Need tip to prevent coolant from being diluted on '92 ST

TMF

TMF

Joined
Oct 27, 2021
Messages
110
Age
66
Location
Brookeville, MD
Bike
1992 Honda ST1100
Like a good boy I ordered the genuine Honda coolant which is a 50:50 antifreeze to water mix. I'll be flushing a neglected but salvageable system then adding the Honda coolant. I'm very afraid to remove 30 year old cylinder drain bolts and so assume there will be some water left in the system after the clean and flush. Assuming I then add the Honda coolant it will be diluted to less than 50% antifreeze. I've heard tell of blowing into the thermostat housing. Does that technique work enough so that dilution is not a problem? * See Final Thoughts below

Followup - I missed the opportunity to measure the protection level of my faded green and brown drain because I added the pristine contents of the overflow reservoir (thermostat housing exit to the coolant reservoir was completely plugged). It's quite possible the drain was overly diluted with water hence it's appearance and my desire to have at least 40% antifreeze in the system. Thanks to Andrew Shadow's tip I have some Honda type-2 concentrate coming in and the problem is solved. Another fine point - I removed the lower left radiator hose and blew out the system with my compressor. taking turns plugging the hose and radiator. Nothing further came out. Now, I'm not sure why the drains behind the exhaust exist if a normal gravity drain removes everything.

*Final thoughts - Now that the job is done the method is: 1) After you've done all the cleaning and flushing add Honda Type-2 or a similar antifreeze mix. 2) Warm the engine enough so that you know the thermostat has opened (the bottom left hose at the radiator will get warm). Let it cool for 10 minutes or so. Remove the now pliable hose at the bottom left of the radiator and drain into a clean pan. Check and adjust the mixture with an antifreeze and coolant tester hydrometer, adding Honda Type-2 concentrate if necessary. Pour the mix back into the radiator.
 
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Check the freeze point for a 60/40 mix for your location. Water dissipates heat better than coolant, so a little more water won't hurt. I'm kinda doubting you'd get to 60/40 with the bit of residual water in there.
 
I'm inclined to measure the drain and compare to Honda's spec on capacity. I've got some Prestone silicate free undiluted antifreeze that is compatible with all coolants. If the final fill with Honda coolant calculates to less than 40% antifreeze the straight Prestone will go in to achieve 50%. I'm reluctant to mix but it's the lesser evil.
 
Not directly relevant but I have just changed the fluid in my 1300. I have never bothered with the drain bolt before on this bike when changing fluid because of the fiddly access that I experienced on the 1100. This time I did remove it. I wish I hadn't bothered. I didn't measure it, but the amount that came out was small. I tried to catch it, but it kept changing where it fell. I just let it fall, and cleaned it up with a small rag. I guess less than a cupful. Say 300ml.
I put in 3 litres of 50:50 coolant. So the 300ml is 10%


So in your case, if 90% of the main drain is 50:50 water:antifreeze. That would be 45% antifreeze, 45% water
Add on the 10% of water that was still in there

55:45 water: antifreeze mix.

Pure estimation. But its the best I can offer.
 
Use the Ron Major's blow job method- not worth it to remove the engine drain plugs.

See below link;

ST1100 coolant replacement odd procedure | ST1100 Related

I'm geting ready to flush my coolant in my ST1100 and replace it. I have watched a couple videos on youtube, just to have a general idea. I bought a few quarters of replacement coolant, and... just opened the "big book" (clymer maintenance manual) to get the real, good, recommended procedure...
www.st-owners.com www.st-owners.com
 
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Pulling the lower rad hose off of the rad will get you more coolant out than opening those block drain bolts will. There's a fair bit that sits below the level of the rad drain plug. Your worry about the dilution ratio is unnecessary. Drain it out, refill with the Honda coolant and fuggedaboudit.

If you really want to be anal about it though, then fill it with Honda, run the engine, drain it again and refill with Honda again. That will make sure your dilution concern is addressed. There is enough in the gallon jug of Honda to do the system more than twice.
 
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Are you really going to run the bike or park it in subfreezing weather (for the coolant)? As @RaYzerman said, check out the freezing point of 60/40 mix and go from there. I found this online for propylene glycol - there is evidently a freezing point and a bursting point (it might not be accurate for Honda Type 2 A/F):
www.shoptalkbyindmar.com

Anti-Freeze Protection Levels

A normal 50:50 mix of propylene glycol provides a protection level that will allow an engine to operate at -26°F (-32°C). That means that no ice crystals will form in the coolant till the...
www.shoptalkbyindmar.com
 
Bush said:
If you really want to be anal about it though, then fill it with Honda, run the engine, drain it again and refill with Honda again. That will make sure your dilution concern is addressed. There is enough in the gallon jug of Honda to do the system more than twice.
Click to expand...

By my calculation the simple drain and blow method got me 80% of the coolant. I did twice, as above, and got 96% of the original coolant, which was good enough for me and used up the jug of coolant. So don't bother with those drain plugs, not worth the hassle.
 
neglected system, make sure to check for blockage in the overflow hose and radiator neck, its kinda normal .
 
I appreciate the tips. I think the book on radiator capacity is way off at 3.2 quarts judging by my initial drain. I'll be measuring the actual amount of drain exiting the system including a blowout with compressed air. It's too much to buy two $30 containers of Honda fluid but if one container can do two drains I'll opt for that. Assuming 3.2 quarts is actually correct I'll supplement with dirt cheap 100% Prestone silicate free using the procedure below. For those who think it's obsessive you are correct with my excuse being that I enjoy working on bikes in the winter. Also, I don't like hearing the voice in my head at speed or far from home saying, "you should have..".

