Heater core flow direction

[codex]

On my way to class today I blew a heater hose that attaches to the left side of the heater core (facing the firewall). I don't think I can count on one hand the number of times I've had problems with the cooling system in my Festiva. It has a head gasket problem so I guess that is expected. Anyways, I'm wondering if the left side of the heater core is the inlet or the outlet? If it is the inlet I'm thinking that my heater core has been plugged from the oil and crud in the coolant and caused the hose to rupture.

[Festiva Time]

The connection closes to the passenger-side is the inlet & the outlet connects to the long coolant pipe back to the water pump.

- Kirk

[codex]

I replace the hose that ruptured today and started it up. The temp gauge rose and began to overheat so I shut it down and checked the hoses. The top radiator hose was hot, but the bottom was not, also the left side heater hose was hot and the right side was not, Is this a bad water pump or a stuck thermostat? I recently replaced the thermostat, but that small coolant hose at the front of the engine has a kink in it, is that hose used to actuate the thermostat? Any help with diagnosing this would be very appreciated.
Thanks

edit: Also the heat was not working, or very sporadic at best, it would blow warm for a second then go back to cold, but it would only get warm if i would accelerate.

[batstiva]

edit: Also the heat was not working, or very sporadic at best, it would blow warm for a second then go back to cold, but it would only get warm if i would accelerate.

Was this before the hose ruptured? I'm assuming yes? Did you verify that there is flow through the heater core? How was the heat working between the thermostat replacement and the hose blowing? Leaning a bit in the direction of a water pump issue, but kind of need more info. Anyone else?

[FestYboy]

1) you have air in the system
2) your headgasket is allowing combustion gasses into the coolent system
3) both the rad and heater core are blocked

those are your options and you may have more than one.

[JoDan]

Well I'm not sure how the coolant system is routed unless I checked it but if the inlet hose blew off my guess would be a plugged heater core. Pull the hoses off and try to blow air inside and see if you get some stuff to come out or if even air is getting through.

[codex]

Was this before the hose ruptured? I'm assuming yes? Did you verify that there is flow through the heater core? How was the heat working between the thermostat replacement and the hose blowing? Leaning a bit in the direction of a water pump issue, but kind of need more info. Anyone else?

The hose ruptured because the the hose swelled from oil in the coolant (although this doesn't mean that blockage could have contributed to it happening, I haven't ruled this out yet). The heat was working prior to this incident, but I'm not sure if the heat stopped right before the hose broke or the heat stopped after the host broke (im 90% certain that the heat was working all the way until the hose broke and coolant was no longer going through the heater core).

What is the best and least messy way of testing the water pump operation?

[Festy46]

You said you recently replaced the thermostat. Did you just slap it in or did you rotate it so that the air bleed hole was at the top of the thermostat? You can backwash your heater core by taking both hoses off and connecting a garden hose to the return side connection of the heater. Water should come out of the inlet side at a full heavy stream if it isn't plugged. You can check the operation of the water pump by removing the thermostat, replace the thermostat housing, fill it with water within about an inch of the top of the radiator, leave the radiator cap off and start the engine. If the water pump is working you will see the water flowing by looking in the fill opening.

[CharlieZ]

Not exactly related to codex's problem.
IMHO, a 13 psi radiator cap is too much for these aging systems. Does anyone know if there is a 7 psi cap available? I didn't find anything at the *Zone* in a Festy size cap.
I have been running with my cap loose but don't like the way a loose cap handles expansion. i.e. pukes out coolant to the ground and not to the reservoir.

[codex]

You said you recently replaced the thermostat. Did you just slap it in or did you rotate it so that the air bleed hole was at the top of the thermostat? You can backwash your heater core by taking both hoses off and connecting a garden hose to the return side connection of the heater. Water should come out of the inlet side at a full heavy stream if it isn't plugged. You can check the operation of the water pump by removing the thermostat, replace the thermostat housing, fill it with water within about an inch of the top of the radiator, leave the radiator cap off and start the engine. If the water pump is working you will see the water flowing by looking in the fill opening.

It wasn't that recent, I changed it last year. I'm not sure of the way that I aligned it, but I tried to put it in the same way the old one came out. What does the air bleed hole look like?

[codex]

I think the problem was air in the system because after it settled and I started it again today it did not overheat. I have a question about this other line though. It is kinked because when it started leaking I replaced it with a straight piece of hose. Can someone identify the purpose of this small hose?

Thanks

[CharlieZ]

Can someone identify the purpose of this small hose?
Thanks

That's the thermostat bypass hose. To quote the manual, section 27, "The bypass circuit distributes combustion heat throughout the engine for quick and uniform warm up."

Were you (or anyone else) able to remove the heater core without removing the entire dashboard as it says to do in the manual. That seems like one heck of a lot of work to pull a heater on such a simple car. :-( There's got to be a less labor intensive work-around.

[econoaddict]

Were you (or anyone else) able to remove the heater core without removing the entire dashboard as it says to do in the manual. That seems like one heck of a lot of work to pull a heater on such a simple car. :-( There's got to be a less labor intensive work-around.

Thats about the only way. once you do it a couple of times it's not really that bad.

[codex]

That's the thermostat bypass hose. To quote the manual, section 27, "The bypass circuit distributes combustion heat throughout the engine for quick and uniform warm up."

That doesn't really make sense to me. The hose is very small, it doesn't seem like much coolant can go through that little hose. I found an intake hose on a JY festiva that looks like the same diameter and has a bend that would allow me to replace that hose without one that is kinked. Is it ok to use a vacuum hose for coolant? Actually, it may be the coolant line that goes to the throttle body and not a vacuum line.

[CharlieZ]

That doesn't really make sense to me. The hose is very small, it doesn't seem like much coolant can go through that little hose.

The small hose provides a path allowing some coolant circulation before the thermostat opens. Even when the engine is cold the area around the valves gets hot real quick. Some coolant flow is necessary to eliminate these hot spots.

The flow diagram in the manual isn't that great but I could scan and post it if you want.

I don't think vacuum hose has a fabric "inner belt" so may not be suitable for long term use as a coolant hose. Fuel hose might be OK.