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Hi all,
I'm a bit confused on what the coolant line plumbing on a 84 4wd pickup is supposed to look like. I have looked at about 50 pics of the coolant hoses and the valve and all have differences. The PO didn't have the valve, he just had a hose going into the heater core from the lower rad hose fitting, and a hose coming out and going to underneath the carb
Now I want to make it correct but can't seem to understand the valve and what Toyota had in mind. Is the valve a bypass valve? I really can't grasp it.
Here are some pics of what I have, Note: the valve I have fits perfectly on the fire wall and the cable will go through the firewall and into the heater control. I just need to know the routing of the hoses, Please.
Pics
This is where the coolant comes from, the bottom rad hose has a tube welded on to connect a hose
This is the valve on the firewall
These are the heater core pipes coming from inside the cab
Another pic showing where everything is on the firewall
The only thing I don't have a pic of is the barb fitting under the carb where the coolant returns ti the engine
Does anyone have a non-modified truck that can take a pic of how this is supposed to look, the FSM doesn't show anything about how to route the coolant hoses
Thanks much for your help
Hump
Mike
Last edited by NYHumpinUtah; 10-23-2020 at 06:23 PM.
Jake
Thanks but I think your truck might have a different setup. I'm finding that a lot of the 84-85 have a different setup then the "as everyone says" 84-89. They are not the same. 84-85 are special birds.
Once I realized that the valve is NOT a bypass valve it all made sense. The valve stops the flow of coolant into the heater core, so in the summer you slide the lever to the cool position which closes the valve. In the winter you slide the lever to the warm which opens the valve and allows coolant to flow through the heater core.
Make sense?
Let me know what you think
Thanks
Hump
That's exactly what that valve is for. It allows water to flow to the heater core what the slide is slid to warm. The further the lever is slid to warm, the more water is allowed.
Those heater core barbs are very thin and delicate. It looks like yours are pretty damaged, too. Generally, you need to carefully cut the hoses off them, making a slit along the length of the hose, not across, or around it. you have to use very light pressure when cutting them, too. If possible, best to try and give the hoses a twist, but remember, they could twist the metal along with the hose. Best, really, to cut them. You may have trouble getting the jumper hoses to/from them to seal up, the way they look now. I suspect you may have to replace them before you get the system sealed up.
Something to remember about the cooling system is that Toyota used a somewhat poor design. The "cold" water from the heater core, that returns to the engine, enters the system just before the main thermostat. This tends to keep the thermostat closed longer when the heater valve is open, than when the valve controlling the flow to the heater core is closed.
Thus, when the heater valve is open, even fairly small amounts, the temperature gauge on the dash will show the temperature of the engine rising much higher than when the heater valve is closed, before the thermostat "pops", allowing the normal, full flow through the cooling system. The "cold" water is holding the thermostat closed, allowing the main engine temp to go pretty high before the main thermostat gets enough "warm" water from the engine to open.
This is why Toyota came up with a "fix" for the situation. They made the thermostat with the large main valve in the center of it, and smaller, lower temperature valve beside the center. A "two stage" thermostat. THIS explains it better, and gives the part number for the two-stage thermostat. When the "cold" water is coming in from the heater core, the smaller valve will open before the larger, higher temperature (195° F IIRC) valve opens. This allows SOME water to circulate through the system, preventing the temperature from going too high before the main valve opens allowing the normal, full flow through the cooling system.
Single stage thermostats tend to "hunt" before they settle on the right amount of open, too. IE: the temp will go high, then drop low, then go less high, then drop less low, etc, until the thermostat finally gets the right amount of open for the conditions. How hard the engine is working, the temperature of the air flowing through the radiator, and over the engine as the truck moves, and so on. The second valve tends to reduce this hunting a lot.
I think your biggest trouble right now, though, is getting those hose barbs from the heater core to seal up properly. I wish you great good fortune on that.
Finally, don't forget to burp your cooling system properly before driving it anywhere. There are a lot of places air likes to hide in these trucks!
Hey all
Quick update,
2ToyGun got me concerned about my pipes so, I removed the dash and the heater core "Again" and since the tubes and seals are no place to be found, at least new, I decied to solder on some copper pipe fittings to the original tubes. Worked out pretty good, a 1/2 pipe was sweaged in the pipe and then I used a 1/2 pipe connector to slip over the pipe and then solder them. Nice and strong now
Take a look:
Thanks Pat for forcing me to address this
Hump
I'm glad I was some small help. Is this absolutely crucial to the running or the truck? No, but it's important to the cooling system. The warm air into the cabin is a bonus
Again, don't forget to burp your cooling system before you drive it. Pretty important to get all the air out. It can keep the correct amount of water the system is designed for from being available to cool the engine. And there are a lot of nooks and crannies where air likes to hide. Chase it out!
I wish you good fortune! Good soldering job, BTW! Just curious, did you blow the dust and crud out of the heater core's fins with compressed air while you had it out to solder on? The heater core in these can "gunk up" pretty badly over the years. Not too much pressure, or you'll bend the fins over, and then have to comb them out straight again. They have a nasty habit of breaking off when that happens, so be careful!
