Runs warm...

[RobertKB]

That thermostat Robert describes is available new from napa. I have one in my p15.

NAPA. Now there's a surprise. I will have to go and get a small supply. I thought you would only find those at swapmeets and on ebay. Thanks for the tip, Ed. Do you have a number?

[Don Coatney]

I have one on the shelf that I have not yet installed. Pipe cleaner shows the water flow path when closed.

[Young Ed]

NAPA. Now there's a surprise. I will have to go and get a small supply. I thought you would only find those at swapmeets and on ebay. Thanks for the tip, Ed. Do you have a number?

As you can see it Don's picture its a 155. I think the full part # is THM 155. Drop the 1 for the other temp. I forget which is 160° and which is 180°.

[Drdialtone]

A couple of general questions about cooling... the "seven" blade fan, is this a generic part or did it come from a specific vehicle? Is replacing the standard four blade just a good idea in general? Next, what about a shroud over the radiator? Is this a good idea? I was told this helps the fan pull more air through the radiator. Truth or bunk?

[Jim Saraceno]

As I said, my thermostat is the more modern choke type such is this:

[Young Ed]

As I said, my thermostat is the more modern choke type such is this:

Jim you are using that in the cast housing with a rubber plug blocking the passage to the top of the water pump correct? How is that thermostat held in place inside the cast iron housing?

[55 Fargo]

Thanks for all the tips!

To answer some of the questions, the engine rebuild was a few years ago. I'm sure I have several thousand miles on it since then. I have checked the thermostat to verify it is opening at the proper temperatures.

I think what I'll do next is to get one of those infrared temperature sensors and see if I can find any hot spots anywhere.

As I said before, the radiator seems to have proper flow. Back in my VW days, people used to take the shrouds off the engines to let the air flow better but others claimed that disrupted the proper flow of air across the cylinder heads and actually made the problem worse. I'm going to re-install all the sheet mettle around the engine compartment to see if that could be a contributing factor.

Of course, right now, I won't have any problems as it is cool and in the 60s or lower. I won't know much until the temps start hitting the 80s. Also, maybe I'm just asking too much from my car to drive 60+ mph on a 90 deg day for any length of time with the 4.125 differential and no overdrive. If I keep it down to the mid 50s, it will creep up to 200 but will max out there.

Thanks again, I'll let you know if I find anything.

Jim, there is something to be said about hot days, 85 to 100 degrees, higher speeds, higher engine rpms. With your lower geared diff, it would be cranking out ta few rpms at 60= mph, add some hills, and load, and things are going to get hot.

I still believe your engine temp should be below 200 max, temps above are not gonna benefit you any. Even on a hot day at Hwy speed, 185 should be a nice operating temp, hitting 195.200.205, things aren't cooling down, but building very high, and ad the under hood temps, and it's effect on fuel delivery and sometime ignition problems, only ads to the problems...

[Jerry Roberts]

As you can see it Don's picture its a 155. I think the full part # is THM 155. Drop the 1 for the other temp. I forget which is 160° and which is 180°.

In the parts list on the old original site ; 160 degrees = 55 , 180 degrees = 155 .

[Jim Saraceno]

Jim you are using that in the cast housing with a rubber plug blocking the passage to the top of the water pump correct? How is that thermostat held in place inside the cast iron housing?

My, my, my, my, my! Ed, your question got me thinking about exactly how it all fit together. I figured I had some pictures somewhere but I didn't so I did a mock-up with a spare head, housing and stat. I didn't like what I saw so I decided I better go back and take a "look see".

Well, to my surprise, this is what I found?!?!?! WTH?!?!?!

I don't know what this is supposed to be but it is nothing like what I thought I had nor what I should have!

I just ordered a new stat from NAPA and should have it tomorrow.

I know I had this open before but that was probably when I first got the car and I was just learning what it was all about. As far as I can see, this stat is like having no stat at all, it should be flowing all the time.

Now all that said, I would think the new stat will help it warm up faster but not cool any better.

I'm just amazed that I didn't figure this out years ago!

[greg g]

Unless the thermostat is deffective, it temperature rating is only a measure of when it opens, without having much influence on what temperature the coolant will ultimately reach. That is governored by coolant flow, air flow and proximity of coolant to the heated surface, and the ability of the radiator to transfer heat to the air.

