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Overheat or bad gauge?


jmooner3

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Hey Guys,

I'm chasing an overheating symptom.  It's a 1950 230ci with external bypass. I've just started driving the truck, first couple of trips temp gauge hung around 180 degrees, was 90 outside but truck ran good.  Now it's cooler out but dash gauge reads hot ~200 and up to 212 when I shut it down.  Could junk have moved around and partially plugged thermostat...? ( I had pulled all freeze plugs, and water dist tube on this motor and purged tons of junk.

 

I dumped the rad and ran water but never really flushed it as I was afraid to cause a leak. Radiator seems to burp a bit of anti freeze each time, down overflow tube - indication of something?

 

I filled Rad to top and ran truck to see if I could see flow from the water pump, cannot see if there is flow at top fill port. Top hose is hot to the touch bottom hose is cooler. Does that indicate the the thermostat is working properly, rad is not plugged, and the water pump is working correctly? How does system work though Tstat> Does water flow into top of rad from block and out bottom of rad back into block?

 

I used my laser temp gauge to hit all parts of the motor a couple of different times.  Net is exhaust side of block is 300+ head just above is 170deg, fitting where bulb end of temp gauge is 160, all areas on head 160, block 165, top of rad 156, bottom of rad 70 antifreeze in top of rad 155.  Seems the engine is actually controlling as it should?  The dash gauge climbing through the roof just has me nervous. I'm trying to convince myself that the engine is running at 160 but feel like I'm missing something...anyone have a gauge run away like this? Are these gauges adjustable or able to calibrate? 

 

Any thoughts or suggestions?

 

Best way

to determine if water pump is working

to verify rad has proper flow

to verify thermostat working and enough flow

The rad seems period correct, but it didn't bolt right in, I had to weld up a bracket - I think it's from a desoto car.  the lip where the cap attaches has an overflow tube above the sealing surface, seems it should have a pressurized cap...should our engines run pressurized or not? and if so what psi?

Idea why rad burps each time, maybe I have rad too full?

All info welcome!

thanks,

J

 

 

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I use straight tap water when doing shakedown cruises so if there is an issue with the cooling system, I'm not out the $$$ for the funny tasting green stuff...1st thing I do is to calibrate gauge on kitchen stove with pot of boiling water, running several ambient-boil-ambient cycles with gauge adjustments as required...running with a 165F thermostat should register under 180F gauge in temps up to the 100s...the original mechanical gauge will start to move the needle when ambient air temps approach 110F (observed this on several occasions)...the original cooling system was NOT pressurized, and running a pressurized cap will be detrimental to the system...fill the system up to about an inch or so over the cores, excess will burp out of overflow as needed...the laser reading at the bulb should be close to the engine operating temp; sounds like your temp.differential on the radiator is good, also uniform temps across head...

the gauge needle can be adjusted by bending the arm that hooks into the needle during kitchen calibration...it takes me several calibration adjustments before I'm happy with the gauge performance...I use my fingers so I do not damage any parts with the "sharp" edges of a pair of pliers :cool:

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Thanks guys, so the update is that it's really overheating now, I headed out to the car NSRA show Saturday and boiled over half way there..... I'm not finished but I got it running on time to get it to this show at the local fairgrounds where there were a ton of really cool old cars and trucks.  So, half way meant decision - home to work on it or short stints with a wait....I drove a little, boiled a bit and waited a couple times but limped it into the show. It was on my bucket list and is a milestone in the life of ol Blue. My son Jake and I started the project when he was around 10....he's 19 now and we still had a ball limping to and from the show... I've got a waterpump on order from Rock auto...

 

So we made it to the show, met some nice folks, and from our multiple tours around the fairgrounds...appeared that ol Blue was the only Pilot house - representing our rigs ? ...

 

Proud moment to have so many people looking at my truck and commenting on how cool it was that it was all original +ground and flathead mostly still getting it done.  Once I get the overheat figured out I'll certainly get back on the road.

JakeJat show.PNG

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I'm not certain that it's waterpump or tstat but they look original, the waterpump did flow water but I'm not sure what amount it should flow and the Tstat appears to be stuck open when I pulled it, I left it in as my thinking was open is good... Tod I did flush the block when I first got it,  removed , poked and replaced all freeze plugs etc. however I don't remember pulling the water dist tube on this one. Honestly I just got the  fresh painted sheet metal all back on, and the wiring finished across the headlights.  The waterpump and Tstat are the easy first try (<$50 from rock auto) without having to dismantle much. If no go then I will pull the doghouse again, pull the pump, dist tube and all plugs again and flush it good.

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