overheating

[oldamigos]

My 92 St1100 overheated on the way to the airport yesterday. The gauge made it to the red but would drop and rise again. There was a great amt of steam but no evidence of coolant anywhere. I topped it off and it took less than a pint. I didn't have time to deal with it so I parked it until I return.
I am not too mechanical so what do you think I will have to deal with? Thanks for any insight.

 

[mcthorogood]

First I would check to see if the return hose to the coolant reservoir is cracked. Remove the right side panel that is located below the seat and check the small hose that is connected to the reservoir. If it is cracked you can usually fix it by cutting a small piece from the end and reconnecting it.

Otherwise, use the search function for this site to check for ST1100 coolant problems.

 

[Mark]

Steam is a bad thing... Cracked elbows under the carbs...
'Topped it off'? Where did you top it off?

If at the radiator then it might be a small crack in the elbows; but, if topped off at the reserve container it might be a cracked overflow hose.
The cracked overflow hose usually presents as a full overflow/reserve container and overheating; but, does not include 'steam.
(I have had both issues! )

 

[dwalby]

My 92 St1100 overheated on the way to the airport yesterday. The gauge made it to the red but would drop and rise again. There was a great amt of steam but no evidence of coolant anywhere. I topped it off and it took less than a pint. I didn't have time to deal with it so I parked it until I return.
I am not too mechanical so what do you think I will have to deal with? Thanks for any insight.

When the gauge rose and dropped, could you tell if the fan was coming on? If the fan was causing the gauge to drop that's a good sign that you still have a fair amount of coolant in the radiator, but not necessarily the correct amount. With a full coolant level it probably wouldn't go all the way up into the red before dropping back down, so you're probably low on coolant. If the fan was not coming on at all then you're probably quite low on coolant.

So the first step is to get the plastic off and remove the radiator cap to see what your actual coolant level is in the radiator. Top it off and run the bike without the plastic and look for signs of leaks. While you're at it check the overflow tube where it connects to the area around the rad cap, and see if there are any visible cracks. Pull it off and take a close look at it, and trim it back if you see any signs of cracks or weakness.

 

[tmds3]

Something else to consider as well, a bad radiator cap can act like an overheating issue. They are designed to hold a certain amount of pressure,if they dont they will pop off and you could think it is overheating when in fact it pops, you loose fluid, get air in the system and get hot.

Some auto parts stores have the part to check the pressure on the cap

 

[oldamigos]

thanks all

 

[dwalby]

Something else to consider as well, a bad radiator cap can act like an overheating issue. They are designed to hold a certain amount of pressure,if they dont they will pop off and you could think it is overheating when in fact it pops, you loose fluid, get air in the system and get hot.

I originally thought if the cap were bad then he'd be able to see it venting while running the bike without the plastic. I always replace caps before they go bad so I'm not familiar with the various failure modes. Can they fail such that you get a very slow steam leak that's not obviously visible, which runs down your coolant level slowly over time? Or do they tend to fail such that its obvious when looking at the cap while running the bike? Or could you get either failure mode so you really have to get it tested to be sure?

 

[Brant]

I originally thought if the cap were bad then he'd be able to see it venting while running the bike without the plastic. I always replace caps before they go bad so I'm not familiar with the various failure modes. Can they fail such that you get a very slow steam leak that's not obviously visible, which runs down your coolant level slowly over time? Or do they tend to fail such that its obvious when looking at the cap while running the bike? Or could you get either failure mode so you really have to get it tested to be sure?

Have had both scenarios in other applications. In the case of my ST, a visual of both seals inside cap told the story. Coolant level would get low over a period of time with no visual drips anywhere. With that issue solved, the system holding pressure under expansion and temp gauge/fan all working correctly again, wasn't long after the coolant elbows AND o-ring seals throwed craps from the system being correctly sealed again............something to consider going forward.

 

[tmds3]

I originally thought if the cap were bad then he'd be able to see it venting while running the bike without the plastic. I always replace caps before they go bad so I'm not familiar with the various failure modes. Can they fail such that you get a very slow steam leak that's not obviously visible, which runs down your coolant level slowly over time? Or do they tend to fail such that its obvious when looking at the cap while running the bike? Or could you get either failure mode so you really have to get it tested to be sure?

Depends,once it hits the failure point it will pop and spew some fluid, the rest may just be steam that he may or may not be able to see(maybe easier since it is cold)if the fluid is low enough it will only be venting hot air so he may not see anything.

