Water By-Pass Hose #6 / Union Leak

[AlbanyAng]

Hello All,

I had an small seeping leak in the region of By-Pass hose #6 so I tightened the worm clamps on it and that just made it worse. Thus I went ahead and replaced by-pass hose #6 (P/N 16283-42010) and replaced the worm clamps with tension clamps (P/N 90467-21010) hoping it would solve my problem. After installing the new hose and clamps the leak unfortunately started again as soon as the thermostat opened up. Thus my next intention was to pull the water outlet housing and replace the water hose joint (union) (P/N 90404-54034), along with the thermostat and associated gaskets and try again. I placed an order for the parts with Mid-Atlantic Toyota but was informed that the union (P/N 90404-54034) is no longer available. Can anyone offer an alternative? Or relay their experiences with leaks in this region?

BTW its for an 86.5 N/A Supra

 

[jetjock]

Have you tried online dealers? There's always used fittings but a replacement shouldn't be difficult to source. I would identify the leak source before continuing to swap parts willy-nilly though. You were right to go with those clamps. Also, make sure that heat shield at the end of the hard pipe is there or the hose won't last.

 

[AlbanyAng]

Thanks for getting back to me jetjock. You are right shot gunning isn't the way to go. I need to get the Supra in a location where I can tear into is and let it sit until I get it repaired. I am think that I will need to pull the water outlet housing since it looks like the water pump is in the way and I won't be able to just loosen the union to remove it. There isn't a lot of room to work on this in this area. Hopefully I won't have to remove the distributor to pull the water outlet housing since the bolts holding it to the block are tuck in and around it. Also, wondering if this is just a symptom of a larger problem like a clog in the water by-pass pipe or elsewhere in the cooling system leading to excessive pressure in this area.

MAybe once I get it off I'll be able to find a generic replacement?

 

[JDMMA70]

If you're bent on taking it off to inspect it before you do that do you know znyone that has an inspection camera. Those are useful for looking at stuff you can't see. At least this way you know what the culprit is before you start removing stuff. I cleaned up my unions l via sand blast and then painting them. When I reinstalled them I wrapped them in Teflon. I have seen those unions break off from rust.

 

[supraguy@aol]

Im not sure which union you're talking about. Is this union the port on the backside of the rear timing cover??

 

[JDMMA70]

He's talking about the one under the tstat housing.

 

[AlbanyAng]

Yes, the one under the tstat housing. The camera option is a good idea. Also, thanks for the tip on cleaning the existing one up and reinstalling it. I am suspicious that the culprit is crud build up around the end of the pipe that is preventing a good seal. Looks like fixing up the existing one is my primary option. I just contacted Toyota Parts Overstock and they told me it's unavailable as well.

BTW: You folks on Supramania are awesome. Always so helpful - thank you so much! I'll post more as a get along. Probably in a few days or so as I need to look into problems on my daughter's '96 Celica GT. Seems to want to keep eating steering and alternator belts.

 

[jetjock]

Wise words about pinpointing the leak before pulling stuff apart. An inspection mirror works too. Fwiw I always keep dye in my coolings systems. AutoZone carries a good one. Between that and a pressure tester leak sourcing is a cake walk. Corrosion can be kept to a minimum with proper cooling system maintenance, something few people do. PH testing, voltage monitoring of the coolant, installation of a filter, fluid changes when required, etc.

 

[AlbanyAng]

It’s been a while since I started this thread & my supra has been idled most of the summer but I wanted to finish it up and post my resolution to the coolant leak problem around By-Pass hose #6 and the water hose joint (union). After a bit of more in-depth investigating I decide that something was up with the water hose joint and when I finally got some time finally attacked it so here’s what I did – pretty much in order (from memory!):

1. isconnected the negative battery terminal
2. Drained what coolant was left
3. Removed most of the intake piping
4. Disconnected the vacuum hoses form the BVSV valve
5. Followed the instructions for removing the distributor presented in the TSRM @ Cygnus supra site
   http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=IG&P=17
6. Removed the distributor
7. Slid the clamp off By-Pass Hose # 6, & detached the hose from the water by-pass pipe
8. Slid clamp off By-Pass hose # 4 & detached hose
9. Slid the clamp off of the top radiator hose & pulled off of the thermostat water outlet:
10. Removed the Water Outlet housing (1-nut, 2-bolts) to get a better look at the water hose joint. It wasn’t hard to see that there was a small hole where the bypass hose joins the pipe that was cause of my leak.
11. http://www.cygnusx1.net/Supra/Library/EPC/291410/catalog.aspx?F=1603&P=1
    