1. Drain old coolant.

2. Add hose water until full.

3. Run engine with hose in thermostat housing until output clean.

4. Drain radiator; blow out residual with compressed air through
the thermostat housing.

5. Let cool

6. Add water from hose and RADIATOR FLUSH; install radiator cap.

7. Run until thermostat opens then 15 minutes more.

8. Drain radiator; blow out residual with compressed air through
the thermostat housing.

9. Let cool.

10. Add distilled water and run until the thermostat opens.

11. Drain and blow out radiator measuring amount of drain.

12. Calculate how much if any undiluted Prestone required given
a 3.2 quart system with no more than 60% water desirable.

13. Fill radiator with Honda fluid supplementing with Prestone
as necessary.
 
I would suggest using the Honda type 2 coolant. Silicate free is not the only concern. There are certainly other antifreezes that will meet the specifications, but if you buy the Honda type 2 you don't have to even think about that, let alone research or worry about. Buying from a Honda car dealer is cheaper than buying it form a Honda motorcycle dealer. The difference between it and any other brand is not worth the time to make sure that what you are buying meets all of the requirements.

If you are really concerned about the negligible amount of dilution that any remaining water in the cooling system might cause, Honda also sells an Extreme Cold Weather
Antifreeze/Coolant Type 2. You can either use this instead of the 50/50 Honda type 2, or supplement the 50/50 with this instead of another brand. This coolant increases the antifreeze ratio to 60%, and is still Honda type 2 coolant. Again, no thinking involved.

If this was used in place of the standard Honda type 2 50/50 mix, the resultant combination of it and the water that remained in the system would result in a final mixture ratio of somewhere between 50 and 60%. You would still have the minimum 50% antifreeze content that is important to you, and you also would not exceed the 60% anti-freeze concentration ratio that it is recommended should not be exceeded for regular service duty engines.

I don't think that it is worth thinking about it all. The small amount of water that remains in the system will affect nothing.
Drain, flush, blow job as much water out as you can, refill, go ride.

OL999-9020_m.jpg
 
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Al st1100 said:
neglected system, make sure to check for blockage in the overflow hose and radiator neck, its kinda normal .
Click to expand...
Absolutely on point. Exit to overflow was completely blocked. Looks good now after scraping, ultrasonic cleaning, new thermostat housing gasket, thermostat and cap.
 
Andrew Shadow said:
I would suggest using the Honda type 2 coolant. Silicate free is not the only concern. There are certainly other antifreeze that will meet the specifications, but if you buy the Honda type 2 you don't have to even think about that, let alone research or worry about. Buying from a Honda car dealer is cheaper than buying it form a Honda motorcycle dealer. The difference between it and any other brand is not worth the time to make sure that what you are buying meets all of the requirements.

If you are really concerned about the negligible amount of dilution that any remaining water in the cooling system might cause, Honda also sells an Extreme Cold Weather
Antifreeze/Coolant Type 2. You can either use this instead of the 50/50 Honda type 2, or supplement the 50/50 with this instead of another brand. This coolant increases the antifreeze ratio to 60% and is till Honda type 2 coolant. Again, no thinking involved.

If this was used in place of the standard Honda type 2 50/50 mix, the resultant combination of it and the water that remained in the system would result in a final mixture ratio of somewhere between 50 and 60%. You would still have the minimum 50% antifreeze content that is important to you, and you also would not exceed the 60% anti-freeze concentration ratio that it is recommended should not be exceeded for regular service duty engines.

I don't think that it is worth thinking about it all. The small amount of water that remains in the system will affect nothing.
Drain, flush, blow job as much out as you can, refill, go ride.

OL999-9020_m.jpg
Click to expand...
Thanks very much. Concentrate is what I've been looking for.
 
Larry Fine said:
Anyone have an opinion on the stuff that makes coolant water "wetter"?
Click to expand...
don't think it's good for cold weather "
  • "Perform & protect - Waterwetter protects from rust & corrosion, allowing the use of straight water in racing or reduced antifreeze levels in warm climates"
 
One video tells us the rubber hose connection at the bottom of the radiator can release more coolant . The problem comes if the hose is stubborn to disconnect. The radiators are made of soft aluminium and the circular nozzle can easily get out of shape if you try to encourage the disconnection with a screwdriver. I still have to find out if my makeshift sealing job is successful under pressure .If you feel rich you can buy a copper and brass radiator which has no front screw for coolant release at all . You have to take off the rubber hose on those .
 
If you change it every 2 years like the Honda manual says flushing it out is overkill. Even at 4 years the blue coolant is not very dirty. I may just do a drain and fill on my 4 year old coolant or use the other of the half gallon i have in storage to do one flush....just depends how lazy I get;)
 
years ago I bought the Honda stuff that was full strength, not 50/50 premix, did they stop selling that?
 
dwalby said:
years ago I bought the Honda stuff that was full strength, not 50/50 premix, did they stop selling that?
Click to expand...
Concentrate is hard to find. Mine was sourced from BernardiParts.com. Part #OL999-9020 for $8.08 plus $12.89 shipping. Thats 1 quart of concentrate which is just enough for the 2.2 quart system in an 1100.
 
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