1940 plymouth running at 212

[Rodney Bullock]

i finally got the coupe out and was driving it today. I was having a great time. I had been driving it for the whole day. I went here and there. I noticed the temp gauge at 195. I was driving the highway to get home and the temp kept climbing. It finally got to 212 I still had 15 miles to go so I did not panic. It was hot outside. The car never acted up or hesitated. When I got home and cut it off it did not run on, it did burp some water out the radiator. I checked the water level after it cooled and it was very low. My question is while driving on the highway no matter how fast I went the temp never changed, was it because it was low or is something else wrong? I will take it out tomorrow morning early and see if it just climbs.

[Rodney Bullock]

As some know I changed my water pump last year and had my dist. rebuilt. could my timing be a bit off. I have it 2 degress before TDC. It starts very quick and I have no ping going up hills.

[greg g]

Rodney if your coolant level was low enough to not surround the sensor, it can not send the correct reading to the gauge and if the gauge tops out at 212, you may have been running hotter. If your are running a 50/50 mix of coolant, your boiling temp is higher than 212. Is your belt tensioned properly? Highway speed will send plenty of air through the rad, but if your pump is not keeping up with the motor the flow through the radiator will be slow. I would check the fan belt and drive her around again after you bring it back up to the proper level. You timing at 2 degrees advance should not effevt running temp by much.

[JerseyHarold]

Partially-closed thermostat or stuck heat riser?

[Rodney Bullock]

The belt is good and tight. One of the things I did last year was to replace the heat riser and tack weld the flap to the rod. I started the car and ran it until the water in the radiator started to circulate as I rev the motor higher the water curculated faster. The thermostat could be sticking a little. My first thought was the timing I read in the archives that 6 degress btdc was good for these engines. The one thing I do need to check is the water jacket. I have one freeze plug by the starter that has a tear drop coming from it evry now and then.

[1941Rick]

If the engine was not up to the operating range of the thermostat when you say you could see the water circulating you have just answered your question........thermostat is stuck partially open...

[Joe Flanagan]

Rodney, if you get to the point where you want to see if it's the thermostat, bring it over and we can drain the system and check it out. I've got all the stuff we need so we can catch the coolant, store it, and pour it back into your engine when we're done. We can test it in some boiling water.

[Rodney Bullock]

Thanks Joe I will keep that in mind.

I drove the car up to THE HOLY DOANUT This morning and discovered something. On the way up 70 miles up and 70 miles back. I noticed the temp gauge was at about 190 on RT95 howeve when I switched over to BW parkway Lots of trees and shade the temp dropped to about 180 When I got to the cruz in the temp ws at about 200 I stayed for about 2 hours then made my way back. The temp gauge was at about 210 all the way back. Thie sun was at it's highest point and it was hot. The motor did not stall or ping. Now this is funny part when I got off the highway and on to the local streets the temp went back to about 185-190 So based on this I think my mixture is not exact mybe I have to much water. when I stooped the car the radiator did not puck or I heard no strange sounds from the motor, You thinh maybe the gauge is wrong? It must be something minor as the car rode very smooth even in some bumper to bumper traffic.

[Plymouthy Adams]

as the motor turns at higher RPM there is the pump's suction action on the lower radiator hose..the actual suction is often greater than the returning water supplied through the radiator core..(partial blocking) and the result is that the lower hose will start to collapse..further restricting water flow..so the question is if your cooling problem componet related, inother words, are you out driving the car's ability to cool (transfer heat) and further, the thermostat also is designed to regualte the heat not only in the point to when it opens but by checking the exchange of water so that the water leaving the block is fully saturated with heat to be exchanged at the radiator core by air movement over the fins...if you move this too fast by the lack of a thermostat, the heat will not transfer properly to the water and the result is the block temp is higher than normal..all the components need to be in working order to properly do thier job..any problem in one area will be transferred to yet the other components in the system

one way to test this exchange of heat is to do the same ride over but this time use the heater motor to exchange heat and see if this will in return lower the temp..if it does..your radiator/thermostat, hose etc is not up to the task..check each for proper operation.

[40P10touring sedan]

Usually there's a coil spring in the lower hose...empty the water and pull that hose to make sure it hasn't rusted away and causing hose collapse...while the system is dry pull the thermostat and put it in an old pot{or don't let the wife see you use a good one!} and heat the water with a thermometer in it to the opening point of your stat - watch it open - as the temp goes higher it should be open all the way at 200...when you start it should be closed all the way. Watch to see that it opens smoothly and doesn't hang up or pop along the way...years of crud can slow the movement on them if not freeze them up in a given position.