If any/all of the thermostates are opening and opening fully, at their designated temp then they have have thier job. The slight difference being how long it takes 155 degree coolant to reach 190/200 vs 170 degree water to do the same. Only when the ambient temp keeps the radiator too effiecient would the thermostat come into play again trying to keep the coolant temp at its rated value by possibly restricting some of the flow through the radiator. So the temp rating of the thermostat has very little to do with normal operating temp.

Rule of thumb hot at idle or slow speed related airflow problem, hot at high speed, coolant flow or problem related to fan belt slippage, water pump problem, restriction withitn the block or radiator, and crud in the block preventing the coolant proper contact with the areas needing is attention.

My car at highway speed 60 + with 4.11 gears hardly ever goes above 170, regardless of the air temp. whent is 80 or above it will get up to 190 when drving slowly climbing hills or in stop and go conditions. It will quickly drop bact to 170/180, upo resuming road speed again.

Edited March 2, 2011 by greg g

[Young Ed]

However if the thermostat isnt the correct type or is stuck open it could possibly be letting the water leave the radiator too soon before its had enough chance to cool.

[Don Coatney]

However if the thermostat isnt the correct type or is stuck open it could possibly be letting the water leave the radiator too soon before its had enough chance to cool.

I think the problem could be just the opposite. Water returning to the radiator before it has had a chance to become heat saturated. Hence the engine never runs cool.

I recall when I was just a pup my neighbor had a flathead ford circle track racer. In order to prevent the engine from overheating during a race he welded a couple washers in the thermostat housings to restrict water flow. I say two washers as flathead fords have two thermostat housings.

[Phil Martin]

I think it was off a chebby. Friend said they used them drag racing for more air flow. Had to drill the center hole a little bigger.

[greg g]

hence the use of the word defective, as in not operating as designed.

An improperly operating stat can in and of it self cause overheating. A properly operating stat in poorly operating system will not exacerbate the condition.

And removing the stat for test purposes an easy way to tell where the problem lies.

[Jim Saraceno]

Well to top it all off, not only was it the wrong thermostat but I threw it into a pan of boiling water and nothing! It was either stuck open or closed, I'm not sure which.

I still can't believe I had never noticed that before! I remember having it out and I remember testing it. I just don't remember when. I thought I had replaced it when I did the rebuild but had I, I would have had some pictures of it.

As I tell people... I have a great memory. It's so good that I can even remember things that never happened!

Edited March 2, 2011 by Jim Saraceno

[greg g]

AHA the old defective thermostat problem........................

[Jim Saraceno]

AHA the old defective thermostat problem........................

I'm more concerned with the defective memory problem.

I would still get the shrouds and such back on. As stated, water cools in the radiator. If the air can go around, it will.

Yes, that definitely on my "to do" list.

Rule of thumb hot at idle or slow speed related airflow problem, hot at high speed, coolant flow or problem related to fan belt slippage, water pump problem, restriction withitn the block or radiator, and crud in the block preventing the coolant proper contact with the areas needing is attention.

Thanks Gregg! That makes a lot of sense. I had originally thought it was a problem with radiator flow but when it passed the simple flow test in the shop manual, I figured it must be something else.

So... I'll be replacing the thermostat tomorrow, I'm going to try to back flush the system, replace the splash pans and shrouding, check the timing and the mixture setting on the carb, and get an infrared temp sensor to check for hot spots... then wait for some hot weather to see if there is any change.

Edited March 3, 2011 by Jim Saraceno

[Alshere59]

Interesting thread.

The obvious answer for the original poster seems to be a properly operating cooling system. He seems to have it figured out which is the most important thing but.

Some things that were discussed generates food for thought, for me at least. Granted they would come into play more at idle and slow speeds but with fans you are turning a bit of weight and alot of drag on an engine.

I thought fan shrouds were introduced around 1953 ish. Right wrong?

Would they be needed or were they even installed on his?

He has the 4 bladed fan with the smaller pulley(?) versus the 7 bladed fan with a larger pulley that was introduced about the same time as the shrouds from what I can tell.

