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Print Dad

315C Running around 200ish ??

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Hello All,

My newest issue started awhile ago. The temp gauge reads high and

pretty quickly. It goes to just about pegged on HOT.

I have done a few things hoping to help. I thought this was

a gauge issue - -BUT now I am thinking it is what the motor is running.


I am looking for a few thoughts on this.


I just replaced my "thermal clutch fan" no change

Today I checked things with a thermal gun and the radiator

seems fine - -but running close to 195 in all areas. This is just with the thermal gun.


I changed the sending unit

My OIL pressure gauge had seemed to be running high for a few times

BUT now seems to be working fine.


So I am thinking I will swap the thermostat to a 180 - -I think I am running

a 195 now - -BUT I can't recall - -about 3 years old.


The car is running HOT for sure BUT never pukes out the overflow.


Many people tell me to swap the thermostat - -and I will - BUT I would think

once the thermostat is open - -it is open. Thoughts on this?


I am running a shroud.


I think I will flush the system and replace the antifreeze (50/50 mix.


Seems like after the thermo swap - -I may be looking at a water-pump.

EVerything on the motor is stock with the exception of Morroso "tall" chrome covers.


I Was just wanting a few opinions on where I should head next.

The radiator is stock BUT seems to have good flow and NO blockages according to the thermal gun.


Please offer a few thoughts - -THANKS


Print Dad


Oh yeah - -do they make more than 1 sending unit for a Clev? Just wondering.



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The stat on a Cleveland is not like the common stat. There should be a plate under the stat with a hole about the size of a nickel. The Robert Shaw Cleveland thermostat Is part # 333-180 is the correct one it has a "hat" that when open closes off the hole.It's there to make sure most of the coolant passes through the radiator, and not just through the block when the thermostat is open. When the thermostat is closed, the hole in the plate allows the coolant to still circulate through the block. The plate serves the same purpose as the thermostat by-pass hose used on all other engines. Without the plate in place, when the thermostat is open, too much water will be allow to just circle through the block, without going through the radiator first.

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First off, is it running hot just sitting at idle or does it run hot when you are going down the highway at 60mph? If you notice the temp creeps up sitting at idle but when you go down the road at higher speeds it cools off, then it is likely a fan issue. If it runs hot all the time, it could either be a partially blocked radiator or a weak waterpump.


I assume you are running a mechanical fan. Is it the stock one or an aftermarket one? How many blades?


If you are running a 195° thermostat, then I would expect the motor to run just above 200°. Keep in mind that 200° isn't exactly overheating. Many people get hung up on high temps but don't realize what temps modern cars run at. You get less emissions and less engine wear at higher temps. I personally wouldn't get worried unless you are creaping up to 215-220°, that that is just me.

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PD, many parts are cleveland only when it comes to the cooling system.

You need to have the restrictor plate under the stat and use the Robertshaw 333-180* stat.

The sending unit is longer and mounts in the block.


As for temps, A 195 stat will be completely open at around 202*

basic rule for all stats is add 7* to stated rating.


Check the coolant flow with the cap off and at temp it should look like a river passing by the neck.

The stat when working correctly will open and close as needed to maintain the temp its rated at.

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Buening is correct, you need to diagnose if in fact it is overheating and the cause. Jim, I know you from another forum so you pretty much know what your doing. I would venture to say you have kept your radiator/cooling system cleaned and flushed.


Because changing a thermostat is relatively quick and easy, many people quickly assume that is the problem. Unfortunately, all to often the incorrect thermostat is installed because the kids at the parts stores don't know to ask if its a Cleveland or a Windsor.


As dennyb68 pointed out, the incorrect thermostat will cause the coolant to not circulate properly through the radiator. The flowkooler stat he recommends is popular among 351C guys but very hard or impossible to get.


See the attachment I provided as it is a good reference to insure you have the proper t-stat when/if you do replace it.

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Hello All,

THANKS for all the info.

I should have included a little more info in my first post BUT

getting OLD and loosing a little umph.


dennyb68 - -You bring up a great point about the restrictor plate. To be honest

the last time I swapped out the thermostat - -I think about 4 years ago - -i DON"T THINK the restrictor was in the block. This could be part of the issue.

How does the restrictor plate get held in place? OR is it just drop in?

I need to remove the neck and see if the plate is there. THANKS



buening - - I am running a 24 inch radiator Ford - (Previous owner had installed). Yes I am running a mechanical fan - - I am using a thermal clutching fan (just replaced the clutch) and running a 7 blade fan.

I have had this set up for the last 5 years and just started having and issue

last year.

The temp seems to climb pretty quickly after start-up and DOES NOT go down. At first I thought it was a gauge issue - BUT now - -no - the temp gauge (factory original) gets almost pegged and stays there. Even driving on the highway it stay HOT.

I plan to check a few things like circulation and clean the fins on the radiator and of course swap the thermostat.


dennyb68 - -I understand what you are telling me. I gotta check for the plate.

I don't know how the plate is held in place, BUT I am fairly certain my motor does not have the plate under the stat



Mach1Rider - I forget what thermostat I installed years ago. I will check when I pull it. I am going to check the coolant flow - BUT not certain what is

happening there. I DO NOT think the restrictor plate is under the stat.

I know the stat in there will be stamped so I'll check it out


Wycked69 - Thanks for noticing me on the other forum. I would like to think

I know a little about classics. Yes the radiator although OLD is in pretty good shape and did have a good circulation - -I will check that today.


Thanks for the helpful attachment - -nice to have numbers.

I am VERY curious now - becuase if I recall back when I first swapped the stat - I don't think the restrictor plate was there. I think people told me that it was NOT needed at that time and I think I MAY have ignored the fact that it was missing.


