Any ideas?

We just fired my friends new 383 blower motor and the tempurature goes through the roof within just a couple minutes. We replaced the thermostat and it didn't make any difference.

The upper radiator hose and the engine block and heads all feel real hot, the drivers side of the radiator feels just a little warm, but the passenger side of the radiator and lower hose remain cold. I loosened the plug in the top of the water pump and coolant started leaking out so I know the w/p is not airbound.

Water is clearly not circulating through the radiator and I know the thermostat is good. Today he is pulling the hoses and looking for blockages, but the radiator and hoses are fairly new and worked fine on his old motor.

Has anyone ever seen an impeller fall off a water pump ??? At this point I am stuck looking at the weird stuff.

Anyone?

yes I have had an impeller fall off...not fall off but spin in the splines
I get the impressionb is a new mator...okd pump, radiator heasders havnt been pulled and cores cleaned, all new qater hoses...
New engine..these should all be done,
It the same as using an old oul pump in a new engine...just not done.

WATER PUMP!

New motor, fairly new pump -- its an aluminum pump that is chrome plated (a bit of a show car) not sure what brand. (Tuff Stuff maybe?)

Steptoe, when it "spun on the splines" could you hear it or feel something wrong when spinning the pump by hand? This one seems to spin freely when I turn the pulley by hand and doesn't make any noise . . .

No...like u I was knocking my head against a brick wall...this was early 80s
What did make me suspect something is I put the stethoscope on the pump, just sounded funny then, and the water coming out of the top cores (radiator cap off) was not exiting as fast as it should be. I dont rem checking the temps of the cores between the top and bottom of the radiator, thu I would suspect if the impeller was slipping, the bottom would remain cold.
It was a weekend, I removed the backing plate off the pump, by hand it sort of seemed ok, but using a wrench it sliped....I tack welded the impeller. A purchased a new pump to replace...eventually the bearings/seal went a yr or so later...I got around to replacing then. It was this pump I meantion in another post that I rebuilt as a spare...wouldnt bother to do that again thu.

take the lower hose off, stick a long screwdriver in to jam the impeller, then try to turn it with the pulley?

gotta be the pump.... unless you have totally wrong head gaskets, or the intake gaskets are on backwards?

Is this the motor you had the timing gear "situation" with?
Murphy's law may be at work here.

Yep, same motor I had the timing gear situation with. Thanks for reminding me Jim ;)

I took the pump off today and removed the backing plate. The shaft turns freely and the impeller rotates too. I cannot see the vanes on the impeller because there is a flat plate that spins on the shaft too that is in the way.

Intake gaskets are on correctly for sure -- they are the Felpro 1205 gasket with the blue rubber toward the intake.

Head gaskets are Cometic. Have never used these before but the holes and everything lined up fine when I put it together.

The only thing I can figure at this point is maybe because the engine has no heater core and the holes are all plugged maybe the pump is having trouble priming while the thermostat is closed? The heater core acts like a bypass when the thermostat is closed so maybe that has something to do with it? I don't know though because his old motor worked fine with this setup.

We're going to try running it without a thermostat and see what happens.

As has been pointed out to me when I said they didn't, small block do have a built in bypass, it's the bottom hole on the pass side.
Regardless, since the level in the rad is higher than the top of the pump, it should self prime instantly.

Double checked, the 1205 has the coolant ports cut out front and back, so no joy there.

got me, unless your perfectly good radiator plugged itself up on you.

Could it be the wrong water pump??? One designed for a serp setup looks the same but spins the other direction.

The water pump worked fine last fall, so I know it is correct rotation.

Jim, I think the small hole you describe is not there in this water pump. You're talking about the side of the pump that uses the longer gasket with the extra 3/8" hole in it right?

May have found something though . . . last night my friend pulled the radiator and tested how fast it filled. Plugged the lower radiator hose connection and filled through the upper rad hose connection. While filling he watched through the rad cap opening. It filled up quickly on the side he stuck the hose in, but slowly on the other side. I had him flush it (using descaler) and afterwards it filled up evenly and quickly on both sides. He said it made a pretty big difference in how fast it filled up, unfortunately I couldn't be there myself to watch.

We're going to try it again with a clean radiator. After a little more detective work I found out he had been using the orange (Dexcool?) antifreeze . . . the stuff that has all the corrosion problems when air gets in the system.

Jim, I think the small hole you describe is not there in this water pump. You're talking about the side of the pump that uses the longer gasket with the extra 3/8" hole in it right?


right, the third 3/8" hole on the pass side mounting flange is the bypass.
Suggest if it ain't there you drill some holes in the thermostat.

The water pump worked fine last fall, so I know it is correct rotation.

Jim, I think the small hole you describe is not there in this water pump. You're talking about the side of the pump that uses the longer gasket with the extra 3/8" hole in it right?

May have found something though . . . last night my friend pulled the radiator and tested how fast it filled. Plugged the lower radiator hose connection and filled through the upper rad hose connection. While filling he watched through the rad cap opening. It filled up quickly on the side he stuck the hose in, but slowly on the other side. I had him flush it (using descaler) and afterwards it filled up evenly and quickly on both sides. He said it made a pretty big difference in how fast it filled up, unfortunately I couldn't be there myself to watch.

We're going to try it again with a clean radiator. After a little more detective work I found out he had been using the orange (Dexcool?) antifreeze . . . the stuff that has all the corrosion problems when air gets in the system.

I have come to hate Dexcool! :sad:

One other thing. I have seen wierd issues when plugging the heater fittings too. Try running a hose from the intake (if it has one) to the water pump. It acts like a bypass as you mentioned earlier.

Good Luck Eric! :D

OK, problem solved guys. Thanks for the help.

Descaling the radiator got rid of the corrosion (1 year old aluminum Be Cool) but did little to help with the overheating.

Tried a different pump, (this one did not have the bypass hole either) and it didn't help.

Removed the thermostat and installed a restrictor in its place. Fired the car it started to warm up and then all of a sudden a mess of bubbles started foaming up in the radiator (the cap was removed). Added a half gallon or so of water and it cooled off and stayed cool.

Looks like it was just a stubborn air pocket in the block or heads. We let the car idle and idle and the temp stayed around 160*. I think we will plumb a bypass and reinstall the thermostat.

If you do not have a bypass you must drill a couple of holes in the thermostat (or install a pre-drilled thermostat, I think Stewart sells them). If you have the bypass you don't need the holes.
If you install a thermostat without holes and don't have a bypass then the hot coolant doesn't get to circulate up to the thermostat and open it. That's why you would need the holes.