Enjoy! These trucks can make you tear out your hair, but they are a joy to own at the end of the day
Pat☺
Pat
Yes, I did blow out the core, carefully.........
Take a bow You got me to do what I didn't want to do but did it.
A long way from being able to burp my coolant system, 1st I have to start it for the 1 st time..............So much to do.
I keep looking at pics on the heater hoses and keep seeing different configurations, I still am confused on the correct hose routing The FSM is completely useless, they don't have any information or pics on it.I'm "pretty sure" I have the correct valve but I've seen so many different ones I'm not sure anymore.
I'm reaching out once again to anyone who has a non-modified 84 or 85 pickup truck that can take a few pics to show me the correct hearter hose routes for all the hoses and the valve.PLEASE
Hump
Last edited by NYHumpinUtah; 10-30-2020 at 12:25 PM.
It is difficult to take pictures of the routing because the metal pipes are so close to the engine where it is hard to get good pictures of where they go.
I am not sure why you removed the metal line coming off of the back of the timing cover (driver's side?). I am assuming that you removed the coolant pipe that ran under the exhaust, right?
If so, that is the return line for the heater core.
If you moved the hose over to the other side of the heater core, I would be worried that the hose would be too close to the hot exhaust.
The routing isn't easy to visually see, but I will try to describe it.
Below is the parts diagram for the heater system. This diagram can get confusing because it doesn't correctly show the location of the pipes and hoses in relation to each other, but it does correctly show how each piece is connected. The pipes and hoses cross paths on the truck, but not in this diagram.
The highlighted yellow parts show the coolant path going into the heater core.
This path starts at a metal coolant pipe that connects to the bottom side of the intake manifold (87248A). This metal pipe should wrap around the back side of the engine and end on the exhaust side of the engine. Then there is a rubber hose (87245A) that connects that pipe to the heater control valve. From the heater control valve, there is a short rubber hose that connects the valve to the inlet of the heater core (you have this part right).
The highlighted orange parts show the coolant return from the heater core.
Starting from the outlet of the heater core, there is a rubber hose (87246A) that connects to a rubber extension hose (87246B) with a metal piece that gives something to clamp both rubber hoses on to. This extension isn't needed, it was only a placeholder for a T-fitting for 4Runners with rear heat. A slightly longer hose can take the place of hose (87246A), the metal piece, and extension hose (87246B). Those hoses connect to the metal pipe that I think you removed that runs under the exhaust and back to the timing chain cover.
This is the best picture I have now of my truck, but it doesn't show the metal pipes:
Jake
Confuse me? ......................
Just a bit...... but I think I see it now. The pipe from the timing chain cover I removed I still have, but is't the same as if I brought the coolant from the lower rad crossover pipe? Look at my pic, the hose that I now have going to the valve. If I just re-route that hose to the passenger side heater core would that work? If not I could always remove the block off plate on the back of the timing chain cover and put back the pipe and block off the hose coming out of the lower rad crossover pipe. I'm hoping that the feed that I have now would be the same as that pipe off the timing chain cover, I'll just re-route it to the heater core.
The 2 hoses/pipes I really need would be 87248A which is a metal pipe, I don't have that but maybe I can just use rubber hose instead since now I have a different intake manifold with a barb coming out of the bottom plate The 2nd hose is 87245A coming from that hose/pipe to the valve, again I might be able to find some molded hoses to fit that.
So now that I'm looking at this I pictured the coolant flow backwards! I thought the coolant flow was from the back of the timing chain cover, or in my case the lower rad hose, instead you're say that it flows FROM the hoses connected under the intake manifold. Interesting.............
Thank you for everything Jake, but please let me now if I can keep the lower rad hose and just re-route it and not have to put that pipe off the timing chain cove back on.
Hump
Last edited by NYHumpinUtah; 10-30-2020 at 09:14 PM.
While you could just connect the hose you have coming off of the lower radiator hose to the other side of the heater core, I would be worried that the hose would lay across the exhaust header to reach. It looks like it is touching the exhaust now.
I personally prefer how the system came from the factory on this generation of Trucks, but if you don't want to go back to that, you could keep your lower radiator hose connection and find or make some brackets that keep that hose away from the exhaust.
On the previous generation of Trucks, Toyota had a similar setup to what you could do:
Jake
That pic shows a completely different routing of the hoses!
I'll have to decide if I want to replace the pipe
Thanks
Hump
The picture was only to illustrate how to keep the hose away from the exhaust.
The routing is nearly the same (the coolant comes from the intake, goes to valve, into heater core, and returns to the lower radiator hose), but they switched which side is the heater core "inlet" and "outlet". Don't get too hung up on the routing of the picture I just posted.
Keep the routing the same as I described originally.
Update
Well I took Jakes advise and put the pipe from the timing chain cover back on and changed out the lower crossover Rad pipe to the one I had without the nipple. I was able to attach a hose to the hose barb under the intake manifold and bring it around the back of the engine and up to the valve where it goes. I had all the hoses for the feed going to the other heater core pipe. Now, it's all complete and with the help of Jake, it's correct.
Some pics:
On to my next adventure
Hump
10-23-2020 | 06:12 PM
