96 5.7L Vortec - production block - Water pump coolant flow and heater core flow direction help

[dtrader]

Searched threads here and on internet for coolant flow on long water pump with two hose connections on top - no internal coolant by-pass on block or pump - with no luck. Lots of diagrams for pre 96, seems a simple topic but.... I am unable to verify info on flow direction and could use some help.

I am adding 2 coolant hoses to 1/4" NPT engine block bosses, on L & R sides between cylinders 3-5 and 4-6, (removing knock sensor & 1 plug), to facilitate adding cooler water at this high temp area. I want to be sure on flow before starting project.

My understanding: this water pump is reverse rotation (C.C.W.) making short hose connection on passenger side of pump, (perspective from center line of pump shaft) would be suction side and for the external by-pass hose connection to front intake manifold under thermostat well.

So, long hose connection on driver side of pump, (perspective from center line of pump shaft) would be pressure side. This hose now goes to heater core.

Since this hose connection is 5/8" on heater core and second connection on heater core is 3/4", I belief this 5/8" diameter to be additional evidence of pressure side since a smaller diameter hose is used for pressure and a larger diameter hose is used for lower pressure return, if engineered to typical standards. The 3/4" hose on heater core goes to top of intake manifold on passenger side which I belief should be return form heater core to intake manifold as factory installed.

I have a 3/4" hose connection on radiator, (now plugged), that I want to re-plumb 3/4" hose from heater core to. Then, change hose connection on top intake manifold, (passenger side) to 5/8" to create pressure feed to heater core completing my project.

thanks in advance for any help,

James

 

[GoToGuy]

Have you looked in FSM under cooling, radiator, routing and operation? There are digrams and system description and operation..

 

[dtrader]

Apologize for lack of knowledge with initialisms, what is FSM? Field Service Manual?

There is a post on this forum "Aftermarket Vortec 5.7 air gap manifold and coolant hoses" that is in conflict with info I've obtained from other sources.

I have found 2 sources of 1996-1999 C/K Factory Repair manuals, the cheapest was $249. Thought this forum might have info in brain trust for less.

I will take the time to verify with actual flow test and water pump inspection, again I thought this forum might save me the time.

 

[Schurkey]

I am unable to verify info on flow direction and could use some help.

Coolant flow through the Vortec engine is EXACTLY like coolant flow through any other SBC engine EXCEPT the reverse-cooled LT1s, with the exception of water pump rotational direction and the lack of a functional coolant bypass via drilled passages from right cylinder head to water pump. The heater-supply plumbing is another area of minor variation. Suffice to say that the heater core is supplied by coolant pressurized by both the rad cap AND the water pump, and returns to the engine somewhere on the suction side of the water pump--either the pump directly, or the "cooled" (suction-side) tank on the radiator.

The water pump is driven from the smooth side of the serpentine belt, which means it spins counter-clockwise as viewed from the front. (reverse rotation) However, coolant flow through the pump is exactly the same beyond the changes mentioned for the coolant bypass and heater connections.

I am adding 2 coolant hoses to 1/4" NPT engine block bosses, on L & R sides between cylinders 3-5 and 4-6, (removing knock sensor & 1 plug), to facilitate adding cooler water at this high temp area. I want to be sure on flow before starting project.

THIS
IS
CRAZY.

That area is NOT a "high temp" area, in fact it's about the coolest (lowest-temperature) part of the entire engine. It's about as far below the cylinder head as you can get and not be in the oil pan. It's getting gushed with coolant directly out of the water pump, flowing through the block before geysering up to the cylinder head--which IS the hot part of the engine, especially the middle of the head.

In COMPETITION--not street use--some guys have added coolant hoses to the CYLINDER HEADS between the center two cylinders, where the two exhaust ports are close together. Because the SBC has exhaust valves next to each other on cylinders 4 and 6, and 3 and 5, the middle of the cylinder head runs hotter than the rest of the engine. This is also why the most-common area for head gasket failure is between the middle-two cylinders.