 

[oldamigos]

47000

 

[vinny]

Some very good advice above, given the AGE of the bike, some of the issues are possible attributed to age instead of mileage of the bike. I second the thought of a close inspection of the entire cooling system. Good luck.

 

[oldamigos]

good advice, thanks

 

[dwalby]

Considering year and the unknown service history I'd go for a throughout inspection & overhaul of the entire system...
Pull the carbs, check/replace elbows & O-rings, internal passage hoses, bypass hose, radiator hoses, overflow hose, fan-thermo (Klixon), the radiator drain plug + gasket, the coolant thermo + O-ring, radiator cap...

And if it hasn't been done yet, do t/belt and w/pump as well...

I would not stop at fixing one item alone and believe that does it... there too many items/parts of unknown condition with risk to fail... the known, long distance reliability of the ST can only be kept by proper maintenance...
The aftermath of unseen/neglected low coolant levels are blown head gaskets and more...

I don't dispute the wisdom of this advice, but... The OP made this comment in the first post:

"I am not too mechanical so what do you think I will have to deal with?"

He may be shocked when confronted with the cost of this level of inspection at his local Honda dealer. Not sure if he even plans on riding the bike long distances either, that topic wasn't addressed. If he just wants it for around town commuting, etc. then rolling the dice on some of the other stuff wouldn't be a bad idea as long as he's aware of the potential risks.

 

[ST1100Y]

He may be shocked when confronted with the cost of this level of inspection at his local Honda dealer.

Didn't point him to a dealer... there might be relatives, friends, neighbours or even cooperative board members avail to happily give a fellow rider a hand... besides that especially on the 1100 basic maintenance isn't that hard to learn, thankfully its not a computerized EFI monster, stuffed up to its gills with sensors and probes acting up randomly... ;-)
Even while only tooling around town could "rolling the dice" as you've put it, bear some risks... having the engine go poof on a busy intersection, i.e. in proximity of a semi/city bus following closely behind, might not be a really great thing...
Besides that it would be a shame to blow a perfectly running SC26 plant over saving a buck or two on simple things like a few hoses and clamps...

 

[scotboy]

Try put in themo switch from a st1100p police bike .it turns the fan on at 185f

 

[scotboy]

The part number is 37760-mt2-003 . 2003 st1100p .police bikes sit with the motor running so they get hot

 

[ST1100Y]

The part number is 37760-mt2-003 . 2003 st1100p .police bikes sit with the motor running so they get hot

Hmm...
I just checked with the parts catalogue for the "civil" as well as for the P-spec models: 37760-MT2-003 just is the standard fan thermo for all years and all versions of the ST1100, as well as various other bikes (and numerous other water-cooled Honda engines and power equipment); can't find one with other set-point for P-spec models, their all 100?C/212?F-ON...

 

[scotboy]

Hmm...
I just checked with the parts catalogue for the "civil" as well as for the P-spec models: 37760-MT2-003 just is the standard fan thermo for all years and all versions of the ST1100, as well as various other bikes (and numerous other water-cooled Honda engines and power equipment); can't find one with other set-point for P-spec models, their all 100?C/212?F-ON...

My 1999 st themo part number 37760-mr1-003 in www.sevice Honda.com .

 

[dwalby]

The MR1 part shows up in the parts fiche as the stock (non-Police) switch, and appears to be set to 100C. The MT2 part shows up as the stock ST1100P switch, and appears to be set to 85C.

I use the word 'appears' because a web search finds some references to the temperature settings, but nothing directly from Honda to confirm.

 

[ST1100Y]

The MT2 part shows up as the stock ST1100P switch, and appears to be set to 85C.

Possible that this is depending on destination/climate?

'99 ST1100A:
http://www.cmsnl.com/honda-st1100a-1999-usa_model743/partslist/F++34.html#results
http://www.cmsnl.com/honda-st1100a-1999-usa_model743/swassy-thermo_37760mr1003/#.VLgytXtc7aI

'00 ST1100A:
http://www.cmsnl.com/honda-st1100a-pan-european-2000-austriaabs_model4697/switch-assy-ther_37760mt2003/#.VLgz3Xtc7aI


'00 ST1100P (Europe)
http://www.cmsnl.com/honda-st1100p-pan-european-2000-austriakph_model4765/switch-assy-ther_37760mt2003/#.VLgzYntc7aI

'00 ST1100P (Australia)
http://www.cmsnl.com/honda-st1100p-pan-european-2000-australiakph_model4769/switch-assy-ther_37760mt2003/#.VLgzi3tc7aI