ST1300 Overheating

Hi, all...

I have a 2004 ST13 which is overheating. Not the usual "this thing runs a bit warm!" type problem, but something new-ish.

Symptoms:
Bike is running much hotter than usual. Up until this issue came about - sometime since late summer - the bike would run fairly cool - there'd be noticeable warmth coming off the engine after 45+ minutes of spirited riding, but nothing that I felt was really hot.

Now, however, it'll be giving off a lot more heat than I ever remember, even in cool temperatures. If I'm on backroad twisties, the heat will build and build, and the fans are obviously running even when the bike is in motion, based on the heat flow. After awhile, the bike will start "bucking" - cutting out and in on the power, although idling OK. I can stop and shut the engine off for a minute, then restart, and it *seems* to work ok for at least a few miles after that.

It doesn't seem to matter whether I'm hard on the throttle for spirited riding or just easing along in top gear - if I'm not moving at freeway speeds, the heat builds incessantly. If I *am* at freeway speeds, it does get pretty warm but it seems to stay under control.

At the end of September, I made a weekender to Sacramento and 95 degree temps, and that's when I first noticed the heat. While wandering around north/east of Folsom Lake, the bike went into bronc mode, so I pulled off and shut it down, forced myself to leave it off for about 20 minutes. After that, I got back on and finished the loop, but it was obviously still running too warm.

When I got home, I pulled it apart and completely flushed the coolant, tested the old thermostat (and put on a new one anyway) to see that both thermostats were opening an expected amount, although the new one was about 15% more open - so I hoped the thermostat was the issue. I took off all major hoses, flushed it quite a bit with fresh tap water, flushed the radiator well, etc etc. Tightened a few hoses that seeped around the top of the engine. Reassembled with new thermostat & o-ring, added straight distilled water and brought it up to running temps to help flush it again (with distilled water vs tap water).

Drained it well, again, then reassembled and added Honda's pre-mix coolant. I picked up a radiator cap/pressure tester and put it on to see if any leaks showed up, but it seemed all buttoned up again.

Other things I did on this pass were:
New spark plugs, correctly gapped.
Fresh oil - Rotella T6 - and oil filter

A few local rides for a couple more days and it *seemed* OK, but the rides weren't long enough to get it hot enough, in retrospect. Then I went off tour/camping - about 1400 miles around central California over a week's time. The ambient temps were in the 50's to low 80's during the week's riding.

It was obvious that my efforts weren't rewarded, as the bike was still running hot. It seemed to vary - sometimes it seemed fine, especially at cool temps, and other days it was roasting my nethers, whether warm or cool ambient temps.

Fuel mileage seemed to vary too - about 40-46 mpg.

The computer didn't seem to think there were any problems - no blinking MIL lights, so it doesn't seem to think any sensors are failing.


So the question is - what do I look at next?

Based on mileage being down and various searches, it would sound like the oxygen sensors are suspect. I looked around the forum and I don't see many mentions of the oxygen sensors - anyone replacing these? Car maintenance sites suggest replacing them at 60-100K intervals - does this apply to bikes, too? I have no practical experience with O2 sensors.

Are there other sensors that might be suspect with these symptoms?

Any other ideas to look at?

What about dealership mechanics? Can the ST1300 be hooked up to diagnostic tools to quickly find the issue, or would they do the same things I do in trying to run this down?

Any thoughts anyone can offer are much appreciated, I'm afraid to take it to the dealer mechanic, fearing that they'd spend a significant amount of time (and R&R parts) and still not figure this out either.

You say that it is running hot but no mention of how many bars on the gauge, so how many are showing? Also, are you sure you bleed all the air out of the system after the flush?

