Yowzaaa! New old bike, new old problems ;) Coolant leak...

Joined
Jun 4, 2017
Messages
14
Location
Sweden
Howdy ho!

Before I start. sorry for all the text.
But it has pics!
Oh yeah!
Don´t we all love pics!

I´ll shoot of some of the facts, as I am hoping for help.
The truth is I am desperate for help to be honest.

The bike is a St1100 from 1991.
I am the third owner.
The bike has 100 000 km on it, which converts to 62137 miles.
It has been serviced properly.
The last big one was in 2013, belt was changed.
Other things like brakes, oil and such were also changed
It seemed to be well taken care of.
It is after all 26 years old.
I got it for a fair price.
Always inspected with a clean sheet.
Not many miles put on it since that last big service.
But inspected yearly without any flaws.

So, let's begin...

I have been driving it for a little bit since purchase.
And I experienced the first hot summer day here (Sweden).
During the drive I saw that the temp gauge almost peaked and the fan kicked in.
I just thought GREAT, it works. it went back to stay way within limits.
Upon getting home and parking.
It gurgled and puked coolant on my driveway.
Nice bike there. pissing allover my property. Hahaha.

I picked up a new thermostat, gasket, and replaced the hose running to the reservoir.
Cleaned out the reservoir tank, it was filled with some dark matter (awesome sci-fi show btw).
Which made it really hard to see the level.
The dark stuff in it made it look like it was always up to the upper marking.

So after changing the above mentioned parts.
I had an upstart today to check if everything was in order.
Now! here is where the real fun begins....

Daaataaaatadaaaaa!

It fires right up.
Reaching the temp at half on gauge. After a long wait...
Fan kicks in with needle at at about 3/4.
I have of course topped off everything with coolant 50/50.
Radiator full, and reservoir up to it´s upper marking.

Suddenly I see water coming out of both exhausts.
They both have 2 small holes in their back mufflers, one in each side.
Left and right. there is where the water comes out.
I tasted it and felt it between my fingers.
And it did not seem to be coolant. I know.
Totally freaks me out, so strange.

I was like, *** is up with that?
Suddenly a blown headgasket? or what?
Just like that, very strange.

I had before all of this happened, seen a small leak coming from back of the engine.
Between the heads, right there in the V.
It drips down right on the exhaust, and some onto the gear leveller.

So here I am.
And this is where I am at.

I have bought a ****load of hoses and clamps.

Any takes ont his u guys?

Is it the old off with the carbs and the whole shabang?
Or even worse, a crackhead.
Sorry, cracked head. or block?

Sincerly Klas

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Byron

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Condensation in the exhaust system will exit as water when the bike is fired up and once running temp is reached should stop. Does the water stop or just keep coming? Not a wise thing to taste something that could be antifreeze, it kills animals. Can't tell a whole lot from the photos, if you see fluid coming out somewhere in the photos, circling it would make it easier to see by everyone else.
 
Joined
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2021 RE Meteor 350
Condensation in the exhaust, as Byron has said. Naught to worry about there. Your other leak is probably coming from very old coolant hoses and leaky gear clamps in the V of the engine. If you can remove the fuel tank - easier when near empty - you can get a good look under the carbs to see the condition of those hoses and clamps. If they have never been replaced, it would be wise to pull the carbs and do that job. You must replace not only the two hoses, but also the elbows, which connect the hoses to the heads and the o-rings under the elbows.

If pulling the fuel tank. note the wire connector on the left side, sort of hidden by the frame, as it will tear apart the wiring if you lift the tank out without disconnecting it first.
 
Joined
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soCal
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'97 ST1100
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687
agree with what Bush said. This is a known failure item as the bikes age, and often the hoses will split lengthwise and puke out all the coolant in a few seconds, so you're lucky you're getting a warning instead of being stranded when all your coolant dumps on the roadway. While you're in there, replace the carb boots, they're cheap and will be too heat hardened to re-use anyway.
 
OP
OP
Joined
Jun 4, 2017
Messages
14
Location
Sweden
Howdy.

Wow. totally amazed here for the sheer awesomeness :)
Thank you very, very much for fast replies.
I am very grateful u guys.