But even most forms of competition don't require external plumbing; the stock cooling system is entirely adequate; and when it isn't, there's internal mods that can be made; primarily by drilling a hole in the block head gasket surface, and in the head gasket. Some blocks/gaskets have these holes already, some don't.

OTOH, using those two block drain holes as OUTLETS, with a hose running from them, up to the cylinder head somewhere between the siamesed exhaust ports--so that additional coolant can bypass the cylinder head gasket and go directly to the hottest part of the engine--has been done for certain COMPETITION engines.

What you're proposing is USELESS. A TOTAL waste of time, money, effort, and enthusiasm.

My understanding: this water pump is reverse rotation

Yes. But not reverse-flow, or even altered flow aside from the coolant bypass and heater connections.

long hose connection on driver side of pump, (perspective from center line of pump shaft) would be pressure side. This hose now goes to heater core.

Since this hose connection is 5/8" on heater core and second connection on heater core is 3/4", I belief this 5/8" diameter to be additional evidence of pressure side since a smaller diameter hose is used for pressure and a larger diameter hose is used for lower pressure return, if engineered to typical standards.

TYPICALLY, the supply hose is smaller-diameter than the return hose. But NOT ALWAYS.

The 3/4" hose on heater core goes to top of intake manifold on passenger side which I belief should be return form heater core to intake manifold as factory installed.

Unlikely. I'd expect any connection to the intake manifold (front...rear...one side or the other side) would be the heater core supply. A connection to the water pump is probably a return, if it's on the front of the impeller.

But all of that is moot since the entire project is nuts, based on false assumptions.

If you're having an overheating/thermal management problem, the solution is to fix what's faulty, not re-design the cooling system to supply MORE coolant to the COOLEST part of the engine.

Don't get me started on the detrimental effect of removing the knock sensor.

The Factory Service Manuals are available for free download from the links in the Sticky thread section of the Engine forum of this web-site.

 

[L31MaxExpress]

Coolant flow through the Vortec engine is EXACTLY like coolant flow through any other SBC engine EXCEPT the reverse-cooled LT1s, with the exception of water pump rotational direction and the lack of a functional coolant bypass via drilled passages from right cylinder head to water pump. The heater-supply plumbing is another area of minor variation. Suffice to say that the heater core is supplied by coolant pressurized by both the rad cap AND the water pump, and returns to the engine somewhere on the suction side of the water pump--either the pump directly, or the "cooled" (suction-side) tank on the radiator.

The water pump is driven from the smooth side of the serpentine belt, which means it spins counter-clockwise as viewed from the front. (reverse rotation) However, coolant flow through the pump is exactly the same beyond the changes mentioned for the coolant bypass and heater connections.


THIS
IS
CRAZY.

That area is NOT a "high temp" area, in fact it's about the coolest (lowest-temperature) part of the entire engine. It's about as far below the cylinder head as you can get and not be in the oil pan. It's getting gushed with coolant directly out of the water pump, flowing through the block before geysering up to the cylinder head--which IS the hot part of the engine, especially the middle of the head.

In COMPETITION--not street use--some guys have added coolant hoses to the CYLINDER HEADS between the center two cylinders, where the two exhaust ports are close together. Because the SBC has exhaust valves next to each other on cylinders 4 and 6, and 3 and 5, the middle of the cylinder head runs hotter than the rest of the engine. This is also why the most-common area for head gasket failure is between the middle-two cylinders.

But even most forms of competition don't require external plumbing; the stock cooling system is entirely adequate; and when it isn't, there's internal mods that can be made; primarily by drilling a hole in the block head gasket surface, and in the head gasket. Some blocks/gaskets have these holes already, some don't.

OTOH, using those two block drain holes as OUTLETS, with a hose running from them, up to the cylinder head somewhere between the siamesed exhaust ports--so that additional coolant can bypass the cylinder head gasket and go directly to the hottest part of the engine--has been done for certain COMPETITION engines.

What you're proposing is USELESS. A TOTAL waste of time, money, effort, and enthusiasm.