12. To remove the joint from the water outlet housing I sprayed it with WD-40 let it sit a little while then cranked it off using an adjustable wrench. Turns out this joint has a ½” NPT male pipe thread. It was difficult get off & in the process I ended up breaking the Water Temperature Sensor (Toyota P/N 89422-12010) – I found a generic replacement that I’ll discuss below. Here’s a picture of the sensor.
13. http://www.cygnusx1.net/Supra/Library/EPC/291410/catalog.aspx?F=8404&P=1
14. As I stated previously I wasn’t able to locate the original water hose joint Toyota part (P/N 90404-54034) so I did some digging with the help of a friend and found a generic replacement that is called a “90-degree Heater Fitting” . Since it had the ½” NPT & I couldn’t get the Toyota part I decide to give it a shot and I purchased one off the Advance Auto website for $12.79. It is a Factory Air P/N 84778. Well turns out this replacement was close but not the exact fit. First off the nipple end is ¾” which is wider than the 5/8” of the By-Pass hose – this wasn’t too bad to overcome but I had to really work to get the bypass to slide over the nipple and get the spring tension clamp in place. Secondly the nut end of the joint is longer than the original so getting it clear the water pump housing was a little tricky.
    Here's a pic:
    
15. For the installation I started out by replacing the thermostat (Toyota P/N 90916-03078) & its gasket (P/N 16341-35010).
16. Then I secured the new water hose joint to the water outlet housing. Like I said the new hose joint nut portion was longer than the original so I tried some fit tests and found out that I was gonna have to play lots of games to get the whole thing back in place. On 1st pass I tightened the new water hose joint into the housing until it felt pretty secure but not too tight for fear of cracking the housing. Unfortunately at what seemed to be the snuggest point, the orientation was such that the nipple part was facing the radiator and it wasn’t fit over the power steering pump mounting bracket and water pump the way it was assembled. So I had no other choice than to tighten the hose joint until the orientation was correct for attaching to the by-pass hose. I really had to tighten the joint into the Water Outlet housing to get it to work and finagle a little to clear everything but it worked out. I had a problem clearing then Water By-Pass Pipe #2. I overcame this by placing an old screw driver inside the pipe and bending it down a little by gently tapping the screwdriver head with a hammer til things cleared. (Once I had everything place I bent the pipe up to close to its previous location.)
    
17. Once the fit tests checked out I put a new water outlet gasket (P/N 16343-42020).
18. Attached By-Pass hose #6 (P/N 16283-42010) to the hose joint and the water by-pass pipe then secured it with the spring clamps (P/N 90467-21010). Getting the clamp to fit over the ¾” of the hose joint was a hassle to say the least so I ended up using a 1” worm clamp that I had instead to get a nice snug fit.
19. Reattached the water outlet housing , bypass hose #4, top radiator hose.
20. Installed distributor referencing the TSRM with a new cap (Beck Arnley P/N 174-6857) & rotor (Beck Arnley P/N 173-7886) that I ordered from Advanced Auto. I also installed a new distributor O-ring (P/N 90099-14088) & distributor cap dust proof packing (P/N 19127-42010).
21. Unfortunately installing the distributor wasn’t so clear for me as stated in the TSRM. I couldn’t identify the protrusion on the drive gear so I did what my Dad taught me years ago and aligned it such that the rotor was lined up under cap where the wire from plug #1 attaches to the cap. This worked out well as she cranked the 1st time afterwards.
22. Installed a new Water Temperature Sensor. I picked up a Duralast P/N S405 from the local Autozone which had it in stock. I had no problems replacing the old one. However my electrical connector has disintegrated so I had to fool with it to get the contacts which are still in tack to get the connections happy. I will need to get a new connector. If anyone has any ideas let me know cause so far I haven’t been able to find a replacement.
23. Reinstalled the vacuum hoses & intake plumbing.
24. Reattached negative battery cable.
25. I filled it up with new coolant/water and cranked her up and finally – no coolant leaks. After I got the timing situated I drove it back and forth for about a week before she started leaking while I was sitting in a traffic jam about 1.5 miles from home. So I got her home just as she stated to red line and found that the lower radiator hose had developed a small leak. I replaced it with one that I got at the local Advance Auto (Dayco P/N C71405) & refilled the coolant & water.

So far so good - on week now. As this is my daily driver I am hoping that I’ve got it straight now. I will keep you all posted if something goes bad. I hope this helps someone down the line. You all have been so helpful to me in the past. Thank you!

 

[Asterix]

Thanks! I've had a leak from that area for a while now that I've not identified. It certainly could be the same place that yours was. Like you, I replaced my #6 hose with new spring clamps first, but it didn't fix my leak either. I've run a pressure test when cold, but it doesn't leak when cold.

It's about time for me to fix this leak as it's getting worse. I'll definitely check that union. Nice to know there's an alternate part that works.