Rusted Out Cooling System - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 9 (permalink) Old 03-29-2012, 05:36 PM Thread Starter
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Rusted Out Cooling System

So my back has been running rough and Seafoam would fix it but only temporarily so I finally decided to pull the carbs and clean them properly. I haven't gotten to that job yet, but in the process of taking apart the cooling system (required to get the carbs) I flushed the cooling system and a bunch of rest came out (not unexpected, happened last coolant flush), but then I take the thermostat housing out and realized the source of the rust.

The end connectors of the housing were rusted away, to the point where half of a connector would be missing! Clearly I need to replace the part. The same rusting away I found had happened on the top of the two metal pieces feeding in to the engine (and maybe the filler cap, I haven't taken the house off of there.)

So basically I need to replace all of the cooling system (probably not the radiator, I don't have a ton of cash laying around :X).

Few questions:

1) What is a good store/website to order the components off? I need to replace the thermostat and the metal engine pieces. I also want to replace the hoses and radiator cap.

2) What is a good way to clear as much of the gunk out of the engine as I can? Ripping the engine out and apart is beyond what I'm experienced with or want to do. Also, what can I do to clean the radiator out as much as possible?

3) Is this a common problem? What can I do to try to prevent a recurrence?

I have had some mysterious (very slow) coolant leak since I got the bike but never could find it leaking anywhere, nor was the bike smoking. Hopefully the replacement parts will fix that

Thanks for the advice guys. I feel like there was some other stuff I wanted to ask to, but at least this should be a good start!

EDIT: Added picture of why I needed to replace stuff! The pic is the thermostat, but the pipes going to the engine are the same way.
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1993 Kawasaki Vulcan 750

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post #2 of 9 (permalink) Old 03-29-2012, 06:18 PM
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04-3,200 miles bought July 2011 with 928 miles. Loaded with acessories to many to list here, see my albums for more details! I also make a custom tank bib specific for the 750 if anyone is interested, ck my albums for some pics.
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post #3 of 9 (permalink) Old 03-30-2012, 12:06 AM Thread Starter
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After pricing OEM parts I decided to hit up fleabay and bought: and

Any advice on how to flush the most rust out of the radiator and the engine would still be greatly appreciated! As well as any other tips??

1993 Kawasaki Vulcan 750
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post #4 of 9 (permalink) Old 03-30-2012, 01:08 PM
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Well i work on cars for a living and id assume doing this to the motorcycle wouldnt hurt it either some of us clean up the rust and stuff from a car is just drain as much of it out as you can and fill it up with water and some liquid cascade dishwashing soap(not a lot), you cant use powder because it gets bubbly but the liquid stuff just cleans it all out and doesnt make bubbles. Put some of that in there and ride it for a few miles then flush it all out with more water making sure you get out all the soap and water, then just fill it up with right coolant/water mix and you should be good!
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post #5 of 9 (permalink) Old 03-30-2012, 01:15 PM
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I have been finding the cheapest parts at this site, Power Sports Plus:

Pete Herrmann
1994 Vulcan 750 40K on the clock and counting....

Bought 4/2011 28k Miles,
New Rick's Motorsports R/R
Tim Parrot Stator
Tuxedo Mod
KAW Saddlebag/signal relocation brackets
NGK Iridium Plugs
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post #6 of 9 (permalink) Old 03-30-2012, 03:19 PM Thread Starter
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Thanks Pete! Those are definitely the cheapest prices I've seen. If the used ones I get don't work out that link will be awesome. Also, bookmarked for future needs

Has anyone else tried the liquid dish washing soap?? K-aultz, about how much do you think is good? Small cap full for the whole system?

Thanks all for the advice!

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post #7 of 9 (permalink) Old 03-30-2012, 07:12 PM
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My guess is someone put water out of a faucet in it at some point, and the rust/corrosion started from there. Mine has never had anything but distilled water and ethylene glycol in it, and is completely rust and corrosion free. I normally wouldn't recommend it, but if the system is that bad, you might want to use a cooling system flush designed for aluminum car engines. It contains an acid that dissolves rust and corrosion. It may or may not damage the water pump mechanical seal, but at this point, if it is that bad, that would seem to be a small thing. If you don't get the corrosion out of it, it will just keep coming back.

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 #8 of 9 (permalink) Old 03-30-2012, 09:21 PM
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We always flushed with white vinegar 50/50 on the Cosworth Vegas when I worked on em. After that, reflush with 6 tablespoons of baking soda and water....leave the cap off...reflush with plain water, then refill with coolant.

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post #9 of 9 (permalink) Old 04-01-2012, 12:03 PM Thread Starter
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Thanks for the tips everyone. I think I'll follow the Clymer flush procedure using the vinegar mixed followed by flush with the baking soda and then flush with distilled water. Will let you all know how it goes.

EDIT: Flushed with vinegar, baking soda, water, then refilled with 70/30 ethlene glycol/distilled water. Thanks for all the help guys. Looks like nothing is leaking

Tip: When I replaced the cooling pipes I had major leaks from both. Took one to O'Reilly's Auto and they had a box of o-rings. Two that fit perfectly were only ~50c each. Was a nice snug fit too! Just be gentle wiggling the pipes back in to the engine so you don't damage the new rings.
O-Ring part number was "NAT 112"

1993 Kawasaki Vulcan 750

Last edited by blastagator; 04-15-2012 at 10:22 PM.
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