1988 wagon 4x4 3AC Coolant Union Bypass Tube leaking

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Joined: Thu Jan 17, 2019 4:41 pm
My tercel:: 1988

1988 wagon 4x4 3AC Coolant Union Bypass Tube leaking

Post by cc93cruiser » Thu Jan 17, 2019 4:51 pm

Just replaced the metal coolant bypass tube along with the 2 o rings with oem toyota parts and it is now leaking after first start up. I made sure both surfaces were clean where coolant bypass tube goes in/ no pitting in metal either (at water inlet housing and on top of water pump housing). Was wondering if anyone has had this problem after replacing the parts. Should I use thicker/bigger o rings or same o rings with some fipg? I am pretty sure I got correct o rings...

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My tercel:: Goldie is a 1986 SR5 attualmente con Weber/also owned the first T4WD in STL in late '82
Location: Kirkwood, a 'burb of St. Louis

Re: 1988 wagon 4x4 3AC Coolant Union Bypass Tube leaking

Post by ARCHINSTL » Fri Jan 18, 2019 12:38 am

Some help?
1. viewtopic.php?f=16&t=12567&p=97224&hilit=bypass#p972242.
2. viewtopic.php?f=16&t=12567&p=97224&hilit=bypass#p97224
3. viewtopic.php?f=4&t=6789&hilit=bypass

What I wrote at the time, 10/20/16, from Butler Toy in Indy:
Water bypass tube 11 $21.23
O-rings1111111111111112.52 (2 rings) WOW for 2 rings!
Gasket for outlet part 1 8.61
Sealed the "leaky" OE tube with RTV and it seems to work, but if not - I am ready!

Then 10/24/16: Installed new water bypass tube, O-rings, and gasket.
The new tube is a bit different from the OE tube, as far as the "ends" of the tube go (sorry, I do not know the proper term for the "ridges.")
No leak since then.

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My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
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Re: 1988 wagon 4x4 3AC Coolant Union Bypass Tube leaking

Post by xirdneh » Fri Jan 18, 2019 1:12 am

I get the o rings at auto parts store. They pull out a box with ring assortment and pick some out. I get what are probably under sized ones because it takes some effort to get them on. Then when you insert the tube it should take some effort to get it in. I always put some non-hardening gasket compound in the hole and on the ring
too. This aways works for me.
Love those Tercell 4x4 wagons but they sure suffer from road noise.

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Re: 1988 wagon 4x4 3AC Coolant Union Bypass Tube leaking

Post by splatterdog » Fri Jan 18, 2019 9:37 am

I used to apply sealant, and still will if corrosion is bad enough. Otherwise I've been using silicone grease. The tube is probably designed this way to allow for expansion and contraction between head and block. I have a lot of O-rings and always select ones that are on the tight side.

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My tercel:: '84 Tercel4wd w/extensive mods
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Re: 1988 wagon 4x4 3AC Coolant Union Bypass Tube leaking

Post by Petros » Sun Jan 20, 2019 5:52 pm

I have had new ones get torn upon installation, and than leak. not unusual.

fortunately I bought some spares (they are cheap), and I put sealant on it to lubricate it as it slides into place. Never had it leak, even when I reuse old o-rings.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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