You rebuilt the water pump so you know that is a given, the belt tension is good, so that just leaves the stat and hoses...remember, these cars ran on "water" back in the day and only tossed in some expensive antifreeze if they had to, to keep the block from freezing. Water was free.

If all the above check out good, the only things left are;

- the PO put stop leak in the rad and plugged it up some...or alot.

- the water distribution tube has an issue

- the temp gauge is off and should be replaced with a cheap aftermarket to confirm that{last ditch thing as you can check the temp gauge the same way you check the stat....bulb in hot water and watch the temp compared to the thermometer}

[Niel Hoback]

Two nitpick things; your 40 should have short hoses connecting steel elbows that really wouldn't let the hoses collapse. I realize that it could easily have been changed to one hose and eliminated all the extra clamps and pipes and should then have a spring inside.

I once put two bottles of BarsLeak in a 75 Dart /6 at the Kmart parking lot. I didn't get home, 5 miles before it had plugged up the entire radiator. It said one bottle was enough but I always say, "if ones good, twos better". I always learn the hard way.

[Rodney Bullock]

I ran the car tonite and it did not get over 160 degress. I think I will change the thermostat tomorrow and see what happens. In the fall winter the thing is great, maybe it's a seasonal car:confused:

[Rodney Bullock]

Hi Shel, I don't remember what thermostst I have, that's a good question. I remember one thing about that thermostat and it's housing. i couild not get it to seal the first two times This is why I am afraid to take it out. I had to let it set up for a couple of days. I have been using sunoco gas so That has not been changed and The timing must be right becuse it does not ping. I will change the thermostat tomorrow. Do you think 180

[greg g]

need to make a stop at Stanleys, in Radiator Springs. Cars opens tommorow at Disney in Cali.

and perhaps some No Foolant Coolant

although at Disney prices hope you don;t need much.

Did you temp the coolant or are you just relying on the gauge???

[Rodney Bullock]

Ok, So I pull everything off this morning and find that I have a 160 thermostst in the car. Does this mean the thermostat in the winter just flows water and in the summer it flows water to fast to cool? I went with a 180. I cleaned everything super good I even cleaned the bolts and the theads:) I think the problem I had in those early years was the thermstat housing can only go on one way. There is a cut out for the head bolt. I must have put it on wrong a couple of times before I got it right. I used the blue sealent and anti seze on the bolts. I am going to allow it to dry for a day before putting fluid back in the system. I think that's something I did not do as well. I want to make the show sunday so I am crossing my fingers:rolleyes:

[chopt50wgn]

One thing about a cooling system.......when the motor runs warmer at highway speeds what can be happening is a cavitational bubble getting stuck. As the internal metal temps build heat, it can start turning the water into steam pockets. Those pockets can float into the block or get stuck at the pump. Eventually they will break and allow for flow.

[Jim Yergin]

I want to make the show sunday so I am crossing my fingers:rolleyes:

Rodney,

I hope you make it to Sully and that you have good time. Unfortunately I am out of town and won't be there this year.

Jim Yergin

[Don Coatney]

Rodney,

I hope you make it to Sully and that you have good time. Unfortunately I am out of town and won't be there this year.

Jim Yergin

Speaking of Sully, anyone heard if Chet will have his blue Plymouth there this year?

[Rodney Bullock]

Thanks jim, Don I don't know if Chet is coming this year or not. I hope I don't have a bubble in the system. I saw an episode of Boyds show where they had that happen it wasan awful mess.

[Rusty O'Toole]

Sounds like a typical marginal cooling system. Try blowing the rad out from behind with an air hose, and flushing the cooling system with vinegar, CLR or your favorite rad flush.

[plyroadking]

I have always seemed to have a problem keeping my '40 cool. Switched thermostats, reset timing, added an electric cooling fan, new hoses, new water pump, and a recore on the radiator. And it still gets hot. Im inclined to believe that the grille does not allow enough air flow through it. However the only thing that has helped was switching the fan out for a six blade dodge truck fan.

[chopt50wgn]

Rodney............forgot to ask................do you have a spring in the bottom hose? if you don't, it may be sucking shut at speed. That's the suction side of the system and that can happen. When it does, the motor will run hotter due to no flow from radiator.

[Rodney Bullock]

yes, I do have a spring in the hose. When I replaced the water pump last year I changed the hose, good thinking your right about the sucktion side of the system. I played with the timing yesterday and then drove the car. The gauge is on 180 which I am not use to seeing however it does remain there. It's funny, now the temp gauge swings all the way to the 212 then after the thermostat opens it swings back to 160 then 180 most of my 6 cly motors do this so I guess the thermostat is working:)