T-shooting cooling problem

Thanks, I was wondering about the fan... it seems slow to me but it is turning. But this is my first clutch-fan (I've had vehicles with electric fans, otherwise). Any specific tests I can do?

Doesn't appear to be any debris in the radiator; has a small radiator in front of the main one; I think it's for trans fluid.

I would check the fan clutch. Sounds like the fan may not moving enough air. It could also be the radiator itself, especially if someone before you loaded it up with stop leak. Watch for leaks to appear when you flush it out. Check the outside of the radiator as well and make sure that the fins are not plugged up with dead bugs and other debris. The fact that the heater core (a tiny radiator) is helping to keep it cool shows that the problem is probably not in the pump

Not that I've noticed, in fact the overflow tank seems hardly to be in the circuit... i.e., when it gets hot I would've expected the overflow tank to fill, but that doesn't happen. Levels are fine there, in fact a little high but stable, cold or hot. So the only shot-gun approach I've tried is to replace the pressure cap, hoping to see more action in the overflow tank. (Just replaced it today, we'll see how it behaves tomorrow...)

street, and when

the gauge. The

stays at or below

run it at idle,

shut it off.)

might be. At first I

gauge is near the

weekend, but

course I'm broke...

start swapping out

since I live on a

it's always exhibited

the defroster is

Does it bubble in to the overflow tank? If so, might be a blown head gasket.

With the engine running at operating temp, watch the fan as someone shuts the engine off. If it stops turning almost immediately, the clutch is doing it's job, and is engaged. If it freewheels for a while, the clutch is shot, and needs to be replaced.

The fins in the water pump are just sheet metal and they corrode off until there is little left and are unable to move enough fluid.

beekeep

. >In my '97 Dodge Ram Van 2500 (3.9L V-6),

street, and when

the gauge. The

stays at or below

it at idle,

might be. At first I

gauge is near the

weekend, but

course I'm broke...

start swapping out

since I live on a

always exhibited

the defroster is

Did this & the fan seems okay. When the van overheats, sitting at idle for a few minutes with the heater going full-blast does bring the temperature gauge back down to the middle.

I had the radiator flushed; seemed like the thermostat must be working right, it did open. Guess I'm starting to suspect the radiator itself, even though it looks to be in good condition.

Thanks, seems like the flow is okay, though. (Per the guy who flushed the radiator.)

If overheating occurs only at periods of extended idle then my kneejerk shadetree diagnosis is the radiator itself may have become internally choked with rust and deterioration, such that the volume of coolant able to circulate through it is significantly reduced.

A "radiator shop" is probably going to cost you less than taking it to a dealership.

few minutes with

it did open. Guess

condition.

What you need to do is determine what is happening. Either the radiator is getting too hot, or it isn't. It's that simple. When the engine is overheating, there should be a lot of hot air coming from the fan, and if you rev the engine the fan should roar. If the air is just warm the radiator is not hot. Before you start laughing, if the radiator is not hot, it's a problem with water flow. Water pump, collapsed hose, plugged radiator, or thermostat. If the radiator is hot, it's a problem with air flow.

Al

If it were a flow problem due to the pump, turning on the heater would have little to no effect.

More than likely it is the radiator. For kicks, check the radiator cap.

Thanks for everyone who replied to this thread.

Replacing the serpentine belt *partially* fixed the problem. It still gets too hot pulling a hill, i.e. the hill up to my house. However it seems okay on the freeway now... at least during this cold-weather spurt we're having.

The serpentine belt seemed fine when I checked it, little wear evident & few cracked v-grooves (none of the long cracks the Haynes manual warns against). I was surprised that changing it made any difference at all. So there's still some problem, but not as bad.

I can only suspect the radiator now, & I'm trying to find a radiator shop with a good reputation (not as easy as it sounds!). Just trying to get the van reliable enough to take on a couple of pending long trips. These vans were designed to last a quarter million miles, weren't they? (i.e. the Ram Van 2500) Mine's less than half that, but I'll say that the overheating is the only problem... everything else about it is terrific!

Thanks, that's not it; periods of extended idle let it come back to a normal temperature range. It's pulling hills (& running the AC) that cause the overheating.

However I'm leaning toward a radiator prob. at this point.

This was good advice, I spent a lot of time thinking about what you've said. Unfortunately, there's not a *firm* failure... pump/hose/radiator/thermostat all indicate that they're working... to some degree! Somehow there seems to be insufficient flow... must be the radiator, is my current thinking (any other component would *noticeably* fail, right?).

Agreed, & turning on the heater effectively makes the radiator *bigger*, right?

Thanks, replaced that (since it's a $6 part).

The suggestions I had for checking operation all passed (this included verifying that the fan "roars" under revving; turning the fan easily w/engine off & cold, & noticing some resistance w/engine warm, off, & battery disconnected). One thing I'm not sure about: is the clutch fan strictly mechanical? Or are there any electrical sensors anywhere in the circuit? I do operate in a very dusty environment; a clogged sensor would be a possibility, were there any sensors.

If not, just how does the clutch fan operate, do you know?