Thermostat.

[grs]

My 327 has a 160 degree thermostat in it. Would it run cooler with a 180 in it? I read it should be a 180.

[AcampoDave]

Is it running hot now? It should be running around 160. A 180 therm should make it run at 180. 160 is kind of on the cool side with regard to burning off engine deposits and getting decent gas mileage. If you are overheating with a 160 therm you may have a different problem and you'll still likely run just as hot with a 180 provided your thermostats are operating normally. I base my thinking on my own truck when my brother installed a 160 stat without me knowing. Eventually I had to wonder why it didn't heat up.

[66Submarine]

x2.

180º or 195º is what they came with.

[grs]

The gauge says 220 at slow speeds and idle. The sender is in the intake near the state. The gauge is an after market one with no name on it. The milage is not good. I think I will put a 180 in it.

[AcampoDave]

I too have an economy aftermarket guage with the sender in the same location as yours and my guage is a lying s.o.b. It says 200-220 but the turkey thermometer in the radiator test says 180. Maybe that's a hot spot up there on the intake by the thermostat. Try the 180 and bring it up to temp with a meat thermometer in the radiator neck and find out what's really going on.

[66Submarine]

Originally Posted by AcampoDave

I too have an economy aftermarket guage with the sender in the same location as yours and my guage is a lying s.o.b. It says 200-220 but the turkey thermometer in the radiator test says 180. Maybe that's a hot spot up there on the intake by the thermostat. Try the 180 and bring it up to temp with a meat thermometer in the radiator neck and find out what's really going on.

That should be the hottest point, since the water has gone all the way through the engine to get there. If you are measuring radiator temp with a crossflow (other type doesn't really have much coolant to stick the thermometer in?), you are measuring the coolant temp after going through the radiator and cooling down.

Running hotter when idling and driving very slowly indicates that he just doesn't have the cooling capacity to maintain temp at idle because of a lack of airflow through the radiator (or something similar, like poor coolant flow); lack of a fan shroud being an obvious potential cause. What's your cooling system like?

[grs]

I have a good radiator. 3row. It is clean inside. A shroud. I took the fan clutch off and put a 6 blade fan on it. It is still the same.

[66Submarine]

Originally Posted by grs

I have a good radiator. 3row. It is clean inside. A shroud. I took the fan clutch off and put a 6 blade fan on it. It is still the same.

That's not right then; my stuff with no shroud will do at least as good or better than that.

You might have a coolant flow problem.

Does it maintain 160º on the gauge when going down the highway? I'd also suspect the cheap gauge at this point.

[grs]

It may be 190 going down the highway.

[LVPhotos]

I just got done doing a radiator fix. New hoses and thermostat. I run mine at 180 and you can watch the gauge climb to 170. Then I like to check the top hose for the opening of the t-stat then confirm it is at 180. Temp probe next to the water neck like yours. Fan is more than 5" from radiator and no shroud and its a 400 block "notorious" for heat, never had issues in the desert heat.

[66Submarine]

Originally Posted by grs

It may be 190 going down the highway.

That's not right if you have a 160º thermostat and it runs 190º on the highway; as LVphotos noted, you shouldn't even need a fan (IME) to maintain 180º going down the road (and probably 160º if you have a 160º t-stat in there--I just never use them).

Something's up with your cooling system.

[AcampoDave]

Your guage is a lyin' s.o.b just like mine. Bring it up to temp with a meat thermometer in the radiator neck and check it before you start throwing money at your cooling system. Cheap guages are only good for a "ballpark" number.

[grs]

Thanks everyone. It has never boiled over, so it must be the gauge.

[66Submarine]

Not to say it's not the gauge, but 220º isn't boiling over unless you are running straight water with the cap off.

[Anthony Fremont]

I have a v8 in my old truck and a 180 thermostat. I have the original top to bottom flow radiator and a hayden electric fan in front of the rad. My thermostat stuck open and the truck would get too hot from the water flying thru the radiator and not cooling. It would take a while to warm up, but it would still end up getting too hot (220F).

I replaced the thermostat with a new 180F and now it cools like it should. I use an IR temp measuring tool (everybody should have one of these) and it never gets more than 195 at the front core plug and top of the radiator even in houston sitting in traffic on a 100F day. On the road it stays at 180. Too much water flow can lead to overheating regardless of what people tell you.

