Cooling system hoses. Are there any hidden ones?

I have a 95 RMW with HD cooling system & tow package. I've only had it for 2 years now and not needed to do much to it, so don't know all the engine details like my older cars. It seems to be almost all original under the hood so I've been gradually replacing the obvious stuff. Did the opti cap/rotor and water pump recently, and now doing the hoses. They were all swollen and soft.

Learning about the stock green silicone hoses available eventually lead me to buy the Samco silicone hose kit for the Impala. I've already put in the upper and lower radiator hoses, both heater hoses and the thin one from the top front of the engine to the reservoir. BTW these hoses are really nice, I got the matte black to keep it looking stock.

The kit came with 3 more hoses, all in the 5/16ish ID, one is a short 90 degree bend, one a 1' long straight piece that is a little thicker, and one 2' long piece the has a 90 degree bend about 6" from one end.

I couldn't readily find anywhere that these hoses might go. The factory shop manual seems to show a 3rd connection to the reservoir, which my car doesn't seem to have. The manual doesn't have any complete hose diagrams for the different versions of cooling systems.

I think I'm done with this and the parts are extras for different configurations. If anyone knows about something hiding that I might have overlooked the info would be greatly appreciated since 15+ years on a rubber hose is asking for trouble.

On the 94 LT1 cars, there was another small hose that ran from the resevoir to the radiator. After 95 that was deleted.

Bill

Thanks convert2diesel. Part of my question eliminated.

The other part of the question is if there are any little bypass of connector hoses on the engine. Possibly hiding within all of the other vacuum hoses and wire harness parts. Whether along the intake, heads, block, or firewall.

The kit from Samco states that it covers '94-'96 Impalas. I was lucky to find out that the radiator hoses are the same as the Buick HD setup (mechanical fan). I thought that there was a chance that one of the hoses would be different and not fit.

There is one other circuit you might have missed. There is a small (1/4 in) hose that runs from the passenger head to the throttle body and than from the opposite side of the throttle body to the top of the resevoir.

If you live in southern climes, this is not necessary. It serves as an intake heater for winter operation and as a steam vent for the head. You can bypass the throttle body completely and run this line directly to the resevoir. Common mod on these engines.

Bill

convert2diesel wrote:

...If you live in southern climes, this is not necessary...

Bill

I live in the Detroit area, which is high in winter humidity, and I haven't had any throttle body ice ups in several years here with the coolant bypassed.around it. It supposedly gives you a few HP.

Oh yeah, there ain't no hidden hoses. You can see all of the 'flexible' ones. There IS a good quality semi-stainless tube assembly coming out of the back of the heads that feeds the throttle body hose. I mention it because I saw one that was rusted out & had a pinhole. This will only happen here in the rust belt over several winters though.

On an LT engine set-up, since the coolant system is at full pressure, a reducer valve was
added in the coolant lines going to the heater to reduce the pressure in the heater core to 5psi, to prevent a blowout at the heater core.
Some of those hoses may be to allow you to add that replacement valve, since the orginal one came crimped in the middle of the heater feed hose. This is buried on the right side of
the engine. Look for it.

rkmdogs wrote:

On an LT engine set-up, since the coolant system is at full pressure, a reducer valve was
added in the coolant lines going to the heater to reduce the pressure in the heater core to 5psi, to prevent a blowout at the heater core..

Now you being a retired engineer, you,d be a heck of a lot smarter than me,.but,...
where did you get this info??
The figure of 5 psi, how did you arrive at this number ,
I,d really like to learn about this once and for all,. as there is so much MISinformation out there,.
centrifugal pumps are kinda tricky to figure out pressures,. and then you add restrictions in the pipe and it gets harder to understand again,.i know if i put my thumb over the end of the hose the pressure goes up and the water squirts further but has less volume,.jeez i, confused on all this,.
Then there is trying to understand about velocity producing head pressure etc,.

Of course i,m always one of the lucky ones that has left a trail of broken restrictor fittings in the junk pile replaced with straight tubing,. and as is well documented, i run my cars pretty hard and i,ve yet to have a heater blow up,. and i,ve yet to have aheater core clog up either,.something in my bald head tells me that there is mystery afoot here i want to know why i always seem to do things different than the norm yet i don't have problems like others do,.
help me and the other members finally understand please,.

