What do you think of my cheap dual thermostat setup

[welpro222]

Hey guys, thought I would post this up and show you my idea for a cheap alternative to the 6.5 dual thermostat setup. Now from the beginning, I already had a crossover from a newer 6.2 diesel truck that has a port for the temp switch or sensor, but these can be source online or even adapt the hose to the bypass. I removed the sensor and installed a 5/8 hose nipple and ran 5/8 heater hose to a heater control valve ($15 from autozone) and is controlled by a generic throttle control knob mounted in cab. From there is runs into the upper radiator hose with hose adapter ($2.99 from autozone). Now, I'm not sure if this would make any different with a standard flow water pump. I installed a penninsular diesel 110gpm water pump and am just finishing up installing a bank turbo system too. I'll update this post with result in the next few days.



My reason for installing this setup is because I have a lifted suburban with the same setup but with the stock cooling system (4 row rad) and experience it getting hot (not overheating) going over the mountain passes. I plan on hauling my camper with this truck, so I want to make sure it stays cool.

 

[Drock]

How exactly does this help cooling? It seems to me your simply bypassing the thermostat?

 

[welpro222]

Same way the dual thermostat system works, but i'm in control of the second thermostat. I believe in the dual thermostat system, one stat is 180 and one is 195. So if i'm hitting a long hill and the temp begins to climb, I can pull the cable knob in the cab and let more coolant flow to radiator until temp level goes back down to normal. It will remain closed until needed.

 

[Ilikemtb999]

Seems overly complicated for something that shouldn't be an issue. I have a hard time getting mine to temp, even in summer it's still under 200* on steep hills and full boost.

 

[welpro222]

My suburban is on 1 ton axles with a 4 inch lift and 37 humvee tires, hauling a load of camping/hunting gear too.

 

[rustystud]

My suburban is on 1 ton axles with a 4 inch lift and 37 humvee tires, hauling a load of camping/hunting gear too.

I towed my trailer over the pass (I90) two weeks ago when the temperatures where in the high 80's and the engine never went over 200 degrees. That was when we where creeping up the pass due to an accident at the top of the pass. It took us two hours to get to the top and I saw several newer trucks on the side of the road due to over heating. Yes I took my 6.2 out and installed a 383 Hi-Torque engine in it's place but that just means it should have been even more susceptible to overheating. With our massive 4 core radiators it takes a lot to get any engine to over heat.

 

[Ilikemtb999]

My suburban is on 1 ton axles with a 4 inch lift and 37 humvee tires, hauling a load of camping/hunting gear too.

And my m1009 is on 1 tons with 35" tires and a 2" lift and frequently gets weighed down with gear going to 10k+ feet.


You've got other issues

 

[MarcusOReallyus]

Somebody does not understand basic cooling systems. A lower temp thermostat will not keep an engine cooler (unless all you do is short runs), it will just make it take longer to get to operating temperature.

A properly sized thermostat (and its associated passages) will allow plenty of coolant to flow. If you are not getting cool enough, look elsewhere for the solution.

Some places to get extra cooling:

1. FIX THE BASICS. Make sure your fan clutch, belts, water pump, are all doing their jobs correctly. Water pumps can have their vanes eroded down to nubs. They don't work very well that way. Flush the crud out. (Use a quarter cup of Amway laundry detergent in there. Run it for a month. It works wonders. No, I don't sell it. Find a dealer online. Some folks say Dawn dishwashing liquid does the same.)
2. Did you do #1? Make sure you do #1. Fix the basics.
3. Install a good external cooler for your transmission and plumb it BEFORE the stock radiator cooler. This will move heat from the transmission fluid to the air BEFORE it gets dumped into your radiator.
4. Install a good external cooler for your engine oil and plumb it BEFORE the stock radiator cooler. This will move heat from the engine oil to the air BEFORE it gets dumped into your radiator.
5. Install a bigger radiator. (By the way, "more rows means more cooling" is FALSE. There is FAR more to a radiator's design than just the number of rows.)

 

[gimpyrobb]

Somebody does not understand basic cooling systems. A lower temp thermostat will not keep an engine cooler (unless all you do is short runs), it will just make it take longer to get to operating temperature.

A properly sized thermostat (and its associated passages) will allow plenty of coolant to flow. If you are not getting cool enough, look elsewhere for the solution.

Some places to get extra cooling:

1. FIX THE BASICS. Make sure your fan clutch, belts, water pump, are all doing their jobs correctly. Water pumps can have their vanes eroded down to nubs. They don't work very well that way. Flush the crud out. (Use a quarter cup of Amway laundry detergent in there. Run it for a month. It works wonders. No, I don't sell it. Find a dealer online. Some folks say Dawn dishwashing liquid does the same.)
2. Did you do #1? Make sure you do #1. Fix the basics.
3. Install a good external cooler for your transmission and plumb it BEFORE the stock radiator cooler. This will move heat from the transmission fluid to the air BEFORE it gets dumped into your radiator.
4. Install a good external cooler for your engine oil and plumb it BEFORE the stock radiator cooler. This will move heat from the engine oil to the air BEFORE it gets dumped into your radiator.
5. Install a bigger radiator. (By the way, "more rows means more cooling" is FALSE. There is FAR more to a radiator's design than just the number of rows.)