QUOTE=Byron;1548248]You say that it is running hot but no mention of how many bars on the gauge, so how many are showing? Also, are you sure you bleed all the air out of the system after the flush?[/QUOTE]


What condition is your air cleaner in?
And like Byron said, did you burp or bleed the air out of the coolant system before you closed her back up?
When was the last time you had your throttle bodies adjusted (sync'd)?
When you installed the T-stat, did you use an OEM one or aftermarket one?
Did you make sure the vent hole was on top?
You say your using synthetic T-6 5w-40, the oil could be shearing down, how many miles since your last oil change.
I'd try the 15-40 delo. That's helped a couple other members who had heat issues.
Keep us informed and we'll do our best to assist you.
Igofar

You omitted any reference to the dash gauge display of engine temp so I assume it is normal at three bars. There is no mention of the fans staying on or not coming on during extended idling so I assume they operate normally. It would be exceedingly rare to have both a malfunction of the cooling system and the gauge at the same time so it doesn't sound to me like there is any issue at all with the engine cooling temperature or cooling system. Do you ride this bike a lot to get a feel for the amount of heat the engine puts out in various ambient temperatures?

A problem with the fuel pump or electrical supply to the fuel delivery system might account for the bucking behavior with it being masked or attributed to the thought or sensation of "too much heat".

I think the O2 sensors are a dead end.

The map sensor is one possibility but I was thinking that would throw a code. They are fairly easy to get to on the top/rear of the air box so checking the wires 1st and seeing that it's seated would be the 1st shot, then replacing the sensor part - pretty cheap part.

Next, the bucking is typically going to point to an air or fuel issues... check all your vacuum hoses under the air box by cleaning them out and make sure none of them are pinched.

After all that, it may be an o2 sensor but it's rare for that to happen w/no code thrown... so the fuel pump is the next possibility but before doing that I'd run some seafoam in it.

Fergie aka Gandolkf had this issue as well but it turned out to be water getting into the ECM on his bike or a loose connection in there which is not something seen on the site often at all.

Hope that helps some.

First thougths of mine are fuel pump or vacuum line leaks. Do the symptoms happen when the tank is full?

When mine acted as you describe for your bike, it was a bit unnerving and it felt like there was more heat from the engine (but in retrospect, I'm not sure there really was more heat to be felt than usual). Mine turned out to be a bad fuel pump.

Assuming the gage doesn't show more than three bars you may have a fuel pump issue.
Wouldn't be a bad idea to check the coolant level at the overflow bottle AND at the radiator cap particularly if you you didn't blip the throttle and burp the system when you filled it.

.02 02 sensor would be way down on the list of things to check at this point.

Check the wiki for pulling codes.
http://stwiki.notonthe.net/twiki/bin/view/ST13/ECMQuickGuide

Dealer *may have a scanner but probably doesn't have the software for the ST unless they service a lot of them.

Responses to various questions, in no particular order...

Gauge: It's always gone to 3 bars and stayed there. I've looked for 4 bars when it's roasting me, but I've never *seen* more than three bars.

Coolant: Yes, I "burped" it per the service manual, and I've verified both the radiator level and overflow bottle are topped up. This was the case before I tore it apart 5-some weeks ago too - it was one of the first things I checked.

Air cleaner: looks fine, and I ride in a relatively clean-air area (San Franscisco Bay Area). It's got about 9K miles on it, I change it at the interval pretty religiously.

Thermostat - new OEM one, air hole on top as required. Since the symptoms occurred both before and after the thermostat change, I'm fairly confident it wasn't the issue.

Oil: I've been running Rotella T (and T6 when it changed) since about 5K on the odometer, and I change at 4K intervals. Currently about 1500 on the oil. I used Delo for the break-in and first 5K miles.

Fans: The fans come on and off at idle and on the road - I'm deaf enough that I can't hear them, but I can feel the change in heat flow when they cycle. They definitely cycle at idle.

Heat perception: I would estimate about half my mileage is long-distance riding on camping tours, general day rides, etc, and the other half is commuting. In the past, I did notice heat, and followed conversations in the forums about it. I actually cut about 6 1.5" holes in each of the inner cowls to try to moderate the heat but I'm not convinced it helped much. At any rate, the heat was never what I thought as being excessive - it was just there. On cool days it was nice, and warm days it was reasonable - I could always hang my knees in the breeze to stay cool.
But now, even in the 60s, the heat coming off is significantly higher than I remember. Riding on the freeway it's reasonable, but if I'm doing 20-40mph backroads, it builds up excessively, to the point I need to get off the bike and cool myself off as much as the bike.

