Keeping it Cool

Hey guys, I am wrestling with a Running Hot problem. I have been getting ideas and info from fellow vanners over at VCVC. I have a 64 Chevy van with a 350/350 setup and the temps have always run high, too high. I am getting good gas mpg and it runs good. There has to be something that I am overlooking. Here is what I have done.

Runs 220°-230° on Highway at 65+ mph, Stays under 190 around town in stop and go traffic. Can idle all day long at 180°. So, here are the things already done or checked.

Less than 500 miles on rebuilt 4 core radiator
Checked lower radiator hose
Checked and reset timing at 8°
Tried every thermostat possible
Install wind tunnel in front floorboard
Install lower air scoop
Install fluid recovery reservoir
Install Taraus/Lincoln Mark III electric fan
Running 50/50 mix of Antifreeze
13psi Radiator cap
Removed Thermostat and parked nose up on the side of a hill, to possibly burp any trapped air out of block.

You suggestions will be appreicated

Eight degrees? Is that advanced or retarded?

Retarded will make the engine run hotter...

You probably know that, though.

How did you check the lower radiator hose? Is the spring inside intact? Can you crush the hose with your hand?

After the van has run hot, with the engine shut off and the key out of the ignition, have you confirmed that the radiator is warm at the bottom?

Is the radiator a horizontal channel affair, the same type that is used on the '67-69 V8 Chevy vans? If not, it probably should be.

Is the block new or used? If used, was it boiled out to make sure the cooling passages are clear? Did you pull the two drain plugs on the block when you flushed it?

My '67 283 runs a bit warm, although it appears that it is now running cooler (and recovering faster from running up to 200+) after adjusting the hydraulic valve lifter lash to spec (idling hot). I believe it must have a 190 or 195 thermostat in it, which is fine with me because that is better for the motor than a 180 thermostat (I understand). Helps to remove moisture and any blowby fuel from engine oil.

It's also my understanding that these vans should have a lower splash guard under the radiator. The one on my van is missing, which may be why it runs a bit warm on the highway, although it makes more sense to me that the lower guard functions mostly to prevent warm air from recirculating through the radiator at idle. But it might also be that the lower guard also helps to prevent some sort of turbulent non-cooling buffeting at highway speeds.

Is there a plastic fan guard behind the radiator, around the fan? That would help to pull cool air through the radiator, as well.

Good luck!

What rpm is the van running at on the highway? You say it is cooling around town but not highway. Sounds to me that the sustained higher rpm on the highway is keeping it hot. If you are running the stock size radiator ( 64-66 ) this radiator is only 17 x 17 3/4 ( fin area )... that may be the problem...just not enough surface area to cool the water fast enough...
Do have a thought.... are you using a high flow thermostat ? It could be that the thermostat is not allowing the coolant to flow fast enough..

these FlowKooler Robertshaw high performance thermostats are designed to resist large variations in coolant pressures that can occur at high rpm. Under these conditions, coolant temperature and pressure fight for control of the thermostat, keeping it from opening at its designed temperature. These balanced, high performance thermostats feature brass-and-copper construction and will open at the right temperature, regardless of engine rpm http://www.summitracing.com/parts/BRA-330-180/

Thanks for your responses. To answer your questions.

I am using a Robertshaw thermostat.
My rear end is a 3:36 and my guess on highway RPMs s 2800-3000.
Van has a new 4 core down flow radiator with a full coverage shrouded electric fan.
Vacuum advance is working correctly.
Timing is at 8° Advanced, idle is smooth and engine runs good, just hot.
Lower radiator hose is a unversal ribbed type with spring inside.
I can not get the hose to collapse by squeezing it, hot or cold.
The engine came out of a running 1986 Chevy factory custom window van.

Hey + all you guys are sending out some great posts - all correct - yet heres my 2 c's worth = runs cool in town=yes= yet -Hot on highway=Yes?= heres what im thinking- Air is not getting into the radiator properly @ faster speeds!! Is there a radiator shroud?? Also the electric fan could be blocking airflow at highway speeds or limiting air flow?? Heres what id suggest - just thinking here?= remove the electric fan- go for a drive at highway speeds- cooler? hotter? The electric fans were mainly installed to cool the engines down @ slow speeds as highway driving usually takes care of cooling process. also what waterpunp & pulleys have been installed? custom or origionals?? if custom are they underdrive ones?? get my thinking? Temps are regulated ny only 2 things =airflow and waterflow rates.I made a metal fabbed shroud years back for my truck- was always running hot in city - now I must regulate the temp only thru the thermostat as it cools so good -it will keep the temps @ thermostst operating temp summer & winter-pulls that air thru as is needed. With that new radiator and all else checked (esp.= pulleys & water pump) as mentioned it must be airflow in my thinking.

