Jump to content
Sign in to follow this  

RMZ450 overheating and losing coolant. Any suggestions?

Recommended Posts

Okay, so I have an 07 RMZ450 that has developed an overheating problem. It has a bent left radiator from a crash about a year ago, but has never had any issues overheating until recently. I have noticed that after the bike runs for roughly 5-10 minutes, coolant starts coming out of the radiator overflow hose. This results in the coolant boiling and steaming away. I've tried adding more coolant, but the problem still persists. Today, I checked the coolant volume by draining everything, and it's only at 400ml. The manual specifies 900ml of coolant.

Is there something wrong with the radiator? Is it an issue with the water pump? Can I try and disassemble the pump to see if it isn't working properly? Would it be worth buying a new left radiator and hoses? Has anyone had experience with this sort of problem before?

Share this post


Link to post
Share on other sites

I would think you would know exactly where your coolant was leaking from if you were dumping that much coolant. My guess is that you are burning coolant which is why it is overheating as well.

Share this post


Link to post
Share on other sites

When you say running for 5-10 minnutes - do you mean sitting still or riding?  If sitting still, don't worry that's normal.

 

My 07 overheated a lot while trail riding, engine ice was enough to stop it.

Sitting still and riding, but only after I add more coolant.  The bike only wanted to accept a certain level, and then the rest would start spurting out of the overflow hose once the bike warmed up.  It would always stop spurting out coolant after a little while.  I just went ahead and ordered a new radiator and hoses.  I was thinking that the bent radiator could possibly have been preventing coolant from circulating properly throughout the radiators and motor.  I'll give the engine ice a try.  I have heard that that stuff is good, but I've never used it. 

I would think you would know exactly where your coolant was leaking from if you were dumping that much coolant. My guess is that you are burning coolant which is why it is overheating as well.

It leaks from the overflow hose once the bike heats up.  

Share this post


Link to post
Share on other sites

I get that but you gotta be dumping coolant out of the overflow to lose 4-500ml's of coolant. 

 

Did you mix coolant?

When you say mix coolant, do you mean mix different brands, or mix with water?  The coolant I bought was from walmart, and it is a 50/50 premix coolant solution.  I never mixed any with extra water, nor did I mix with a different brand.  As far as the amount of coolant that the bike was losing, it was a considerable amount that dumped out of the overflow hose.  The radiators only wanted to hold 700ml to begin with, even though the manual specified 900, and when the bike would come up to temp, there would be a puddle of coolant on the floor beneath the bike.  It was doing the same thing when I tried to add coolant at the track.  I would ride for a few minutes, then someone would point out that steam was coming out of the overflow hose.  So, I never noticed any coolant leaks, only a considerable amount coming out of the overflow throughout the day.  

Share this post


Link to post
Share on other sites

Is your coolant bubbly when you take the cap off after the bikes been running?

The coolant level is so low that you can't tell.  The bike wont allow you to fill up the coolant all the way, because it will dump out of the overflow hose when the bike come up to temperature. 

Share this post


Link to post
Share on other sites

Could it be a seal in the engine gone? Have you drained the oil recently?

Every 5 hours, and I was planning on doing oil plus filter today.  Is there anything I need to pay attention to that could indicate what the issue is? 

Edited by uninc4life

Share this post


Link to post
Share on other sites

Sounds like it could be a bad headgasket. Popped head gasket can cause the coolant to blow out the overflow. Maybe try a stronger rad cap first though.

Share this post


Link to post
Share on other sites

Sounds like it could be a bad headgasket. Popped head gasket can cause the coolant to blow out the overflow. Maybe try a stronger rad cap first though.

I'll just go ahead and replace it too along with the rads and hoses.  I talked with a mechanic I know, he said replacing the head gasket is a yearly maintenance requirement, and since it hasn't been done since I've owned the bike, and the previous owner never did, it's probably time.  I just don't know why it would be the rad cap.  It never did this with the OEM cap until about a week ago.  

Share this post


Link to post
Share on other sites

I'll just go ahead and replace it too along with the rads and hoses.  I talked with a mechanic I know, he said replacing the head gasket is a yearly maintenance requirement, and since it hasn't been done since I've owned the bike, and the previous owner never did, it's probably time.  I just don't know why it would be the rad cap.  It never did this with the OEM cap until about a week ago.  