Bucking: I have actually had this problem in the past, too - I attributed it to just long miles and slow speeds climbing into the mountains bringing temps up high enough to boil fuel. But, I understand this to be essentially impossible with EFI since the fuel recirculates back to the tanks, keeping it relatively cool. This happened twice that I can remember, 3+ years and probably 40K+ miles ago.
The first time, maybe 4 years ago, it was during an extended section of tight curves, climbing maybe 2500 feet total - after about 45 minutes of this, the bike started bucking and it caught me off guard - never had that problem. After fighting it for a minute or two I pulled off and let it cool. I don't think the altitude change was significant enough to cause the computer to get lost, but I could be wrong. The ambient temps were probably in the mid-80s.
The second time was probably a year later and actually up in the same area (the hills E and NE of Eureka, CA), and this time the altitude change was bigger - roughly 3500 feet. I again shut down and let it sit for 10-15 minutes, and after that it seemed to be OK again. On the downhill run back into Eureka, the fuel guage started the all-blinking thing that I've had for the four years since. This *could* be related, I suppose, since it's probably the thermistor in the lower tank.
I don't remember any more incidences of this up until 5 weeks ago in Sacramento, and I detailed this already.

Fuel Pump: I'd hate to have to spend $450 on a new pump (even if it does get me a new thermistor too), unless I could be reasonably sure it's related. The heat issue doesn't appear to change relative to fuel level - it'll roast me with a full tank just as well as with a half-full tank.

Fuel mileage: Since my fuel gauge isn't working at this time, I tend to fuel up at about 200 mile mark, and almost always, I put in less than 5 gallons, so I'm rarely, if ever, emptying the top tank. I actually fueled yesterday at 224 miles and put in just over 6 gallons, so that's about 37 mpg; this was about half freeway and half runaroundtown miles. On the trip I saw it as high as about 47 mpg, but usually lower.

Plugs: When I pulled the old plugs out a couple weeks back, they looked nicely tan to light-brown, so I think it *was* fueling well enough at the time. I will need to pull them again and see what the new ones look like since this 1400-mile trip.


Other random thoughts: perception of heat again -- I *could* be wrong, but I'm pretty sure this thing is giving off significantly more heat than I ever remember prior to September. For the past two years, I hadn't taken the bike out for much long riding, mostly just commuting - so it's possible this problem started occurring earlier than 6 weeks ago. My perception is that the bucking problems were directly related to heat coming off the engine.

I'm getting to where I'm losing interest in the ST1300, to be honest - I've had it 8 years and had fantastic trips with it, but the weight, the struggles with heat and annoying issues, the windshield buffeting, bad wheel bearings, shaft-drive leaks, blah, blah... might be time to move on. :-/

What position do you run your seat in, is it stock or after-market?

Some have noted heat coming up the front of the seat between it and the tank. This doesn't normally happen in the low position but does in middle or high position even with the stock seat. Some after-market seats don't have the same piece of material that acts as a dam across the front and may leak heat even in the low position.

Adding the holes to the plastic may have increased the airflow bring the heat to your attention more, try sealing it off and see if it gets better. Have you changed riding gear? Mesh will allow the heat closer to your skin than solid gear.

The only other thing I could think of and not even sure if it applies to the ST's muffler is the cat may be clogging cutting off airflow through the exhaust and bringing up the engine temperature. If that was the case then you should see higher temperatures on the gage and possibly some sort of code.

I'm out of ideas.

Running lean would cause more heat. Could me a number of factors. I myself like the simple ones.

