The Stovebolt Site Forums The Shop Area Engine Shop Why overheating now ?

I took my truck for a test drive today after the oilpan,valve adjust, vac adv replacements and it overheats. went to 210 in about 5 min on the road. came home and checked the radiater , full no leakes. I pulled the thermo housing and no thermo , went to napa got a 180 and replaced it. filled tank to about a half in above the cores. around the block still 210. checked timing ,on the dot with no vac. the centrifical moves when i rev . vac works when reconnected. i had put in ac r45 plugs with the valve adj . replacing r43. it ran around 180 before i started to "fix" it any ideas where to start?

well, like they say, if it ain't broke, fix it til it is
R45 plugs should be OK .... maybe valves too tight? should be a bit noisey, like a good sewing machine .... how are you seeing the 180/210, got an aftermarket gauge? I always ran 160's in a 235, they'll run cold if you let them and the stat sets the minimum temp, I'd be surprised if it ran an actual 180 with no stat, if it did you have cooling system issues, rad or pump - have you checked it with a good infrared thermometer? maybe the rad is gumming up? maybe it's just too hot in FLA?

Bill

The only thing that may have changed is the timing. Where in the manual does it say to remove the vacuum?

The R45 plugs are the standard replacement plug now. I've tried getting 43's, no go, also 44-5 commercial's because they are called out in the manual but they aren't made any more either. R45's are avalable everywhere from the vendors, farm supply and most FLAPS and run just fine in these engines.

Unless you're running something other than the Rochester 'B' or the throttle setting higher than the 450-500 rpm there is no need to disable the vacuum to the distributor when timing the ignition, the vacuum port is above the throttle plate.

Denny Graham
Sandwich, IL

Just a suggestion......bring the engine up to operating temperature.......TURN IT OFF.....and then run the palm of your hand over the inner finned surface of the radiator.....trying to find SPOTS that are cooler than the surrounding area. Cooler spots will indicate areas that are clogged up and you'll need to seek out a good radiator shop. An infared thermometer would make it easier but the ole "palm" can also work. The hot water flows into the top of the radiator and cools as it decends.

You didn't mention anything about your engine.....6 or 8....but if by chance it's an 8 you'll more than likely need a good fan shroud and if it's a replacement 8 in a 6 cylinder truck you need to make sure that the fan is oriented high on the radiator. The more info you can provide will get you specific info to cure your issue.

Dave

Yes i have a 236 6 cyl it has a 6 blade 18 " dia flexfan mounted on the waterpump pulley. no spacer, from fan to rad is about 1.5 in.yes its been hot here 95 in the barn. I have a aftermkt guage autometer elect. If i put a paper towel infront of rad it gets pulled to rad. so fan must be doing something. i discoed the vac adv to time and to drive around because the old one didnt work and the engine ran cooler then. i also had it disco to see if the cent adv was working. will try for hot spots in a.m. too many mosquitos out now. thanks for the ideas.

you do know that the factory requirement was for the fan to be within a 1/2" of the rad? you may think it's pulling enough air, but the factory would disagree - a spacer to get the fan up close would fix your problem

Bill

I'm speaking in generality now, but I've found that in cooling system changes to inadequacy over time that if the temp is too high on the road with unhindered air flow and no thermostat we can't blame the fan/shroud.I would look closely at core cleanliness both inside and out.I have seen some overheating caused by restricted air passages that were not easily detected by eye.
Also seen pump impellers loose or eroded that would decrease cooling ability.
One more comment on fan problems --have seen them reversed,which will make the fan very inefficient and usually noisy.The fan should have the concave side of the blade toward the engine for a normal "sucker" fan rotating same direction as the crank pulley.

tried it again today. still gets to 200 at idle in about ten min. turned it off and felt the radiator. about the same temp all over. once the thermistat opens i see water moving in rad. pump is the one that came with truck 12 years ago. rad fluid is nice green with little rust ??? pumps look pricey wonder if a backflush with the hose would help.

Does it get to 210 when going down the road? Does it puke out a bunch of coolant when you stop?

How did you check the timing?

Taking that long to warm up makes me think the radiator is slightly plugged up.

Go back over the timing and vacuum advance unit just to be sure all is in order. Unhook the vacuum line to the distributor and plug the hose and go for a test drive.

Wheres the timing set?
Where is total timing with vacuum plugged on?
Does the timing change with and with out vacuum?
Are you running ported or non-ported vacuum advance?

