Possible heater core bypass fix?

[zachmac]

I've been noodling the heater bypass versus heat on my feet in the summer problem in addition to the poor design of the flow having to pass through the heater core to get to the back of the block. What does anyone think about a manual, three-way valve in the engine compartment in the heater core supply line with the third leg branching to a new three-way T connection (no valve) that mates the new three-way valve second outlet and the heater core return line to the block supply?

In the summer you position the manual valve to shut off the heater core and still supply full flow to the block. Come chilly weather you just pop the hood and reposition the valve to restore heater functionality.

The two benefits over just bypassing the HC are 1) you can un-bypass without any messy hose connect / diconnect issues and 2) during the warm months you can occasionally reposition the valve and run the heater to overcome the no flow to heater rust issues.

What do ya think? Before I go source valves and start cutting hose, anyone see a fault in my thinking or an improvement in what I propose?

[mbouse]

I've been noodling the heater bypass versus heat on my feet in the summer problem

What do ya think?

with a replacement heater control valve there should be no such thing as heat on your feet when you don't want heat. simply replacing the valve should take care of any unwanted heat issues associated with the heater core.

i own two Spiders, and will letcha borrow either one to test this statement... any day. in fact, i routinely use the flapper in the cowl to send COOL air to my feet most of my driving season.

[zachmac]

[/quote] with a replacement heater control valve there should be no such thing as heat on your feet when you don't want heat. simply replacing the valve should take care of any unwanted heat issues associated with the heater core.

i own two Spiders, and will letcha borrow either one to test this statement... any day. in fact, i routinely use the flapper in the cowl to send COOL air to my feet most of my driving season.[/quote]

That is all true and I know there is vendor selling a ball valve to ensure total shutoff. But I think you have overlooked the other problem, the original design flaw. Shutting off heater flow also shuts off coolant flow to the back of the block. You can argue that so what, it seems to work okay. But you can also find lots of history of cylinder 3 / 4 gasket problems. More cooling and less heat is always good. I was mainly interested in being able to NOT have heat AND have rear cylinder cooling but also be able to quickly restore the heat function when desired (versus a heater core bypass).

The bottom line is Fiat got it wrong when they put the heater core in series with the block cooling. I'm just suggesting a design fix, nake it a parallel circuit with the ability to quickly select the desired flowpath.

[wengr]

The bottom line is Fiat got it wrong when they put the heater core in series with the block cooling. I'm just suggesting a design fix, nake it a parallel circuit with the ability to quickly select the desired flowpath.

Is it not possible to have a parallel circuit, where the engine circuit works, irrespective of what the heater circuit is doing? without the need to bypass the heater circuit? Also who is listing a ball style shutoff valve, and are these likely to last longer than what is generally available?

[zachmac]

Is it not possible to have a parallel circuit, where the engine circuit works, irrespective of what the heater circuit is doing? without the need to bypass the heater circuit? Also who is listing a ball style shutoff valve, and are these likely to last longer than what is generally available?

First, anything is possible given an infinite amount of time and money!

If you go back to my inital post, I am suggesting creating just such an option. In the engine bay you insert a manual three way valve into the line coming from the water pump hard pipe to the inlet of the heater core. This leaves a third leg. You pipe that with some new hose to a newly inserted three way T connector in the line returning from the heater core to the block. You now have two possible paths: through the heater core to the block or to the block bypassing the heater core by simply repositioning the manual valve under the hood. You would only do this at the season changes and you want to allow or disallow flow to the heater core.

In the heater core bypass mode flow is from the pump to the three-way valve, through the new hose, to the block. You can also once a month still reposition it for a few minutes to flush the heater core and avoid any stagnation corrosion.

All this gains is the ability to do the exact same thing as bypassing the heater core under the hood but you no longer need to re-route hoses or open the system every time you want to change status, bypassed or not. It is NOT to make sure there is no heat in the passenger compartment (as was noted a working heater valve can do that) but to give you the ability to do so and STILL HAVE flow to the back of the block.

BTW, the ball type valve was on the Performance Fiat site if memory serves.

[zachmac]

Quick follow up: ball type heater valve is indeed on Performance Fiat site but you have to know to look under Electrical and then Heating under that tab on their site!

