I have a 1938 Cadillac 60 special with a 455 Oldsmobile V-8. The engine was completely rebuilt by a local machine shop. The only mods are an Edelbrock 2130 Intake, and HEI Distributor and an Edelbrock mild camshaft. When we started the engine for the first time it got boiling hot in a short time. Is there a difference in water pumps for the 455? I'm using the recored 38 Cad radiator.
I appreciate any help I can get.
thanks!

 

Do you have a fan on it

 

I have a pusher electric fan on the radiator, none on the engine because the lower hose is to close to the water pump.

 

I'm no expert but check for blockages and check your thermostat it may not be working

 

your problem may be a combination of new build and application... if the rebuild was tight with piston/bore clearance its going to run a little warm and should settle down if the machining was done properly 2nd, your radiator/waterpump/shroud and the distance from waterpump/fan to radiator may be a problem because its a caddy

 

I had a 160 degree thermostat in the engine when it overheated, took the thermostat out and the engine still over heated. There is no fan on the engine, just the pusher in front of the radiator.

 

Would there be an advantage to a high volume water pump? I'm usint an OEM pump now.

 

How short of a time? If it was shorter than what it normally would take for an engine to warm up, quite possibly you have an air pocket in there.

 

Within five minutes, it gets to 210 degrees and starts blowing water out of the overflow hose on the radiator. We used an infared heat gun, the water going into the radiator was the same temp as was coming out at the bottom of the radiator. Super hot!

 

You've got a radiator problem, then, provided the fan is actually blowing air through the radiator.

- Eric

 

Not to insult intelligence or anything but maybe the fan isn't a pusher maybe its a puller?

 

ALWAYS a good point.

We've seen this before here, with mechanical fans.

- Eric

 

First check your fan, If its a recore your rad should be fine, 2,3 or 4 row? I would drain the system at this point install a 180 or 195 stat. Fill it back up to the top of the transmission cooler , start up and let run with the defrost on high /heat to get the air locks out. The coolant will drop below the transmission cooler as its running,. Keep filling a little at a time until you see circulation through the tubes not going past the top of the cooler, it may want to burp over, allow it to do so. After about 10 -15 min give it some high idle and then top it off.
Hope this helps
Cheers
Eric

 

There is a reverse rotation WP used on diesel v6's
how about a pic of your water pump or state its casting ID?
it's not converted to serpentine system and running a v-belt pump right?

proof once again that "no" thermostat is not the cure for overheating. It can help pinpoint a faulty thermostat though.

I think I recall that reverse rotation flex fan incident. "what's wrong with this picture?"

 

Thanks everyone for the info. Yesterday I took the radiator back to the shop to have a couple of pinholes repaired. The guy at the shop said to remove the thermostat, fill the block with coolant, replace the thermostat, fill the radiator start the engine with the cap off the radiator and allow it to "burp". He dais there is an air pocket somewhere in the system. So I will try that whn I get the radiator back. The fan is a pusher fane, the new water pump is a stock OEM aluminum pump and the thermostat is new.

 

That's what I'm leaning towards.

 

impeller loose on the shaft in the WP is not unheard of

 

I ordered a new water pump from O'Reillys in Yakima, Wa. Removed the GMB Aluminum pump and found the impeller in the pump I was using is half the size of the new pump for the 455.
The pump casings were exactly alike but the impellers were quite different. So...When I get the radiator back from the shop, the problem should be solved. I don't know what engine the water pump with the small impeller will fit. Maybe the Mfr just installed the wrong impeller. To much Saki, maybe!

 

To much Saki, maybe!.... I dont know about that, I would take a Japanese water pump over a Chinese water pump anyday

 

Installed the new water pump. The impeller in the new pump is twice the size of the one I tried previously. Had the radiator (38 Cadillac) pressure tested, installed new 160 degree thermostat. Started the engine with the radiator cap off to burp out any air. When the thermostat opend, a geyser of coolant shot out of the radiator and the engine overheated. Filled the radiator again, started it with the cap on, still overheated within 5 minutes at an idle.
Don't have a clue now!
Thanks for any more ideas.

 

Time for a photo of your WP and driving belt system. And fan.

Fans can be wired backwards and run backwards which kills the prop efficiency. Just because it is blowing towards the thing you want it to does not mean it is going the "right direction" [for the prop in use].

Retarded timing will do that too, but usually not as quickly.
What is the timing running at?

