1100 Overheating at Idle

bradwilder1

Recently bought an 1100 with 80K and have no issues with it riding short rides, long rides, and even traffic. But left it idle one morning longer than I expected to and the needle was all the way to the right almost in the red. I've checked for leaks and there's nothing on the ground. Oil is at proper level, and coolant is too but it looks watery. I'm not too mechanically inclined and may have to have the shop check this out, but if I get some feedback here that seems like something I could look into myself, I'll do it.
 
Check your lines to the bottle. They can crack with age and draw air rather than coolant, thus emptying your rad.
 
The fans should be easily heard. And I think you should be able to shine a light onto the back side of the radiator (through the side grills, around the valve covers) and see a portion of the fan blade to see it turning. Keep in mind that they won't run 100% of the time, but they should cycle on and off as needed to keep engine temperature in range.
 
Replaced my hose a year ago with a new factory piece after careful inspection and verifying correct fan cycling.
Fans are not real loud but you should be able to hear them, observe a drop in voltage when they come on if you have a volt meter and feel the warm air push out of the tupperware openings above the engine.
It didn't leak onto the ground but would push antifreeze into the tank (over full) with just a hint of leakage near the thermostat, then suck air into the cooling system when it cooled down after riding it eventually causing an overheating condition.
Worth checking, took care of my issue...
Good luck.
 
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bradwilder1 said:
How can I check that, should I listen for something?
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Brad, If you can turn a few nuts and screws, there are many things that you can DIY quite easily. Checking this hose is one. It will require the removal of some plastic on the right side. Here's where it is good to have a Honda Service Manual for the bike, as it details most of the services the bike may need, including plastic R&R.

You would have to remove, the lower cowl (bottom grey piece), the right side panel, the right maintenance panel (where you see the engine) and the lower right fairing. Once you locate the hose from the reservoir to the filler neck, see how the hose looks at the filler neck, as that's where it usually splits. It needs to be removed for a proper inspection. Whether it is split, or not, cut off about an inch and reattach it. The clamp should be quite snug, but not gorilla handled. Before reattaching the hose though, it is a good idea to blow into it, as they tend to get clogged up over time. Clean out the reservoir tank also and refill with new coolant, to just over the lower limit line marked on the bottle.

It sounds like your coolant might need changing and you could do that too. Remove the radiator cap from the filler neck. Locate the rad drain plug (white) on the lower left side of the radiator. Unscrew that plug for several turns and catch the old coolant. This will not drain the entire system, but it gets most of it, sufficient for our purposes. Refill with a quality non silicate coolant. I prefer Honda Type 2, sold at all Honda car dealers. Don't know who makes it for them, but it saves me the hassle of reading a bunch of labels, that may, or may not, tell you what's all in it!

Fill to the bottom of the filler neck, screw the rad cap on completely and run the engine up to temperature, check the fan comes on and off and there is no leak. Then, the engine needs to fully cool BEFORE you take the rad cap off to check the coolant level in the rad. Top up, if necessary and refit the cap. Plastic back on. Done. Easy peasy. Hope that wasn't too descriptive for you, but you sounded like you could use the help.
 
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If, as already mentioned, you can access the engine, mainly the left side maintenance panel.... if you can remove this, you will find a sensor in the left side of the radiator....

Disconnect the wire and using a length of wire connect this to the battery negative terminal, the black cable on the battery.... turn on the ignition and the fan should start right up.

What the sensor does is connect the radiator to the negative or frame to make the return circuit for the fan, the radiator is not "grounded" and the fan negative lead is connected to the radiator..... therefore when the sensor reaches temperature and closes the connection, it grounds the rad and makes the return for the fan.... connecting this lead straight to negative or "ground" as it is often called, then turn on the ignition, it should run the fan straight away.
You should, of course, check the fuses also.... as a blown fuse will only confuse the issue.
If the fan fuse has blown, you need to find out why before testing the fan.... there could be a stone trapped in the fan preventing the blades from rotating.

If it doesn't work, you may have found the culprit, or one of them anyway..... I suspect that as already said, you have a problem with hoses on the header/overflow bottle.....

This fiche may help identify the parts. There are other fiches on this site that may also help.

http://www.cmsnl.com/honda-st1100-1991-usa_model739/partslist/F++33.html#results
 
I will tear into it and take all the suggestions mentioned above, while I'm at it, what can I do since I don't see or hear the fans running?
 
There is a fanstat in the radiator that you can check. Open when sold; closed when hot. Multi meter set ot ohms. Or jumper the connector to the fanstat to see if the fan starts.

You can check to see that you have 12v to the fan. The fanstat completes the circuit to ground.

The fan on my 1982 Sabre just plain gummed up and quit working. Now the fanstat is dead (confirmed with the open when hot test)

Same principles.

Neal
1982 VF750S
 
bradwilder1 said:
I will tear into it and take all the suggestions mentioned above, while I'm at it, what can I do since I don't see or hear the fans running?
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First things first. If the rad is actually low on coolant, the fan will not operate anyway, as it relies on that fan switch, mounted in the rad, to detect the high temperature of the coolant. It then closes its contacts and the fan comes on. This won't happen if the coolant level is below the switch position in the back of the rad. If you can get to the point of removing the rad cap to see if the coolant is low first, that may tell you why the fan isn't coming on. You could do the electrical check mentioned by Firstpeke, just to be sure the fan is working, but it won't necessarily tell you if the switch is working properly. Once the coolant is replaced and topped up, running the engine up to operating temperature should cause that switch to close and open, starting and stopping the fan. If the fan doesn't come on and the temperature gauge continues to climb, the switch is likely faulty - but a stuck closed thermostat will do that too.

