Coolant leak 75'

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redglbx
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Re: Coolant leak 75'

#16

Post by redglbx »

For me I use scotchbrite to clean the sealing surfaces and then I wipe a very light coat of clear rtv on the sealing surfaces just before assembly. I do this because the surfaces tend to not be all that smooth after all these years of service and it gives me leak-free operation.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
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Sidecar Bob
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Re: Coolant leak 75'

#17

Post by Sidecar Bob »

I keep saying this: RTV means Room Temperature Vulcanizing, which refers to any rubberlike compoind that doesn't require heat to cure.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
redglbx
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Re: Coolant leak 75'

#18

Post by redglbx »

Sidecar Bob wrote: Mon Nov 15, 2021 9:46 am I keep saying this: RTV means Room Temperature Vulcanizing, which refers to any rubberlike compoind that doesn't require heat to cure.
????
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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Sidecar Bob
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Re: Coolant leak 75'

#19

Post by Sidecar Bob »

You probably meant silicone sealant when you said "a very light coat of clear rtv" but RTV can refer to any of a number of rubberlike compounds.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
redglbx
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Re: Coolant leak 75'

#20

Post by redglbx »

Bob, not trying to be a smart aleck here but I’m trying to understand the point of your post. I know that RTV means Room Temperature Vulcanizing, and I’ve used several different brands/types (not water soluble Type) and know you can’t use it in conjunction with gasoline or brake fluid as both dissolve RTV, so please help me understand what I’m missing here.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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Sidecar Bob
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Re: Coolant leak 75'

#21

Post by Sidecar Bob »

If you mean silicone sealant you should say silicone sealant. RTV is not necessarily silicone.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
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Whiskerfish
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Re: Coolant leak 75'

#22

Post by Whiskerfish »

Sidecar Bob wrote: Wed Nov 17, 2021 3:15 pm If you mean silicone sealant you should say silicone sealant. RTV is not necessarily silicone.
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Dr. Frankenstein
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Re: Coolant leak 75'

#23

Post by Dr. Frankenstein »

Those Laser bits are for the hand-held 'hit-me-with-a-hammer' type, but I love these - they of course fit into my electric impact driver, but when it comes to working on old bikes they are indispensable. I have both types, depending on how big the problem is:
ImageDSCN1843 by Dr. Frankenstein1, on Flickr


Get 'em here: $18 and worth every penny!
https://www.amazon.com/B4633-Screw-Driv ... B085TDRBPM
Prospect
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Re: Coolant leak 75'

#24

Post by Prospect »

Installed the orings on both crossover tubes and installed new gaskets. I pinched one badly but I didn't have any spares so I had to use it. I ran the engine for about two minutes (first start since early 90's) and didn't see any leaks. This is my first water cooled bike so this might some dumb but does the pressure inside the cooling system increase with rpm? I'm wondering if the pressure increases with rpm would a leak show at higher rpms that doesn't at low due to pressure increase. Since it was a first start I didn't run the engine too high.
Current Bikes
1969 CB750 Sandcast
1971 CB750K1
1972 CB750K1
1975 CB400F
1975 GL1000 Goldwing
1954 Harley Davidson Panhead
1957 Harley Davidson Panhead
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Sidecar Bob
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Re: Coolant leak 75'

#25

Post by Sidecar Bob »

The pressure in parts of the cooling system near the output of the water pump will have higher pressure and that would increase a bit at higher RPM. BUT the pressure increase from the coolant trying to expand as the engine warms up is so much greater that any increase near the pump's outlet at higher RPM won't matter (not to mention that the pressure in parts of the system near the pump's inlet will be lower at higher RPM).

And then there's the thermostat. When the engine is cool the thermostat is closed, limiting the amount of coolant that can be pumped through the system until the engine warms up and the thermostat opens. Generally the system won't reach full pressure (regulated by a valve in the rad cap) until the thermostat has opened.

In other words, let it warm up a while and see if it starts to leak.

BTW: Any engine will warm up faster at varied throttle openings and under load, which means riding it if possible but at least revving it up to 2-3,000 during the process.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
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flyin900
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Re: Coolant leak 75'

#26

Post by flyin900 »

FYI, If you ever bought the Princess Auto large red plastic Metric O ring assortment kit (200+ O rings in various sizes) it frankly is pretty useless for almost any Honda correct sized O rings. Yet a number of years ago I had this kit and discovered it has an O ring that is a perfect fit for these coolant crossover tubes.
There are a few other O rings that can be used as Honda subs, yet you need to buy this kit on sale for dirt cheap, for it to be worth while.
Current Bikes:

1966 CL77 - Honda 305cc - Dual purpose - "Gentleman's Scrambler" was a period moniker.
1967 CL175K0 - Low production number with #802 engine serial- winter 2019/2020 full restoration.
1972 CB350F - Baby Four with low mileage - Cosmetic refresh to the next level 2021/2022.
1978 CB550K - Very original bike with only 7499 Km. from new - light cleanup and refresh done.
1983 CB1100F - Canadian model - DOHC Supersport in pristine low kilometre condition from new.
1984 GL1200 - Standard model in showroom condition - two owner bike from new.
1984 CX650E - Restored summer 2017 - a rare Eurosport model - excellent one owner bike.
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Sidecar Bob
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Re: Coolant leak 75'

#27

Post by Sidecar Bob »

I bought the assortment in the smaller translucent white box from Princess and it had a couple of sizes that were close enough to work and used them up on the winter machine over a period of several years (Honda specifies the same o-ring for the water pipes on the CX/GL500/650 family as they do on 4 cylinder GoldWings). When they ran out I bought a lot of 50 on Bay, as well as similar lots of other sizes I'd found I used a lot of and I've been using them since, except when I bought gasket sets that included o-rings and at the rate I've been using them I may just have a lifetime supply of some sizes.

A few notes about o-rings:
- Honda lists the sizes of o-rings by the INSIDE diameter and the cross section (wire) diameter
- A lot of the o-rings Honda used when these bikes were made are actually inch sizes with the dimensions converted to metric (hence all those odd sizes)
- Rubber is flexible so o-ring sizes don't need to be absolutely precise.

As an example, Honda specifies a 21.9 x 2.3mm o-ring for the water pipes. You will never find a 2.3 or 2.4mm cross section o-ring from a regular supplier but you will find 3/32" cross section o-rings.
BUT a 2.5mm section o-ring is only 8.7% larger than a 2.3mm diameter one and a 22mm ID o-ring is only 0.46% larger than a 21.9mm one so there should be absolutely no problem using a standard 22mm x 2.5mm o-ring on the water pipes.

FWIW, the ones I bought for water pipes are similar to the 27x22mm ones in this listing.
https://www.ebay.ca/itm/174310594026
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
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sickradsean
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Re: Coolant leak 75'

#28

Post by sickradsean »

Partzilla has all the O rings and gaskets available. Waiting on mine to show up.
1977 GL1000 "Goldie"
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