 

Some of these new thermosts are strange...its not upside down right

 

Looking over the posts...
Is the radiator taller than it is wide with top and bottom tanks?
If so the radiator width limits the diameter of the fan.
A previous post said there was no fan on the engine. Does that mean that the water pump is not being driven? Equal temps in both tanks means no flow, which means no cooling. Also with no circulation, the heads and intake will get hot fast.
The J-tube and design of the thermostat will vent the system of air, if the coolant is flowing.

 

CutlassDad, good questions! The radiator is rectangular in shape, taller than the engine. Thus, unless I come up with a way to clear the bottom radiator hose, a fan won't clear the hose. I did put in a 190 degree superstat thermostat yesterday and this seemed to help to heating problem. The radiator guys were adamant about using a steel fan on the water pump pulley. I used billet pulleys, the crank pulley is 51/2" the water pump pulley is 5" in diameter. The original 455 crank pulley was 71/2 " in diameter. I'm 74 years old and have built many engines in the past, mainly Chevys and never had a heating problem before.
Thanks, for the help everyone.

 

By help the heating problem, do you mean it took longer to overheat?


X2 Octania...we really need pictures, preferably from both sides of the engine, with hood sides removed.
Be sure to include a shot of the lower hose connection.

 

x3. Pictures, please.

- Eric

 

What temp is it actually reaching when it overheats? x4 on pictures.

 

I say scrap the whole thing and put a V-16 in it.

- Eric

 

Ok, EJ Potter.

 

X2 to this. I saw in another post that a 190 thermostat helped. Then I saw that you removed the thermostat and it made no difference? I would remove the thermostat until the problem is resolved. That eliminates it from being part of the problem. Since this is a hot rod and nothing is standard you are basically engineering a cooling system from scratch. You will need to consider the pulley diameters and pump speed. Also take a big box fan and put in front of the radiator. If that helps it may tell you if the problem is related to the size of the fan or radiator. It sounds like a flow problem. Good luck!

 

I disagree.

The thermostat, even when open, provides a designed-in flow restriction, which, when the system is working properly, causes an increase in pressure between the water pump and the thermostat (ie: around the heads), as much as 40 or 50 psi when hot, which helps to reduce areas of micro-vaporization and maintain good fluid contact with the passage walls.

- Eric

 

try drilling a small pin hole in the thermostate it will let any air out trapped in the motor

 

Eric, I agree with your point in a car that the system was designed for. And that will be true in this application as well. But the elimination of the thermostat will not result in the behavior the OP describes. Or the inconsistency of the statements concerning the thermostat. I have known many cars run without a thermostat. They may not perform as origionally designed but will not blow coolant out of the radiator like a geyser.

 

Maybe the recored 38 radiator cant handle the 455....

 

The only time I've seen coolant blow out of a radiator is when the idle is high when the thermostat opens. I've never seen a cooling system overheat in 5 mins.

 

But remember, he's go no flow at all, as indicated by the radiator inlet and outlet being the same temperature.

Presumably, a certain area (like the heads) is heating up enough in that time to cause it to boil, and then POW! out it comes, pushing all the water between it and the radiator car in front of it.

- Eric

 

I can tell you from personal experience that if the thermostat does not open temperature can elevate quickly and blow water out of the radiator as the OP describes. I presume from water boiling in the block and building pressure at the bottom of the system and coming into the radiator from the bottom hose. Now does this happen in 5 minutes? I do not know. I have also seen this happen as Eric # 2 describes through an air bubble. Once the bubble passes through you add more water and the system settles down. Again we have to consider this is not a stock 455 in a 71 442. As to flow, rather than look at inlet and outlet temp look down in the radiator fill neck. You should see the flow through the radiator. If the water is not moving ( I suspect it is not) you have a flow problem

 

I hear ya but he said it did the same without a thermostat. At first I thought it was an air pocket. That you can see on a temp gauge with wide swings in temperature from really low to pegging the gauge. I agree with Sampson, it burps then add more water. Repeat until air is gone. I've had some stubborn air pockets where I had to jam the water hose in the radiator neck and force water through. Just thinking out loud.

 

Before offering further conjecture, I will say again: "Pictures!"

- Eric

 

By the way, the '38 60 Special originally came with a 346ci V8, so the odds that the original radiator would be inadequate for a 455 are actually quite high.

- Eric