1.Is the tank venting properly? When it starts bucking if you open the fuel cap is there vacuum? Are any of your vacuum lines under the tank routed poorly or pinched when you lower the tank?
2. The evap canister on the lower right side is it blocked?
3. The evap canister electric valve in this line. Is it operating?
4. Are you running wires thru the foam barrier from the back of the tank to under the seat? Could this be open causing hot air to reach under the seat?
6. Fuel pump-- Check with pressure gage or unhook the lower fuel line return hose at lower fuel tank and connect to a container. Turn the key on for 10 seconds and you should have about 6.1 fluid oz of fuel. (as per repair manual 5-54). Low fuel flow would be pinched or clogged fuel hose and fuel return hose , clogged fuel filter, pressure regulator,or fuel pump.

Good point Byron about the heat around the seat.

sbixby, if this were my bike, my first look would be at the vacuum lines and 5-way tee for plugs or leaks, and most specifically plugging in the dead-end line to the MAP sensor. I'd also find every wire harness connector and make sure that there's no wiring discoloration (heat) and that all the connectors are tightly pressed together.

Presuming the vacuum lines are clean/clear and all connections are good, I'd also have a low cost fuel pump replacement in hand to put in place: https://www.st-owners.com/forums/showthread.php?122391-Sudden-Engine-problem!&p=1546645&viewfull=1#post1546645

sbixby, I understand your growing tired of the bike, but I do think this is solvable relatively easily.

I'm only about 30 minutes from you. You could swing by and we'll check it out and do a TBS and check the map sensor switch and vacume lines for ya.
PM me if you'd like to stop by.
Igofar

Followup #2, no new progress to add - been too busy to do anything.

But to answer some new questions:

Seat position: Seat is stock and in the middle slot on the front, but a lower shelf in the back. However -- this is what I've been riding for years, and the heat is no different around the seat, just on the feet & legs.

I also need to point out that the "additional heat" came as a change to a bike that had always run nicely for me. I cut the holes in the inner cowls some 7 years ago, so nothing changed in that regard. About the only thing I've changed in the timeframe where I noticed the heat change is a new shield - I swapped out my old stock shield (with a laminar lip) for a new V-Stream shield. The old shield was pretty much opaque from years of bugs and daily riding. While weirder things have happened, I'm 98% sure the new shield isn't affecting the heat on my ankles & calves.

So at this point, from suggestions received, it's probably time for me to pull it apart again, and go over everything with regards to vacuum hoses, fuel-pump flow, and so forth. I'm loathe to go under the throttle bodies again, that's always a PITA, but it seems like I'm going to have to.

I will probably drain the cooling system again and see if I can find any clogs in any of the various paths through the system. I'm fairly sure that if the coolant flow was impeded, I'd see more bars on the gauge.


So one general question: Many people mention vacuum issues and fuel-pump flow - but I don't understand how this would affect the amount of heat being generated in the system. Similarly, the MAP sensor - how is that going to affect things?

I'll also check the codes again but as I recall, if any codes are triggered, the MIL would be blinking, right? The last time I fired up the bike with the airbox off, I did get the two codes for MAP and (one other sensor) in fail mode, and I cleared them as I usually do when going under the airbox.


Finally -- thanks for all the thoughts and efforts on this; I may not get-to-it very quickly as it's a lower priority at this time of the year. But I'll keep this thread posted as I go along.

Before you start tearing down your bike again, are the radiator fins 100% open and not bent over blocking air flow. Rad shops have a tool to make the fins perfectly straight. I use a small screwdriver myself.

Have you confirmed that both fan motors are running. One might be unplugged or seized.

This is how I got rid of excessive heat on my ankles and calves. Spend $40 and switch over to synthetic oil.
Friend of mine at work was selling Amsoil and I thought I would help him out with a sale and bought the M/C 10W-40.
I'm not the only one on here that stated this, I was surprised that other riders found this true also.
I would like to explain why, but won't get into a long drawn discussion on your post here.

Also, are you are wearing riding boots, say a minimum of a 8" in height protecting your ankles.

This is an OLD thread, but the story is completed, so I thought I'd pass on what I found out.

I did try once more to tear down and look at things, I wanted to have a radiator shop do fin straightening with their tools, but he quickly pointed out that the tools are designed for car radiators with the larger spacing between fins. So I gave up on that angle.