What type of gauge are you using?
Where on the engine is the sender?
Have you double checked the temp with second gauge or thermometer?
Does it feel hot? tons of heat radiating off the engine?
Hows it start?
Hows it sound? lifter noisy (yes/no), valves adjusted loose, tight?

The 45 plug is just a hotter heat range plug then the 43's, so it should not cause any problem. The electrode is slightly less insulated to allow the tip to run hotter and help burn off carbon deposits. Its a effective way to keep the plugs cleaner longer.


Joe

ok timing is on the BB with vac disco and pluged, i dont know where the total timing with vacume is. when i rev the engine the timing moves but i dont know how far. is that the other marks on the fly wheel?
at idle the timing does not change with or without vacume. with vacume attached the dist moves when i rev the engine.
i have not checked the guage but i do have a mechanical i could swap to.
the guage now is a elect autometer unit mounted in the head behind carb.
the engine does not feel overly hot and at 210 if i open the cap i get a little spurt of steam but the fluid is about a inch above the cores.
ot it will start right up , no lugging. the lifters are quiet at idle but make some noise when i rev. a smooth noise not like some are looser than others.
actually the engine runs nice and pulls smooth up to about 3200 rpm. i need to adj throttle linkage to get anymore,but thats another day.today was a cool day 81 and it still heated up. i washed the rad tonite and blew out the veins. a little dust but they didnt seem cloged. gona try to find a rad shop and maybe it needs a bigger core.

I would sure double check the gauge before pulling the radiator. Mount the sender in the thermostat housing for more accurate reading. My 250 read 20 degrees hotter between the cylinders then at the thermostat. The water leaving the engine is what you want to measure anyway, not whats deep inside it.

Drop a cooking thermometer in the radiator and see what it says, its quick and easy.

Sounds like its running OK, if it was truly hot, you would be able to tell. And as far as fan spacing, it would cool off the faster you go if it was air flow causing this. Fans do most of there work at idle and slow driving speeds where there isn't much air coming in the front.

Joe

Strongly agree on checking the ACTUAL temperature
with a known good gauge before tearing everything apart.

The best investment I've made lately is the "laser" or "infra-red" thermometer.
You can take highly accurate readings at various point on and around the engine
in seconds. I used it for years on my front engine alcohol dragster. Since it had NO radiator, water pump, etc. I Needed to know exactly where the hot spots were
cylinder by cylinder and top to bottom.

I, too, have always put AutoMeter gauges in my cars... Guess what. They are not
that accurate! I have found the electric sending unit units can be off by 10-15 degrees! Big difference between 195 to 210, when you are getting nervous out on the highway while eyeballing the rising gauge needle.
I take the laser unit with me when driving any of my old cars now.

my 2 cents
mike

i see the hole in housing , may put my mech guage there and compare readings. I went thru the guage issue with oil press also. 3 guages had 3 readings. +- 3 psi.If i can get to town today will look for a spacer also. will try a 1/2 in one. my rad sits at a slight angle and closest blade is about 1.25 in from rad.will check pump price while there also.wonder if its worth getting a gasket and pulling pump to see what it looks like. where would one find the infra red thermo?

You can get them online at Amazon or,
even at Sears Craftsman online.... they sell all the brands
I believe RayTech is the high end one, but you should be able to
get a good one for 50-75 bucks

mike

that is my thought roy i bet its got an air bubble under the thermostat. if you drill a 1/8 hole in the flat part of the thermostat
you will eliminate this as a possibility and
it wont hurt anything. philip

I really doubt that the pump itself is the problem, the pump failures I've seen would cause a progressive rise in temperature no matter the load or how driven up until it boils/steams and you shut it down.It did it that way at idle or at work-it just takes longer at idle.

more info. went to napa today they have the pump. one is 4.25 in and one is 5.5 in (is that the long and short pump?) took the long way home and it stays at 195.at 45 mph so its getting good air flo. but when i stop and open the gate and drive in it has jumped to 210 + it feels hot when driving, there is no cover on the pking brk lever and my leg was warm.i measured my pump and from base to front of pulley it is 5.5 in and that was the cheaper pump. could i be lucky. i am leaning toward a new pump (rebuilt) when the cap is off and the thermo open there is waterflo. but looking at my other truck not a rush of water. what do you guys think?

What is this 235 in?