Is one better than the other? He has a 230 motor which I don't think that is stock for that year. Would the fan and pulley be matched for a shroud and/or 7 bladed fan? Agreed his problem seems to be speed related, which indicates flow of coolant versus air. However pulley size does increase coolant flow with a smaller pulley and decrease with a larger one.

My questions are

Was the change due to inadequate cooling on the 4 bladed fan or was it slowing the 7 bladed fan down with the larger pulley for another reason? Do we need to think about this when changing out engines?

Was the 7 bladed fan and shroud introduced at the the same time?

I can't find the answers.

Some things I have looked at are:

Cooling obviously. Any historical problems they (factory) addressed?

Sound as fans are loud. A marketing issue?

Loss of horse power and the gas mileage as well. (Which is why I am looking at it in all honesty.) Did the factory also?

Picture included of the factory for the right year I believe. I don't see a shroud around the fan but it is not very detailed. Or are the shrouds discussed the "shields" in the manual? They woudl funnel air at speed I think. Either way I like the picture.

Edited March 3, 2011 by Alshere59

[greg g]

I believe the 7 bladed fan was introduced on commercial vehicles like taxi's, police cars and other vehicles sold for use primarily in urban areas, and then perhaps to cars sold for sale in the deep southern states. Shrouds were maybe intro'd in 53/54 As hood lines got lower and grill openings smaller. Taking radiators down in height with them, and fan smaller in diameter.

[Drdialtone]

Gentlemen, way back in this thread I was wondering about installing an aftermarket shroud. I've scanned the replies and saw the year 53(?) they were original equipment, but nothing about "adding" one to the 47. Does it help? Do nothing? Or cause more heat issues? Thanks!!

[Alshere59]

If you are overheating that needs to be addressed as to the cause. If your running warmer than normal in city traffic, parades it should help in those situations. A shroud thread here gives an excellent way to make one.

http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=25606&highlight=shroud

Edited March 3, 2011 by Alshere59

[Dodgeb4ya]

6 bladed fans were what were used on the bigger trucks and 1953 and up plymouths ect. Fan shrouds are used on all the inline 8 cylinder Chrysler flatheads,. as were the 1951 and up Hemi Chryslers.

[Jim Saraceno]

I installed my new thermostat. While I was at it I replaced all the hoses and clamps. I then poured in some radiator flush ran the engine for 20 min. back-flushed the system.

I put in some rust inhibitor and something akin to "water-wetter". I put new coolant in, then took her for a ride.

I was gone for about two hours and she ran at a steady temp of 180. I even had her out on the highway doing close to 60 and the temp stayed right at 180.

It is only in the mid 60s here today so the real proof will come when it's in the upper 80s but I was real happy the way she performed. I think even on a cool day like today, if you drove her 60 the temp would slowly creep up.

I'm still beside myself about that stat. I could have sworn I replaced it with a choke type. The only thing I can come up with is I had it open early on when I first bought the car and didn't know exactly what I should be looking for. I must have just seen the 160 degree mark on it, tested it, and put it back in not knowing any better.

[55 Fargo]

I installed my new thermostat. While I was at it I replaced all the hoses and clamps. I then poured in some radiator flush ran the engine for 20 min. back-flushed the system.

I put in some rust inhibitor and something akin to "water-wetter". I put new coolant in, then took her for a ride.

I was gone for about two hours and she ran at a steady temp of 180. I even had her out on the highway doing close to 60 and the temp stayed right at 180.

It is only in the mid 60s here today so the real proof will come when it's in the upper 80s but I was real happy the way she performed. I think even on a cool day like today, if you drove her 60 the temp would slowly creep up.

I'm still beside myself about that stat. I could have sworn I replaced it with a choke type. The only thing I can come up with is I had it open early on when I first bought the car and didn't know exactly what I should be looking for. I must have just seen the 160 degree mark on it, tested it, and put it back in not knowing any better.

I also installed a 180 t/stat today, the black rtv I used on the gasket is still setting up, will re-fill system tomorrow and see what I got....Fred

[55 Fargo]

Added, the coolant this morning, all is well, engine temp to 180 then t/stat opened, added a bit more coolant to previous level. The engine then ran at 155 while idling in driveway, did not run long, maybe 10 minutes, it was close to 0f outside. Is this normal, would have though it would stayed at 180, but maybe it would take a road trip to build up engine temp in the cold....