coolant flow through the heater core?
#1
coolant flow through the heater core?
I think I have found conflicting information. So I'll ask:
Does the coolant flow from the water pump via long pipe to the upper heater port, then out of the lower port to the valve then to the manifold?
or is it the other way around, which to me makes more sense.
does the valve stop the coolant before it reaches the heater? or after it comes out.
simple question, but hanging me up.
1977 xj6-c
thanks all.
geneo
Does the coolant flow from the water pump via long pipe to the upper heater port, then out of the lower port to the valve then to the manifold?
or is it the other way around, which to me makes more sense.
does the valve stop the coolant before it reaches the heater? or after it comes out.
simple question, but hanging me up.
1977 xj6-c
thanks all.
geneo
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adenshillito (04-13-2021)
#2
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#8
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That is my take. Normaly open. So, hot water ism in the pipes and matrix all the time
I decided to change that. No heat in the cabin in the summer!! My objective.
So, I added a manual valve in the hose that did not have the vacuum operated on/off valve. Off in the summer on my manual did that. On with a fan and get power vent sans heat.
I call that hardware store source manual valve. my winter/summer valve.
I went to market yesterday., Cool almost cold weather. Nice Jaguar heart!!
Carl
I decided to change that. No heat in the cabin in the summer!! My objective.
So, I added a manual valve in the hose that did not have the vacuum operated on/off valve. Off in the summer on my manual did that. On with a fan and get power vent sans heat.
I call that hardware store source manual valve. my winter/summer valve.
I went to market yesterday., Cool almost cold weather. Nice Jaguar heart!!
Carl
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adenshillito (04-13-2021)
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#10
Sorry to disagree.. maybe on older carbed engines but with FI things are a bit different.
TBI ENGINES
Long hose comes from heater outlet to radiator return nipple. Hot coolant comes from rear of intake manifold into the heater valve. Restrictor plates are used in the intake manifold gaskets to block the rear coolant head ports and thereby direct some coolant through a short hose from the heater coolant outlet (at rear of the intake manifold) to the heater valve..through heater core then back to radiator.
Lots of confusion as GM changed some things over the years.
TBI ENGINES
Long hose comes from heater outlet to radiator return nipple. Hot coolant comes from rear of intake manifold into the heater valve. Restrictor plates are used in the intake manifold gaskets to block the rear coolant head ports and thereby direct some coolant through a short hose from the heater coolant outlet (at rear of the intake manifold) to the heater valve..through heater core then back to radiator.
Lots of confusion as GM changed some things over the years.
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adenshillito (07-16-2021)
#12
#13
Alan,
The GM thinking has changed with the introduction (back in 1988 or so) of EFI engines. Mine is a TBI version. And after researching "why do I have these restrictor plates blocking the intake rear water passages from circulating coolant through the rear of the block" ?
ANSWER:
Because the GM engineers wanted to keep the bottom of the intake manifold up to temperature (to prevent the throttle body from icing up during cold weather operation).
So they routed the coolant from the front of the engine (water pump)
through the lower portion of the intake manifold and redirected some of it out at the back of the intake manifold at the heater pipe outlet. They redirected the coolant by blocking the rear water passages (with restrictor plates) and forcing some of the coolant to the heater. Also the coolant returned to the front of the engine going through the heads and out the front of the intake to the top of the radiator.
After reading articles from various GM related EFI bulletin boards / forums
I discovered that TBI engines have a different way of circulating coolant. Does not affect other GM V8s but it does pertain to mine.
The GM thinking has changed with the introduction (back in 1988 or so) of EFI engines. Mine is a TBI version. And after researching "why do I have these restrictor plates blocking the intake rear water passages from circulating coolant through the rear of the block" ?
ANSWER:
Because the GM engineers wanted to keep the bottom of the intake manifold up to temperature (to prevent the throttle body from icing up during cold weather operation).
So they routed the coolant from the front of the engine (water pump)
through the lower portion of the intake manifold and redirected some of it out at the back of the intake manifold at the heater pipe outlet. They redirected the coolant by blocking the rear water passages (with restrictor plates) and forcing some of the coolant to the heater. Also the coolant returned to the front of the engine going through the heads and out the front of the intake to the top of the radiator.
After reading articles from various GM related EFI bulletin boards / forums
I discovered that TBI engines have a different way of circulating coolant. Does not affect other GM V8s but it does pertain to mine.
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#14
I want to thank all the experienced Jaguar owners that continue to post valuable information in the forum. Sometimes you help me solve problems, on rare occasions I can add something I've learned (usually the hard way), and like this thread on coolant flow through the heater core, you just help me to verify that my car is put together properly. I have an SIII with a small block v8 that previous owners put together. Some things they did beautifully and others "what were they thinking". I have owned dozens and dozens of cars over the years but my lumped SIII is my favorite.
Jeff
Jeff
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#17
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My way of thinking is that the Delanair in our Jaguars cares not as to which engine provides the hot water. So, only where to tap the pipe to the lower part of the core via the water valve is the question. flow in the matrix is best from bottom to top. Physics. Heat rises!!!
Then the return line goes back to the engine. To the Pump intake to be moved through the engine to acquire heat.
Now, my LT1 features what GM thought up. Reverse cooling. from rear to front!!! My water pump has two spigots, in and out for the heater. In turn the pump is mounted in the center of a manifold of the two banks. Hot out cold in suits the matrix just fine. Still controlled by the Jaguar vacuum operated water valve.
Oh, the LT1 is happy at 190 to 200 F.
Carl
Then the return line goes back to the engine. To the Pump intake to be moved through the engine to acquire heat.
Now, my LT1 features what GM thought up. Reverse cooling. from rear to front!!! My water pump has two spigots, in and out for the heater. In turn the pump is mounted in the center of a manifold of the two banks. Hot out cold in suits the matrix just fine. Still controlled by the Jaguar vacuum operated water valve.
Oh, the LT1 is happy at 190 to 200 F.
Carl
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adenshillito (07-16-2021)
#18
The GM thinking is that they try to restrict the amount of coolant that goes through the heater core by placing a restrictor in the hose to heater and the extra coolant then circulates through the engine back to radiator instead of all of it going to heater... core to help with cooling.
There are various ways to route the coolant when it comes to FI engines.
There are various ways to route the coolant when it comes to FI engines.
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adenshillito (07-16-2021)
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Hm, I sure am not an expert in thermal hydraulics! I coined that term!!!!
But, it seems that if added cooling was the incentive, flowing as much coolant as possible through the heater matrix would work. The matrix is a small radiator and transfers heat from the coolant !!
An old tech and highly uncomfortable way to deal with an over heating engine, As it usually happens in hot weather. Turn on the heater!!!!!
Carl
But, it seems that if added cooling was the incentive, flowing as much coolant as possible through the heater matrix would work. The matrix is a small radiator and transfers heat from the coolant !!
An old tech and highly uncomfortable way to deal with an over heating engine, As it usually happens in hot weather. Turn on the heater!!!!!
Carl
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adenshillito (07-16-2021)
#20
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