nujeepguy

i always figured the hoses were different sizes so the couldnt get hooked up wrong,,,but i dont know why it would matter the direction of flow!!,,??

DFlintstone

I like that one. Even a fully open stat, like you mention is gonna help it move water through the heater. (couple that with an airlock?). Also never seen it in person, but from time to time someone posts a pic of an impeller that's flat as a dime. Any chance the flush water froze somewhere?There's gota be a bunch of "mid ground" there. Best of the holidays to you and all!

BlueRidgeMark

Some day if I have time I'll experiment with heater core flow on a clean engine, with and without the t-stat.

I'm betting the t-stat does have some effect on redirecting some of the flow out to the heater core.

Between that and the rusted impeller, it just wasn't moving anything.

Anybody have an answer to my question about the intake manifold?

BlueRidgeMark

Well, it's all back together, and my boys inadvertently did a test of the coolant flow with no thermostat installed. Yeah, they forgot to put in the thermostat.

With the new water pump and no thermostat in place, we got good flow through the heater hoses.

So, no, it's not dependent on the thermostat to create a pressure differential.

Oddly enough, it's dependent on a functioning water pump to create pressure!

EZEARL

GLAD it's going well for you. Forgot the thermostat?! No bonuses for the hired help.

cruiser54

We all knew that......

DFlintstone

Warning,(s). Simple job eh, the T-stat. (I managed it in just two days) It's easy, and natural for it to slip down in the housing, the result being it snaps the ear off the housing when you tighten the bolts.
Also, my lower bolt it awkwardly behind the belt. Not such a big deal, but that makes it easier to drop it's washer. Mine just vanished, spent a good while not finding it. Oh well, moving on. I finish and fire it up to hear an instant sort of explosion. Found the washer! It had landed between the belt and sprocket. Now I'm stranded on a remote hill-top miles from town. A friend had to drive one out to me.
Do hope your upper bolt hasn't "become one", with the housing. Mine had about fused with corrosion. I could loosen and turn it easy, but only something like 1/2 a turn before the housing hit's I forget what. No room to get a blade in there to cut it free. I may have drilled or cut the head off, then with wedges driven the housing outwards, off the bolt.

Easy piece of cake otherwise.

cruiser54

Loosen the belt to do the job. Add a dab of sealant. NOT RTV!!! to hold the stat in place.

BlueRidgeMark

It's all done. Buttoned up, new coolant, and a good test drive. All good as far as engine temps, but still not getting good heat. It gives me warmish air. I used to be able to roast myself on a cold day.

I think my heater core is still sludged up. I did pass water through it, but that gunk was thick in there, and it's probably got a lining of sludge preventing the heat from transferring.

I'm going to pick up a few fittings at Lowes and connect the heater hoses directly to my garden hose and see if I can get it clean. Alas, I have lousy water pressure at my house....

drewactual

borrow an airlift to clear all the air out. takes seconds for something that may or may not happen via usage over time.

the smaller line to the core is to create greater pressure- the larger return line is to decelerate the flow, promoting the vomiting of air in the system... you want a low pressure return to the engine...

if you fellers want to see vanes worn to nothing with zero exterior indication, hang out around inboard raw salt water marine engines... it's a rule, not an exception... helz, i've seen them freeze up/corrode to the housing before over the winter or after sitting a good while and not being ran...

nujeepguy

careful, too much pressure may break the core.

nujeepguy

ive never heard this before, where did you find this detailed info. id like to read more about it.

drewactual

you're asking me a question i asked to a group when i was a grasshopper. not that i'm not still a grasshopper... just a much older one now.

so, it's debatable. up front- it's a debate. however...

some will swear to you the only reason is so people working the assembly line don't reverse it.

some will swear to you it is due to the centrifugal engine speed based pumps inability to sustain a steady pressure/volume, and intent to keep the volume of flow through the heater core at a level sustainable for heat transference, so an operator doesn't have to eff with the controls constantly.

some, related to the last and where i've decided to plant my flag- is a bit of all three- the hoses altering diameter disallows a assembly monkey to eff it up, and it negates the need for a expansion/catch basin attached to the core by performing the same function- the same volume of flow is traveling the smaller diameter tubes as is flowing into the larger, which means volume flow rate, measured by pressure, is less- slowing it down and giving it an opportunity to uniform it's temperature. if it decreases enough (and it does) it isn't sprayed back into the pump so much as it trickles, which means the pressure side isn't equal to the pressure being generated by the pump and it doesn't fight it and can't hydro-lock it. because flow is rushing in (pressure greater) than it is leaving, the air that is trapped in the top of the core is more easily pushed out instead of being pressed into place under the pressure- making it hard to eliminate/purge/burp.

i suggest an air lift tool to evacuate the entire system under a vacuum. it's good for testing for leaks before wasting time/money on coolant, and filling under a vacuum eliminates the dead space where air is compressed and trapped. liquids don't compress, but they certainly expand under heat. when it is shoved through that heater core, they cool pretty rapidly- especially when you're pushing air through the exchange. that allows for even slower movement of flow (pressure) on the return side as compared to the feed side. it also disallows the easier expulsion of air if the pressure is great enough to compress that air in the nooks and crannies (top, usually) of the core or exchange. the height of the core is pretty close to the height of the degas and the rad cap- which means every bit of the pressure differential is appreciated to fill and not compress the trapped air.

I'm not good at expressing these things, and there are a lot of words north of this sentence/paragraph that i hope explain it better than i think they did. if you want to play (which I have in the past), use a same diameter in/out on a core without a booster pump, at the same height as the degas, and see how long it takes to purge. it may or may not purge, if you want the cliff notes. open the return side, though, and it will purge pretty quick... that open line represents a drastic drop in pressure the air is seeking, and it's exit will be replaced by the rising fluid. the larger hose is a way to do the same thing with less pressure differential.

BlueRidgeMark

Yep. Not likely to be a problem with my water pressure, though.

If it does, I guess I won't be worrying about a clogged core, right?

DFlintstone

I've just held the end of the hose, and the end of the garden hose in my hand, then reverse, repeat. I did see a little crud, but my heater is still "moderate".

Never worried myself about an airlock. If I was, I suppose in a Jeep one could park with the front way high and run up the rpm's for a few secs.