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1956 chevy 210 del rey sedan
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Discussion Starter · #1 ·
I am a bit perplexed . My stock short waterpump was weeping out the weep hole so I bought a new one from kmj perf on ebay. . before I put it on my car ran perfectly at 185 all the time . now it gets to 185 for a while then quickly goes to 230 then back down to 150 then slowly back to 185 for a while then shoots back to 230 again and again a repetitive cycling . I have made sure it is full of coolant , no air pockets etc. I was told that possibly the pump is flowing to much volume for the thermostat and the volume is pushing it closed till the water temp gets high enough to force it open . etc . was told to drill a couple of 3/16 holes in the thermostat and it would solve the problem. any ideas?
 

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Long shot but some are made to turn the other direction meaning the impeller would be different, something to check.

Good luck, let us know what you find.
 

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"now it gets to 185 for a while then quickly goes to 230 then back down to 150 then slowly back to 185 for a while then shoots back to 230 again and again a repetitive cycling."

What you're describing is an air pocket. It should eventually resolve itself (and require more coolant). That is if it's a traditional small block. If it's a Vortec L31 engine, or if it has the L31 heads, you may need the holes drilled in the thermostat. If it's a BBC, you need the bypass hose between the water pump and intake crossover passage.

To help get the air pocket to circulate out, jack the front end up and run the engine with the radiator cap off. If you have the heater connected, turn it fully on while you do this.

I've found that with the Vortec heads, the fluctuation goes away once the engine is fully warmed. I think what happens is that the bubble/pocket is still there but compresses to where it's really small.
 

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1956 chevy 210 del rey sedan
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14,553 Posts
Discussion Starter · #4 ·
So, after numerous attempts to get the air out with no changes in how it worked I got fed up. I went to napa and got a stock cast iron short water pump . painted it,put it on and guess what ? absoultly no problems what so ever!!! car warms up slowly to 185 degrees then the thermostat opens and the fan comes on and the car stays at 180 degrees . no matter what I do, flogging the crap out of it, idling for 1/2 hour in 1 place, or cruising in city traffic . the thing just stays at 180 degrees . I am going to cruise it to work tommorow. all the guys dig it . they all want to know whats up with the big meats out back. HeHeHe.
So lesson learned here , dont buy the procomp piece of @#&* pump it sucks !!! :bowtier::happy0030::bowtieb::wavey:
 
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