Thanks


Nick

Velocity x Area = a constant

If the area inside of a pipe decreases, the flow through the pipe will increase as it passes through the restriction.

Capacity

The amount of fluid the pump will move is determined mainly by the width of the impeller and the shaft speed.

phantom 309 wrote:

rkmdogs wrote:

On an LT engine set-up, since the coolant system is at full pressure, a reducer valve was
added in the coolant lines going to the heater to reduce the pressure in the heater core to 5psi, to prevent a blowout at the heater core..

where did you get this info??

Right in the FSM! 1995 Caprice, Impala book! I'm looking for the exact page # to give it, but I ran a copy before --- if I can find it in my files!
I also ran it on the V8S10.org forum when using an LT engine.

After a quick look, I only found partial info. GM no longer has the part, but the original replacement is an AC-Delco # 15-5423.
[You must be registered and logged in to see this image.]

.... and here is the factory service manual page:
[You must be registered and logged in to see this image.]

but i don,t see the 5psi figure anywhere,
and is a restrictor fitting considered a valve?
I,m not sure,..

Nick

I went back into my files and.....
This item is called a Coolant Flow Control Valve.
It was GM part# 10157988

The replacement is AC-Delco part # D15 15-5423.
It is available from RMS Auto Parts. Ask for John & tell him th at rkmdogs sent you!
The current price is $12.50 plus shipping.
His toll-free phone number is:1-888-658-4675 x1012

rkmdogs wrote:

I went back into my files and.....
This item is called a Coolant Flow Control Valve.
It was GM part# 10157988

The replacement is AC-Delco part # D15 15-5423.
It is available from RMS Auto Parts. Ask for John & tell him th at rkmdogs sent you!
The current price is $12.50 plus shipping.
His toll-free phone number is:1-888-658-4675 x1012

Nice of you to help with the purchase, and full description etc,.

but i,m still puzzled at how you arrived at the 5psi number?

Nick

phantom 309 wrote:

but i don,t see the 5psi figure anywhere,
and is a restrictor fitting considered a valve?
I,m not sure,..

Nick

Sorry, the manual says 5 gal per minute, which I translated into 5psi.
Read the reason, which is in the highlighted section!

I've been there! ---- and had one blow apart on my 9C1 Caprice!
It was not a pretty mess. Trust me, you want this item in your coolant lines when you are running an LT engine,
with full system pressure!

rkmdogs wrote:

phantom 309 wrote:

but i don,t see the 5psi figure anywhere,
and is a restrictor fitting considered a valve?
I,m not sure,..

Nick

Sorry, the manual says 5 gal per minute, which I translated into 5psi.
Read the reason, which is in the highlighted section!

Oh k,.

well thats a big difference right there,.

maybe just go back and edit your post?? Otherwise it'll turn into interent gospel pretty soon,.and folks will be scared to run there cars without the restrictor in case their heater core explodes up thru the windsheild killing some poor innocent low flying bird,. i,m just saying,.

Nick

Let's just say, it is a condition you don't want to have!
Mine occurred when the coolant pressure valve blew apart, so my dilemma was all inside the engine compartment, fortunately!
If you run WITHOUT this flow control, you are putting a full 15psi on the heater core!
------- since the closed cooling system on an LT engine does not have a pressure cap on
the radiator.

rkmdogs wrote:

Let's just say, it is a condition you don't want to have!
Mine occurred when the coolant pressure valve blew apart, so my dilemma was all inside the engine compartment, fortunately!
If you run WITHOUT this flow control, you are putting a full 15psi on the heater core!
------- since the closed cooling system on an LT engine does not have a pressure cap on
the radiator.

ok i,ve had enough ,. you are so full of **** it hurts,.
i,ve tried to give you a chance, but now you piss me off,. you are totaly wrong,.
You sir are the automotive equivalent of mrs malaprop.

go and learn about centrifugal pumps and pressures and how they work,. velocity VS pressure,. RPM of the engine to flow to pressure yada yada,. whats the pressure at the various different rpms' of the pump,. what rpm does the pump dead head etc,.

your valve blew up like everyones does because it,s a piss poor cheap ass GM made crimped connection,.
and it blew up at the weakest point,.

