Trying to troubleshoot why I've got weak heat (getting 105F at the floor vents). Looking at the FSM for 1998, looks like the flow from the thermostat should go to the bottom heater core port, and the top port should go to the water pump? Looking at my setup, looks like it's backwards, the thermostat hose is connected to the top heater core port, and the bottom hose is going to the water pump. Am I right? There's a pretty significant difference in temp between the hoses. The one going to the top is 155F, the one at the bottom is only about 115F (see pics).
Need confirmation: My heater hoses are backwards, aren't they?
- Thread starter Mogul345
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I agree it looks wrong from the diagram but I think the hoses are different sizes so they couldn't be connected wrong.
Thanks folks. I just found another thread that said the diagram is backwards in the 2006 FSM. Guess it's backwards in the 98 FSM too.
Unhook both the hoses from the motor and backflush it with a hose. The smaller,lower one is the exit so spend most time running water through it. I had to do it several times to get mine clear and blowing heat.
Beware though. It also removed the chunks of stop leak that kept it from leaking which lead to replacing the heater core
Beware though. It also removed the chunks of stop leak that kept it from leaking which lead to replacing the heater core
Is the engine reaching normal operating temperature? Could you possibly need a new thermostat?
Pretty sure it is, IIRC the FSM says the thermostat opens at 195F and this is where my temp gauge was sitting when I was running the test, a little below 210F.
I think I'll be taking it to the shop soon. I've got other HVAC problems; when in defrost zero air comes out the defroster vent in the middle of the top of the dash. But it definitely is sending air out the little vents above the corner vents for defrosting the side windows. Kind of figuring that this means the dash is coming out to repair the box, and if that's the case, gonna replace the heater core while I'm in there.
if that pic is at full operating temp your running too cool. it should be on the 1 on 210 or just below it. on the defrost not working there are 3 control arms on the actuators that are known for breaking, I'll see if I can find the thread that shows them .
Interesting. Yes, that's the highest I've ever seen the temp gauge go to. In this specific case I idled up to this temp, but even after driving it for an hour or so, it always stays right there on the temp gauge.
I would put money on you having a 185deg. thermostat in it. should be a 195deg
I wish I knew why people do things like this, especially here in CA where running cold can only hinder the smog test. I had similar happen in my other toy car (Mercedes 560SL) when I first bought it. I'll keep that in mind. I do need to get the coolant flushed at some point. When I had it inspected the mechanic said it's good enough for now. But it's got the green coolant in it, and reading the forums here, looks like the consensus is to flush and replace with G05 even if it's a model year that came from the factory w/ green.
Was putting that off, but perhaps it's time to do it all - thermocure, flush, G05 fill, new thermostat.
changing the thermostat is easy, 2 bolts. just clean the housing really good before installing. youtube can teach you almost anything. I agree with going to G05 coolant
Oh yeah, it's right out in front and super easy to do. I'd do it in a heartbeat myself under other circumstances. Unfortunately I live in an apartment, and I street park. My neighbors are very gracious and let me borrow their spots in the back to do work on my cars all the time, but the stipulation is that I have to be done by the end of the day so they can have their spot back. So I'm always hesitant to do stuff where if things go sideways (like say, bad thermostat, or gasket or whatever) and I might not be able to reliably finish in a day.
We have an errata thread near the FSM thread, I wonder if that is reflected there? Where/how did you discover that the FSM was wrong?
I’m a bit confused. It looks like all the different diagrams I’ve found show the same flow as the OP diagram.
Is the bigger one going in and smaller one going out?
Is the bigger one going in and smaller one going out?
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