Need help with diagnosis and possible heater core replacement\bypass...

[yarborg]

Hey all,

Yesterday I was grabbing my gymbag from my passenger seat floorboard under the dash and felt this wet sticky stuff on it. Of course I did the first smart thing and tasted it. It was obviously coolant. When I got back to work I was sitting in the parking lot and decided to run my AC. When I turned it on a small fog came out. The AC had been running for about 15 minutes before and I had turned it off for about 2 before turning it back on.

I did some research on this and a few post have said faulty heater core or a leak in the hoses. I am pretty convinced this is it but am trying to figure out the AC problem and if they are related.

Also, I want to bypass the heater core for a while until I can tackle the problem. I have a service manual but pics always help. If anyone can post a pic of what 2 hoses to undo and link together that would be great. I just hate trying it and not knowing for sure until I am down the road a bit. If I bypass I will post some pics for the other newbs.

Thanks

 

[jfz80]

in the engine bay IH8MUD™ Forums - View Single Post - Outstanding news for 80 owners

and under the passenger https://forum.ih8mud.com/80-series-tech/226721-repaired-rear-heater-rotted-pipe-problem.html

and on this note i had the tell tell symptoms of a blown heater core a couple weeks ago. Ran up to the foothills (1hr) w/ A/C on and watched a movie, ran same 1hr trip home windows open, cool night and whole time engine temps were fine (via scanguage) When i returned home my pass. floorboard was soaked w/ a surprising volume of scalding water???? did not smell directly of coolant, but stained the carpets orange. Im not low on coolant and all i could find was a disconnected a/c drain at the firewall. Ive since ran the 80 w/ a/c on/off and heat on/off and not noticed one drop, and coolant level is still fine. any thoughts? a burp in the system? a/c drain and just heated by exhaust?

would bypassing in the engine bay reduce enough coolant to be of concern running the s/c ?

 

[SBFJ60FIG]

Though not there when it happened...but your A/C gremlin could be a function of high-humidity and the air cooled below the dew point. At times, not often, it is possible to see "fog" in the air coming from vents with A/C on if the day is particularly hot and humid. It's just the humidity condensing as it comes out of the vents. If you've not seen this issue again since, or it only happens when hot and humid, I'd say that's your dealio there...as in "normal operation."

Heater hoses...hell, I think the heater control valve is dead center on the firewall behind the valve cover. Sorry tho, no pics from me.

Heater core installs suck...never had to put on in any Toyota product I've owned tho....and I've owned plenty!

 

[yarborg]

Thanks. That pic was what I needed. I may post my own once I get it done.

 

[yarborg]

Just to be sure I have this right. Here is a pic. The hose in Red is what I need to make a single line correct? And the one circled in Green is attatched to the Red but I need to plug where it is feeding into the small metal tube against the firewall?

Well that is what I am going to do. I hope it is correct.

 

[snowwolf]

Let us know how you get on Yarborg and take a pic if you can, always good to have pic info

 

[gisham]

Yarborg,

seems what you are doing is cutting the rear heater system out of the loop. This is great if you have faulty coolant lines that run to your rear heater, but if your "in dash" heater core is leaking this will not help. You would actually need to loop the direct lines coming out of the motor and bypass the entire heating system all together. I am just not sure how much of the loop you can cut out before cooling becomes compromised.

 

[yarborg]

Yeah that was what I figured out. I definately wanted to bypass the main heater core. After reading through my Haynes manual and looking for some other examples I still couldn't figure out where to place the bypass hose. One reason is because Haynes shows the flow of fluid going differently than it did when I removed the hoses to see for myself. Here is an attached pic that shows the inflow near the drivers side. But in my observations it looks like the flow is just the opposite. Then you have that 90 degree elbow that passes through something that is some kind of flow regulator\switch I guess. Anyhow, here is the Haynes manual page (Chapter 3 fig 1.1) (If I am violating any laws here I apologize):whoops:

 

[yarborg]

And here is what I came up with. Please let me know if this is not right!!

 

[gisham]

thats what you are looking for- just watch the temp gauge-

 

[fj40fax]

Did that one hose do it? Did it bypass the entire heating ssystem?

 

[bryson]

Did that one hose do it? Did it bypass the entire heating ssystem?

I have no idea if it fixed the OP's problem, but yes, in that picture, the front and rear heaters are both bypassed with that single hose.