QUIT spouting bullshit ,.

there is a very knowledgeble fluid dynamics engineer right on this forum, and i,ve been chatting with him,. so out of courtesy to you as a supposed engineer,. i,ve given you ample time to see the error of your ways,. first clue was when you erroneously READ the 5 GALLONS per minute translated to 5 POUNDS pressure,.

now you pick 15 pounds pressure out of the air (or your fucking arse) and it,s because the lt1 has no radiator cap,. really? then just how do they "boil over" and expel fluid and pressure when they do get hot,.

what temp does the 15psi in the cooling system come into play,.right from stone cold? where is the psi? as fluid does not compress ,.atmospheric pressure is irrelevant inside a pipe filled with fluid,.unless it,s full of steam,.

Diplomacy is a waste of damn time,. and folks wonder why my attitude is bad?

NICK
REDNECK ENGINEER
CERTIFIED JB WELDER>

MEH!

This is straight from page 6B-2 of the Factory Service Manual.
Coolant Recovery Reservoir Filler Cap
A plastic pressure-vent cap is used with the coolant recovery reservoir to allow a build up of 103kPa
(15psi) in the cooling system. This pressure raises the boiling point of engine coolant to approximately 125*C(257*F)
at sea level.".....
"The pressure-type cap contains a blow-off (pressure) valve and a vacuum (atmospheric) valve. The pressure valve is
held against its seat by a heavy spring. This spring protects the cooling system by relieving pressure exceeding 103kPa (15psi)!

AND THAT is what the factory engineers had to say about it!!!!!!!

Learn before you speak!

Update!
On the purchase of GM parts at a discount,
RMS Auto Parts has moved from the address I gave previously.
Their new info is:
RMS Autoparts
965 North Walnut Ave.
Suite 500B #235
New Braunfels, TX.
78130
Their new telephone # is: 830-214-0022

You can also contact them by e-mail at:
[You must be registered and logged in to see this link.]

rkmdogs wrote:

This is straight from page 6B-2 of the Factory Service Manual.
Coolant Recovery Reservoir Filler Cap
A plastic pressure-vent cap is used with the coolant recovery reservoir to allow a build up of 103kPa
(15psi) in the cooling system. This pressure raises the boiling point of engine coolant to approximately 125*C(257*F)
at sea level.".....
"The pressure-type cap contains a blow-off (pressure) valve and a vacuum (atmospheric) valve. The pressure valve is
held against its seat by a heavy spring. This spring protects the cooling system by relieving pressure exceeding 103kPa (15psi)!

AND THAT is what the factory engineers had to say about it!!!!!!!

Learn before you speak!

you are on medication right?

whats the difference between a rad cap and the aforementioned cap with a spring,.? wrong color for you?
oh,. sorry your right it,s not actually on the rad,. silly me,.it,s a pressure vent cap,. doh.

I would like to see you take the time to put a PRESSURE gauge in your heater hose, and measure the amount of water pressure at idle, then at 5000rpm,

Perhaps a real world test such as i,ve done in the past to find water leaks,. plug off one side of the heater core and jam shop air in the other side,. should detonate quite dramatically according to you,.

well here's a news flash from the guy who actually gets his hands dirty and learns the the hard way at the school of hard knocks, not from the damn shop manual or the friggin internet,.
the heater cores do not explode at a mere 15psi,. in factthey don't explode at 90-100psi,.
atleastnot the ones i,ve pressure tested,. and i,ve re
verse flushed them with shop air too,. and yes i was dumb enough to have my face in the line of fire as all that sh!t came out,.so we all know i,m not that bright,.

I think you fail to grasp the specifics of how a rad cap works in conjunction with engine HEAT. expansion of air in the reservoir etc, etc,. Another manual reader that fails to grasp the fact that the cooling system does not function like an electrical switch there is no 'on',. then 'off'

I think most car guys have removed a rad cap from a motor that was not real hot,. and it,s a lot less pressure than 15 psi,. i,m just saying,. course there will always be one idiot that tries to remove a rad cap when the motor is still making those 'ticking' noises as its cooling down from a hard run,. then there's likely close to 15psi that rapidly accelerates to much higher psi as steam forms,.

oh sht!! i think i just blew a gasket because my rad cap is screwed on too tight!!

Nick
a hands on car guy.

