Cooling problem...any ideas?

[73z-6sp]

Im a little baffled by my problem. I suspect it is the way I have my heater hoses connected but not sure. I am going to change it and see. I have the GM serpentine set up, Be Cool radiator and mark VIII fan. Everything is new. The water doesnt seem to be circulating at all and the temps are spiking. Im not sure how long this has been going on because the gauge was not working initially. I have driven the car only a few miles but it has had a lot of garage run time. It never seemed to be overheating is the strange part. But now I can see that something is wrong.

The pump is the reverse rotation pump. It had a plug on the top which is where I connected the return heater hose. I suspect that having that hose connected there is preventing it from pulling from the radiator? Im not sure about that. I replaced the thermostat and pump yesterday. Same thing. So tomorrow I will remove the heater hose. But I dont know how to connect it. The one hose connects to the manifold as normal but the other hose...where should it go? Does it need to dump back into the radiator? Can I make a small hard inline connection to the lower radiator hose or does it need to be in the upper radiator hose?

[Texas Hotrod]

Old cooling systems circulated by-pass coolant back into the (suction side) radiator tank.
New designs circulate coolant internally and don't have a by-pass dump system. It's critical for new engines to reach operating temps quickly (within a few minutes) because of stricter federal smog laws. Either system won't circulate coolant through the radiator unless the t'stat is open.

I usually drill a 1/8" hole into a thermostat before I install it. That allows a place for air to escape and makes a goofy (hot/low spikes) thermostat stable.

My Dodge diesel would heat up then cool down several times at highway speeds before it would finally stabilize. I got tired of it and fixed the problem by drilling a bleed hole in it. Problem solved.

[73z-6sp]

I am having the toughest time figuring this out. I drilled the hole like you suggested just to eliminate that problem. I replaced the thermostat and the waterpump. I've checked belt positioning atleast a dozen times. I had my radiator checked today and the shop says there is no way that is my problem. I am running out of ideas. My biggest fear is that there is some restriction in the block. I dont know how to confirm or eliminate that idea. Has anyone ever heard of sucha thing? Its a new crate motor.

The sad part of this is that it is just par for the course with this engine. It has been a nightmare for me since day one. I cant understand how I can have so many problems from one engine. FWIW...I am an idiot. Man...I am just sick of it!

[baskin]

Confirming a restriction should be pretty easy, my guess is that you're tapping the heater input off of the intake manifold, so if the heater is working, then the water is flowing through the block.

At low rpm, the water pump doesn't flow much and so the water will take the path of lowest resistance, which generally corresponds to the height that it has to pump the water to, if the heater inlet from the engine is lower than the radiator inlet, it will move the water through the heater and it's for that reason that there is usually a flow restrictor either integral to the heater core or as a separate piece that limits the flow of water through the heater core.

A second possibility is that the radiator cap is bad, the cap will have two pressure valves, a positive pressure valve that limits the radiator pressure to typically 14 psi, and a negative pressure valve that allows coolant back into the radiator as the average temperature of the coolant drops. If the second valve is plugged, the pressure of the coolant will drop below ATM, which will cause the coolant to boil at the lowest pressure point, typically the inlet to the water pump. Once the coolant starts to boil, which can be far below 212 degrees, the steam will cause the pump to cavitate, which in turn, will keep the pump from providing any coolant flow

Is the heater core dissipating any heat?


Also, are you positive that you have the correct rotation pump? The vanes should point away from the direction of rotation

[camcojb]

one last thought, how did you fill the system? This is real common if you just fill it through the radiator and end up with a huge air pocket at the top of the engine. I always remove the thermostat and fill the block full first, then re-attach the housing and finish filling through the radiator.

The holes in the thermostat should help bleed the air, but may take too long if the water level is real low in the block itself.

Jody

[HILROD]

A friend of mine had what sounds like the same problem. His waterpump was a standard rotation with a serpentine set-up. You said you changed it. what was the application the new one came from? Can you check it against a known good pump?

[6'9"Witha69]

Here is a common issue. The old lower hose (suction side) had a winding in it to prevent being sucked closed. Does the upper line have this now? If not it will cause issues while driving. Do you have a block off valve in you pressre line to the heater?

[73z-6sp]

Thanks for the replies. At first I had the heater connected. It would dissipate heat there but not proportional to the heat of the water...or atleast in my mind. The hoses were extremely hot though. I thought maybe the connection of the return line to the water pump may be bleeding pressure off and not letting the water flow so I disconnected the heater all together. No change.

