heater core bypass?

[vtec-e]

Would it not be the same as leaving the temp dial set to cold? Like we've always done it? Or are we talking about removing the heater core completely? Because thats a bit excessive, given that most of us need it!

[t vago]

Originally Posted by vtec-e

Would it not be the same as leaving the temp dial set to cold? Like we've always done it? Or are we talking about removing the heater core completely? Because thats a bit excessive, given that most of us need it!

older vehicles with A/C had a factory heater bypass valve installed. Newer vehicles do not. All well and good, except for the fact that there's still heat going into the cabin of the newer vehicle.

All we're talking about is installing a valve to bypass the coolant flow through the heater core during summer months, and during warmup.

Generally, one could get about a 10 to 15 degree colder discharge temperature coming out of the A/C, with a heater bypass in place. As for warmups? I'm not entirely sure a heater bypass would provide any sort of measurable decrease in warm-up time.

[brent777]

Originally Posted by t vago

It's hard to say how much warmer my truck would warm up with the bypass, as I've never really tested it. I installed my heater core bypass to make my A/C put out colder air.

For some engines, one can get away with using a two-way valve. However, that presumes a good understanding of one's engine internals. For instance, on my truck's engine, there's already an internal bypass between the heater supply port and the heater return port.

is there any way i can mess up my motor by doing the bypass? i have a 97 nissan d21 pickup aka nissan hardbody 2.4L

[t vago]

Originally Posted by brent777

is there any way i can mess up my motor by doing the bypass? i have a 97 nissan d21 pickup aka nissan hardbody 2.4L

Well, if you install a bypass and don't properly remove all of the air out of your cooling system afterward, then it is possible to do some major engine damage. Not terribly likely, but it is possible.

However, if the bypass is properly installed, and the coolant system is properly burped of air, then the bypass itself should not cause any problems.

[brent777]

Originally Posted by t vago

Well, if you install a bypass and don't properly remove all of the air out of your cooling system afterward, then it is possible to do some major engine damage. Not terribly likely, but it is possible.

However, if the bypass is properly installed, and the coolant system is properly burped of air, then the bypass itself should not cause any problems.

okay sweet no prob can do thanks for the q and a

[ECONORAM]

When I installed my heater core bypass, I used some C-clamps to clamp the hoses closed, then cut them so I could minimize coolant loss while trying to shove the valve into place.

[NoD~]

Question: If you bypass the heatercore, warm up, then turn on the heat, would the cold coolant entering back into the engine cause any potential harm? I know it's not a lot of fluid and it will probably warm up quickly, but isn't metal not a big fan of a quick cool down, even in small doses like that? I don't think it would crack a block or warp a head by any means, but is it possible that, with enough uses, it could cause some potential long-term damage?

[Daox]

No. The temperature difference isn't that large. Its not like your engine block is glowing cherry red and you're dropping it into a huge vat of water. That would be a problem. Your engine gets sprayed by water all the time when you go through puddles, this is no different.

[dwtaylorpdx]

On a Jeep 4 cylinder if you bypass the heater core or block the heater hoses of the engine over-heats. Its in parallel with the radiator, but does not get controlled by the thermostat. I finally stuck a valve in the hose to meter the flow until I got the new heater core in.

Later model jeeps (89 and up) dont use the old valves, they use a damper that blocks the heater core out of the air flow through the duct exactly like a chevy pickup.

I use a cheap harbor freight IR gun to check temps.

Dave