Not reaching full operating temp
Thread Starter
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
Not reaching full operating temp
I know tstats have been covered here a lot. I did try a search of the forums before asking this.
Just got my 77 back on the road after a top end engine re-do. Installed a new 195* tstat since I have a good DeWitts radiator and a high flow pump. Logic being the higher temp would help the car make horsepower.
Well I drove her into work today (a 25 to 30 minute commute) and my temp climbed very slowly to only about 155 or 160*. It was cool this morning, but not cold, and I really think she should have heated up especially once I jump on her entering the highway. So, what are my troubleshooting steps here? Temp sending unit? Gauge? Bad tstat out of the box?
It should be about 70* on the drive home. Will be interesting to see what she reads then.
Just got my 77 back on the road after a top end engine re-do. Installed a new 195* tstat since I have a good DeWitts radiator and a high flow pump. Logic being the higher temp would help the car make horsepower.
Well I drove her into work today (a 25 to 30 minute commute) and my temp climbed very slowly to only about 155 or 160*. It was cool this morning, but not cold, and I really think she should have heated up especially once I jump on her entering the highway. So, what are my troubleshooting steps here? Temp sending unit? Gauge? Bad tstat out of the box?
It should be about 70* on the drive home. Will be interesting to see what she reads then.
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
Did you have this problem before the top end rebuild? If not, are you running electric fans with the DeWitts radiator? What temp do the fans come on if you are? Are you sure your full of coolant? That can cause issues too.
Thread Starter
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
Did not have this issue before the top end rebuild. Before the top end rebuild I used a 160* tstat to help control a slight over heating problem. Then I replaced the stock/original radiator with the DeWitts and the car would heat up to 160*, and sit at 160* in the heat of summer or on a cool fall morning. I am not using any electric fans. I'm pretty sure its full of coolant and the coolant is all fresh.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
You never really know how accurate the temperature indicating system is unless it's been tested. I recommend getting one of the IR guns like are now cheaply available at some outlet stores and checking it.
BTW, a temp gun is also good for identifying a missing cylinder because the gun will show that the offending cylinder's exhaust is cooler than the others.
BTW, a temp gun is also good for identifying a missing cylinder because the gun will show that the offending cylinder's exhaust is cooler than the others.
Burning Brakes
Joined: May 2009
Posts: 850
Likes: 36
From: Providence RI
I second the recommendation to check the actual opening-temp of the thermostat with a meat thermometer in a pan of water on the stove.
I've seen 180" thermostats that are fully open at that specified temp, but that begin cracking open at a lower temperature.
If your thermostat cracks open at a temp lower than its rated temp, and you have a very efficient cooling system and a cool-running engine, your thermostat may never do more than crack open, and your engine may never get up to the rated temp of the thermostat.
I've seen 180" thermostats that are fully open at that specified temp, but that begin cracking open at a lower temperature.
If your thermostat cracks open at a temp lower than its rated temp, and you have a very efficient cooling system and a cool-running engine, your thermostat may never do more than crack open, and your engine may never get up to the rated temp of the thermostat.
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I second confirming the actual temp with an IR gun pointed at the area of the upper radiator hose near the thermostat housing. Alot of these out of range readings are due to send units that are not compatible with the gauge or a faulty gauge. I have seen alot of parts thrown at a problem that didn't exist.
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Thread Starter
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
Le Mans Master
Joined: Jan 2006
Posts: 6,504
Likes: 139
From: Butler Pa
I don't remember what brand I had either, but I know it had provision for allowing a small amount of coolant through it even though closed, like when people drill holes in them to burp the air out.
Thread Starter
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
I second confirming the actual temp with an IR gun pointed at the area of the upper radiator hose near the thermostat housing. Alot of these out of range readings are due to send units that are not compatible with the gauge or a faulty gauge. I have seen alot of parts thrown at a problem that didn't exist.
I head home in an hour so it will interesting to see how hot she gets on a sunny 70* day. Thanks for the suggestions so far, guys!
Race Director
Joined: Aug 2004
Posts: 10,628
Likes: 132
From: Duvall, WA
Everyone says that Robertshaw makes the best thermostat. I've been running one for quite a while and never had trouble with it. When they fail, they are designed to fail open so your car won't overheat. They make a 195° one that will should work for you, if that's the issue.
Thread Starter
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
Everyone says that Robertshaw makes the best thermostat. I've been running one for quite a while and never had trouble with it. When they fail, they are designed to fail open so your car won't overheat. They make a 195° one that will should work for you, if that's the issue.
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
I agree with the bad tstat diagnosis, or inaccurate reading on the gauge. But about your desired operating temperature - the difference won't be major, but you'll make more power at 180 degrees than at 195.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
+1
Cooler temps = more HP. No doubt about it. I have dyno tested and track tested this.
Don't buy into the warmer temp are more power BS.
You want hot oil, cool water for peak power.
Here comes the cylinder wear ***** in 3...2...1....
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Did you change the temperature sending unit? If you did, your guage is under-reporting.
There is no temp sender out there, except the originals that came on our cars, that reports correctly; they all under-report. The closest SU is the BWD part.
As stated above, an IR gun will tell you what's going on with your coolant temp.
There is no temp sender out there, except the originals that came on our cars, that reports correctly; they all under-report. The closest SU is the BWD part.
As stated above, an IR gun will tell you what's going on with your coolant temp.
Last edited by 73, Dark Blue 454; Mar 4, 2011 at 11:50 AM.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
But, the oil temperature in engines is engineered to reach 212f (the vapor point of water) to cook out the liquid water that condenses in the crankcase. Then this vapor is extracted via the PCV system.
Your coolant's theremostat regulates the coolant's temp, which regulates the oil's temp.
Your oil will not be an effective lubricant below 212f as it is above 212f. Agree?
Thread Starter
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
Did you change the temperature sending unit? If you did, youre guage is under-reporting.
There is no temp sender out there, except the originals that came on our cars, that reports correctly; they all under-report. The closest SU is the BWD part.
As stated above, an IR gun will tell you what's going on with your coolant temp.
There is no temp sender out there, except the originals that came on our cars, that reports correctly; they all under-report. The closest SU is the BWD part.
As stated above, an IR gun will tell you what's going on with your coolant temp.
I will probably go with my original thinking and get a 180* to replace this 195* as I think a 160* is too low for an efficient cooling system. A IMO a 180* will help the car produce more horsepower than a 160*.
Thanks for all the replies!
Thread Starter
Racer
Joined: Feb 2008
Posts: 427
Likes: 32
From: North Alabama
St. Jude Donor '24-'26
BTW...On the drive home today, with it being sunny and 70*, she still didn't heat up past 160*. Barely reached 160* really. With the way she's slowly warming up I gotta think the tstat is opening too soon.
Race Director
Joined: Aug 2004
Posts: 10,628
Likes: 132
From: Duvall, WA