jon, I'm sure pulling for you man!

Fergy
Kyle, TX VN750.com member #707 VROC#19556
2002 VN1500 Classic
Spline Lube Procedure, with photos, R/R Relocation and Coil Mod
Rusty Tank Cleaning!
Electrical Fault Finding Flowchart
SEAFOAM JUNKIE!


fergy is offline  
post #10 of 12 (permalink) Old 05-12-2007, 01:40 AM
 
Join Date: Sep 2006
Posts: 238
iTrader: (2)
 
If the pistons and rings are good and the valves remain closed it should take hours to bleed off and lose pressure.
When you don't have close to 100% sealing ability due to bad compression rings, this is when your compression reading will be low. If you have a seriously bad oil ring, you will be consuming/burning oil constantly.
This is why you have to do a compression test--to make sure the compression is in a tolerable range. This rules out bad rings/piston or scored cylinder walls (then you can stop troubleshooting and pull the motor and tear it down to find the problem i.e. pistons, rings, valves--or keep riding it until it blows the motor). Then you know it will hold pressure to do the cylinder leakage test. If the compression is bad there is no point to doing a cylinder leakage test since it won't hold air pressure.
Also while doing the compression test
1) Disable the coils
2) Take out only the plug from the cylinder you are testing. Leave the other plugs in the motor.
3) Thread the tester into the plug port and crank motor for about 3-5 seconds on a fullly charged battery. Look at your compression gauge and note the psi reading and cylinder. You do not need to crank the motor over for more than 5 seconds. The piston only needs to turn over about 3-4 complete revolutions.
racohoon is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Once registered, your User Name"cannot be changed". We can make exceptions within 7 days, but after that, it is set in stone.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome