okay,since I've tried everything I can think of is it possible that the radiator isn't big enough? it's the original to the truck. It had a 216 in it.
250 versus 216 engine radiator ! Compare measurements of the original radiator heating core for the 250 engine with the 216 engine radiator ! I doubt that there is so much difference in size but you never really know ? If you have tryed out all the recommendations and nothing helps it has to be your present radiator that has failures. If you choose to buy a New radiator i would advise you to buy an aLuminum model as these cool Down much faster as they have a wider register core. Martinius.
Radiator Capacity The original 216 radiator was plenty sufficient to cool a Caddy 500 C.I. V-8 . Look in the open cap and count how many rows of tubes there are ~ there must be three or more ~ I once bought a " rebuilt " radiator that had only two rows of tubes in a brandy new core and it overheated like mad . You previously mentioned your hand gets hot near the top but cools off near the bottom ~ if the engine's running hot , you should be able to feel heat across the fins as you move your paml flat against the radiator going side to side and working downwards ~ any cold spots indicate plugged tubes . If it's hot up top and cool near the bottom . the tubes are plugged . You can clean it out by using citric acid powder mixed one pound to each gallon of plain water , fill the cooling system with this pre mix (DO NOT mix it in the radiator !) and run it a while ~ the crud that plugs then tubes will come loose and turn the water dead black .
already did the acid thing,only thing I did different was take the radiator out and lay it flat then fill it full of straight phosphoric acid and forget about it for about three hours then dumped it into a bucket and it was the same color comming out as it was when I put it in. no gunk or rust. I called the shop that did the rebuild and they don't have any record of how much they bored it out to. They insist it's the radiator. I also took off the top hose and stuck a garden hose in the top. started it up and all I did was make a mess out of the shop floor. What I did find out was the watter pump works fine but it still gets hot. cold water going in hot water comming out.
I don't think they cleaned out the block. Pull the drain at the lower back of the block and see if anything comes out.
did that plus While I had the head off (checking head gasket) I checked looking down in the block and flushing it out same with the head,looked new from what I could see.
It's not stock. Thinner cylinder walls means additional cooling capacity is needed. A shroud helps to pull air across all of the radiator, thus increasing cooling capacity. Does an engine that is overbored really need extra cooling capacity? If you buy an aftermarket radiator, such as a "Walker", they specifically state: "Cobra Standard Series radiators are NOT DESIGNED TO COOL any engine that has been BORED. Also big block Chevrolets, big block Fords, Ford flatheads, big block Mopars, 400 small block Chevrolets and anticipated hot running applications such as SUPER CHARGED engines. The above engine applications should use our COBRA Z Series radiators" http://www.walkerradiatorworks.com/about.cfm It really is that big a deal, the thinner the cylinder walls are the bigger of a deal it really is. It's not just a horsepower thing, case in point, the "Ford flathead" is in the list above. Food For Thought...
I am thinking that a blanket statement like so.... is not correct ...... Some 47-55 trucks did have a shroud
no I don't have a shroud for it but the electric fan is almost as wide as the radiator so I doubt a shroud would do much good.
Just curious as to why you are using a pusher fan instead of a puller? There are two disadvantages: A) the fan itself blocks air flow B) there is no good way to use a shroud If you do the math on these two factors they can be significant. The biggest impact of (B) is when the truck is not moving. The effect of the "giant barn fan" you talked about in your initial post, using it to supply additional cooling, really is negligible unless it too is shrouded and forcing air through the radiator. The air will always go the path of least resistance, which isn't through a tight radiator core, unless it is shrouded and the air has no other path but through the core. I learned some of this based on an engine start up I did many years ago. The car had a stock un-shrouded motor driven fan and it heated up quickly during the initial engine firing / start-up. We put a large box fan in front of the radiator and it didn't help at all. We shut off the engine and I removed the motor driven fan and replaced it with an electric puller fan / shroud combination. I have never had an overheating problem since.
Excluding not having a shroud, because you "doubt a shroud would do much good." How tight is/are the belt/s Is there a belt on the water pump Is there a blockage in the block Is there a blockage in the radiator Is the radiator any good Has a radiator shop checked the radiator Is the water pump any good Is there a thermostat installed Is the thermostat stuck Is the thermostat installed backwards Is the engine timed correctly Has the cooling system been back washed Is the heat raiser stuck Is the radiator installed, for this truck Have you listed the items asked in this thread and once checked marked it off the list and reported back?? If so; Sounds like you have a heat problem and need to return the engine to the re-builder. Cause there are only so many items which can be wrong here.
The reason it is pushing instead of sucking is there is not enough room between the water pump and the radiator for the fan. The barn fan sits close to the truck with a homemade "shroud" of cardboard ducting most of the air into the front of the truck. about 90 percent of the air goes through the radiator.t I've checked all the other things listed and they are okay. about the builder,let's just say the last bill will be the last bill. I'm not a happy camper with that little deal.I'm now trying so find someone close by that I can borrow a radiator from or stick mine in there's and put an end to the radiator possibelity.
YEE HAW I think I may have solved the mystery.I took off the fan and switched the blade over,now it's seems to run a lot cooler. Would have been a damn shame had there been something such as instructions come with the fan saying something about this.
I couldn't help but notice the implication that a fan mounted backwards would push instead of pulling air.... It happens that that is not true. The pitch of the fan is in the same direction, forward or backward. It's just that the cupping and the blade tip shape causes the fan to not move near as much air when installed backwards. I have my fan off to get radiator repaired, so I went and checked that info.
