The Stovebolt Site Forums The Shop Area General Truck Talk overheating problem

Truck overheated today after a 10 mile drive some of it in a traffic jam. The radiator is new , the engine is 350 w/ headers. Took the thermostat out,it was open when cool--shouldnt it be closed? it looks fairly new and just like one I put in a Tercel once. What pressure should it be? What pressure should the radiator cap be?
Appreciate any help with this. :confused:

Hy redtruck65MA, You are correct when the coolant is cold the thermostat should be closed. The temperature for the thermostat could be anywhere from 160 degrees to 195 degrees [ I like 180 myself]. As for the pressure cap, if the engine is in a 65 truck the correct cap for that vehicle should work fine. The reason it overheated is probably because with the thermostat stuck open the coolant circulates too quickly through the system, and doesn't have time in the radiator to "radiate" its heat away. Hope that helps.

Thanks 3B, The themostat I took out was 160 degrees. I'll put in a 180 and see what happens. I'll leave the pressure cap-- it seems ok-- and check out a new thrmostat tomorrow.

Also check the tension of your fan/serpentine belt. I had a slight heating issue at idle and found it was caused by a loose belt.

Do you have a fan shroud? How is your ignition timing?

I do have a fan shroud--dont know about timing.
I put in a 180 degree thermostat but it overheated again today -- the belts are tight and the hoses are new. Would the water pump be the next thing to check? This truck is keeping me busy just trying to keep it on the road.

Do you see any bubbles in the radiator when you remove the cap with the engine running? Don't remove the cap while it is overheating, bad burns could result.

Baldy, I have to check that and the timing. The radiator was almost empty when I stopped. To make things worse the temp lights dont work so I dont know there's a problem till I stop and see steam. Before I get to things on my list something else craps out. At least the weather's not too cold to work on it.

Redtruck,my first thought is where did the water go?If a full system overheated i'm sure the water would blow out the cap.You would know when this happened.Possibly you have an internal leak[head gasket perhaps or intake gasket]

Are you running a fan clutch? If so check while hot and see if you have resistance.Lower radatior hose could be colapsing.

Sometimes the problem can be aggravatingly simple.
I found that the lower hose was not tight. Hope that's the only problem. I'll check it today.
The PO's mechanic should be taken before a stovebolt jury and sentanced to pushing a truck for a mile-----uphill. Thanks everyone for your help.

I always replace the cap first. It is cheap enough to eliminate that first. Then look for bubbles in the water, this is easiest to see if the thermostat is in and closed. If it bubbles with no radiator flow, you have a cracked head/block or blown headgasket, Since you are losing water, you probably do have a leak somewhere, check the freeze plugs, I had a new set corrode out on an IHC v8 once in 8 months. Without the thermostat in, or with it open, make sure you are getting fluid flow in the radiator, if you see no flow, the water pump impeller could be loose or eaten up. If all this checks out, have your radiator rodded out. If you have ever used any stop leak in it, they tend to restrict a bit.

I bought one once that had a replacement motor,overheated sometimes in traffic, found out the radiator was for a straight 6 needed a double core for the v-8, problen solved.

I thought problem was solved but....noooo it overheated again today after I tightened the clamp on the lower hose. Under the truck in the parking lot it was hard to see exactly where it was leaking from. It looked like it was coming from the hose but what would cause that much pressure to loose almost a gallon in 10 miles. No steam from the cap, it's a new radiator, no bubbles, new thermo. hoses tight--must be like you say fireballv8 a head gasket or freeze plugs--dont want to even think about the worst senario... Have to find those freeze plugs tomorrow. Could the water pump leak -- antifreeze seems to come down in the front and ends up dripping from the lower hose at radiator.

redtruck65MA...Check that "WATER PUMP" before you do anything else ! Also, check the oil & see if there is any
discoloration (like water / murky) ! Pull a plug on each side
if you think it is a head gasket, check & match the plugs from each side, if one is a different color (brown / wet ) that would
give you an idea if it is a head gasket & if so, which side is
gone! If it is the water pump, get a HD unit to replace the
old one! Had the same problem & replaced the WP with a HD &
it made a world of difference ! Hope this helps....

Also, make sure the water pump is spinning the right way. With so may new engines running serpentine belts, a lot of the water pumps are backwards from the old style motors. My buddy just replaced a Ford pump because of that, it idled fine, but on the road it over heated in a matter of miles/minutes! Joe

Hope this helps. I had the water circulator in the water pump crack partially, it would work for a while and when it would heat up it would expand and not spin, thus not circulate water. Maybe something similar???

Good Luck! Jeff

could it also leak from the temp sending unit into the block... just a thought..

I would wipe ever thing off real good, crank it up and look real close for the leak, maybe have someone else help... usually with anti feeze coming out, you can see it real quick..


check the intake bolts,, looks like the water pump would be a good bet as mentioned.. good luck with it.. let us know

I think your water pump is out. You said
"antifreeze seems to come down in the front and ends up dripping from the lower hose at radiator"

When the waterpump goes, it will leak from a small hole, on the surface of the pump, near the bearing. If it has been slowly getting worse, many times you can tell by the paint washing away from that hole in the water pump. The paint washes away along the path that the antifreeze runs.

you might also wiggle on the fan and see if it is tight,,,,and sometimes they make a heck of a racket and sometimes not..

You could just get a 50 gallon barrel and pipe it into your cooling system. Maybe you could get 50 or a 100 miles before you needed a refill. HEHEH

might try some of that UV dye additive and use a blacklight to find the leak, it will make the velvet elvis poster in your shop look cool.