Cleaned it all out as well as I could, one more time, buttoned it up with new coolant and the like, did all the burping and etc... no difference. When it got hot, it started stuttering & bucking. Right about then I got the joneses for a new bike and bought an FJR1300, so the ST1300 got secondary status. Then I moved to where I didn't have much room for two bikes, so I considered whether to sell it, trade it, etc. In the process, I spoke to a friend-of-a-friend, an Air Force serviceman who liked to buy older bikes and repair & ride, so I gave him a generous price and he bought it. He messed around with it for awhile and decided to get a new fuel pump (and thermistor) and poof -- it's all good again! I don't know if runs any cooler, but it's definitely stabilized the engine, and the fuel guage works again. He dared a $400 gamble and won, whereas I was sure it wasn't the fuel pump.

Ah, well. It's gone now. I have some left-over parts in a thread in for-sale stuff, I'll bump that thread once more to see if any new interest, but otherwise I'll probably start listing on ebay. (Pain in the butt.)

sometimes someone gets it their head that something is wrong and it's because of this.. cylinders and cylinder heads are surrounded with coolant. Along with the cooling properties of aluminum it would be hard to say that the bike is running hotter but the gauge says otherwise. The engine may be lean or rich( rich causes more heat, like adding fuel to a fire)but the coolant should dissipate any excessive heat, and if the coolant and fans are doing their jobs temps stay in range Stick a cooking thermometer in the coolant (in from the radiator cap off ) and verify temp gauge is working correctly. cooling fans should turn on somewhere over 200 degrees. I don't have st spec but average car fan turns on about 207. As far as the bucking goes I'm pretty sure it's not related

Thanks for coming back and closing the loop on your issue. It's too bad that you didn't know back than that its relatively easy to replace just the fuel pump out of the assembly for less than $100.

Enjoy the FJR...

fnmag said:

I'm glad your friend found the problem; fuel pump. Are you happy with your new FJR?
Have a great summer.

Click to expand...

I bought my FJR in late June 2013, so I have almost two years on it. Overall I like it a great deal. Compared to the ST1300 there's several aspects that go either way for me:

ST1300:
Smoother, at least at highway speeds
Somewhat better wind & weather protection (stock)

FJR:
Sportier/faster - more fun on the twisties.
Lighter - easier to shuffle around
Modern electronics -- love the electronic cruise and throttle-by-wire.
Cheaper. The newer ST's were about $5K more than I paid in 2004. OUCH!

All in all, I would pick either one again if I'm up for a new bike. I am disappointed Honda hasn't updated the ST1300 - yet, if ever. I do understand that the US market is smaller for sport-touring rigs, but still, Yamaha and Kawasaki have kept up with development, why not Honda?

Al st1100 said:

... it would be hard to say that the bike is running hotter but the gauge says otherwise.

Click to expand...

I put about 75K miles on the ST1300 in perfectly fine comfort levels. When it started acting up, it was very obviously emitting more heat, A simple case in point, the fans would come on *while rolling*, whereas previously they would only come on when I stopped, and then it would take 10-15 seconds stopped before they'd come on.

That said, I don't know if it was or is related to the fuel pump and it makes sense it wouldn't be. Unfortunately, it's new owner only knows what it is like now, and I only know what it was like before, so it might not be reasonably possible to know if it's any better. I don't have much contact with him to where I could as for a memory-lane ride, so I'll just leave it at that and move on.

Put red ST1300 for sale last week. Bought a newer blue one. Took red for ride yesterday. Of course it developed a problem.... Pissed at me for putting for sale sign on her!!
over heating. Fans both working. Spitting coolant. Gauge went to 5 bars many times. It has never gone past three bars before. Limped it home after many stops to let it cool. Tore it apart today. Rad full. I assume thermostat. Just removed thermostat. How do I know if if it is stuck closed. 1000,000 kms, never replaced thermostat before.
Is this stuck closed? Are there measurements for open and closed?