Boiling Overflow Bottle - Frustrated

[MasterGuns]

OK; I've had this 92 for about a month now and have performed a lot of stuff in the short time I have had it. Great looking bike so I really don't mind spending the time and money; but one thing has really got me baffled. One of the items I changed was the coolant. Drained it all out and added new coolant to the radiator and "burped" it as Squidley put it. The radiator was plum full after running it for a while with the drain cock to the "off" position at two o'clock. Here is one confusing item... Dingy indicated to another member that the off or run position was a five o'clock. But if I turn the plastic indicator and wait until I hear/feel it click into position, it is at two o'clock. So that is where I've had it since changing the coolant. My problem is that it runs very low in the green but as soon as I leave the interstate and head home (which is about 1 mile from the interstate) the temp guage starts to climb. By time I arrive at home and into my garage it is about 3/4th of the way up the green. When I kill the bike I can hear the coolant boiling up into the overflow bottle. The first couple time it did that, the overflow tube released a puddle of coolant about the size of page of typing paper. Before I left this evening I checked the level in the bottle and it was at the full mark and the motor was bone cold. My 86 has never done this. I thought it just had air in the system the first time or two it did that but nothing is improving. However, tonight it did not pee on the garage floor was just bubbling away. This worries me.

 

What is going on with this thing? I want to take it to Oklahoma and Arkansas but I guess I can't until this is resolved. Will have to take the older gal when I go. Any suggestions will be most welcome.

 

Thanks

 

Herb

[utadventure]

I've had my '86 have an audible boiling when I part the bike on a hot day. It's typical for the bike to run up just shy of the red area in hot stop and go conditions.

 

The puddle on the floor could still be from an overfilled condition given the temps. As far the drain outlet position, some one else will chime in and give you better direction.

 

Enjoy your trip!

 

Dave

[Venturous Randy]

Herb, to me, the correct position to run the bike on the bypass is if the top of the letters are pointed toward the 5 o'clock position.

RandyA

[KIC]

Hope this helps:

 

The first picture is by-pass off - Normal running condition

 

2nd picture - Bypass on - for draining.

 

I have also attached some Word Doc's that show/explain it. I just did mine about 6 weeks ago. It spit coolant out and acted weird on the temps for several days until it seemed to "burp" the air out.

 

Now it is fine and runs just over 3/4 way up in traffic and 1/2 way on open road.

[bkuhr]

Don't trust the bottle for radiator liquid level. My 83 did same, and turns out the hose from the rad to the bottle was collaspsed internally. pressure from hot rad would open tube and allow coolant to flow to bottle under pressure, but would not let coolant back to rad from bottle as engine cooled.

 

After all coolant spilled at bottle overflow, turns out radiator was low level and ran excessive hot.

[frankd]

Also check the radiator cap and that the fan comes on when the heat gauge is about 3/16" below the red.

 

When you inspect the radiator cap, make sure the rubber gasket isn't all dry rotted. If it doesn't seal to the radiator, the coolant in the engine and radiator will boil much sooner (no pressure) and you will hear it going into the reservoir. Normally, you hear nothing.

 

If you want to replace the radiator cap, you don't have to buy the Yamaha cap if you don't want to. You can use a cap designed for a car and grind one of the ears off so it'll go onto the radiator. You can use a Stant 11227 or 227, and I bought one at O'Reily's Auto.

 

If your fan isn't coming on, check the connector at the temperature switch (right side of bike). I've seen a couple that have become oxidized and then they don't make connection. Clean them with a soft wire brush and coat them with di-electric grease or even regular grease to keep the air from contacting the terminals.

