P15 Thermostat 160 Vs 180

[larryconnors]

P15's came with a 160 thermostat but a 180 was optional. Did the 160 make the temperature guage read dead center straight up while the 180 has it read a little to the right all the time? I'm asking because my temperature guage always reads half way to overheating but it never overheats. I'm thinking that this is because I have a 180 thermostat.

[doctor dirt]

In Florida I'm sure the 160 is where my car needs to be. Plus I found the DV 3 instead of the "more modern" napa offering that didn't work well at all! Car spiked at 212 within 15 minutes and although they are hot bloodied I prefer the old school thermostat, all the old designs are avalible! Doc.

[55 Fargo]

160 t/stats were used with alcohol based antifreezes too, the lower boiling temps for this stuff made it necessary.

A 160 t/stat, opens at or around 153, and is fully open at 180 degrees.

A 180 t/stat begins toopen at about 172, and would be fully open at 195 or so, according to specs.

Now on hot days, if your engine runs at 180 while driving her, a 160 t/stat will not keep the temp lower, as it would be open all the way. A 180 t/stat of course would open at higher temps, but would be slowing tyhe flow down, which can regulate the temp too.

having an engine run at 150-160, is really not the way to go, 170-180 would be better for the engine,less wear, less sludge, less internal condensation.

ButI am like you guys, feel better whne the temp is belopw 165, but is it really good for the engine. I do no the oil take sa lot longer to heat up in this heavy cast engines....PS if you have overheating issues, a 160 t/stat will ot save you, you need to address the problem, clean rad, clean block, good flow through water dist. tube and through head, is critical. Many of us have had to pull side plugs, and water tube and flush thee blocks clean, that with a good rad, poper t/stat, and these engines run at the right temps, as long as the timing is in line, and you dont' have the rpm level well over 3000...

[Old School]

P15's came with a 160 thermostat but a 180 was optional. Did the 160 make the temperature guage read dead center straight up while the 180 has it read a little to the right all the time? I'm asking because my temperature guage always reads half way to overheating but it never overheats. I'm thinking that this is because I have a 180 thermostat.

I tried a 180 after a 160 and it did what you described.  I concluded that the 180 was only suitable for cold climate winter driving and replaced it with the 160.

[larryconnors]

Thanks for all of the information you guys have provided. Since I don't have an overheating problem, I can run with either a 160 or my current 180. The 180 is likely the cause of my temp guage reading a little to the right. If I switch to a 160 my guage may read in the middle. If I do develop an overheating problem switching to the 160 probably won't cure it.

[Don Coatney]

. If I do develop an overheating problem switching to the 160 probably won't cure it.

 

Very true! If your engine and engine cooling system are healthy 180 is the way to go in my opinion.

[greg g]

I guess the ultimate question is what temperature is your car actually running at. I guage marked from the factory doesn't really give the actual temp of the coolant. So your little bit high actually means what???

[martybose]

I guess the ultimate question is what temperature is your car actually running at. I guage marked from the factory doesn't really give the actual temp of the coolant. So your little bit high actually means what???

For years I thought my motor ran hot, the one day while I had the head off I took the factory temp gauge and put the sender in hot water with a couple of thermometers.  That's when I found that the temp gauge read 20 degrees hotter than actual.  After recalibrating it I now get accurate readings.

 

Marty

[Adam H P15 D30]

I too have been pondering a 180 thermostat as my cooling system is healthy and mine runs at 165 with a 160 thermostat.  BUT....  with a non pressurized system the boiling point is lower, even lower if you live at higher altitude.  My oil temp still gets to approx 200 deg according to the lazer on the pan, so sludge is not an issue (detergent oil, short change intervals).  I have seen temps go to 185 - 190 climbing some passes in the summer.  Higher elevation only leaves me about 10 degrees before boil over (theoretically).  Probably just leave the 160 in it.

Edited May 8, 2013 by Adam H P15 D30

[P15-D24]

I too have been pondering a 180 thermostat as my cooling system is healthy and mine runs at 165 with a 160 thermostat.  BUT....  with a non pressurized system the boiling point is lower, even lower if you live at higher altitude.  My oil temp still gets to approx 200 deg according to the lazer on the pan, so sludge is not an issue (detergent oil, short change intervals).  I have seen temps go to 185 - 190 climbing some passes in the summer.  Higher elevation only leaves me about 10 degrees before boil over (theoretically).  Probably just leave the 160 in it.

