Coolant Flow

[rebelyell]

I think I have a cooling problem. First thing I noticed was that my temp gage in the car stays on low until it randomly decides to chill in the middle, then keep going up. Sometimes I can coast in neutral, turn the motor off and turn it back on after a minute and it's back to the lower side. Sometimes I have to sit on the side of the road for a few (only happened once). A few weeks ago when I replaced the fan clutch, I pulled the radiator cap and let the car idle for a while. Didn't see ANY coolant movement aside from a gurgle here and there. Made a mental note of it and figured that the thermostat must be sticking. No problem. Replaced the thermostat today (finished stripping a bolt a previous owner left me with ) and let it idle up to temp again. No coolant movement.

Should I be able to see the coolant move in the radiator? In my Dakota, it looks like a river running in the radiator when the thermostat opens. I'm new to big block Mopar, so maybe it's normal behavior. 

Other relevant information: aluminum radiator gets too hot to touch on top and the clutch fan never "turns off." It's one of the temp controlled ones so I know it's supposed to. I'm also using a fan shroud with the fan in the correct position. It's pulling a lot of air through the radiator. 413RB motor with a 440 intake that needs a new gasket.

Do I have a problem?

[Chryco Psycho]

I think you have a problem  , what shape is the rad in , maybe pull it & flush it out , using  spring inside the lower hose will prevent it collapsing but that is generally at higher RPM

[Cuda Cody]

Yes, it sounds like you have a problem.  Do you have the thermostat in correctly?

[rebelyell]

As far as I know, the radiator is in good shape. I've only had the car since memorial day. It handled a 1000 mile road trip pretty well.

Thermostat is in correctly with the cylinder inside the intake.

The only thing I know to do is flush the radiator (with a hose??) and replace the water pump...which I could do when I have the intake manifold off.

[Marc70challenger]

Process of elimination.

Are you sure WP (and or flow through block) is functioning properly?  Remove thermostat and pull rad cap. What is flow like?

Are you sure your gauge is reading properly?  If you don't get a laser temp reader and test it on intake outlet, heads. Etc. they are great to have anyway.   I would bet since the thermostat controlling the fan is engaged that you are running warm.  But it may not be "over heating"


Can you find any repeatable  circumstances as well when it over heats? 

[lulurocks(Ken)]

It may not apply but just a thought:

Did the previous owner put a high flow pump and a standard stat?  The increased volume can cause fluctuation   issues .  They make high flow stats to match the pump.

Again just a thought .. May not apply

[Marc70challenger]

It may not apply but just a thought:

Did the previous owner put a high flow pump and a standard stat?  The increased volume can cause fluctuation   issues .  They make high flow stats to match the pump.

Again just a thought .. May not apply

Good point.

[HP_Cuda]

First start by finding out what temp thermostat you have installed.

Next, warm the car up without the cap and put a thermometer in to see if it opens correctly and you have flow.

Lastly, you may have to take your radiator in to get cleaned out if it's blocked.

[Cuda Cody]

Here's a thought.... you could drain the coolant.  Start the car with the radiator cap off and have a hose running in to the radiator.  While the car is running with the radiator drain open, you will see the water run clear out the bottom.  Once the thermostat opens it should flush the coolant out of the engine and you'll see the color change.  Close it off before a bunch of coolant flushes on the ground, but that might tell you for sure if the thermostat is opening and coolant is getting in the engine.   

[rebelyell]

To answer some questions.. No, I'm not sure anything is functioning properly. The previous owner stripped the thermostat housing bolt and painted the outside of the housing with sealant to cover it up. I'm assuming it's a standard water pump because it's painted the same orange as the rest of the motor.

The gage could be screwed up too. I bought a different temp gage which I haven't installed yet because 1) I don't know where the new sensor goes and 2) I don't have any wire to run it to the gage.

It had a 160 degree thermostat, I put in a 180 and got the same result as before. I have not pulled the thermostat and run it to see what the flow looks like. I've got no problem pulling the radiator and flushing it out, but I have no idea how to do that other than sticking a hose in it.

When I get the tstat housing tapped for the new bolt, I'll start it up and get some temp readings with the laser thermometer. That radiator top get HOT.