I ran into the same thing last summer on mine in 85 degree weather. Same thing on regular around and about speeds , it does fine. Im running a 2 core aluminum crossflow, not oversized at all, 16lb cap, a 16" single spd fan stuck to the rad. 350 engine 4.11 gears and a 700 which brings my 70mph rpms to around 25-2600. 60 mph seems to be it's happy place, at 70 it creeped up to the makes me nervous level. This winter I lowered the rad 3 inches for another unrelated reason and I am waiting on the weather to see if that makes a difference getting it into the wind alittle more. If enough of us are running into the same thing with similar set ups, Im leaning towards the idea that at higher speeds we are creating an airflow problem somehow in the DH/rad area yet to be solved. I see twinpilot is on the same wavelength,,lol

I don't know what to say here? I am running a 305TPI engine that is suposed to be run at 223* for best eficiency. with the 342 rear gear and a 700R4 my engine runs at around 1750 to 1900 rpm at 55 MPH.
If your engine is running 2500 to 3000 rpm at high way speed I would say you need to look at that, most engines are designed to be running in the 2200 to 2400 rpm range on the highway.

What transmision are you running? You might have a dead torque converter that is slipping excessivly at high way speed. That would cause overheat for sure.

I don't use the belly pan
Have a 180* thermostat
4 core cross flow rad with the Toraus 2 speed fan shroud and all. That fan puls more air then any higway speed so I don't belive it is restrictive.
I have one of those stupid gauge in the rad cap piece of garbage. The idea of a gauge in the cap is a very good idea but the quality of that $40 cap is crap. It did not fit the mount right , was too hard to install and leaked. After fileing and adjusting it to fit and seal it lasted one run and every run for five runs afterward the neddle would return less as the engine cooled. Now ot reads in the red with the engine cold.
My engine now runs around 210 when run around 70mph.
The only over heat issuse I have ever had is when the mixture was so lean the engine was pinging and the 195* thermostat was hardly begining to open at 220.

What trans are you running? do you have a tachometer?
can you connect a vacuum gauge and go for a run? Maybe you are getting exhaust restiction at highway speed? that too will make overheat.
Did you look further into the carb boging and mixture/float level issuse?

M1D

Latest

I took off the Taurus electric fan and put on a 7 blade factory 19 inch thermostat controlled fan. Also noticed that the aluminum pulley that I put on the van after replacing the engine is about 1/4 inch bigger than the factory stock pulley. I put the stock pulley back on. Removed the thermostat housing and back filled the block, installed stat and topped off radiator. Ran it about 4 or 5 minutes to get up to temp and re-checked fluid level. Drove 3 miles to get on Interstate and temp is at 168 (outside temp 83°). Get on Interstate and drive 5 miles at 70ish mph, temp is now 235° as I exit. Drive back through town about 3 miles in 'stop and go' traffic and temp is holding steady at 230°. At least with the electric fan I was able to get the temp back to 180° in town. I have about had it, someone come look at my van, to buy it, and if you decide not buy it after looking it over ---- then just shoot me. I'm serious, I am ready to get another van and start all over and just keep it simple this time. Shit!

So what trans are you running?

bACK OFF IT A FEW DAYS = remember this - does the electric fan run all the time?? As I dont know or is it temp controlled?? Youre establishing a few basics now- put the electric fan back on - re test it without changing anything?? post the results.. Now ill ask this question- what is the manafacturer of the water pump- stock Chev/ standard rebuilt from auto parts ?? or fancy aluminum one from a speed shop seller?? Gettin curious? is there a fan shroud anf if so how far fron the end of shroud is the fan blades>> -Toward the waterpump side i mean. on the clutch fan is it close to the rear of shroud?? On electric same or near the radiator fins? How about the clutch fan blade diameter >- close to the shroud diameter or like 1-2 inches smaller?? Our new engines- hehe last 25 years the mfg's raised the operating temps up high to get a better emissions result- went to the electric fans to save only the manfacturing costs.These engines were never ment to run hotter than 180-190F - yet back to emissions tests & certifications?? Think about it? Post all results here and do only 1 change at a time. Is it possible on your install that the clutch fan & electric fan can ber run?/ Thats what ive done to my pickup with the clutch fan blades inside the shroud 1 inch -and within 1" of the diameter of the shroud also. Now ill ask = did u build the motor yourself?? = ?? what heads are u using? aftermarket alu? or steel - or standard chev iron heads?? again- food for thought=? let us know -

