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post #1 of 12 Old 07-31-2020, 08:48 AM Thread Starter
geraldanhorn
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1981 CJ7 
 
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cooling problem

Hello jeep experts,
I need some help on my CJ7 rebuild. 1981 with 258. Complete overhaul on engine but it will not cool. I checked the water pump for the correct direction of flow and it is correct. The engine will start and run but doesn't move coolant. It builds pressure on both the top and bottom hoses. It has a brand new aluminum radiator and new thermostat and water pump. I did install an electronic control valve on the heater hose line to control the heater and wondering if that would create this problem. The question is, Did jeep use the heater core as a bypass for the coolant? Another thing is my starter seems to be binding when trying to start, heating up the starter and cables. Once I stop the starter and try again it goes for a bit and stops. I thought that it might be associated with the back pressure on the hoses so tried turning it over without the water pump on and the starter acted normally, no stopping. I have tried everything I know and am at wits end. Anybody got Ideas?

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post #2 of 12 Old 07-31-2020, 09:29 AM
Matt1981CJ7
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The factory heating system already has a heater valve. When the valve is open the coolant flows thru the heater core then returns to the water pump. When it's closed, the coolant circulates past the valve then back to the water pump. So your additional e-valve may well be causing a flow restriction when it's closed.

Why did you think you needed the additional heater valve?

Matt


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post #3 of 12 Old 07-31-2020, 09:58 AM
pedal2themetai
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First did you install the thermostat properly? pointing away from the motor? That is the usual cause of over pressure and no movement... the water pump shouldn't stop the starter from turning over.. What temperature is it running at? Are you running performance headers, they can cause starter problems if they run close to the starter by over heading it..
good luck
tim
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post #4 of 12 Old 07-31-2020, 10:25 AM
JEEPFELLER
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Is you stat installed with the spring side down (pointy side up)

Personally, I see no need to electronically valve off the heater hose. Maybe this also valved off the intake's heater hoses?

This might not allow for the air to bleed from the system and maybe leaving the water pump spinning in air?

I'm going to show you two of my "High Speed" super secret "maxing interior heat" method, as well as (my belief) in a "better thermostat"

At the present, just as a test, you might remove your valve and install a temporary (or permanent) heater hose coupling to take it's place.

Pic 1) "THE NORM"
Pic 2) Better on a YJ
Pic 3) Here's a real Jeep!
Pics 4 and 5-----explanations

Pic 6) Thermostats

MY PICS POSTED OUT OF ORDER-LOST ON HOW TO EDIT/ FIX 'EM---IT'LL BE OK!

---JEEPFELLER
Attached Thumbnails
YJ ROUTED BETTER DONE.jpg   Copy of MR JEEPS HEAT SYSTEM BEST VERSION.jpg   ABCD 006HHHHHHH.jpg  
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post #5 of 12 Old 07-31-2020, 10:54 AM Thread Starter
geraldanhorn
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Matt,
there was no valve on my heater lines. That is why I installed the electric valve. the valve is installed on the incomming heater line, thus blocking any flow. My theory is it isn't allowing the air to bleed out. one of the next posts actually has the same theory. And yes thermostat is correct and it is the third one!
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post #6 of 12 Old 07-31-2020, 10:59 AM Thread Starter
geraldanhorn
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no performance headers, starter is on the other side with the straight 6, yes thermo is correct, third one
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post #7 of 12 Old 07-31-2020, 11:09 AM Thread Starter
geraldanhorn
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Jeepfellow,
Thanks for the super secret flow for heaters. You have the same theory that I have come up with. Air isn't bleeding from the engine because I have blocked off the heater intake hose, which in this application seems as the "bypass" hose. That does leave the water pump spinning in air. Thanks for the pic of the subbby thermo. I was going to just open the electronic valve and see if I can get it to cool. I do not know actual temp. It gets Hot. I turn it off before it buries the gauge. another thought was to install water pump leave thermo housing off and fill with coolant so air has a place to go. Then put thermo and housing in. Maybe easier to just remove electric valve. The electric valve idea came from my 77 Bronco but ford has a "bypass" hose, the jeep does not.
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post #8 of 12 Old 07-31-2020, 04:53 PM
turbogus
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Neat post about the Subaru thermostat, as long as the temp for opening is the same.

The parts shop that stocks part for Skylab II will not have parts for our year/model of Jeep
We cannot accurately judge the trajectory of a speeding critter (cat, dog, sasquatch)
Record heat waves and floods only occur when we visit that area
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post #9 of 12 Old 07-31-2020, 06:46 PM
Dryseals
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Quote:
Originally Posted by JEEPFELLER View Post
Is you stat installed with the spring side down (pointy side up)

Personally, I see no need to electronically valve off the heater hose. Maybe this also valved off the intake's heater hoses?

This might not allow for the air to bleed from the system and maybe leaving the water pump spinning in air?

I'm going to show you two of my "High Speed" super secret "maxing interior heat" method, as well as (my belief) in a "better thermostat"

At the present, just as a test, you might remove your valve and install a temporary (or permanent) heater hose coupling to take it's place.

Pic 1) "THE NORM"
Pic 2) Better on a YJ
Pic 3) Here's a real Jeep!
Pics 4 and 5-----explanations

Pic 6) Thermostats

MY PICS POSTED OUT OF ORDER-LOST ON HOW TO EDIT/ FIX 'EM---IT'LL BE OK!

---JEEPFELLER
So if I go to the auto parts store what model Subaru is that for???
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post #10 of 12 Old 07-31-2020, 07:45 PM
JEEPFELLER
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Several models use this stat (I've heard some parts guys say it's for an old Subaru) I don't think they know what "old" really means.

I've always asked for a 170 degree 2000 Outback 2.5 liter, they may bring out several, you'll have to pick out the right one!

I do have a part number, you may have to cross reference to another brand: GATES 33857

----JEEPFELLER
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post #11 of 12 Old 10-15-2020, 08:49 PM
BadBradWilson
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Jeepfeller- thanks. That is science! I’ll be improving my system next, and adding a valved bypass for the summer.
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post #12 of 12 Old 10-16-2020, 05:00 AM
ECJ-7
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you are probably correct about the HCV causing your issue, if you want to continue using the valve you bought, just install a "tee" before the valve, and bypass it to a "tee" on the return line. That will shut off the heater, and will still give you good heat when it's open.

As for the subaru t-stat, the size of the whole in the oem t-stat is designed intentionally to slow down the flow of water threw the radiator to help it cool the water. I would stick with the original style.
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