Your nailed it! WIth a non pressurized system the extra "headroom" a 160 stat will give you may mean not sitting on the side of the road boiling away on a hot day. The 180 stat is for cold weather use.  These boil at 212 degrees, not 250 degrees like modern pressurized systems.  

[larryconnors]

Tomorrow I pick up my P15 with a new 180 thermostat and water distribution tube in after it it had a number of mechanical repairs to get it to daily driver status. The temperature will be in the 90's all weekend. I'm driving ten miles to the Blast From the Past diner in Waterboro Maine Friday and about 200 miles to Marlboro Ma and back to Topsfield Ma on Sunday. After that I'll have a report on how the 180 themostat worked out.  

[busycoupe]

I picked up one of those IR point and shoot thermometers at Harbor Freight.  I was surprised to find that my temp gauge on the dash is apparently fairly accurate.  With the temp meter you can measure spot temperatures on the head, block, top of radiator, bottom of radiator, thermostat housing..  wherever you like.  By checking along the length of the head you can check coolant flow in the head.  It is a handy tool for troubleshooting the cooling system.

Dave

[larryconnors]

I drove 200 miles this weekend and had no overheating problems wiith my 180 thermostat even though the temps were in the 90's. The temp guage is clearly reading wrong since it goes to 212 and stays there. I need to recalibrate it. How is that done?

[TodFitch]

I drove 200 miles this weekend and had no overheating problems wiith my 180 thermostat even though the temps were in the 90's. The temp guage is clearly reading wrong since it goes to 212 and stays there. I need to recalibrate it. How is that done?

 

1. Remove the temperature gauge from the car (good chance of damage doing that).

 

2. Put sensing bulb in to boiling water (known 212°F)

 

3. Bend linkage between the coiled up Bourdon tube and the needle to adjust reading. Do not bend the needle or the Bourdon tube itself.

 

4. Re-install temperature gauge.

 

Manual says there is a limit to the adjustment possible service manual says 30°F.

[martybose]

You should get a candy thermometer and check the readings at several different temperatures rather than just set it at 212.  It took me about 6 tries before I could get mine to read within a degree or two from 120-212.

 

Marty

[blucarsdn]

160 t/stats were used with alcohol based antifreezes too, the lower boiling temps for this stuff made it necessary.

A 160 t/stat, opens at or around 153, and is fully open at 180 degrees.

A 180 t/stat begins toopen at about 172, and would be fully open at 195 or so, according to specs.

Now on hot days, if your engine runs at 180 while driving her, a 160 t/stat will not keep the temp lower, as it would be open all the way. A 180 t/stat of course would open at higher temps, but would be slowing tyhe flow down, which can regulate the temp too.

having an engine run at 150-160, is really not the way to go, 170-180 would be better for the engine,less wear, less sludge, less internal condensation.

ButI am like you guys, feel better whne the temp is belopw 165, but is it really good for the engine. I do no the oil take sa lot longer to heat up in this heavy cast engines....PS if you have overheating issues, a 160 t/stat will ot save you, you need to address the problem, clean rad, clean block, good flow through water dist. tube and through head, is critical. Many of us have had to pull side plugs, and water tube and flush thee blocks clean, that with a good rad, poper t/stat, and these engines run at the right temps, as long as the timing is in line, and you dont' have the rpm level well over 3000...

The above comment about stats/cooling systems saved me a lot of typing...

The average person fails to realize that the internal combustion engine requires heat to make it run properly, the higher the operating temp, within reason, the better, and longer the engine will run.. Of course, a good multi viscosity oil, is a must because over 50% of the engine cooling is in the oil..

When I was a teenager, during the late '40's, early '50's, I worked in several service stations and a few garages.. During that period, the spring ritual was to dump the anti-freeze and remove the thermostat, replacing same with water, come fall, out went the water, anti-freeze and a stat was installed.

The oil that we drained out of the engines was usuallly so contaminated with acids, etc., would burn the skin on our arms.. A good indication of why the older engines were all done by the time they had 40k on them.

We pulled the pan off of a '49 engine the other day.. The pan had over an inch of thick sludge laying in the bottom. the valve push-rod chamber was equally all sludged up..

I know... Don't confuse me with facts, I already have my mind made up... Bill

[Adam H P15 D30]

You should get a candy thermometer and check the readings at several different temperatures rather than just set it at 212.  It took me about 6 tries before I could get mine to read within a degree or two from 120-212.

 

Marty

 

Bingo.....  Double check that boiling point.  It is much lower than 212 at higher altitude.