Yo Nick, I am a very new guy to this forum and I am possibly out of line writting this.
You are a real piece of work,but I have to say that I usually laugh my butt
off at most of your responses. It also appears that most of the guys are good
sports regarding your tirades. I belong to four other automotive type forums
and I have yet to run across another Nick. On a good note, I believe you
help to reduce unnecessary B.S and really make the guys think about what
they are writting. I hope i've not pissed everyone off and that I am still
allowed to post on Longroof. ed

rkmdogs wrote:

I went back into my files and.....
This item is called a Coolant Flow Control Valve.
It was GM part# 10157988

The replacement is AC-Delco part # D15 15-5423.
It is available from RMS Auto Parts. Ask for John & tell him th at rkmdogs sent you!
The current price is $12.50 plus shipping.
His toll-free phone number is:1-888-658-4675 x1012

Hey, thanks for the info, rkmdogs. If you recall, were any of these valves made of metal? I've only seen plastic ones.
Regarding the maximum pressure in the cooling system, the 15 psi system pressure is probably not the big issue with the heater core, but it adds to the pressure the core would see when the pump is revving high. I wonder how much pressure the pump creates at the rev limit? It could be way up there.

jimbeau wrote:

rkmdogs wrote:

I went back into my files and.....
This item is called a Coolant Flow Control Valve.
It was GM part# 10157988

The replacement is AC-Delco part # D15 15-5423.
It is available from RMS Auto Parts. Ask for John & tell him th at rkmdogs sent you!
The current price is $12.50 plus shipping.
His toll-free phone number is:1-888-658-4675 x1012

Hey, thanks for the info, rkmdogs. If you recall, were any of these valves made of metal? I've only seen plastic ones.
Regarding the maximum pressure in the cooling system, the 15 psi system pressure is probably not the big issue with the heater core, but it adds to the pressure the core would see when the pump is revving high. I wonder how much pressure the pump creates at the rev limit? It could be way up there.

I have never seen any in metal. The only metal I have seen at these items is the crimp clamp that the factory used.
If you go to the RMS catalog page, they show the AC-Delco replacement item pic. It is all plastic. My first one blew apart at its seam,
where it is put together after the restrictor is assembled inside. These go in the inlet heater hose with two aircraft-style hose clamps.

My original broke many years ago. It gave me a chance to see the engineering genius in it. It allows full flow through until the flow reaches a point where it pushes the spring. Once the spring is fully compressed, no coolant can flow through the spring coils. The only flow is through the center hole (1/4"? 5/16"?). It works on the same principle as the PCV valve.

jimbeau wrote:

Regarding the maximum pressure in the cooling system, the 15 psi system pressure is probably not the big issue with the heater core, but it adds to the pressure the core would see when the pump is revving high. I wonder how much pressure the pump creates at the rev limit? It could be way up there.

Coolant has the same density hot or cold,. it doesn't get "bigger" as it heats up,.
The"pressure" is contained in the coolant reservoir, as we all know air compresses and coolant doesn't,..
If the coolant is under pressure (it can be pressurised without reducing its's volume,) it does not increase in pressure with heat until steam bubbles are formed while passing over hot metal parts of the engine .
The water pump turns at camshaft speed,.If the impelller cavitates bubbles are formed.
I,ve summized that the restriction is there to stop the waterfall sounds, and to make sure the pump doesn't cavitate and quite pumping, as both in and out heater hoses run directly off the waterpump. which will lead to over heating,.cavition will also prematurely wear the impeller,

As i,ve stated before, i,ve put shop air pressure (over 100 psi) in more than 1 heater core and have never experienced catastrophic failure.

JM2C

Nick

Nick,
Actually, coolant does expand when heated.

From 68F (20C) to 140F (60C), ethylene glycol's volume will expand approximately 2.25% (.00057 unit volume change per degree C).

The density drops from approximately 1.12g/cc at 20C to 1.09 g/cc at 60C

These properties are for ethylene glycol. The exact properties for ethylene glycol/aqueous blends vary based on the proportions of water/ethylene glycol in the blend.

(Physical property data per: [You must be registered and logged in to see this link.])

The expansion of the coolant as it is heated creates pressure in the (closed) cooling system. This pressure is relieved by venting to the overflow reservoir via the pressure relief valve (radiator or reservoir cap).