All very enlightening suggestions that I will try as a last resort but first ---- I discovered that the antifreeze and steam was coming out of the overflow which ends down at the lower hose. I only had time to put on a new radiator cap and will check it out tomorrow on a long run. I was told that if it was the water pump it would overheat a lot quicker than it does....after about 10 miles. Because the radiator is oversized maybe I need an electric fan.
I never knew there could be so many causes of overheating.

A radiator that is too large wouldn't be on my list as a cause of overheating. In the radiator game...bigger is better!


Stuart

boy, you got that right..

But then you have to have a stronger fan-----maybe?

here is a link that may provide some help

click here

hi, i learnt the hard way on a 41 caddy it had a 500 cube motor fitted, wouldnt run for more than 10 minutes without boiling,did head gaskets, skimmed heads, pressure checked heads and block, new water pump, stat, rebuilt the darn thing, had rad recored , elec fan fitted, still boiled after 10 minutes, lots of mechanics looked at this aswell, then did the simple thing , replace the rad cap, 3 quid from corner shop, that cured it, modern cap on old rad neck, just was not seating right, a lot of people learnt lots of new swearwords that month,, check simple things first, made me smile now though,

Just a thought.....you mentioned PO....have you been driving the truck with normal temps and this was just a sudden occurance, or is this a new truck to you that has overheated from day one?

If it just started overheating after the thermo change...did you make sure the thermo housing was clean where the thermo seats and is it installed with the correct side up? If you got it clean, so the thermo functions properly then I would suggest putting a Stant pressure tester on the radiator..with a cool radiator...fill rad....crank engine....pump up the tester to the correct system pressure (say 13-15 pounds), and watch for the gauge pressure to either build or drop. If it builds up pressure before the engine gets hot you've got a potential head gasket problem. This buildup will push the water past your pressure cap....engine will overheat. If the pressure drops you've got a leak and it should be evident dripping. If you've noticed antifreeze under the water pump the pressure should eliminate any doubt as to the problem. Hopefully, the hot empty radiator hasn't had cold water added without the engine running....great way to crack a block.

The Stant radiator testers are an invaluable little tool to have in a restoration shop. They take the guess work out of engine diagnosis and can verify that your cooling system/cap is functioning properly. Adding a coolant recovery system for $10-12.00 from most parts suppliers will keep a good cooling high pressure system from belching out small amounts of coolant. All of the guys suggestions are good advice as long as you don't have a leaking head gasket. I hope this helps.

also make sure the thermo is not installed *** backwards..............

bet your water pump shaft seal is leaking and running down the hose

Took a 15 mile trip today (with new rad cap) stopped 4 times and checked with engine running -- all was fine but when I turned off the engine there it was again---pouring out the overflow. Later when it cooled checked the water level---could see water so I didnt loose much..drove 15 miles home--turned off engine expecting to see antifreeze but all was ok. So with a combination of cap, water level down 1 or 2 inches and the temprature being 48F instead of in the sixties it seemed to be ok. I think it runs hot--have to check timing. I have learned from all of your suggestions and will go back and read them again as I continue the saga. Thanks and I will keep you posted if I find more causes--cant imagine it running cool in summer ..by then I should have it figured.

Take the radiator overflow tube and run it into a container. I have used a tall quart jug. The container that Hypoid oil came in. I cut off the tip enough to get the hose to the bottom of the container. I cut the bottom of the hose at an angle so it doesn't suck to the bottom of the jug. Poke a nail hole near the top of the jug somewhere so it can breath. Fill it and the radiator to the top and drive it. After a few times it may overflow the container but will set itself to it's own level.

Also, when you shut the truck off after a run, the heat isn't circulating anymore and the anitfreeze temp goes up and boils.

Try letting the engine idle for a few minutes when you stop. That will help cool the antifreeze a bit and may stop it from over flowing.

I remember replacing a radiator once. It was plugged (on the outside) with mud dirt and bugs. I always had a problem flooring it to pass someone and blowing the hose off.

You might want to have the radiator boiled out and cleaned if nothing else works.

hi, also try different rad cap poundage 10-12-or even 15, not much higher though, 50-50 mix anti-freeze or stronger, shouldnt really need these extremes though, getting into racing numbers here, all helps a higher boiling point, apparently,

You have been given some GOOD advice. Right before the timing gears on a 350 I had went south, the motor was overheating so badly I couldn't get to the corner store.

I had the exact same overheating problem with my 283. After 2 years of fighting with it, found out it was the thermostat housing. I had one of neat looking chrome ones with an O-ring. Took the O-ring out and used a gasket. The problem was it wouldn't seal. Replaced the housing with an original 283 one I got at a swap meet for $1 and my problem was solved! It's the simple things that getcha.

pablos49---Mine has a chrome thermo. housing--I put on a gasket along with the ring. I'll keep an eye on it.
stevie-t---I have a 13 lb cap -- tomorrow I'll put on a 16 lb.
Builder---Today I put on a plastic jug and no antifreeze flowed into it..tomorrow I'll half fill it and see what happens.

A lot of new thermostats are defective.

did you flush that block when it was rebuilt?
They will collect crud in the bottom of the jackets sometimes.

With the overflow plastic jug a new radiator cap I drove 15 miles and later 15 miles back with no problem. Whoever said start with the simple things was right--what I should have done right at the start was the thermostat the cap and the overflow jug. Now I know-- but every case is a mystery until you track it down. I hope I have it solved at last.
Happy Thanksgiving everyone and thanks for all your help.