Yes. But not reverse-flow, or even altered flow aside from the coolant bypass and heater connections.


TYPICALLY, the supply hose is smaller-diameter than the return hose. But NOT ALWAYS.


Unlikely. I'd expect any connection to the intake manifold (front...rear...one side or the other side) would be the heater core supply. A connection to the water pump is probably a return, if it's on the front of the impeller.

But all of that is moot since the entire project is nuts, based on false assumptions.

If you're having an overheating/thermal management problem, the solution is to fix what's faulty, not re-design the cooling system to supply MORE coolant to the COOLEST part of the engine.

Don't get me started on the detrimental effect of removing the knock sensor.

The Factory Service Manuals are available for free download from the links in the Sticky thread section of the Engine forum of this web-site.

For competition engines like older Nascar 18* engines it was common to plumb AN lines from the pump to the block drains to help distribute coolant flow evenly to the rear cylinders. The coolant has to flow around the jugs to get to the back of the engine and it has heated substantially by the time it rearches the rear cylinders. They are used in combination with the rear coolant outlet fittings on the manifold.

 

[df2x4]

I have found 2 sources of 1996-1999 C/K Factory Repair manuals, the cheapest was $249. Thought this forum might have info in brain trust for less.

They're available to download here for free.

https://www.gmt400.com/threads/88-98-service-manuals.43575/

If you don't see the year you need in the first post keep scrolling, other members have added to the collection over time.

 

[dtrader]

I appreciate the info, I have downloaded the manuals, spot on help Shurkey with tech info.

My surprise on this is posters assumptions of what I am doing, why and for what application.......

I understand that you can't post an encyclopedia on a project, this post was a small part of a much bigger project, looking for knowledge base input to speed process.

I think it would be great if replies could stay in a respondents wheelhouse. I never mentioned I had an overheating problem or why the knock sensor is being removed. Interesting to hear the factory puts the knock sensor, to detect pre-ignition, in "the coolest (lowest-temperature) part of the entire engine".

A point of matter, I have used a temp gauge in every coolant boss available on an L31 production block and production Vortec heads. The results are empirical.

Thanks again all for help/info.

James

 

[L31MaxExpress]

The newer method is supply the head with added coolant below the siamese exhaust ports. Felpro 1003 head gaskets I have on my 383 are re-designed for additional cooling in that area as are others.

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[L31MaxExpress]

On a Vortec pump, both smaller fittings on top are suction ports. For some reason GM used 3/4" as the heater core supply and 5/8" as the return on these trucks.

 

[Schurkey]

Interesting to hear the factory puts the knock sensor, to detect pre-ignition, in "the coolest (lowest-temperature) part of the entire engine".

It's a knock sensor, not a temperature sensor. Vibration--the result of detonation pressure-spikes ringing the combustion chamber(s) like a bell (heard all the way in the passenger compartment as "Ping" or "Knock")--travels very nicely through iron.

And...GM being GM...the hole was already there, unused and plugged.

A point of matter, I have used a temp gauge in every coolant boss available on an L31 production block and production Vortec heads. The results are empirical.

Infrared thermometers are notoriously inaccurate. Aside from largely being cheap Chinese, there's also the emissivity of paint to contend with.

The newer method is supply the head with added coolant below the siamese exhaust ports.

I looked all over the Internet for a photo of that. I guess I wasn't using the right keywords. I read about this years if not decades ago, in the Chevy Power book, 8th Edition.
www.amazon.com/Chevrolet-Power-Prepare-Engines-Performance/dp/1557880875/ref=sr_1_1?

Water pump pressure side drilled for outlets, leading to the "siamesed" exhaust ports, adding coolant that doesn't have to squeeze through holes in the block/head gasket/cylinder head. I've also seen photos of the hoses leading from the block drains, where the cool coolant from the block is re-routed to the hot cylinder head, bypassing the head gasket.

But again...there's mods to the block deck and gasket that can also improve coolant flow there.