Hey guys,

A month or so ago I posted that I had a problem with my VN1500 cooling - the fan wouldnt stop. With help of members of this forum I resolved the issue - air caught around the stat.

Today a new problem arose, after a small journey (Around 20 minutes at 40mph) I parked up the bike, and saw steam flowing out of a breather tube at the bottom of the bike, also lots of bubbles in the coolant resivoiur, almost like it was boiling over!.

However, the fan was not running and the radiator did not feel too hot (It was warmer around the outside then in the middle. The outside was probably around 40 - 50c).

Any suggestions?

Many Thanks

 

rudi, I have a suggestion, but you may not want to hear it. I would initially suspect a head gasket.

 

Do a leak down test. Verify if you have a gasket issue.

 

Thanks for the responces. I dont have the equipment to perform a leak down test, so will need to ask my mechanic to do this. before that Im just irradicating other possible causes.

Although I understand this problem could be symptomatic of a failed head gasket do not believe it is a head gasket due to the fact that it appear the coolant is not circulating.

Anyways today I removed the thermostat housing. I found a few things:

Upon opening the thermostat housing I found I have no thermostat. However I have not had any problems starting the bike =/

The radiator cap had alot of grit around the seal.

I have a small leak around the radiator drain plug. - Im now starting to suspect this to be the issue. Any thoughts?

 

hahaha, that is a good one. So why was the fan running continuously? I am getting involved with your new novel now. lol

 

To my understanding the fan is controlled by a thermostatic fan switch at the bottom of the radiator. The thermostat in question is to restrict coolant flow during warm up.

Apparently lack of a thermostat can cause the pump to cavitate, I hope the impeller is still good >_<

 

Rudi, I'm a bit confused. A "thermostatic" fan switch is merely a temperature-"closed/open" electric switch to the rad fan. I don't think it actually restricts anything, does it? There is also a mechanical thermostat which opens and closes to regulate the flow of coolant, at a predetermined temperature (around 180 degrees) to regulate/maximize the combustion within the heads. OK, after re-reading your post several times, I think I understand; we're on the same page. Let's call the fan switch a "fan switch."
Bad things happen if your coolant a.) deteriorates in quality to the point of attacking your radiator, b.) gets so hot and expands/warps/destroys things it shouldn't. Grit around the rad cap is a little ominous.
Test the coolant in your rad. If it has deteriorated, it can be worse (i.e. more harmful) than using plain water and can lead to the "grit" you describe.
After you test, the cheapest route is to thoroughly flush, refill, install thermostat, bleed, and check for proper flow and cooling, including your rad fan operation. If coolant is not flowing, it's probably time to check the pump. I would NOT ride the bike on the street (around the block to test, maybe) until the problem is resolved.
Keep us posted.

 

Yes mate. That is what I was trying to explain to the poster above as they had been part of a previous thread in which I had been having issues with the fan switch - sorry for the confussion.

Excuse my ignorance, being an engineer and not a mechanic, Im always a little puzzled as how to bleed the cooling on the VN1500. There doesnt seem to be a bleed valve/AAV in site, and the manuals not much cop either.

Do you have any infomation on bleeding the coolant, and also on correct flushing procedure?

Previously to bleed the coolant ive just rocked the bike side to side with the rad cap off - not sure if that is good enough really =/

 

The saga continues:

I repaired the leak, installed a thermostat and refilled with coolant. Started her up let her run for around 5 minutes - everything seemed to get hot - great! But then she just started to dump the coolant over the floor through the breather pipe. The pump seemed to be working so Im guessing the only thing left is head gasket?

Will take her to a garage on monday to get her tested.

 

Guys,

Have been thinking over the symptoms and have some questions:

Although the whole system got hot evenly (All pipes) the water that was dumped out the bottom was cold. Im starting to think this indicates faulty radiator cap rather then head gasket - would you agree with this?

Also, Ive been reading about a product called steel seal that claims to be able to seal failed head gaskets - has anyone tried or heard of this product? Does it work?

Many thanks as always