I don't know anything about the flow controller that is being discussed, but I do know that coolant DOES expand when heated.

Joe,isnt that why your coolant recovery tank has a full cold and a full hot slash on the side?You
put the explanation into print much better than I could have.
Thanks
Jim

you are right,.i thought 2.25% is negligible in myl world,.so i skipped past that part, sorry.I,m as guilty as others of not posting precisely and concisely, and genral statements do cause problems
definitely wrong on the density part oops,. mebbe it,s my density that remains the same hot or cold,.


The hairs have been split here, but the flavour of my posts remains,.that centrifugal lt1 water pumps, do not make enough water velocity to create enough pressure to blow up a heater core,

.i,m trying to show my real world experiences and examples for the interent crowd that loves to expound on half truths until they become dramatic enough to be considered gospel,.

nuff said from me.

Nick

Wow guys!
I did not mean to start a world class disertation on cooling systems, merely
inform some of the forum car owners about a peculiarity in the LT 1 engine systems
if they have that engine in their vehicles!

Next time, I'll just keep it to myself!!!!

Rkmdogs, Please dont keep it to yourself,this is how we learn and become
more knowledgable about our hobby. What some people call frivolous others
call necessary or important. Possibly we dont need to know every detail,however
in some situations it helps give us understanding. ed

Flasheroo wrote:

Joe,isnt that why your coolant recovery tank has a full cold and a full hot slash on the side?You
put the explanation into print much better than I could have.
Thanks
Jim

Yes, that is why there are Hot and Cold level indicators on the recovery tank.

JoeT wrote:

Flasheroo wrote:

Joe,isnt that why your coolant recovery tank has a full cold and a full hot slash on the side?You
put the explanation into print much better than I could have.
Thanks
Jim

Yes, that is why there are Hot and Cold level indicators on the recovery tank.

The coolant in the "closed" part of the system (rad/pump/heater core/block/heads/hoses) expands as it absorbs heat from the engine. The pressure relief valve (pressure cap) limits the pressure increase to (typically) 15 or 16 psi above atmospheric pressure. When that pressure is exceeded, the cap releases small amounts of hot coolant to the expansion reservoir until the pressure in the closed portion of the system drops back to the cap's pressure rating. (I don't know the specifics of the LT1 cooling system design; this is assuming that the pressure cap is on the closed portion of the system and that the cap on the recovery tank is vented to atmospheric pressure)

The coolant shrinks as it cools, taking up less space in the radiator and reducing the pressure in the "closed" portion of the system. The ambient pressure acting on the coolant in the recovery tank forces the coolant back into the radiator to bring the system pressure back to atmospheric pressure. The shrinking coolant reduces the pressure in the closed system, which is filled by the coolant returning from the expansion reservoir.

The pressure relief (radiator) cap has both a pressure relief function and a vacuum function built into the cap design to allow the coolant to move in both directions as needed.

That's how the coolant level in the recovery tank increases when the coolant is hot and decreases when the coolant is cold.

Joe your info is not correct for lt1 reverse cooled engines. You need to read about the steam tubes,. the water flow for an lt1 etc,. the reservoir is also the expansion tank on b-bodys, no rad cap.
maybe i missed it somewhere, but do you have an lt1 car? or have you experience working on them?

Nick

Oops...sorry about that.

Nick;
No, I am not an LT1 owner, nor have I ever spent any time on them. That's why I included this statement in my previous post:

"(I don't know the specifics of the LT1 cooling system design; this is assuming that the pressure cap is on the closed portion of the system and that the cap on the recovery tank is vented to atmospheric pressure)"

I'll go back and modify my post...I shouldn't have included all that common stuff in an LT1 thread.
Joe

Each pound of pressure that a cap has, adds ~3 degrees to the boiling point of the system. So, a 15 psi cap will add ~ 45 degrees to it, which means that unless the system gets hotter than 212 + 45, or 257 degrees, nothing boils. The whole point of having a pressurized system is to allow the manufacturer to downsize the cooling system as a whole. The system on today's cars is good enough that unless you are in Death Valley, you aren't going to lose any coolant. The reason for the 'partial fill' of the expansion area is to allow the expansion of the coolant from ambient to operating temperature (and above) without pushing raw coolant out of the pressure cap.