I am VERY CURIOUS how the restrictor plate is held in place in the block. Is it something that just presses in or is it kinda held in place after the thermostat is installed. Damn - I gotta go out in the garage now and check this out.


Will post in a little bit about the restrictor.


THANKS ALL - -I must admit I am loosing my confidence in wrenching on the car and I sure would like to resolve this issue


THANKS so MUCH to everyone



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the restrictor plate is pressed fit into the block, without it the coolant will NOT be forced to the rad when the stat is open.

This will cause temp to creep upwards no matter what speed the engine runs at.

Same thing happens when the wrong stat is used on a C block.

Edited by Mach1Rider

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Print dad, "if" for some reason the bypass restrictor plate is not there, The only place I have found them was from this person on ebay.



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Hello ALL,

I had to go out and check the thermostat.

I am GLAD I found it does have the restrictor plate under it.


The thermostat I took out - seems to be OK BUT of course

I am going to swap it out. The one in there is the correct style

for the C but it is a 195 and I would like to drop down to a

180. Not sure what brand it was BUT said "303-403 195.

I am going to the parts store and see what they have available.

Thanks to the link from Wycked69 I can just call and see if they have the part.


I know the thermostat needs to be tested BUT from looking at it - it appears

to be working and was NOT stuck - -I was wishing it was LOL


THANKS all and I'll post my progress



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I would also recommend installing an aftermarket temp gauge (even if temporary). The factory gauge should be taken with a grain of salt, as it is easy for them to get out of whack and what exact temp is the "H"? It varies from car to car and once it pegs you have no idea just how hot its getting. I think my gauge pegs at 190-195° if I remember correctly.

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Hello All,

Well I replaced the thermostat TWICE LOL

I had a 190 in the garage and today bought a 180.

Somehow I installed the 190 instead of the new 180.

The thermostat that was in the motor was a 195.


I started the car and let idle. I watched when the thermostat opened

and the radiator fluid was flowing REAL WELL - - but looks merky.


I most likely should have flushed the radiator I have a bottle of flush,

BUT was hoping the new thermostat would help/cure the issue.


Well after sitting at idle for about 15 minutes the gauge was reading pretty

hot. NOt quite as high was before BUT still was around the right side

of the "M" in temp.


I kinda am hoping if I take it for a ride - -he may cool off a little more.


Looking into the radiator - -I can tell it should be professionaly flushed

at a radiator shop. I MAY go that route next or a MAY just go for a new

radiator. I DID NOT have the thermal gun today - -but the radiator feels

about the same TEMP at all spots.

Not sure where I stand now.


I will also get a gauge and see exactly what temp it is running.

FOr a quick test - -can I use the same sender that I am using on the

factory gauges????


I sure would like to get past this. The car is running GREAT - -the OIL

looks real real clean and NO signs of foam or anything on the stick.


I need to figure out what I am dealing with. Like I said - may take her out for a drive and see if the moving air helps.

LAstly - -I blew out the FINS on the radiator to see if that would help.

SO some progress BUT still not satisfied yet


Thanks fro hanging with me on this



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Need to figure out what your dealing with?


From what I am reading, you had a 195 stat in there and it was running about 195. Then you installed a cooler stat and it appears to be running a little bit cooler but you haven't pointed the thermal gun at it yet.


Am I missing something here? The car seems to be running at the temp of the thermostat you are installing in it. Other than a somewhat inaccurate factory gage (common), and slightly dirty coolant, I am having a hard time seeing that anything is wrong at all.


Forgive me if I am missing something....

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Hello Max Power,

When you write it out that way - I sure look goofy LOL




I have had this car for over 35 years and the needle on the temp gauge

always ran just over the center of the gauge. Last season the needle started

to get higher on the gauge. I KNOW the factory gauges are not all that accurate and I am going to do a few more tests including hooking up a set of gauges at least temporarily to see what exactly I am dealing with.


I would like the temp to run in the 190 range BUT I would like to have room

on the factory gauge so I know when I am getting into trouble.


As mentioned this started last year. In an effort to help cool things down

I installed a thermal clutching fan and a 7 blade fan I had in the garage.


This is just a CRUISER - -not a show car or anything. I like to keep things

inside looking pretty darn stock and still listen to the 8-track I insalled

back in the 70's. To be honest - I probably should not own this car as

I can't afford all the things I would LOVE to do to it.

Teachers pay is not the best and a son in Med school makes things tight financially. In many ways the car deserves a better home BUt it is part of the family and I do the best I can. The only thing I have ever had done on the car was a custom exhaust - -getting too OLD for me to be crawling around in the rust. LOL


So yes - I MUST figure out exactly what I am dealing with here.

I will figure this out - -it may take a little time



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I'm using a RobertShaw 333-180* stat, 24in stock rad with shroud

& 7 blade clutch fan with ac condenser infront.

Temp was verified to guage readings with thermo in neck of rad in coolant with engine at operating temp with stat open.

Sitting idling in the garage at 186* the gauge reads just right of the E's down leg(sort of splitting the E on an angle)


Sitting in traffic at a stoplight in 95* temps it may slowly run upwards of 190-195

But will quickly drop back down once rolling again with air flow.

This is how I guage if the cooling system is working properly.

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Thanks Mach1Rider,

I was wondering where the needle would be if the motor was running

around 190-195. I think it always used to be there.

My plan now is to take the car for an inspection sticker and see how the

temps run. If it is still high on the gauge - -I think I will have the radiator

cleaned out at a local shop. They want $100 BUt it sure would be nice to

not have to worry about the whole issue.


Thanks again - - Jim

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My car runs around 195-200* on a hot day. I have the 190 thermostat installed, original rad and fan. I am wondering what 'normal' temp. is supposed to be? Just for the record I am running a Clevor so the cooling system is different than the 351C.

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