Hi there,

I need some advice on this. I bought a truck recently and it seems to run hot while in traffic or under a load. It has overheated a couple times now while moving my camper and utility trailer on the highway. I have replaced the thermostat and flushed the radiator. The radiator looks fairly new but I'm not sure about the water pump. The fan seems pretty small to me. It has about 1 1/2" of space around it to the inside of the fan shroud. It does stick into the shroud a good 1/4" but is the extra space around it too much?

Any advice would be great.

Ken

 

How do you know it is Actually over-heating?

Are you getting it blown-out the overflow tube?

Or are you going by the gauge ?

 

It's blowing coolant out the overflow and the engine completely shuts down. I have to wait about twenty minutes and then poor gas straight into the carb to get it started again.

 

Ouch! Much more of that and its all over.....

To check low speed air flow, stick a red rag in front of condenser (or radiator if non-A/C). If it sticks completely, you have acceptable air flow.

Because it heats on the freeway though, I am leaning more towards water movement or radiator build-up. Take the T-stat out temporarily and observe water flow at the cap. It should be ripping pretty good and really go when you rev the engine a bit.

Digression: Info from the Prestone people book: a T-stat is essential for cooling because it raises the pressure in the block by creating a restriction that in turns raises the boiling point of the solution which, in turn, prevents "spot boiling" (like in the heads around the exhaust seat.) Once this starts, the steam created there leads to even more boiling.) This leads me to believe a pressure cap that holds is a good thing.

Anyway, if you have good water flow, and the T-stat is in right... (I never trust those T-stat makers... boil it on the stove with some water and a thermometer and SEE that in REALLY works, and, the stove is near the fridge which has the beer, so this is a Very Good test to do.).... the next step I would go to is get that radiator rodded.

If none of this helps, write back.... I have to go test a T-stat right now.

 

It sounds like you have the wrong fan on your engine. It should be larger and deeper into the shroud. Check with some junkyard trucks and see if you can find a thermostatically controlled fan for your application.

Check your rad pressure cap for proper operation.

 

I was thinking that I had the wrong fan because I know the engine was replaced. It has a 360 in it now and it sits way too far back. I have two fan spacers on it now which makes it about 5" total. I'll try to get a picture on here because it looks goofy but I don't know any other way to get the fan near the shroud.

 

I have a picture but can't figure out how to load it. Anyway, the fan clutch was dead and the old fan was no where near the shroud. I put two spacers on which puts the blades about 1/4" into the shroud but there is still about 3" to the radiator.

Any ideas?

 

Your fan should be about 1/2 way into the shroud. The radius should have 1/2 to 3/4" space around it to allow for engine movement and frame flex. If you don't rock crawl crowd it a little closer but not under 3/8". It sounds like you need to do some scavenging.

Do you even have the right engine mounts?

The picture does not show. Put it in your gallery.

 

I'm not sure about the engine mounts. I know the engine was put in by a professional local shop but it looks like they put the engine in and that was it. The fan was around 2" outside of the shroud when I got it. I do have room to add another spacer but that would put me up to around 6 1/2" bolts to hold it to the water pump.

I put the pictures in my gallery.

 

hey,instead of trying to bring the fan closer to the shroud,how about bringing the shroud closer to the fan?perhaps your local salvage yard might help you locate a more suitible shroud.also consider a 5 or 7 blade fan.the wonderful thing about this problem is vehicle manufacturer does'nt matter.almost all v-8 fan blades share the same bolt patern,just remember to grab those bolts with the fan,as well as the nose cone.they might come in handy.

 

That looks like some sort of aftermarket flex fan. If it is they are absolutely worthless. Go out and find a stocker thermostatic fan.

 

It does have the aftermarket fan on it now. It had the stock fan but I switched because I heard these pulled more air. The stock fan is the same diameter though. From what I'm hearing, going to a larger fan and moving it into the shroud more would help. What about the water pump? Could that be causing a problem too? It runs normal if I'm moving and not carrying a load but once I hit traffic or pull the trailer it runs hot constantly. When I get it moving again though the temp drop back to normal.

 

I don't think that is a shroud for a 360/390. Mine are a much deeper shroud. I have a '76 and it was a little deeper. It almost looks like that shroud came from a truck with a 460. I would look around for the correct one..

 

"sits way too far back", I bet that 360 is almost sitting on your lap..I am guessing you have an automatic?..I would stay away from this pro. shop that installed it..That set up is a little scary..Your best bet may be to get an elec. fan or move the rad. closer to the fan..Your big clue is that it runs normal when you are moving so that points to an air flow problem..Try fixing the fan problem first and go from there..JMO..

 

Yep, the 360 sits right against the firewall and has lots of space in front of it. The guy I bought it from had the rebuilt engine put in but it just doesn't look right. I was thinking about keeping the fan where it is and putting an electric pusher in front of the radiator. Has anybody done this with success?