I think a new water pump will not make any difference, and you forgot to pick up a fan spacer, as well as being determined to spend money fixing things that aren't broken

Bill

i looked at the fan spacer they had a 1" one but i think that would put the fan too close to rad. going to another parts place in am they have more stuff hope for a 1/2 one. pulled the old pump. looks ok ( I had to do it) i must have rep it long ago cause there was neverseize on the bolts. drained the rad and ran a hose in it. some rusty water came out but not alot. ran it into the block and it came out clean. Is there a block drain in the rear of engine. like to get the water out before i refil

When I changed radiators on my '37, the lower inlet was in a different place so my fan wouldn't fit any more. I had to step down one inch in diameter to a 17" low profile Flex-o-lite fan. These are the sharp as razors, stainless steel jobs that don't pull much air. The 17" was really bad at idle so I changed out the water pump pulley to a much smaller one. This not only spins the fan faster but also moves more water at idle. On the road its probably robbing hp, but for now its working OK till I figure out how to get more fan space. It did solve my heating problem.

You haven't changed pulleys have you?

Harbor Freight sells the infra-red heat guns.

Joe

Joe - you should try to fit a shroud, makes a world of difference when standing still to have the fan only pulling air thru the rad instead of pulling air in from the sides as will happen with too much space

Bill

I was looking in the parts book and they make fans with a more agressive bite. mine is like you describe ss with small SHARP blades. My big truck has the fact fan and the blades are bigger and have more pitch.
What concerns me is it ran cool 180 for yeARS and since the oil pump , valve adj and vac adv it is much hotter. i have unhooked the vac adv, cant see oil pressure being a prob . if i get the waterpump back in tomorrow i am gona look at the valves again. Re; fan spacer my big truck , s10 and two ford (sorry) tractors have the fans 2" away from the rad and run fine.

Check your pm box

Got the truck back togather last nite, Orig water pump, brushed and repainted, filled it with coolant and see the benefit of the air hole in thermo. after the thermo opened and all the air came out it setteled at 212. put a big shopfan in fromt of rad. checked timing and bumped it up a bit from the BB, revs nice and dosent pop when you hit the gas, went thru the valves and loosened all 1/2 flat. that dropped the temp to about 200 ???
filled the rad to about 2 in from the top . adj carb to idle around 600 rpm . no road test. thinking of swapping the flex fan for the orig x fan. may put shroud on my wish list. Thank to all for the help and support. No rain tonite I am off to the cruise.

My situation is a little bit different from yours, but the outcome may be the same. I have a 283 in a 60 vette here in Southern Cal, and whan I put that thing together, I couldn't get it to run cool if I had to. New water pump, new fan, electric fan, new gages, different thermostats, etc. For what ever reason, if I run what the book calls for on timing, I can't go a mile down the road without it getting hot. I finally said the heck with the book, and advanced the timing out, and it runs the same if it's 60 or 105 out. It doesn't cost anything to try it, just a little time.

Timing is one thing you can not go buy the book unless you are running stock NOS parts, and the same gas formulation being sold at the same time the engine was produced.

You mean that SUNOCO 210 dosen't have lead in it ? I sure miss that pump. When it is set at the BB what is that timing? 0 deg or + something. I bumped it up a bit , but have no idea where we are. I have thought of marking my harmonic balancer and trying to degree it . but dont know where i am starting from.

On most but not all the ball is 5 degrees BTDC. Most are stamped next to the ball what degree it is.

I bump my timing up until I hear a little clatter while pulling a load or hill, then back it just enough to stop the preignition clatter. If it tries to grunt when I start it hot, I back it up just a little more so it doesn't grunt while cranking.

Doubtful the problem is with the fan, you water pump be turning too fast to allow the water to flow through the rad; are you losing h20 when hard driving?

dosent loose water at all driving or when parked hot. i believe the pump/ balancer pulleys are origional.right now it will sit at 200 at a slow idle, and cools to around 190 driving 45 . i am stumped

How slow is the idle?

i have it at 550 rpm. runs smoothe there and will rev without that pause when you hit the gas. i think the carb is ok no gas smell in the exhost.

If the fan is a aftermarket flex fan take it off and replace with a stock fan,30 years ago I had a 72 AMX that came with one of those aftermarket flex fans and it would get hot idling. I put a stock fan back on and problems went away.

Just as a simple experiment try putting a washer (with a hole) into the hose to the top of the radiator. This will restrict the water flow and allow the water to cool when flowing through the rad. If the engine is new it will run hot for a couple thousand miles, until the rings have smoothed-out the bores. If you don't have a cracked valve seat then it must be your radiator. In the past I've had more than one water pump that appeared to be ok (no woble) but in actuality the impellor was sheared in the middle of the pump body.