New Build.. Cooling Problem? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

IntegratedTJ · 04-26-2015, 09:33 PM

Got a 1972 Chevy C10 - So I just rebuilt my motor after it warped the heads due to lack of cooling (Thermostat pooped out and I didn't have a temp gauge) and I am running a JEGS Mechanical Water Temp Gauge, the sending unit part is installed in the top of the intake manifold on the passenger side. I am new to mechanical gauges AND engine building, however it runs great and.. am I just paranoid? The gauge randomly spikes up to 200-230 but then immediately goes back down to 185-195. I was just wondering if this is something to worry about or am I just paranoid? My theory was that maybe it was the hot coolant circulating out of the engine on that passenger side and the cooler coolant circulating in behind it? Thanks in advance!

IntegratedTJ · 04-26-2015, 10:18 PM

Anyone? Really gotta get this solved asap..

Wrenchbender Ret · 04-26-2015, 10:30 PM

Most therms. will go higher on the initial opening & then drop back. If it doesn't heat up any other time. You are OK. A lot of new therms. we get now are defective. Make sure you have 50-50 mixture of a-freeze & a good pressure cap & you will be OK.

IntegratedTJ · 04-26-2015, 10:32 PM

Quote:

Originally Posted by Wrenchbender Ret

Most therms. will go higher on the initial opening & then drop back. If it doesn't heat up any other time. You are OK. A lot of new therms. we get now are defective. Make sure you have 50-50 mixture of a-freeze & a good pressure cap & you will be OK.

Thanks for the reply! Looking around.. I see a lot of people saying to bleed the cooling system. I haven't bled the cooling system. Would that cause this problem?

Acorn · 04-26-2015, 10:55 PM

You can never be to paranoid about the cooling system on a rebuilt engine. I collapsed my rings once because I was to broke to buy a gauge.
It sounds like you just have an air pocket in the cooling system. The air/steam will be much hotter than the coolant and could cause the gauge to spike momentarily as it circulates past the sending unit. Just a thought.

IntegratedTJ · 04-26-2015, 11:01 PM

Quote:

Originally Posted by Acorn

You can never be to paranoid about the cooling system on a rebuilt engine. I collapsed my rings once because I was to broke to buy a gauge.
It sounds like you just have an air pocket in the cooling system. The air/steam will be much hotter than the coolant and could cause the gauge to spike momentarily as it circulates past the sending unit. Just a thought.

I thought the same thing right when I saw the bleeding the coolant system deal. I didn't even know that was a thing. New to the whole building and working on cars thing.. Thanks for the input. Going to bleed the system first thing in the morning and get her nice and hot and see if that does the trick. Will post back with results in case anyone has a similar problem.

EDIT: That'd explain the steam coming from the radiator when I cut off the engine, too.

**71CHEVYSHORTBED402** · 04-26-2015, 11:31 PM

When I flush the system, I remove the thermostat and bolt the thermostat housing back on. Run water to radiator with the upper radiator hose disconnected from thermostat housing. Then run the engine for a bit (approx. 5 minutes) while the heater is running. You might try it. Get a new thermostat while you're at it.

cdowns · 04-27-2015, 06:59 AM

i'd have the sender unit in the heads not in the intake for a more accurate reading

**67 cst swb** · 04-27-2015, 08:45 AM

/\ agreed
The head is the best location for accurate temp reading as its always submerged in coolant.

IntegratedTJ · 04-27-2015, 02:25 PM

For bleeding the cooling system, won't I HAVE to remove the thermostat? It is bled by going through cooling cycles, right? So if I have my thermostat in (192*F Spec/OE) won't it not open, thus not bleeding the system?

Edit: Mind you, this is a new build so I don't really wanna keep the RPM's at, say, 2500, for as long as it'd take to bleed the cooling system

cdowns · 04-27-2015, 04:46 PM

bleeding a cooling system is way overrated basically a waste of time and effort

engineer_gregh · 04-27-2015, 08:46 PM

Hand held thermal guns are a great help as you can aim it at different parts of the radiator and engine as an aid in troubleshooting. I stick to 180 degree thermostats and use 50/50 premixed antifreeze. I had lots of overheating problems when the 402 was rebuilt, ended up going with aluminum radiator and electric fans before it was resolved. Good luck and please post what you find.

