Want to take heater out of cooling circuit

[Nitrate]

1981. 2000. I'm sweltering mo matter what position my levers are in. Is there a noticeable difference in interior temperature when you bypass the heater core? Rich B.

[Frog2Spider]

If your heater is 'off', it is effectively bypassed. The levers are confusing, so check a owner's manual. You can download one from the Internet, if you don't have one..I keep a copy in my glove box, just as a reminder.

Dave

[DieselSpider]

A lot of heat can come up from the center console if the insulation and rubber shift boot is not sealing correctly.

You can verify by using a pinch plier on the heater hose. If that helps chances are that the shut off valves control cable has come undone or is broken pr that the valve itself is not sealing when closed.

http://www.harborfreight.com/radiator-h ... 99704.html

[Nitrate]

Diesel, Thanks for your reply and the photo. Is there any member who can tell me if there is a noticeable difference in the cabin temp with the heater core bypassed? My control valve may not be closing completely and I'm wondering if I can gain even a small improvement by bypassing the heater core. On cars this old I'm thinking even if the lever cables are working correctly and the heater valve is not leaking there could still be some flow into the heater core by a slightly deteriorated seal in the valve. Anyone done the bypass who can relate if it made a big improvement? Rich B.

[Ragno124]

The heater control valve is a simple "ball valve" so you should be able to find the correct "sweet spot" to get it to 100% closed (unless it's frozen and doesn't move). On mine, I have to pull the lever up to the closed position (the point end of the triangle) and then slowly push back 1/4" or so to get the correct alignment for it to be 100% closed. My feet can feel the difference as I always keep the air vent fully open. I'm too lazy to get under the dash to adjust the cable to fix this minor issue.

[Nitrate]

It doesn't have a rubber seal of some sort? RB

[burgandy81]

Nitrate,

I have had a similar situation and just haven't got to fixing it yet.

My guess is that hot water is migrating back into the heater core through the hot water return pipe as the water in the system heats up.

My next step is to put a ball valve in the hot water return line after the heater core ( in the engine bay). This would allow me to turn it off in the spring and back on in the fall.

Might be worth a shot??

[DieselSpider]

Mine is bypassed and I still get a ton of heat since the insulation and seal around the shifter was not installed correctly. They bypassed things by literally looping the heater hose past the core and right back into the water jacket which reduces coolant flow to the radiator so that the cooling system has trouble keeping the engine cool when driving at Interstate Speeds during the warmer months.

My temptation if I were to fix the heater would be to put something similar to this $15 non-bypass valve under the hood on the heater cores inlet hose, set the valve under the dash to full opened and then run the operating cable to the new valve under the hood putting in a longer cable if needed. That way if the valve leaks its under the hood and service/replacing it is easier/cheaper.



For now I may just use the same valve and tie it off in the fully closed position to help keep the engine cooler in the Dog Days of Summer. Florida roadway temps can hover at well over 100 degrees at mid day.

[Nitrate]

Thank you for all of your replys. Very educational. Now for my rather embarrassing confession. Having misunderstood the meaning of the arrows on the lever controls my heat was on full blast the entire time. Never to be mentioned again. Rich B.

[blazingspider]

They bypassed things by literally looping the heater hose past the core and right back into the water jacket which reduces coolant flow to the radiator so that the cooling system has trouble keeping the engine cool when driving at Interstate Speeds during the warmer months.

.

Could you please explain why you think that bypassing the heater core by looping the heater hose back to the water jacket creates a cooling problem? Wouldn't this be the same condition encountered when the heater valve is closed?

In either scenario, coolant would exit the back of the head via the nipple and be returned via the return pipe along the block to the suction side of the pump, or am I way off base here.

[DieselSpider]

When you have a system with a non-bypass shutoff valve the heater hose diverts a good bit of the coolant away from the radiator many times before the thermostat going to the radiator so that whatever heat is available goes to the heater/defroster coils so on those vehicles when you loop the heater circuit instead of closing it off you chance permanently recirculating 20% to 30% of the coolant flow into a loop bypassing the radiator altogether.

When you loop the hose you have even higher flow then when the valve is in place and left open since you eliminate the restrictions of the heater core and valve body. The condition is as if you had a higher flow valve that was left open without any heater core to drain heat from the coolant.

I might just take some bar stock and make a light clamp using a couple of #10 or 3/16" bolts to pinch the hose off until I can get to it so I don't have the extra weight of a clamping plier hanging from the hose for an extended period of time.

[davery]

Thank you for all of your replys. Very educational. Now for my rather embarrassing confession. Having misunderstood the meaning of the arrows on the lever controls my heat was on full blast the entire time. Never to be mentioned again. Rich B.

Been there. Done that.

[Frog2Spider]

Good that you got it figured out, Nitrate.
Don't feel bad, as I said, the controls are confusing and lack reasonableness! That's why I keep a copy of the explaination in my glove box,
Dave.

[KevAndAndi]

I realize that the premise of the original question has been withdrawn, but FWIW, bypassing the heater core in my case did virtually eliminate unwanted cabin heat. It made a noticeable difference.

[DieselSpider]

I realize that the premise of the original question has been withdrawn, but FWIW, bypassing the heater core in my case did virtually eliminate unwanted cabin heat. It made a noticeable difference.

So you had a bad control valve or one that was poorly adjusted so it was not shutting off completely.

You might get away with that up North however in the Deep South you can have problems on hot humid days when roadway temps are sizzling at close to 120 degrees.

Today it was so hot out I could not go over 55 mph without the temperature gauge passing 205 with the bypassed heater hose noticeably hotter than either of the radiator hoses. I really need to put a full shut off on that bypass to make it work as designed at the factory or possibly connect a universal heater core to it up front by the radiator to provide additional engine cooling for the Turbo Diesel.