Looking for help and I know this is the place to go to ! I recently installed a be cool radiator in my 65 401 GS (with new 180* thermo) Its running hot at low engine/driving speed . Stuck in a traffic jam and went up to nearly250*:af: After motor is off and cools downs, the upper radiator hose will colapse. I do have a catch can which I believe is non-vented. I have run it with the cap off to vent and let any trapped air escape ..... Also my fan is a cheap flex a lite but does fit good .... Any suggestions ? Thanks to all ! ............... Jimou:
Any mechanical fan setup should have a shroud. Do you? Do you have a clutch on the fan? If you have a recovery tank you should have a vented radiator cap, so it can recover the lost coolant back into the system. That should also fix your collapsing radiator hose. In addition to those things, make sure your timing is set correctly, and your not running lean.
I had the same problem. Heating up at stop lights. After I put on a higher pressure radiator cap. And, got the timing right. It runs cooler. No overflowing of cooling. I would ditch the flex fan and go with a clutch fan, seven blades or more. And a shroud, as Andy says. Mine still has the original four blade fan bolted straight to the water pump pulley. A seven blade clutch fan is on my list.
All common radiator caps are vented, the difference is that some have a rubber seal where it mates to the radiator opening. The ones with the rubber seal are intended for use with coolant recovery systems, so the vent draws coolant back into the radiator. Ones without the seal--where they're metal-to-metal--are for use with overflow hoses and no recovery bottle. They draw air back into the radiator. If the upper hose is collapsing, the cap is not venting properly OR the overflow hose/coolant recovery bottle hose is plugged.
Yup. The hose is collapsing due to vacuum in the system. The cap is letting coolant out, but not back in. I'll also go along with James. I would ditch the flex-fan and go with whatever setup the car left the factory with. I like clutch (viscous) fans - the more blades the better. If the car came with a fan shroud, it needs to be in place. All things being equal (fan diameter, number of blades, RPM, blade pitch, etc), a ducted fan is more efficient then an unducted fan. An engine's cooling fan without an effective shroud is unducted and significantly less efficient then a the same fan with one.
Running hot at low speeds means the rad needs more airflow. How far from the rad is the fan? If it's several inches, it's too far away. Is the fan on backwards?(it happens!) Double check that! I've had good luck on my 66's using either clutch fans or the 7 blade fixed fan, both without a shroud.
Thanks for all the imput...... I will order a fan with clutch ( I do have the shroud in place ) I will also look into my catch can / cap / vacuum set up. . Possibly drill a small hole to break the vacuum .... Running lean.... I don't think is the issue, but will double check ! keep you all posted ! Jim
A hole drilled in the thermostat is a good idea. (Edit: see Shurkey's comment below) Don't put a hole any where in the radiator cap. It'll fail to pressurize. That will lower the boiling point. That's not good.
It's common, but "good idea" is another matter. A hole in the thermostat does nothing beneficial after the cooling system has been filled and burped provided the original bypass system is still in place. In other words, it's almost always a total waste of time, AND because most folks drilling their own thermostat use a drill bit that's seven times too huge, it delays proper warm-up. THAT'S accurate!
The Robertshaw thermostats have a designed-in vent of appropriate size. The vent makes filling the cooling system after service work slightly easier, but the vent is also small enough to not interfere with cooling system operation. As far as I'm aware, the Mr Gasket thermostat is a Chinese knock-off of the Made-In-Mexico Robertshaw. Both have had some complaints regarding thermostat sticking. The last Robertshaw I bought was probably ten years ago, and I took it back out of my Toronado because I couldn't trust it to open properly. Coolant temp would hit 220, before dropping dramatically. Keep in mind that this is a sample size of "ONE" and may not mean anything significant--anyone can produce a defective product now 'n' then. What can I say? I've been buying plain ol' ordinary Stant thermostats ever since, and the lack of a vent doesn't particularly bother me. At any rate; here's a photo of the Robertshaw style. The designed-in vent is at about 7:00 on the photo, the vent is the hole (unseen) left by stamping the sheetmetal where you see the little ridge near the edge. I may still have that thermostat, and if I do, I'll poke a drill bit into the little hole to see what size it is. I'm guessing no larger than .062, likely even smaller.