Ill add this - dont get discouraged- let me know if i need to buy a one way airline ticket over to you & bring my gun?? HaHa -matt OH by the way is the title signed?? just kiddin u

Stock engine from 86 Chevy conversion van. I have not rebuilt it or know if it has been rebuilt. Clutched fan is a GM 19 inch 7 blade. Electric is a Ford Taurus 2 speed manual controlled LOW-OFF-HIGH. Probably parts store rebuilt water pump. Ran clutched fan with not shroud 2 inches from radiator. No room to run both fans.

Some additional thoughts...

You're running the stock size radiator for a six cylinder engine, albeit with four cores instead of just two. What I'm thinking is that the frontal area of the radiator is still less than that of the horizontal radiator that GM put on the V8's starting in '67. Perhaps that makes a difference, despite the two additional cores in your radiator?

Also, M1Dadio says his motor runs 210 or more on highway, right? So I'm thinking these 350 motors tend to run a bit hot in the early vans.

Another thing to check - the preload on the hydraulic valve adjusters. My 283 was running poorly, low on power, running hot, etc. As part of replacing the valve guide seals, I also had to re-adjust the valve lash preload. They were ALL way too loose (not enough preload). So the valves were not opening enough, and this meant the motor wasn't gettting enough air/fuel mixture and it wasn't getting enough of a chance to blow it out the exhaust. Once I adjusted the valves to correct range, it has way more power, runs smoother and quieter, and seems to run cooler as well. It may be worth checking the valve adjustment on your motor, as well.

just saw a fan shroud on e-pay. item #290546588922. you cold use mechanical fan and shroud plus electric in front of rad as a pusher, most can be reverse wired.

Sorry M1DADIO, I am running a TH350 tranny. I have been talking with several people here and on VCVC that have a V8 in a 1st gen early and they are not having these problems. I like the valve lash idea, definately going to check that. And then today another brainfart. I have a 4 core downflow radiator and I was thinking maybe, being a 4 core, the stock (Autozone probably) water pump can not move that volume of water. Let me back up a few years, when I got the van it had a 6 banger with a 2 core radiator. Talking to experienced V8 swappers on this site said I would need to have my radiator re-cored to a 3 row. When I took in to the shop, the guy said he could build me a 4 core for the same price. Me figuring more is better, I said okay. Before Katrina, I had only put maybe 50 miles on the van and that was around the neighborhood mostly. And it does seem like I was having some cooling issues back them. After the engine was destroyed in the storm I got my current used engine and have had cooling problems. What do you think?

To go another way in the BF dept, I was wondering if the fact it is a down flow ,, if its possible to move the water to quickly through it?? You mentioned that you changed out the WP pulley to one that is 1/4" smaller now .. was it running abit cooler around town with the underdriven pulley?

Oh yes, I cleaned that radiator inside and out. There are less than 500 miles on this re-cored radiator. I am thinking that I did have o/h problems with the other V8 that was in there before the storm. So, basically, I haven't driven this van that much, since the original V8 conversion was done 7 or 8 years ago.

Temp sensor is a good idea. But you can also determine if radiator is doing its job by checking the temp with your hand at the bottom after motor has been running hot. Make sure the motor is off and electric fan is disabled, first!

Do check valve lash. Even if it doesn't affect the cooling, if it's off (valves not opening enough) , that could definitely make the van motor work harder and run rough. My 283 feels like it's had a complete rebuild after I adjusted the valve lash. Runs much smoother, quieter, stronger, and seems to run cooler as well.

If there is too much valve lash preload... then that can burn the valves. But I suspect most motors tend to wear in the direction of not enough preload.

If you need help/advise on adjusting valve prelash, just ask. It's not difficult but there are some tricks that can make it more pleasant.