04-26-2015, 09:33 PM	#1
IntegratedTJ Registered User Join Date: Jul 2013 Location: Vallejo, California Posts: 71	New Build.. Cooling Problem? Got a 1972 Chevy C10 - So I just rebuilt my motor after it warped the heads due to lack of cooling (Thermostat pooped out and I didn't have a temp gauge) and I am running a JEGS Mechanical Water Temp Gauge, the sending unit part is installed in the top of the intake manifold on the passenger side. I am new to mechanical gauges AND engine building, however it runs great and.. am I just paranoid? The gauge randomly spikes up to 200-230 but then immediately goes back down to 185-195. I was just wondering if this is something to worry about or am I just paranoid? My theory was that maybe it was the hot coolant circulating out of the engine on that passenger side and the cooler coolant circulating in behind it? Thanks in advance!

04-26-2015, 10:18 PM	#2
IntegratedTJ Registered User Join Date: Jul 2013 Location: Vallejo, California Posts: 71	Re: New Build.. Cooling Problem? Anyone? Really gotta get this solved asap..

04-26-2015, 10:30 PM	#3
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: New Build.. Cooling Problem? Most therms. will go higher on the initial opening & then drop back. If it doesn't heat up any other time. You are OK. A lot of new therms. we get now are defective. Make sure you have 50-50 mixture of a-freeze & a good pressure cap & you will be OK.

04-26-2015, 10:55 PM	#5
Acorn Registered User Join Date: Jul 2013 Location: Winnsboro Texas Posts: 367	Re: New Build.. Cooling Problem? You can never be to paranoid about the cooling system on a rebuilt engine. I collapsed my rings once because I was to broke to buy a gauge. It sounds like you just have an air pocket in the cooling system. The air/steam will be much hotter than the coolant and could cause the gauge to spike momentarily as it circulates past the sending unit. Just a thought. __________________ The bitterness of poor quality lingers long after the sweetness of a low price is forgotten.

04-26-2015, 11:31 PM	#7
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,322	Re: New Build.. Cooling Problem? When I flush the system, I remove the thermostat and bolt the thermostat housing back on. Run water to radiator with the upper radiator hose disconnected from thermostat housing. Then run the engine for a bit (approx. 5 minutes) while the heater is running. You might try it. Get a new thermostat while you're at it. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025

04-27-2015, 06:59 AM	#8
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: New Build.. Cooling Problem? i'd have the sender unit in the heads not in the intake for a more accurate reading __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

04-27-2015, 08:45 AM	#9
67 cst swb Senior Member Join Date: Nov 2001 Location: Rapid City, SD Posts: 2,281	Re: New Build.. Cooling Problem? /\ agreed The head is the best location for accurate temp reading as its always submerged in coolant. __________________ My Trucks: 1967 Chevrolet Short Wide Box 327 TH350 9" w/3.90 gears paint will be White - Current Project 1967 Chevrolet Custom LWB 283 TH400 3.73 Posi, no-AC, no-PS, no-PB, bench-seat, small-window - mostly orig driver 1967 Chevrolet CST LWB originally a 327 TH400 3.73 Posi AC PS PB, had Buddy Buckets, Small Window - parts truck 1967 Chevrolet CST LWB, 283 MT 3.73 had Buddy Buckets, Panoramic Window - parts truck 2001 Chevrolet 3500 2WD Crew Cab Dually 8.1L Allison White

04-27-2015, 02:25 PM	#10
IntegratedTJ Registered User Join Date: Jul 2013 Location: Vallejo, California Posts: 71	Re: New Build.. Cooling Problem? For bleeding the cooling system, won't I HAVE to remove the thermostat? It is bled by going through cooling cycles, right? So if I have my thermostat in (192F Spec/OE) won't it not open, thus not bleeding the system? Edit: Mind you, this is a new build so I don't really wanna keep the RPM's at, say, 2500, for as long as it'd take to bleed the cooling system Last edited by IntegratedTJ; 04-27-2015 at 02:33 PM.*

04-27-2015, 04:46 PM	#11
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: New Build.. Cooling Problem? bleeding a cooling system is way overrated basically a waste of time and effort __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

04-27-2015, 08:46 PM	#12
engineer_gregh Registered User Join Date: Feb 2012 Location: Smyrna TN Posts: 1,153	Re: New Build.. Cooling Problem? Hand held thermal guns are a great help as you can aim it at different parts of the radiator and engine as an aid in troubleshooting. I stick to 180 degree thermostats and use 50/50 premixed antifreeze. I had lots of overheating problems when the 402 was rebuilt, ended up going with aluminum radiator and electric fans before it was resolved. Good luck and please post what you find. __________________ 1971 Longbed BB Cheyenne Super 1972 Longbed SB Cheyenne Super 1972 Longbed Highlander Custom Deluxe 1975 K5 4x4 full convertible Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=645165 Greg Smyrna TN



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