Byron. Yeah.
That was what I should have done, sorry for that.
I´ll see if I can fix this in a program, mark it up properly.
You´re totally right.
Sometimes you just act too fast :)

Ran it for 8 minutes or so.
So I could get the fan going, and get correct pressure and heat.
Yes, the water kept coming out.
Comes out through those small holes, and creates little puddles on the ground.
Not like a lake, but moisty puddles. yepp, moisty puddle wuddles.
But now the leak seems to be gone in and around the v. Very odd.

Tasting wasn´t so bad, It was not like I drank it.
And the amount of crap that has hit this body.
A wee bit of coolant on the tongue won´t shorten my life ;)
A bottle of moonshine had me almost killed once.
As comparison, I am alright :)

Bush and Dwalby:

U guys seem to be right.
Tomorrow I´ll get back on it and pull the rest of it off.
So much plastic it´s insane hahaha.

I did find a parts list here in some other thread.
Owning a St sure has given my a heads up I have gotta say.

A big thanks to everyone!

U rock!

Sincerly Klas
 
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2010 ST1300
A cracked head is the last thing you should expect. Docs have a saying, "If you hear hoof beats, don't look for zebras" - meaning check the obvious, common causes first. Having restored a couple of old bikes, I'd replace any and all accessible rubber parts at 25 years once I dived into repair something. Only reason not to would be because said hose/bushing, whatever was soft and pliable like a new one. This is purely my preference - I dislike unforeseen breakdowns when I'm having a good time on a trip. Someone here suggested replacing the upper tank to lower tank hose at 7 to 10 years. Since I have a 1300, and am not familiar with the 1100, I don't even know if the setup is the same. Just a suggestion.
 
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2021 RE Meteor 350
Since I have a 1300, and am not familiar with the 1100, I don't even know if the setup is the same. Just a suggestion.
Not at all the same. No upper and lower tank - Honda did it right the first time! ;)
 
OP
OP
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Jun 4, 2017
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Sweden
Ya never know when a crackhead suprises ya .
I sure hope it is not a crack.
Can't wait to dig into this tomorow.
Gotta do some trucking before I git home and can get the hands dirty again.

Will pop by a Honda dealer at lunchtime and order some more rubber tomorrow.
have a parts number list now too. Yey

Grateful for your advice. I will definetly follow up on that.
I am embarking on a long trip in July. So I am on a tight schedulengeting the bike back in shape.

Thank you for your input.
Greatly appreciated :)
 
OP
OP
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Oh. Btw.

Do I have to remove gastank?
or is it doable with it on?
I am leaning towards that the problem is under the carbs.
 

Slydynbye

Will ride for Pie
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Oh. Btw.

Do I have to remove gastank?
or is it doable with it on?
I am leaning towards that the problem is under the carbs.
Start by emptying the Tank as much as possible.
Remove the (red?) Connector for the Fuel level unit on the left side of the tank.Underneath the left side panel.
Disconnect 3 connectors on the Top of the Tank.
Disconnect Fuel hose.
Remove the 6? Bolts holding the tank down to the frame.
Lift the Tank being careful not to bind the Fuel level connector.
 
Joined
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Auckland, New Zealand
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2005 ST1300
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8901
If the bike puked coolant out on your driveway, did that come out of the reservoir? If so I'd suggest that you add a new radiator cap to your shopping list. A faulty cap means lower system pressure and a lower boiling point (e.g. 107C with no pressure, 130C with a working cap at 1.1 bar). For reference, 80C is about 1/4, 100C is about 1/2 and 120C is 3/4 on the gauge.

In my experience it is much easier to remove the airbox/carbs for coolant hose access than the fuel tank. While we are spending your money, buy some new inlet rubbers as well, makes for a happier time when you refit the carbs and guarantees no air leaks.

I would also replace the small bypass hose between the thermostat and the pump outlet, 5.5mm id vacuum hose IIRC.
 
Joined
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2021 RE Meteor 350
In my experience it is much easier to remove the airbox/carbs for coolant hose access than the fuel tank.
Of course, the carbs do have to come out for this task, but if one simply wants to get a good look at the conditions under the carbs, pulling the tank leaves a hole big enough to stick your head into to see, or, using a mirror would be easier, as twisting your head and neck to look in there requires some tricky calisthenics, but I've done it!

I found pulling the carbs was easier with the tank out as well. Easier access to the throttle cables.

One word of advice about removing the carbs. Do NOT remove the rubber snorkel and plenum assembly on the top of the carbs. Pull that and the carbs out as a unit.
 
