Ok this might be long but im trying to be as specific to the problem as i can. i bought a 1970sx that had a bad overheating problem, it has no shroud and a 4 blade fan with no clutch. After tinkering with it a little bit i adjusted the timing(it was way off) i cut cut the thermostat spring out(testing purposes) and added coolant. to my surprise it took a little longer than normal to heat up and on a drive about a half hour away it was at 190 on the highway were normally it would shoot up to 250!! At a stoplight i sat through twice off the highway it went up to 210 and rising but once i made it through and was cruising again it dropped to 190(im making headway).. Now. I installed a shroud, 6 blade fan and clutch thinking it would be better at idle. to my surprise it was worse on the highway running at 200ish instead of 190 with old setup, and on the side streets it will run at 210 moving instead of 190 unless i come to a stoplight or traffic where is rises to 220 and climbing? what is going one here?? How it worse with new setup?

 

Maybe the new setup has a bad fan clutch.

- Eric

 

Any way I can tell?

 

You can drive it around for a bit,
get it up to temp, and see how it
is turning at idle. If just barley spinning
the clutch is shot. Does it have any wobble?

 

The shaft should be tight, there should be no wobbling or play.
When it is cold, you should be able to give a blade a hard push, and the fan should rotate about half a turn.
When it is hot, you should be able to move it by hand, but there should be resistance, and it shouldn't turn at all once you let go.

Also, are you sure it's the right clutch for the size fan you have, and not one for a smaller fan?

- Eric

 

ok i just took the car out. it definatly takes longer to warm up then with old setup. it drives right around 200 unless you come to a stop then it bumps to 210 213. sitting in my driveway at idle it went up to 215 then backed down to 210(hood open) i took it back out and cruising it drops to 211 again. came back idling in the driveway again it stayed at 210 for about 2 mins then went to 216 and stayed steady going up a degree at most. seems with hood closed its hotter at stoplights and signs but that obvious being air is trapped? as far as the fan it definatly blows like a mother and does have a slight very slight wobble and spins somewhat not completely free with car cold, with car hot its spins just under half a turn. the clutch is correct to the fan and came off of olds with a 455.

 

Hmmm. 3 or 4 core rad?
Did you have it taken to the radiator
shop for a cleaning? Is it a little on
the crusty side around the passages
when looking down in?

 

I'd consider a new fan clutch.

I also agree that it's worth having a look at the radiator.

Finally, what kind of thermostat do you have in it now?

- Eric

 

4 core, not crusty and never cleaned. Just find it weird that it ran cooler not at idle but moving with the old 4 blade fan with no clutch or shroud.

 

On his first post he said he cut the spring off his thermostat. So maybe that's his problem?

 

Also do you have the rad by-pass seals
in place on both ends at the rad support?
These help to draw air across it as well.

 

Yeah, I read that, but still wasn't sure whether it's his current configuration.

Also, having never heard of cutting a coil off of a thermostat spring (I mean, this isn't the Great Depression, and we do have auto parts stores), I wasn't really sure that he meant what he seemed to mean.

- Eric

 

yes still have the gutted thermostat, did it yesterday night for testing purposes incase it was stuck, parts stores were closed last night and obviously closed today so i havent picked a new one up yet.

 

Weird. They're all open today around here.

I'd recommend a Robertshaw high-flow thermostat (sometimes sold under other brand names, usually less than $10).

I like 180°, others may argue for 160° or 195°, but that's a separate (and recurring) discussion.

When I want to know whether a thermostat opens, I put it in a pot on the stove and heat up the water.
When I'm in a really fancy mood, I use a candy thermometer to see what the temperature is when it opens.

To reiterate, we may all be barking up a bunch of wrong trees, but my feeling would be to replace the thermostat with known-good high-flow model, and to replace the clutch if it's not completely tight and wobble-free on the shaft, and then try it again.
These things can be very frustrating sometimes.

- Eric

 

thanks everyone i really appreciate all the responses, iv been on many other forums(iv owned lots of different cars) and usually get one to two or no responses. i appreciate everyone taking the time to read and respond. thanks again guys.

 

That cannot possibly make the thermostat work better.

Trust in the engineers
Do not molest parts at random

Start with a proper new thermostat, the purpose of which is to properly control engine temperature.

 

Depending on what your ambient outside temp is your last test are not abnormally high. Can you post a picture of your fan position in the shroud? It should be half in and half out.

Which distributor are you running? Timing can wreak havoc on engine temps.

 

It sounds like you have a non air car. Make sure you have the correct fan clutch. A non air car takes a fan clutch without a spring ( on front of clutch ) and a air car takes one with a spring ( thermostatically controlled ).

 

It is a non ac car, I'm not sure about the clutch it's possible it is wrong then. Maybe that's why it ran cooler with the 4 blade fan and no clutch?

 

The clutch does have a spring in it. Would that help me to cool better? How's it all work.

 

The non-A/C clutch is centrifugal (if I recall), and it releases as the fan spins faster.
The A/C clutch with the bimetallic spring is thermostatic.

The A/C clutch will probably work better, as it releases when the fan is not needed, thus saving fuel and your ears.

If the clutch is worn out, though, it doesn't matter what kind it is.

- Eric

 

X2 Oldscutlass- timing and or distributor issues will heat these babies in a hurry. Question:what is the timing number at idle with the vacuum advance plugged at the carb and at full advance around 2500rpm? ( I say around 2,500 RPM because I'm sitting at the computer without a spec book in front of me) but I know its very close if the 455 is stock with a GM HEI. Really check on it because it also give you an indication if the chain or cam sprocket is worn.

 

Did some testing yesterday canned a few things. Took out 6 blade fan (found out it's a flex fan where the blades slightly flex under load don't know if that matters). Installed my old non flex 4 blade (no clutch) and the car seems to run cooler. With the shroud, 6 blade fan and clutch was at 200 highway sometimes slightly higher and 210/212 on side roads and it would go up from there at a light or traffic. With the old setup and a shroud I'm at 185/190 highway and 195/200 on side roads. It still likes to shoot up at lights and traffic to 210ish(keeps rising the more I'm sitting still) but it drops back down right away once im moving.

 

Ohhhhhh... Minor detail. You didn't mention that it was a flex fan.

This is why we like photos.

Go get a proper original fan and use it with a proper original fan clutch, and tell us how it goes.

- Eric

 

So a flex fan is a bad thing in guessing? Going to try to find a 6 blade non flex if I could.

 

Some flex fans work well and others are just junk.

 

True, but none of them works at all with a fan clutch.

- Eric

 

+1

 

+2

 

Are you sure the Shroud is the right one? The fan blades should be close to even with the edge of the shroud and about a quarter inch from contacting it. Also make sure the radiator is FULL. Add some WWetter additive also and read the label. Good luck.