so i have the brand new gm L31 engine in my 1987 truck with a edelbrock rpm intake with the 1988-95 style water pump for reverse rotation for serp belt . my heater core feed is intake front right / return rad pass tank top nipple . i have a 195*t-stat with a pin hole drilled in it for burping air as the t-stat with the dingle thingy was 20 bucks more no thanks . rad is a 3 core copper/brass unit for 1981-1991 square body with hd cooling . has a factory shroud on with factory hd fan with thremo clutch that works good .
truck runs 195*-200* all day no problems . tons of winter time heat in the cab no problem . no leaks on the floor from bad heater core .
i was smelling coolant and have checked it 3-4 times no leaks . no loss of coolant . overflow jug is spot on cold line cold and up a inch or so from cold when up to temp.
i notice a growling almost low decibel air horn sound when the t-stat has opened and then i smell coolant . it looks like the system is pushing out the rad cap and in to the overflow tank and sucking it back in . but when i pushes it in the overflow i am getting the hot coolant smell in the cab .
as i said i have not lost any coolant / the rad is to the tip top / overflow working as it should receive and give back .
is there something i missed or did wrong on the system i put together ? or do i just have a super weird weak pressure cap (16psi ) ? or do i need to pull a little coolant from the rad and give a small air bladder of room to keep it from pushing in/out all the time ?
------
update : so i still get the weird noise and coolant smell . i stopped and got a fresh bottle of block test fluid from napa since my old bottle went bad . i tested the system warm and not 1 bubble up threw and fluid never changed color .
so i called the dealer i got the engine from and he gave me the gm tech line # to call . so i called and talked with a guy and he was a fellow square body gm truck owner so he knew just was i was describing .
i told him i have supply for heater core from intake to core then return from core to upper nipple on rad tank .
he said that's fine for the older stuff NON vortec head engines . but the way the vortec heads flow water inside its starting to boil the coolant and form gas / air bubbles and this is were i am getting the sound from when i bypasses the rad cap and in to the overflow .
he said try this and it should fix my problem . hook the nipple to the h2o pump top port and feed the heater core . then return the heater core to the intake crossover port .
so i guess i will drain some fluid off and re-route my lines and give this a try unless this dosn't make since to you guys .
i told him i had it hooked up the way my old tbi engine was basically plumbed and he said nope the vortec head flow a bit different .
--------
so dumped the coolant down below the h20 pump level and flipped the hoses around like the GM corp tech guy said to do .
added a 1/2" pipe thread to 3/4" hose nipple to the h2o pump top port location.
then the 3/4" hose to heater core.
5/8" hose out of heater core to 1/2" pipe thread 5/8" hose nipple on intake front right corner.
then i filled / burped / topped off the system for around 15min and a few t-stat cycles.
i noticed before the test drive a lot less micro size bubbles in the rad tank with the cap off. i also still had lots of heat maybe even a bit faster ? ?
road test i smelled a few hints of coolant but i figure its some i didn't get rinsed off and maybe a few air bubbles working there way out of the system. i spent prob around 20 min driving it the normal way it would do its noise and massive smell before with i would say about perfect results. time will tell if this has fixed it as i still need to get the engine bay dry and no extra coolant on stuff from the work i did .
will report back in a few days with the status of the fix. . . .
---------
well the truck has sat for 2 days out in the cold . its 27* out today .
i fired it up and took it out for a trip to the local quicky mart store 3 blocks away . i left it running when in the store for 2 min time . drove the truck home and left it run another min or 2 and when i shut down the truck i was at around 120*F temp range on the digital temp of the efi unit .
few hr's later i go out side and walk past the truck and spot coolant on the ground under heater core area ? ? ? pop the hood and i have no coolant in the jug / rad full and dead cold / coolant has leaked past the heater core 5/8" hose at the core & the radiator hoses all points and i even have a puddle on the intake just off the side of the t-stat hose area .
this was fresh from todays run as the truck is now backed in the same spot and fluid all coming from were it is now .
i think i have a big cooling system problem ! ! !
i cant win with this dam thing .
truck runs 195*-200* all day no problems . tons of winter time heat in the cab no problem . no leaks on the floor from bad heater core .
i was smelling coolant and have checked it 3-4 times no leaks . no loss of coolant . overflow jug is spot on cold line cold and up a inch or so from cold when up to temp.
i notice a growling almost low decibel air horn sound when the t-stat has opened and then i smell coolant . it looks like the system is pushing out the rad cap and in to the overflow tank and sucking it back in . but when i pushes it in the overflow i am getting the hot coolant smell in the cab .
as i said i have not lost any coolant / the rad is to the tip top / overflow working as it should receive and give back .
is there something i missed or did wrong on the system i put together ? or do i just have a super weird weak pressure cap (16psi ) ? or do i need to pull a little coolant from the rad and give a small air bladder of room to keep it from pushing in/out all the time ?
------
update : so i still get the weird noise and coolant smell . i stopped and got a fresh bottle of block test fluid from napa since my old bottle went bad . i tested the system warm and not 1 bubble up threw and fluid never changed color .
so i called the dealer i got the engine from and he gave me the gm tech line # to call . so i called and talked with a guy and he was a fellow square body gm truck owner so he knew just was i was describing .
i told him i have supply for heater core from intake to core then return from core to upper nipple on rad tank .
he said that's fine for the older stuff NON vortec head engines . but the way the vortec heads flow water inside its starting to boil the coolant and form gas / air bubbles and this is were i am getting the sound from when i bypasses the rad cap and in to the overflow .
he said try this and it should fix my problem . hook the nipple to the h2o pump top port and feed the heater core . then return the heater core to the intake crossover port .
so i guess i will drain some fluid off and re-route my lines and give this a try unless this dosn't make since to you guys .
i told him i had it hooked up the way my old tbi engine was basically plumbed and he said nope the vortec head flow a bit different .
--------
so dumped the coolant down below the h20 pump level and flipped the hoses around like the GM corp tech guy said to do .
added a 1/2" pipe thread to 3/4" hose nipple to the h2o pump top port location.
then the 3/4" hose to heater core.
5/8" hose out of heater core to 1/2" pipe thread 5/8" hose nipple on intake front right corner.
then i filled / burped / topped off the system for around 15min and a few t-stat cycles.
i noticed before the test drive a lot less micro size bubbles in the rad tank with the cap off. i also still had lots of heat maybe even a bit faster ? ?
road test i smelled a few hints of coolant but i figure its some i didn't get rinsed off and maybe a few air bubbles working there way out of the system. i spent prob around 20 min driving it the normal way it would do its noise and massive smell before with i would say about perfect results. time will tell if this has fixed it as i still need to get the engine bay dry and no extra coolant on stuff from the work i did .
will report back in a few days with the status of the fix. . . .
---------
well the truck has sat for 2 days out in the cold . its 27* out today .
i fired it up and took it out for a trip to the local quicky mart store 3 blocks away . i left it running when in the store for 2 min time . drove the truck home and left it run another min or 2 and when i shut down the truck i was at around 120*F temp range on the digital temp of the efi unit .
few hr's later i go out side and walk past the truck and spot coolant on the ground under heater core area ? ? ? pop the hood and i have no coolant in the jug / rad full and dead cold / coolant has leaked past the heater core 5/8" hose at the core & the radiator hoses all points and i even have a puddle on the intake just off the side of the t-stat hose area .
this was fresh from todays run as the truck is now backed in the same spot and fluid all coming from were it is now .
i think i have a big cooling system problem ! ! !
i cant win with this dam thing .
