Heater Core O-Ring Backup Seal (1 Viewer)

[Rimmeh]

•For those replacing or re-sealing a heater core who are not crazy about the vulnerable o-ring seals to the extension pipes, and yet are not thrilled about a rigid solder joint alternative, here is a belt and suspenders redundancy seal that might provide some peace of mind:​

1. Parts used:​

• Toyota o-rings part number 96711-19016 (thanks SpikeStrip)​

•4”L X ¾” ID silicone hose NAPA part number H-167 or equivalent @$2.49 /ft​

•6”L X 1” ID radiator hose, scavenged from Autozone formed hose part number C71218 ($7.99).
​

•4 X 1.5” stainless hose clamps​

2. Replace o-rings and pressure test factory seal configuration @ 20 psi. Used a tire valve stem clamped in hose.
​

3. Cut 4 pieces each ½” in length of the smaller 3/4" tube. Using a new blade remove a strip about 1/8” wide from two for the core side and about ¼” wide for the firewall side. Use a new razor and cut as a guillotine along the tube markings as reference for a straight, square, aligned cut. Final diameters of the sliced segments when squeezed together will be just slightly larger than the pipes so that the two faces are pressed together upon clamping. Clearly a non-split solution would be more ideal but the o-ring flange presents a fitment problem against using the proper diameter hose as bushings. Perhaps multiple layers of heat shrink tubing would work for this step instead of the slotted bushing approach.​

4-7. Lightly coat bushing segments with high temp RTV on outer diameter and on both sides of the slit and slide larger hose over the two smaller bushing hoses.​

8. Clamp tightly, verifying solidly contacting butt joints at the slits (RTV squeeze-out)​

9. Final trim of hoses to clear housing interfaces.



Will it work? Probably couldn't hurt. Anything that might forestall the massive effort to get to this part has got to be a good thing.

Jeff

​

 

[Spike Strip]

Yeah, that outta keep coolant off your floor. Nice work.

 

[TobyB]

at the very least, it'll keep it from dumping hot coolant all over your legs

t

 

[Elbert]

What holds the two "flanges" together where the hard line mates to the heater core?.... I've not yet taken mine apart to get at the leaking heater core and I want to make sure I have all the parts other than the new heater core, which I have now. Any close up pics of this seal area I'm referring too?

 

[Spook50]

Great thinking. A couple suggestions though:

1) Use spring clamps (like the OEM Toyota stuff) instead of the screw-on hose clamps. That way there will always be tension on the joint and that extra little bit of leakage protection.

2) Ground the heater core itself to the chassis. That'll prevent pinholes from forming down the road due to electrolysis. It's a fairly common killer of heater cores and radiators, and having them electrically bonded to the chassis/body ground prevents it.

 

[Rimmeh]

OEM Clamping

Elbert- the two flanges are clamped together in the OEM configuration by a "U" shaped clip than spans a little over half the circumference of the mated flanges. It is the "blue" part shown in the schematic above and can be seen between the two slit bushings in the image below. They slide off fairly easily but probably not easy enough to accidentally pop off if touched the wrong way. Regardless I imagine the backup seal hose could be viewed as a positive clip retainer, for whatever that's worth.
-Jeff

 

[roalco]

Why not just do away with the seals and solder the horns in place when you have the core out for repair? Gary at AER rads up here in North Vancouver has been doing that for years for 60s, it works a treat, and NO leaks, ever.
Apparently the only reason for the seal was so Toyota could use a common core with a variety of horns for different applications.

 

[Elbert]

Yea I can't get over how this is a screwed up setup from OEM, I wonder why the stock heater core does not just have some long end on it, to run all the way out to the firewall. Or bring in heater hose type setup through the firewall but that might be a flaw I guess.

I'm tempted to get my heater core soldered before I go through the process of swapping everything out.

 

[Elbert]

Elbert- the two flanges are clamped together in the OEM configuration by a "U" shaped clip than spans a little over half the circumference of the mated flanges. It is the "blue" part shown in the schematic above and can be seen between the two slit bushings in the image below. They slide off fairly easily but probably not easy enough to accidentally pop off if touched the wrong way. Regardless I imagine the backup seal hose could be viewed as a positive clip retainer, for whatever that's worth.
-Jeff

View attachment 778013

How sturdy are these "U" shaped clips...I wonder if you can still buy them new or if I should go on an order them if they are still available? I hope my soon to be heater core repair lasts the next 20 years.....

