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overheating since engine rebuilt

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Dads CJ2A View Drop Down
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    Posted: 26 May 2018 at 7:34pm
Along with a newly rebuit engine on my '46 CJ2A, I've added the following:
  • new 160 deg thermostat and retainer
  • pressure tested and painted radiator
  • new upper and lower hoses
  • rebuilt water pump (which has a small leak coming out through the weep-hole on the bottom of the housing!)
  • standard 4 blade fan with no shroud
  • Cap labelled 4#
  • fresh 50/50 coolant
With the Jeep on jack stands, I can get it idling although a bit high (est 1000 RPM) and it will stay smoothly running on partial choke until the temp rises over 200 and she boils over with steam and/or coolant coming out the overflow tube. Since no airflow from moving, I placed a box fan in front of the grill to 'pull' air through the rad but no difference.

I've scoured the forums for ideas and wonder what is most likely my issue:
  • timing? - although it seems to idle smoothly - I did install a solid state distributor
  • lack of fan shroud? - prior year before the rebuild no shroud didn't seem to matter
  • system pressure? - measuring my cap 'height' compared to radiator 'throat' it does not seem like there is enough 'length' to completely seal the system
  • water pump issue? - maybe the leak is trying to tell me something
Other notable (maybe) items:
  • newly installed 'production' PCV system
  • new Autolite 295 plugs
Thanks in advance for suggestions!
I cut it off twice and it's still too short!
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Mark W. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 26 May 2018 at 7:56pm
it should idle at 650 rpm easily. I would look at timing and your over all tune. If you take the cap off (before starting) do you see water flowing in the top of the Radiator?


Chug A Lug
1948 2A Body Customized
1949 3A W/S
1957 CJ5 Frame Modified
Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vince Quote  Post ReplyReply Direct Link To This Post Posted: 26 May 2018 at 8:18pm
Also, does your new thermostat have the 1/8 hole to allow bypass (and prevent an air lock)?
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Dads CJ2A View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dads CJ2A Quote  Post ReplyReply Direct Link To This Post Posted: 27 May 2018 at 1:38pm
Yes, I see some movement there. Upon my very first start with a "full' radiator and after running for only a few minutes I turned the engine off to check for oil, gas etc leaks since this was just rebuilt. Before starting again I did have to add a few quarts so I'm guessing that was the thermostat opening and creating the void from the air in the block?

Thanks for the tip on the timing and idle. I knew the idle should be a bunch lower. Would it be best to work on getting the idle down first, then look at timing? Or does it matter?
I cut it off twice and it's still too short!
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Dads CJ2A View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dads CJ2A Quote  Post ReplyReply Direct Link To This Post Posted: 27 May 2018 at 1:43pm
I didn't drill one myself like I've seen other guys mention in other posts, so NO on the 1/8 hole unless it was built into the part. I know I got the orientation right and I'm pretty sure it's opening based on the "top-off" I had to do.
I cut it off twice and it's still too short!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rus Curtis Quote  Post ReplyReply Direct Link To This Post Posted: 27 May 2018 at 3:04pm

The leak in the pump is a failure indicator. The pump should be replaced. 

The cap should seal as the extra pressure will keep the solution from boiling at lower temps. This shouldn't be a factor at idle.
 
You pressure checked but what about restrictions?  Did you clean out the radiator before painting/install? 
 
Don't overfill but leave the cap off and observe while idling.  You should see flow each time the thermostat opens.  If it rises up and overflows, I would suspect blockage.  This could be the radiator, the thermostat (bench test in a bowl using a thermometer) or pump not pumping.
 
Water is cheaper than antifreeze.  If you can collect the coolant, troubleshoot with water until you solve the problem.  Since you're trying to solve this, any water is ok but I personally prefer distilled water when mixing with antifreeze as this reduces mineral deposit buildup.
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Dads CJ2A View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dads CJ2A Quote  Post ReplyReply Direct Link To This Post Posted: 28 May 2018 at 9:01pm
New pump on order along with a shroud.

As far as rad restrictions, I absolutely flushed it good with water when it was loose from the vehicle. It seemed to flow from the neck to the lower tube nicely so I'm guessing there is no serious blockage. It was pressure checked a a pretty reputable radiator shop so I'm counting on that as another assurance that the rad is good. 

Drained the block at the petcock by the oil fill tube and drained the radiator at the lower hose petcock today. Love the tip on 'troubleshooting' using water Rus, thanks. 

Plan is to install new pump and shroud, drill the 1/8" hole in the thermostat that Vince recommended above while everything is tore up, then fill with water and work on the timing. 

Thanks to all. 



I cut it off twice and it's still too short!
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Dads CJ2A View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dads CJ2A Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2018 at 7:39pm
Special thanks to Mark W., Vince and Rus!
After a new H20 pump, new aftermarket shroud (+some required tweaks), 1/8 inch holes in thermostat and probably my biggest factor - setting the TIMING, I'm back on the road. I was quite a bit off when I originally set the timing by 'ear'. 

After the 2 laps around the subdivision it's clear what my next task is - brakes! Modern DOT 3 fluid acceptable?
I cut it off twice and it's still too short!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark W. Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2018 at 9:26pm
YES DOT 3 fluid
Chug A Lug
1948 2A Body Customized
1949 3A W/S
1957 CJ5 Frame Modified
Late 50's 134L 9.25"clutch T90A D18 (1.25") D44/30 flanged E-Locker D25 5.38 Since 1962
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike S Quote  Post ReplyReply Direct Link To This Post Posted: 22 July 2018 at 7:36pm
Glad you got it running correctly
'47 CJ2A -- #114542
Warn FF D41 rear
Lock-Right locker
11" drum brakes
Dual master cylinder
T90C Transmission
16 X 6 Jeep truck wheels
Cooper STT Pro tires
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