So you can see there are a lot of variables in this cooling system. A complete going over to check all of these things wouldn't hurt and gets you peace of mind. Again, if you intend to take up some wrenching for yourself (you will save a ton of money in the long run) get yourself a Honda Service Manual for your year of bike. I think there are also PDF versions of the manual online at some web sites.
 
bradwilder1 said:
I will tear into it and take all the suggestions mentioned above, while I'm at it, what can I do since I don't see or hear the fans running?
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The initial coolant level IS suspect low based on temp gauge fluxuation.
Low coolant level WILL keep fan from coming on when below immersion level of sending unit.

Those two things in itself says there IS an external leak SOMEWHERE.
Initially, the leak won't be necessarily visible, or smelled either.......BTDT.
First suspect things to check for a colored residue ARE all the hose clamp connections at themostat housing, a split in overflow hose at top of radiator neck or even farther down hose, and finially coolant elbows/O-rings at top center of each head
Those ARE the most common issues associated with cooling issues on these ole' 11's, and listed in 'ease of fix' order;).
 
Is your coolant reservoir over full? This is an indication that the fluid is not being drawn back into the rad due to an air leak in the hose.
 
If the plastic over flow bottle is full and the radiator is low, the hose is cracked.

Other leaks are probably slow enough for the coolant to dry or burn off. You'll have to look for residue left.
 
Thanks so much for all the helpful, and very descriptive, feedback. My idea is to replace everything mentioned once I go through the trouble of tearing that far into it. My thoughts on this are; I don't want to get all the way into it to fix the problem once (let's say it's the thermostat), just to turn around and have to do it all again because of an o-ring. Any thoughts on this?
 
Go with the simple things first. Take off enough plastic to get to the radiator cap. Start with the seat, saddle bags, then right side cover. Then the piece that covers the valve cover. Then the piece that has the right side glove box in it, screws are under the lid and a few around the edge. Oh you may need to take the fake tank cover off to get to some of those screws. Working from memory here. From this point you should be able to get to the radiator cap. Open it up and check the level. If it is down more than 3 inches from the top, and you have antifreeze in the overflow bottle, your problem is either the overflow hose or the radiator cap. You can get a similar hose at you local autoparts store. Inside diameter is really the only important thing you need to match. Now, if the antifreeze level in the radiator is at the top you have a fan issue. I would rule out the overflow hose before delving into all of that.
 
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bradwilder1 said:
Thanks so much for all the helpful, and very descriptive, feedback. My idea is to replace everything mentioned once I go through the trouble of tearing that far into it. My thoughts on this are; I don't want to get all the way into it to fix the problem once (let's say it's the thermostat), just to turn around and have to do it all again because of an o-ring. Any thoughts on this?
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yes, my thought is none of the steps are all that tedious that you have to worry about having to 'do it all again' because you overlooked something.

1. determining if the fan is operational takes almost no time, so do that first. Find the thermo switch in the radiator, remove the wire, jump wire to ground.

2. if you can jumper the fan and make it work, the next step is to check the coolant level, which also takes very little time, but requires a surprisingly large list of plastic removal to get at it. (yes you do have to take off the top tank shelter to get at the last screw for the right cover with the glovebox). At that same time and location you can check the overflow hose for cracking at the bend just underneath the radiator cap. Also take a look at the rubber gasket on the radiator cap and determine if you need a new cap.

3. If no problems found up to this point, you're 2 or 3 bolts away from replacing the t-stat. You need to pull the small plastic shroud in front of the stat housing (1 screw on top) first, then the bolts are accessed from the front of the frame. also change the o-ring while you're at it.

4. Put it all back together and ride it. If the problem persists then your last item is the thermo switch, which you already located in step 1. I think that's the most expensive part in this list, and least likely to fail, so that's why I put it last. You could remove it and test it in boiling water in step 1, but it requires draining the radiator, which may not be necessary if you find the problem elsewhere.
 
dwalby said:
yes, my thought is none of the steps are all that tedious that you have to worry about having to 'do it all again' because you overlooked something.

1. determining if the fan is operational takes almost no time, so do that first. Find the thermo switch in the radiator, remove the wire, jump wire to ground.

2. if you can jumper the fan and make it work, the next step is to check the coolant level, which also takes very little time, but requires a surprisingly large list of plastic removal to get at it. (yes you do have to take off the top tank shelter to get at the last screw for the right cover with the glovebox). At that same time and location you can check the overflow hose for cracking at the bend just underneath the radiator cap. Also take a look at the rubber gasket on the radiator cap and determine if you need a new cap.

3. If no problems found up to this point, you're 2 or 3 bolts away from replacing the t-stat. You need to pull the small plastic shroud in front of the stat housing (1 screw on top) first, then the bolts are accessed from the front of the frame. also change the o-ring while you're at it.

4. Put it all back together and ride it. If the problem persists then your last item is the thermo switch, which you already located in step 1. I think that's the most expensive part in this list, and least likely to fail, so that's why I put it last. You could remove it and test it in boiling water in step 1, but it requires draining the radiator, which may not be necessary if you find the problem elsewhere.
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This is good info but the easiest way to tell if the fan is operational is to ensure there is antifreeze in the radiator then run the bike up to temp. If the fan runs you do not have to go through all the trouble shooting as the trouble was lack of coolant. If the coolant is low you are then trouble shooting how you lost coolant. And the common culprit is the overflow hose.
 
Less chance of engine damage if you test the fan the way I suggested.......
 
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