My summit electric sending unit stopped working a long time ago and they want a fortune for a new gauge and sender. They don't just sell the sending unit. That's why I use the handheld to keep an eye on things for now. I'm going to replace it with an old-fashioned mechanical gauge probably this weekend. My stupid electric fan sender also quit so I have the fan running all the time. All the 50 year old parts work fine, the new stuff is junk and breaks in no time. With 180F water going in the top of the radiator it comes out the bottom at 160F or less.

[cg285]

Originally Posted by Anthony Fremont

Too much water flow can lead to overheating regardless of what people tell you.

it's hard to convince people of that. i quit trying

[cortcomp]

Originally Posted by cg285

it's hard to convince people of that. i quit trying

I've had it both ways...i had a truck with an SB400 with no thermostat and it would never get warm, couldn't get heat out of it in the winter AT ALL. I put a 160 in and finally got heat. It ran damn chilly.

I also had another car with no thermostat in it, would run boiling hot. Put a 160 in it, ran completely normal.

There is no blanket rule how a setup will run with too much flow, each one seems to react one way or another.

I would check timing also, when i broke my 455 in i had it at 10-12 degrees which was a little conservative and it ran 210 all the time, either 60 degrees out or when we were idling through a fairground for half an hour in 115 degree heat, never moved, always 210.

I finally fine tuned the timing where she liked it, 15-16 initial, and the car runs 180-190 all the time now. Was a huge difference for just about 5 degrees advanced.

Also, the Mr. gasket radiator cap with the thermostat in it is dead on, i have a couple i use to keep an eye on new motors, or during break in. They have read dead nuts on with the laser thermometer and trusted dash gauges. Cheap good troubleshooting tool to have, although i think they look gaudy.

[Anthony Fremont]

Originally Posted by cg285

it's hard to convince people of that. i quit trying

I hear you, but it's the truth. I put a mechanical gauge in the other day to replace the failed summit gauge's sensor. It's in the driver's side head up front. It shows anywhere from 185-210 even though the water coming out the neck is dead on 180. I used a laser thermometer to verify it and even the brass nub sticking out is showing that temp. It might be that the head heat (from exhaust manifold) is transferring to the sensor or maybe the sensor is too close (or touching) the metal in the head. Seems like on the road, the gauge is showing 190 most of the time, but starts climbing as soon as I stop. I'm not worried, just annoyed that extra heat is transferring to the sensor somehow, and it's not from the actual water. It's a cheap equis gauge from o'reily. The summit gauge didn't do that as I recall. My haden electric fan is set to run all the time since the controller for it stopped working right. That sensor is always at 180, but then it's in the intake manifold next to the thermostat housing/water neck.

[Anthony Fremont]

Originally Posted by cortcomp

I finally fine tuned the timing where she liked it, 15-16 initial, and the car runs 180-190 all the time now. Was a huge difference for just about 5 degrees advanced.

Yeah, that's another thing that can make a big difference. Late timing can make the engine run quite a bit warmer.

[AcampoDave]

My lying guage is an Equis too. But it's electric

[grs]

My timing is 6 degrees before tdc. I think it should be 8 degrees. I don't think 2 degrees will cause it to get hot. It gets hotter at idle. Maybe the idle screws need adjusted.

[markeb01]

Another consideration if an electric temp (or oil pressure) gauge is reading incorrectly, make sure there isn't any Teflon tape on the sending unit. They need to be bare metal for the correct ground. If it leaks without sealant, use "sensor safe" sealant like Permatex Ultra Black - it's listed as sensor safe, and I'm sure there are others.

[Snailed]

Sensor safe RTV is safe for oxygen sensors down stream of the sealant. It does not mean that they conduct electricity. Even the copper colored one which has no metal in it.

[markeb01]

That's good to know, they don't bother mentioning that anywhere on the package. I had to use some on my engine fan thermostat. Just to be sure I only applied sealant near the top of the threads. I left the nose bare just in case, and it works fine. Thanks for the input.

[Anthony Fremont]

Originally Posted by grs

My timing is 6 degrees before tdc. I think it should be 8 degrees. I don't think 2 degrees will cause it to get hot. It gets hotter at idle. Maybe the idle screws need adjusted.

Is that with the vacuum line connected? If so are you using manifold vacuum or "ported" vacuum? If you have manifold vacuum connected and only have 6 degrees advance, then it is way too retarded.