 

[Dynosoar]

I have not had a leak in 31 years! OEM o-rings seem to do the trick.

Dyno

 

[Elbert]

agree...with the age thing. I assume my truck has the OEM original heater core and that makes it some 26 years old and it just failed a couple of weeks ago. I don't DD mine so its sat for a while. If the stock setup lasted that long it has proven the test of time... hopefully the small parts are still avaliable in case something breaks.

 

[Elbert]

IF you are replacing the heater core in a conventional sense....do I just need the heater core and the o rings mentioned in post #1?

I've looked all over the shop manuals I have.....little to no information on the heater core. Not a big deal but I assume there would at least be some notes on diss-assembly? I don't have the "repair manual supplement for chassis and body" but I do have the chassis and body repair manual...in my case it says 1984 on the cover, Toyota OEM. I also have teh 2f engine manual, emissions manual, and one or two other ones that are small in page count.

I've done heater cores before and don't expect any great surprises, but always good to read ahead if possible. I've got the heater core and looks like I just need the o rings now..

 

[OGBeno]

IF you are replacing the heater core in a conventional sense....do I just need the heater core and the o rings mentioned in post #1?

I've looked all over the shop manuals I have.....little to no information on the heater core. Not a big deal but I assume there would at least be some notes on diss-assembly? I don't have the "repair manual supplement for chassis and body" but I do have the chassis and body repair manual...in my case it says 1984 on the cover, Toyota OEM. I also have teh 2f engine manual, emissions manual, and one or two other ones that are small in page count.

I've done heater cores before and don't expect any great surprises, but always good to read ahead if possible. I've got the heater core and looks like I just need the o rings now..

I answered your question today sir. There are 2 orings.

Replace and move on.

 

[Elbert]

I answered your question today sir. There are 2 orings.

Replace and move on.

must be a delay on the email reply...

Appreciate it... I will try and call you tomorrow at work to order.

 

[Elbert]

OEM o rings on back order, no details from Toyota as to the correct size o ring. I assume the o rings are metric just like about everything else. Once I get the heater core out maybe I'll have teh toyota parts or maybe not, but between now and then if anyone knows the correct metic size o ring used to mate the heater core with the metal tubes let me know. I may end up just doing my best to match up what I can find, my normal parts store does not have metric o rings but I'm sure I can find some around.

I appreciate Beno....helping me out. Not a huge deal but since the core is a pain to get to I just would like to have the right part ready to go. I ordered from nearest toyota shop, as I have a friend who works there, but right now unknown on backordered parts.

 

[Elbert]

Ok....hopefully last question on this...(I did get the OEM o rings). Since I can't find any instructions in the manuals I have. Are people installing the o-rings dry or using something to "lube" the o-rings? Obviously I don't want to do anything that degrades the lifespan of the o-ring as its a little painful to gain access to them.

 

[OGBeno]

Ok....hopefully last question on this...(I did get the OEM o rings). Since I can't find any instructions in the manuals I have. Are people installing the o-rings dry or using something to "lube" the o-rings? Obviously I don't want to do anything that degrades the lifespan of the o-ring as its a little painful to gain access to them.

I've always used dielectric on orings that are HVAC/water related.

Never had any issues.

 

[Spook50]

I've always used dielectric on orings that are HVAC/water related.

Never had any issues.

For anything that seals antifreeze/glycol I'm with you on the dielectric. Makes for much easier removal of hoses several years down the road. For A/C systems I would lubricate them with whichever oil the system uses. Mineral oil for R12 systems and whatever the hell r134 systems use for them.

When I first got into aircraft maintenance they trained us to lubricate any O ring, seal or gasket with whichever fluid it was meant to seal against. The only exception was glycol based stuff. I started doing that with any other system I worked on too, and not once have I ever had one leak. Between that and proper surface preparation (more for gaskets), you'll never need any kind of RTV and will likely never had a leak.

 

[Elbert]

ok thanks...I've used o rings on AC and hydraulic and oil based fluids.. where as noted you generally lube with the fluid being used or engine oil or refrigerant oil. with coolant its a new game at least for the most part. After this...its on to a remote resivor ps setup.

 

[cruiserpilot]

I did mine last year. I ended up soldering the connection. Here in Nanaimo I was unable to get metric o-rings. Toyota just said obsolete, so sad too bad. I didn't have time for anything else. This is a good write up, really clear and helpful. Thanks.