I am certain I have the correct pump though I have not removed the cover plate from the new one to check it. The serpentine set-up is the one GM sells. It came with a new pump which is the original one I had on the car.

You are right, that is how I filled the water. I was hoping that the hole would eliminate that possibilty. I am going to remove the thermostat all together and remove the inlet hose from the radiator just to see what happens.

The lower hose does not have any windings in it. I thought about that too. I see no collapsing when its in the garage running it...but that doesnt mean it doesnt collapse during driving. The problem occurs even sitting in the garage idling. So I dont think that is my main problem.

The heater/ac is a vintage air setup with the inline valve to control the water to the heater core. I opened it (i.e. turned on the heat) to see if it blew hot air and to let any air escape.

Thanks again for the ideas.

[camcojb]

Thanks for the replies. At first I had the heater connected. It would dissipate heat there but not proportional to the heat of the water...or atleast in my mind. The hoses were extremely hot though. I thought maybe the connection of the return line to the water pump may be bleeding pressure off and not letting the water flow so I disconnected the heater all together. No change.

I am certain I have the correct pump though I have not removed the cover plate from the new one to check it. The serpentine set-up is the one GM sells. It came with a new pump which is the original one I had on the car.

You are right, that is how I filled the water. I was hoping that the hole would eliminate that possibilty. I am going to remove the thermostat all together and remove the inlet hose from the radiator just to see what happens.

The lower hose does not have any windings in it. I thought about that too. I see no collapsing when its in the garage running it...but that doesnt mean it doesnt collapse during driving. The problem occurs even sitting in the garage idling. So I dont think that is my main problem.

The heater/ac is a vintage air setup with the inline valve to control the water to the heater core. I opened it (i.e. turned on the heat) to see if it blew hot air and to let any air escape.

Thanks again for the ideas.

I bet when you fill the block first completely and then top off the radiator your problems disappear.

Jody

[73z-6sp]

I bet when you fill the block first completely and then top off the radiator your problems disappear.

Jody

How much are we talking here? 5 bucks? 10? More? I cant afford too much so...But hey...if you are ever in Tucson and need something or want a cold "Kool Aid" let me know.

You were right Jody. I took the thermostat out, left the t-stat housing off and filled it from the radiator until the water level reached the t-stat opening. Put it all back together minus a t-stat and the water flows like no tomorrow! I hope it will continue to do that once I install a t-stat. Are those super stats worth installing or just a normal t-stat. The gauge never reached 150 without the t-stat!

Jody...you're a dang genius!

Know anything about fuel injection?

[camcojb]

How much are we talking here? 5 bucks? 10? More? I cant afford too much so...But hey...if you are ever in Tucson and need something or want a cold "Kool Aid" let me know.

You were right Jody. I took the thermostat out, left the t-stat housing off and filled it from the radiator until the water level reached the t-stat opening. Put it all back together minus a t-stat and the water flows like no tomorrow! I hope it will continue to do that once I install a t-stat. Are those super stats worth installing or just a normal t-stat. The gauge never reached 150 without the t-stat!

Jody...you're a dang genius!

Know anything about fuel injection?

Not a genius, but been around the block a time or two. Glad it worked, it's a pretty common mistake.

Everything I build and tune is EFI, what do you want to know?

Jody

[73z-6sp]

Well...today I finished flushing the system and installed another thermostat. 180 degree. Same thing...filled it until the intake was full, then installed the thermostat and housing then hose. Filled it some more. Started it. Ran it for 20 minutes in the garage. temp hovered around 150 according to gauge. Thermostat still not open as the flow was nill. I did drill two small holes in the thermostat. I tried running it at a higher rpm and next thing I know the temp gauge jumps to 240 and the water overflows the cap. The water never did begin to flow through the radiator like it did without the thermostat. How in the world can three thermostats be bad? The first two I even boiled in water to be sure they opened and they did completely. Any more ideas? Do I just go without a thermostat? All I have ever heard is not to do that.

Thanks,

Aaron

[6'9"Witha69]

This is a long shot, but do the reverse rotation pumps need a different tstat, one that was meant to flow better the other direction?

[73z-6sp]

I dont think they do. I did not have to use anything different in my 73 with this same serpentine set-up. It worked perfectly. I have decided to just walk away from it for a while. I havent a clue where to go next anyway and I need to focus on school. I need the break.