I think my next step is to drain the coolant, replace the intake/valve cover gaskets, and then test all this.

I appreciate all the suggestions.

[Burdar]

Sometimes I can coast in neutral, turn the motor off and turn it back on after a minute and it's back to the lower side.

This has me questioning if you have a cooling problem at all.  This sounds like a gauge or temp sender/wiring problem. 

What temp thermostat did you put in the car?
Did you drill a small hole in the stat to eliminate any air pockets?(some stats already have a built-in vent)
What water pump is on the car? Stock cast iron or aftermarket aluminum?
What water pump housing is on the car? Stock cast iron or aftermarket aluminum? If aluminum, who's is it?(MP, 440 source?)

What I would do is go to the parts store and buy a cheap mechanical temp gauge.  Install it in the intake and bypass the stock temp sender/wiring/gauge.  This is just temporary so you know you are getting an accurate temp reading from the engine.  Buy a cheap laser temp gun from Harbor Freight.  It doesn't have to be 100% accurate.  With the engine warmed up, start taking temp readings at different places along the face of the radiator.  Is one area cool while another area is hot?  This would indicate plugged tubes in the rad. 

The first thing to do IMO, is to get an accurate temp gauge hooked up to verify you actually have a problem. 

The gage could be screwed up too. I bought a different temp gage which I haven't installed yet because 1) I don't know where the new sensor goes and 2) I don't have any wire to run it to the gage.

I would use a mechanical gauge to do your testing.  They are historically more accurate than an electric gauge.  You don't need any wire.  The mechanical gauge has a probe built-in that goes into the intake.  The kit usually comes with a few adapters so it will fit a wide range of engines.  Just pick the adapter you need, thread it into the water pump housing and then install the gauge probe.

[rebelyell]

This has me questioning if you have a cooling problem at all.  This sounds like a gauge or temp sender/wiring problem. 

I thought so too until I let it idle with the cap off and didn't see any coolant movement. The top of the alum radiator gets scalding hot and I don't think that's normal.

What temp thermostat did you put in the car?

180

Did you drill a small hole in the stat to eliminate any air pockets?(some stats already have a built-in vent)

No, but I can check. After filling it up with coolant, I usually run it until the thermostat opens to watch the coolant flow and to bleed out any air. Never heard of drilling a hole in it.

What water pump is on the car? Stock cast iron or aftermarket aluminum?
What water pump housing is on the car? Stock cast iron or aftermarket aluminum? If aluminum, who's is it?(MP, 440 source?)

I'm assuming both are stock to whatever car this motor came out of. Didn't even know you could split the two, ha.

With the engine warmed up, start taking temp readings at different places along the face of the radiator.  Is one area cool while another area is hot?  This would indicate plugged tubes in the rad. 

The first thing to do IMO, is to get an accurate temp gauge hooked up to verify you actually have a problem. 

I didn't think about getting temp readings on each area of the radiator. I can do that pretty easily with the laser thermometer. Probably pick up a mech temp gage this weekend. Good idea. Thanks.

[Burdar]

There was an issue at one time with 440 Source water pumps and housings.  The internal passages of the aluminum housings were a lot smaller then a stock piece.  Lots of people had cooling issues.  I THINK, the problem was actually traced back to the pumps themselves and not actually the housing.  However, if you have the option, I think it's probably best to stay away from one of those old 440 Source housings.(they may have corrected the problem by now)

By drilling a small hole(1/16" works fine)in the thermostat, air doesn't get trapped underneath while you are filling the system.  The hole is small enough not to affect the function and allows you to fully fill the system without having to watch the coolant level with the cap off/engine running. Some more expensive thermostats already have this feature.

[Chryco Psycho]

If you pull the rad & stick a hose in the upper hose inlet the water should be coming out the bottom as fast as it goes in , if the rad starts to fill up the core is blocked , any rad shop should be able to clean it & test it  or you can flush it at a car wash using the pressure hose to blow it through

[HP_Cuda]

Darren

I have a 440 source housing and have no problems but I cannot seem to give away my 440 source water pump. As for the housings I think they worked it out.

B