Coolant leak - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 11 (permalink) Old 12-03-2011, 11:24 PM Thread Starter
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Coolant leak

I ride a VN750 2006 with 8000miles. I recently got a leak of coolant. After some digging I found and confirmed the leak to come from the front cylinder: gasket between engine block and cylinder at the rear of the gasket (between the 2 cylinders at the bottom of the V).

I have removed the engine and I am in the process of removing the cylinder to replace that gasket.

If it happens to be a bad gasket then that would make sense (will know soon). But I am still puzzled to have this issue with so few miles. I am wondering if it might be the consequence of some other issue: coolant excess pressure, temperature gauge defective,....?
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post #2 of 11 (permalink) Old 12-04-2011, 10:16 AM
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While those things are possible, many of the later models of the VN 750 had crappy cylinder base gaskets from the factory. The gasket usually fails near one of the bolt holes.
The aftermarket gaskets are heavier than the ones I had originally. I had a similar leak a year ago.
Once that engine is out it's time to think about the stator too. Maybe do the mod to make it changeable without pulling the engine.
If you want to do the earshave, now is the time. The carbs can come off for rejetting, and you will save time and irritation getting the airbox back together.
There is a little sintered metal filter in the head that should be replaced once you take off the valve cover. Be sure and look for this in the manual to see what I'm talking about.
I doubt that you had excessive pressure in the system. My money is on the gasket.
Bronson

2005 VN 750
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post #3 of 11 (permalink) Old 12-04-2011, 12:33 PM
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Same place mine leaks.
I would certainly like to hear what you discover when you pull the cylinder off.
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post #4 of 11 (permalink) Old 12-04-2011, 09:32 PM
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Quote:
There is a little sintered metal filter in the head that should be replaced once you take off the valve cover. Be sure and look for this in the manual to see what I'm talking about.
The little disc shaped oil filter in the cylinder head that Bronson mentioned is shown as #14043 in this diagram link.

http://www.bikebandit.com/houseofmot...m4555#sch47838

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
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Fiamm Freeway Blaster horns
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Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
https://www.vn750.com/forum/11-vn750-general-discussion/9127-top-ten-items-you-would-suggest-new-owner-do-his-new-ride.html
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post #5 of 11 (permalink) Old 12-05-2011, 05:31 PM
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What year did this start happening? I have an '02 with 70,000+ miles which has never leaked. With only 8000 miles, it is most likely a defective gasket. Kawasaki never took the Vulcan 750 seriously, and sold it completely unchanged for 22 years with nothing but different colors. The used the tooling till it wore out, then discontinued the model. It is likely new parts will be made with that same worn out tooling, that would explain why my original cam chain tensioners lasted 15,000 miles, but the new oem ones I replaced them with only lasted 10,000 miles. I was not aware you could get aftermarket gaskets. I am about to pull the front bevel drive gearcase on mine, so I can get the driveshaft out for maintenance. I have never had the driveshaft out, thought I would do it right this time. It is a lot easier to remove that gearcase than the swingarm. Was going to use a stock gasket. I just replaced my clutch with a new Kawasaki gasket, and it seemed fine.


I think there is a design problem with the coolant passages between the cylinders and the bottom end, they come too close to the edge. There just isn't enough room for gaskets with enough material to properly seal these passages, and being so narrow, it would be easy to deform the gasket while installing it. As far as I know, this issue exists with all years of the Vulcan 750.

I am a motorcyclist, NOT a biker.


1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
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post #6 of 11 (permalink) Old 03-31-2012, 03:45 AM Thread Starter
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Almost there

All,

Thanks for your replies. Very useful. some a bit cryptic for me yet. But I'll come back to them later on.

I have taken the engine out of the motocycle, removed the engine cover, the middle block (i think it is the piston block) and not i am trying to remove the engine block (the one at the bottom). I needed a special tool to pull the fly wheel of the alternator. It supposed to be delivered home this coming week (18 mm x 1.5 mm RH bolt). Still to do some work after that but i think it should come up easy now.

As i am presently thinking of re-assembling the whole i am looking for engine gasket kits. thought you might point me to some places on the web.
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post #7 of 11 (permalink) Old 03-31-2012, 10:44 AM
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Don't know anyone who sells kits. Think you have to order tham separately from folks like these: http://www.cheapcycleparts.com/model...semblies/74325

http://www.indyoem.com/fiche_section...1989&fveh=9032

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
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1989 VN750 acquired December, 2008, 6,711 miles
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post #8 of 11 (permalink) Old 06-24-2012, 05:18 PM Thread Starter
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A new step in my vn750 engine disassembly

I finally was able to remove the alternator flywheel. I didn't know that I had to hammer the rotor puller so strongly.

Found the leaking gasket. Yeahhh..... The corners were cracked. I also noticed that one of the coolant-tunnel-ends had a deposit of greasy gunk.

Here I have attached 4 pictures showing this.

My next step is to order the gaskets. Thanks again for your input, it helped me.
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Last edited by potimo; 06-24-2012 at 05:28 PM.
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post #9 of 11 (permalink) Old 06-24-2012, 07:31 PM
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Quote:
Originally Posted by potimo View Post
I finally was able to remove the alternator flywheel. I didn't know that I had to hammer the rotor puller so strongly.

Found the leaking gasket. Yeahhh..... The corners were cracked. I also noticed that one of the coolant-tunnel-ends had a deposit of greasy gunk.

Here I have attached 4 pictures showing this.

My next step is to order the gaskets. Thanks again for your input, it helped me.
Nice work.

It seems some of the rotors are on there really good, and some come right off. Mine popped off with very little torque, and had a satisfying "pop" sound. Glad your venture was successful!

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
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1990 Kawasaki Vulcan 750

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post #10 of 11 (permalink) Old 06-26-2012, 11:30 PM Thread Starter
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Quote:
Originally Posted by Bronson View Post
While those things are possible, many of the later models of the VN 750 had crappy cylinder base gaskets from the factory. The gasket usually fails near one of the bolt holes.
The aftermarket gaskets are heavier than the ones I had originally. I had a similar leak a year ago.
Once that engine is out it's time to think about the stator too. Maybe do the mod to make it changeable without pulling the engine.
If you want to do the earshave, now is the time. The carbs can come off for rejetting, and you will save time and irritation getting the airbox back together.
There is a little sintered metal filter in the head that should be replaced once you take off the valve cover. Be sure and look for this in the manual to see what I'm talking about.
I doubt that you had excessive pressure in the system. My money is on the gasket.
Bronson


You were right. The problem is the gasket. See pictures in the thread.
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