Caps can get weak and not hold the pressure of the cooling system, thus allowing coolant to blow out of the overflow

  • Like 1

Share this post


Link to post
Share on other sites

Caps can get weak and not hold the pressure of the cooling system, thus allowing coolant to blow out of the overflow

That is what I was getting at but wanted to rule out a bad head gasket first. A fresh cap wouldn't do much with a blown motor.  :thumbsup:

Share this post


Link to post
Share on other sites

:thumbsup:

Caps can get weak and not hold the pressure of the cooling system, thus allowing coolant to blow out of the overflow

Thanks for clearing that up for me!  

 

That is what I was getting at but wanted to rule out a bad head gasket first. A fresh cap wouldn't do much with a blown motor.  :thumbsup:

When I replace the head gasket, should I also replace the base gasket on the bottom of the cylinder?  Is it possible that the base gasket could also be causing the problem?  To know for sure if the gasket was the issue, will it be noticeably ripped or torn?  Also, is there a top and bottom to the head gasket?  How do I know if the correct side is facing up?  Thanks for all your help :thumbsup:    

Share this post


Link to post
Share on other sites

:thumbsup:

Thanks for clearing that up for me!  

 

When I replace the head gasket, should I also replace the base gasket on the bottom of the cylinder?  Is it possible that the base gasket could also be causing the problem?  To know for sure if the gasket was the issue, will it be noticeably ripped or torn?  Also, is there a top and bottom to the head gasket?  How do I know if the correct side is facing up?  Thanks for all your help  :thumbsup:    

I personally wouldn't replace the base gasket given your issues. I actually wouldn't bother with the head gasket either. It doesn't sound like you are burning coolant. If you were the bike would be puffing white smoke.

 

Usually there will be markings on the top side of the head gasket.

 

As for it being obvious, it may or may not be. I have had leaky head gaskets on 2 strokes that looked perfect and I have had some that were obviously blown out.

Share this post


Link to post
Share on other sites

:thumbsup:

Thanks for clearing that up for me!  

 

When I replace the head gasket, should I also replace the base gasket on the bottom of the cylinder?  Is it possible that the base gasket could also be causing the problem?  To know for sure if the gasket was the issue, will it be noticeably ripped or torn?  Also, is there a top and bottom to the head gasket?  How do I know if the correct side is facing up?  Thanks for all your help  :thumbsup:    

Yes replace the base gasket. It is decompressed when you do the head gasket, and is not worth the risk of it not sealing back up when you are that far into the motor already. Base gasket will not cause an issue with the cooling system. Head gasket can be hard to tell if its popped, you may be able to see track marks from the piston hole into one of the coolant galleries. The head gasket will only fit 1 way.

Share this post


Link to post
Share on other sites

I personally wouldn't replace the base gasket given your issues. I actually wouldn't bother with the head gasket either. It doesn't sound like you are burning coolant. If you were the bike would be puffing white smoke.

 

Usually there will be markings on the top side of the head gasket.

 

As for it being obvious, it may or may not be. I have had leaky head gaskets on 2 strokes that looked perfect and I have had some that were obviously blown out.

Sometimes bad head gaskets will leak with cylinder pressure, causing the combustion pressure into the cooling system creating too much pressure for the cap to handle and blow out the overflow, so it may not be noticeable "burning" coolant or a lot of smoke out of the exhaust and still have a bad head gasket. I would personally just replace the cap first as it is the cheapest and easiest method to at least start eliminating issues lol

  • Like 1

Share this post


Link to post
Share on other sites

Sometimes bad head gaskets will leak with cylinder pressure, causing the combustion pressure into the cooling system creating too much pressure for the cap to handle and blow out the overflow, so it may not be noticeable "burning" coolant or a lot of smoke out of the exhaust and still have a bad head gasket. I would personally just replace the cap first as it is the cheapest and easiest method to at least start eliminating issues lol

Another thing that leads me to believe that the head gasket is bad, is the fact that I am noticing a very small amount of oily residue right where the cylinder and head connect.  I have never noticed any oil in this spot before, so this may be the source of the problem.  The new radiators I ordered come with a new radiator cap, so hopefully that takes care of the problem, along with the new gasket.  I just never noticed the coolant overflow until I also noticed the oily spot on the cylinder. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...