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Of course, the carbs do have to come out for this task, but if one simply wants to get a good look at the conditions under the carbs, pulling the tank leaves a hole big enough to stick your head into to see, or, using a mirror would be easier, as twisting your head and neck to look in there requires some tricky calisthenics, but I've done it!

I found pulling the carbs was easier with the tank out as well. Easier access to the throttle cables.

One word of advice about removing the carbs. Do NOT remove the rubber snorkel and plenum assembly on the top of the carbs. Pull that and the carbs out as a unit.
I've had the carbs out of my ST more times than I care to admit. One tip is to disconnect the throttle cables after the carbs are popped up off the rubbers. Once they're up, you can easily unscrew the two screws that hold the throttle cable bracket onto the carbs, and then just unhook the cable ends without touching any of the slack adjuster screws. And no need to remove the tank at all.

Naturally, installation is the reverse of removal, so it pays to refit the throttle cables before re-seating the carbs...

I agree 100% on not pulling the snorkels off the top of the carbs; I did remove mine (major carb cleaning project) and they were a real curse to put back together. Possibly if I had three hands it would be easy, and I imagine they were assembled on a jig back in the factory.
 
Last edited:
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I hope the coolant spigots under your carbs look better than these.
DSC02444.jpg

These are off a 2000 ST and are well past their due date. Just order new ones and the O rings.
 
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I suspect coolant elbows(one on each head, upper center of engine) and O-rings need replacing. At same time replace carb boots with new OEM ones. Once those are clamped in place, spray a shot of silicone inside each one, as this will allow carb bank to slip right into place. Pay special attention to upper carb boot clamp location BEFORE removing old ones. That location is needed to access upper boot clamps to carbs.
 
OP
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Jun 4, 2017
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Sweden
If the bike puked coolant out on your driveway, did that come out of the reservoir? If so I'd suggest that you add a new radiator cap to your shopping list. A faulty cap means lower system pressure and a lower boiling point (e.g. 107C with no pressure, 130C with a working cap at 1.1 bar). For reference, 80C is about 1/4, 100C is about 1/2 and 120C is 3/4 on the gauge.

In my experience it is much easier to remove the airbox/carbs for coolant hose access than the fuel tank. While we are spending your money, buy some new inlet rubbers as well, makes for a happier time when you refit the carbs and guarantees no air leaks.

I would also replace the small bypass hose between the thermostat and the pump outlet, 5.5mm id vacuum hose IIRC.
Howdy :)

Yes, cap and thermostat changed. It reaches half now on the gauge when fan kicks in.

thank you for your input.
Greatly appreciated :)

/K
 
OP
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Thanks a bunch everyone for all the help.
It means so much!

I am now in the waiting game.
Ordered a bunch of parts this morning during morning coffee at work.
Think I covered everything by ordering these parts:
Part NumberDescription Qty.Comments
16211-MT3-000 carburetor insulators (4) optional but recommended
91315-MT3-003 water pipe seal (1) [13]
19300-MG9-000 thermostat (1)
91307-MB0-003 o-ring (54X2) (1) thermostat
19503-MT3-000 upper radiator hose (1)
19505-MT3-000 lower radiator hose (1) [2]
91331-PC9-003 o-ring (21.2X2.4) (2) [14] cyl. head hose fittings
91311-KE8-000 o-ring (47.5X2) (1) [12] engine block inlet fitting
19504-MT3-000 hose (1) [1] LH cyl. head to thermostat housing
19506-MT3-000 hose (1) [3] RH cyl. head to thermostat housing.
19520-MT3-000 oil cooler hose (1)
19525-MT3-000 oil cooler hose (1)
18604-MT3-730 tube, air suction valve

No reason for me to mention prices here.
Since they ship it to dealer from central warehouse in Gent.
So yeah. it won´t come cheap.
But the bike was cheap :)

I am so grateful for all the help u guys.
It has really helped me out not loosing hope in me and the bike.

Sincerly Klas
 
OP
OP
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Jun 4, 2017
Messages
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Location
Sweden
I hope the coolant spigots under your carbs look better than these.
DSC02444.jpg

These are off a 2000 ST and are well past their due date. Just order new ones and the O rings.

Wooowa.

Would say they are fixable though, if no cracks :)
Just a little tlc :)

Hehe.

/K
 
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