[MasterGuns]

This 92 has been a real challenge figuring out why it runs much hotter than my 86. The 86 has an 89 motor so I am comparing an 89 in really good condition in all respects including the temp at which it runs with a 92 that is also in great condition yet runs noticeably hotter; not only as idicated by the temp guage but by the feel of the heat on my legs as I move down the highway at 70. This morning I ordered a new rad cap, thermostat and all the o-rings and gaskets and was planning to put them all in to see if that made a difference. Then I read Tacoma Pete's response to why his scooter gets 47 mpg. He stated it was bone stock and he could determine how well it was running by holding his hand up to the exhaust. Well, after a few minutes I headed back out to the garage and lined up the 86 and the 92 side by side and started em both. After they were very warmed up, about 20 minutes and the rad fans were both cycling on and off, I held my hand up to each bikes exhaust, my left hand on the 86 and my right on the 92. Then I switched hands because at my age I never know if what I am feeling is correct. The 92 was very noticeable warmer, almost hot on my hand I held up to its exhaust. I could not hold my hand there for more than 10 or 15 seconds. Ah huh, possibly carb issue. So, I had already synced the carbs twice since bringing it home, however I was unable to adjust the air fuel mixture screws because the brass plugs were still there. So I commenced to drilling them out. What I found was weird; two carbs were only set 1/2 turn out and the other two were about 3/4 turn out. Now then; I don't know if this would have any impact on engine temp but it sure did lower the temp of the exhaust after moving them out 2 1/2 turns; permitting more fuel at idle and up through the entire range that the idle circuit impacts. I have read that its way above idle just cant remember how far up the rpm range. The exhaust on the 92 is now about the same as the 86. I don't know if anyone has ever run into this sort of thing but I just did. Can't wait to ride the doggone thing to see if it operates cooler; engine temp wise.

 

Thought I'd post my findings. Still can't believe a 20 year old bike still with the tamper proof brass plugs but even more surprised at the 1/2 - 3/4 factory setting. What this means is this bike has never run right. Interesting.

 

I would truly appreciate anyone's comments regarding the above issue and whether or not they feel the set screws could have any impact at all on operating temperature.

 

Herb

Edited September 13, 2013 by MasterGuns

[tomephil]

Hey Herb,

 

I can't comment about the carbs but I had a similar problem with my 84.

Coolant was boiling.

With Big Bob's help I realized it was the rad cap.

The rad cap wasn't holding proper pressure and that lowered the boiling point of the coolant.

I think the 84 is rated for about 12 psi.

I picked up a car rad cap that was rated for 15 psi and the problem was solved.

 

Hope this helps.

Tom

[Squidley]

Herb,

 

I had the same issue with my '83, puke all over the place. I ended up gutting the thermostat and leaving the body in it for restriction. I still get up to operating temp, but it doesn't boil over anymore.....

 

1 more thing, is the fan coming on? I know that wire by the sensor tube on the right side can get fussy if it's not tightly connected to the sensor. I have had several of them needing to be reseated to get everything back running in sync.

[MasterGuns]

Herb,

 

I had the same issue with my '83, puke all over the place. I ended up gutting the thermostat and leaving the body in it for restriction. I still get up to operating temp, but it doesn't boil over anymore.....

 

1 more thing, is the fan coming on? I know that wire by the sensor tube on the right side can get fussy if it's not tightly connected to the sensor. I have had several of them needing to be reseated to get everything back running in sync.

 

Yep, the fan cycles on and off as it should. But now that I found the carbs air fuel mixture screws each less than a full turn out, I can't wait to ride it tomorrow to find out if anything changed. I did put about 7 miles on it after straightening out the carbs and to my surprise it didn't boil at all. So, we'll just have to wait and see tomorrow. I did order the parts listed in my last post so if it still runs to hot tomorrow, I'll just park it until the parts arrive.

 

TTYL

[93 venture]

The only time my 93 boiled over was from me putting in straight water for coolant, think you have more like thermostat or have water pump impeller problem.

[MasterGuns]

The only time my 93 boiled over was from me putting in straight water for coolant, think you have more like thermostat or have water pump impeller problem.

 

Thanks 93 Venture; you may be right. So, when I tear it apart to replace the thermostat since I will have already drained the system, I have a new impeller and a good complete water pump. May as well do em all at the same time. But I am about to take it out since drilling the EPA plugs and moving the needles out from a ridiculous factory setting 21 years ago of 1/2 turn out to 2 1/2 turns out and if runs any better I may just leave it all as is.