[wengr]

Hello Jeff, and thanks for the explanation. I believe I understand what you are proposing. what I'm considering is similiar, but without an additional valve. simple a heater core "bypass", but used in addition to the heater core circuit. So the hard pipe off the waterpump would need to be Y'ed, with one outlet going thru the core and one directly to the head. the heater core output would have to Y back in at the head. There of course may be issues with coolant volume, flow rate etc? but maybe better than the stock situation?

[zachmac]

what I'm considering is similiar, but without an additional valve. simple a heater core "bypass", but used in addition to the heater core circuit. So the hard pipe off the waterpump would need to be Y'ed, with one outlet going thru the core and one directly to the head. the heater core output would have to Y back in at the head. There of course may be issues with coolant volume, flow rate etc? but maybe better than the stock situation?

I think the problem your way could present is inadequate flow through the heater core? With the heater control valve to "cold" you would have all the flow to the block (desirable) but opening it wouldn't insure flow through that leg of the two parallel paths (and could even cause backflow) so I am still thinking a three way valve in the supply to only allow one or the other is best.

[mbouse]

Jeff, my apologies; i understand better now what you are proposing. my speed reading caught me falling short on full comprehension the first time around.

still, in all i question the need. where is the "lots of history of cylinder 3 / 4 gasket problems " data for the DOHC Fiat engine, as related to the poor design of the heater core?

i'd much better accept the argument that most Fiat owners poorly understand the proper techniques behind purging their cooling system of air... resulting in overheating issues and resulting damages. not a month goes by on this forum or others where Spider owners complain of overheating--to discover they don't know how to "burp" their coolant systems. then once they understand how to purge their engine of unwanted air, their overheating issues are gone..period.

i'm not attempting to pick an argument, just thinking that you are chasing phantoms. then again, maybe you have a unique situtation.

then again... i may be all wet. if so, teach me.

[zachmac]

Jeff, my apologies; i understand better now what you are proposing. my speed reading caught me falling short on full comprehension the first time around.

still, in all i question the need. where is the "lots of history of cylinder 3 / 4 gasket problems " data for the DOHC Fiat engine, as related to the poor design of the heater core?

i'd much better accept the argument that most Fiat owners poorly understand the proper techniques behind purging their cooling system of air... resulting in overheating issues and resulting damages. not a month goes by on this forum or others where Spider owners complain of overheating--to discover they don't know how to "burp" their coolant systems. then once they understand how to purge their engine of unwanted air, their overheating issues are gone..period.

i'm not attempting to pick an argument, just thinking that you are chasing phantoms. then again, maybe you have a unique situtation.

then again... i may be all wet. if so, teach me.

No harm or offense. Getting other perspectives and opinions before jumping into something unneccesary was one of the reasons I posted the idea before doing anything. While it may not be needed, I can't see where my solution could hurt?

AND, I was thinking the new piece of hose going to the block would be the perfect place to include a Prestone flush connection to accomodate both flushing and high point burping!

[lanciahf]

I spliced a t in my heater hose and added a nipple to the water pump pipe to aid in the circulation when the heater valve is off. The t is only 5/16 but at least the water is moving back there. I'll take pictures tonight.

[mbouse]

great, Jeff. glad that we are both level headed about this. cuz, if you have a better way... i'd like to know.

and the prestone t-fitting thing is not a new idea...

this is Bernie's car, but many of us have been using these fittings for a long time to aid in "burping"
as you say, this might be a great place to put the bypass as well.

[wengr]

I have a plastic tee just like the one pictured. iirc, years ago they were commonly available in brass. can you still find the brass tees anywhere?

[zachmac]

I have a plastic tee just like the one pictured. iirc, years ago they were commonly available in brass. can you still find the brass tees anywhere?

I think you can find them in brass at Lowe's or Home depot. They use a garden hose connect which is perfect! I was looking last night at all there stuff trying to figure out how to do what I am thinking about. Brass is expensive! Looks like I would have to make up the T from a threaded T and a couple of lengths of pipe and you can easily spend 30 to 40 bucks on pieces parts. The Prestone kits are about $7.

[cdnclipper]

Hello,

I just purchased a 1978 Fiat, experienced a vapour lock the first day.

Sounds like I need to burp the baby.

This looks like a great site; pardon my infant navigation skills- looking for my profile.