NO NOT DAWN, Cascade. You want a soap that has a low amount of suds so it doesn't foam up.

 

[welpro222]

Ok, well my suburban does have a aftermarket temp gauge with the sensor mounted in the crossover pipe right next to the thermostat. Would this give it a higher reading, rather then the stock location next to the #1 cyl? Also what was the purpose of GM changing to a dual thermostat and HO waterpump in 1996? I was not trying to coverup any problems my cooling system might have, just trying to duplicate the dual thermostat system.

This truck has a rebuild 4 core radiator, new 190 degree robertshaw thermostat, fresh 50/50 green stuff, pennisular HO waterpump, and nice big plate style tranny cooler.

 

[Kaiser67M715]

Gm went to a dual thermostat and HO pump to combat higher temps in the rear two cylinders. The setup did work, although there is some debate as to if the dual thermostat setup was really needed; most see an improvement with just the HO pump, but there are those that say without the dual setup you risk cavitation issues at high rpm.

And the dual thermostat had two of the same degree stats, although the actual temp rating did change based on EGR stuff, one tons (no egr) got a 190, egr trucks got a 195, don't ask me why, or if this is true for only a couple years, but that is what I found out for 97 year trucks.

On the other side, if you pass the coolant through the radiator too fast, it won't cool down enough, and that will create heat issues as well-a thermostat even fully open still blocks a significant portion of the outlet, thus limiting flow.

Have you made sure the radiator isn't plugged?
EDIT: just saw you had a rebuilt radiator. Is the HO pump for serpentine of not? That will definitely affect cooling.

Sent from my iPhone using Tapatalk

 

[welpro222]

The penninsular HO pump was made for standard rotation v-belt setup, its rated at 110 gpm vs 140gpm with the 6.5 HO pump so I would not be risking cavitation. So with the dual thermostats, wouldn't it flow to much to fast? I have heard of 6.5 engine builders that run just a single thermostat on performance builds.

 

[welpro222]

I'll just play with it and see what happens, if it is not needed then i'll just remove it.

 

[Kaiser67M715]

The penninsular HO pump was made for standard rotation v-belt setup, its rated at 110 gpm vs 140gpm with the 6.5 HO pump so I would not be risking cavitation. So with the dual thermostats, wouldn't it flow to much to fast? I have heard of 6.5 engine builders that run just a single thermostat on performance builds.

yes and no, you will flow more with the dual thermostats, but the 6.5 also had a larger radiator-like 2 inches taller, and about 6 inches wider. same 4 core, it had the ability to cool with the increased flow. your bypass is a small diameter, so it shouldn't actually have as much affect on flowing too much, unlike running no thermostat, which flows really fast. Playing with it would certainly tell you what affect it has.

on performance builds, I have only seen them use a single thermostat outlet, rather then the dual thermostat setup, with the HO pump. and this is were the the debate come is on possible cavitation issues.

one last thing, test your aftermarket gauge, either against another different brand gauge, or a IR thermometer, typically the engine retains heat(I've seen the engine be as much as 20 degrees hotter then the water), so you should try to get temps at the radiator. check inlet temp,(upper hose) and outlet temp(lower hose) typically it is around a 20-30 degree drop, any more, and your radiator is working real well, and possibly overcooling(yes its a thing), less then 15 degree drop-something is wrong in either the flow, or the radiator.

location of your temp sensor shouldn't be that big of a deal, where it is currently located is fine.

 

[welpro222]

I think the cavitation issues we're do to running a non-bypass style crossover or restricting the bypass.

The truck in the picture is getting a aftermarket temp gauge with sensor also mounted in crossover pipe and it still has the factory temp gauge setup (just wanted a more accurate temp reading). My suburban has a dummy light from the factory, so I only have the aftermarket gauge to go by on that one.

 

[welpro222]

So I took it for a test drive to work today. Temp gauge was reading right at 200, so on the freeway I pulled the knob and open the bypass. The temp decreased by about 5 degrees, so my plan looks like it should work but still does not tell me what it might do it a up hill climb. Hopefully I get to test it before the summer ends. I'll keep you posted.

I agree with most here that this will most likely not help in an overheating situation. That is not my goal here, I am trying to decrease the high end of the running temp (220 on steep grades, loaded down). Many people will tell you that running these engines at 220 for a long period of time is no good. Now I have not tested this truck in these conditions yet, so it may not even get this warm anyways. My other suburban has a stock WP and a used radiator (not sure of condition), so these two things may be causing it to run hotter then normal.

My other understanding is that running a turbo can also increase overall running temps too is these conditions.