Running hot
Thread Starter
Instructor
Joined: Dec 2012
Posts: 107
Likes: 4
From: AZ
Running hot
Well, after pulling engine (454) for reseal and paint the engine started running hotter than before. Only change I made was swapping out water pump for a chrome Tuff Stuff high flow pump. It's not overheating, just running about 10 degrees hotter than before. Verified by lazer temp gun. Using about a 60/40 water/coolant. Was running about 190-195 in traffic. Now running 200 to 210. It has a 180 thermostat now (cheap stock replacement ). I was thinking that that the stock thermostat is restricting the flow of the high flow water pump. Going to try hi-perf 160 thermostat. Hopefully this will cure the issue.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
If you remove that fancy high priced water pump, your system will return to a normal operating temp....A high flow pump passes the water faster than a stock pump and does not get a chance to cool....
The timing your running and thermostat at 180 degrees is good....don't change ither one.........
The timing your running and thermostat at 180 degrees is good....don't change ither one.........
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
That new 'hi-flo' pump is creating a LOT more suction on the input side of the pump than the stock pump did. My bet is that you don't have an anti-collapsing spring inside the [lower] radiator suction hose...or it has rotted away over the years. If that hose closes down when the pump is revved, you won't get enough cooling flow.
P.S. Most car parts places will sell you a new lower rad hose...but they don't tell you it also needs the internal spring--which is sold SEPARATELY.
P.S. Most car parts places will sell you a new lower rad hose...but they don't tell you it also needs the internal spring--which is sold SEPARATELY.
Le Mans Master
Joined: Oct 2007
Posts: 7,410
Likes: 949
From: Tennessee/Rhode Island
As Melwff suggested, I would think that you should look at the thermostat since many high volume water pumps require a different than stock type thermostat. Did you replace your thermostat when you did the water pump? I have a Stewart Stage 2 high volume water pump on my 78 and did not change the thermostat when I initially did the swap...the car ran hot. When I installed the Robertshaw thermostat suggested for my pump the car ran MUCH cooler than with the stock water pump. The only thing I noticed is that the description for your pump states that it is ideal for RPM operation and racing so It may not be ideal as a street pump...just a thought.
Melting Slicks
Joined: Apr 2006
Posts: 2,331
Likes: 60
From: Sunnyvale CA
I'm not defending high-flow water pumps for stock applications, but I'm not sure of the logic. Yes, on each lap through the cooling system, each water molecule spends less time in the radiator getting cooled, but it also spends less time in the engine getting heated.
Drifting
Joined: Feb 2005
Posts: 1,879
Likes: 38
From: Los Gatos CA
The high flow water pump myth just won't die. If the coolant flows twice as fast it is there twice as often. Just sayin... Heat transfer is a product of thermal efficiency, air flow across the radiator, etc. Radiator dwell time does not change with coolant speed.
Last edited by Jeff_Keryk; Feb 21, 2016 at 09:12 PM.
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Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Some of my BB inventory
5 BB Camaros, 2 with AC, an 4 T400`s
73 El Camino, with AC an T400
68 Vette
And all run a 180 thermostat with factory replacement parts if and when necessary....Those parts are just pulled from our shelving and removed from inventory...the same auto parts we sold over the
counter
73 El Camino, with AC an T400
68 Vette
And all run a 180 thermostat with factory replacement parts if and when necessary....Those parts are just pulled from our shelving and removed from inventory...the same auto parts we sold over the
counter
Instructor
Joined: Dec 2012
Posts: 118
Likes: 2
From: rancho cucamonga ca
Why install a high volume water? What is the purpose? A stock type does a good job, has for years. I could see looking for a lighter one, but as for flow you can't beet them. Sitting in line at the boat ramp 125 deg. outside, big block air on high and the temp. Does not move.
Last edited by colesweat; Feb 22, 2016 at 08:24 AM.
Pro
Joined: May 2013
Posts: 672
Likes: 31
From: Rapid City South Dakota
And I'm quite sure the high flow water pump robs more horsepower than stock.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
It will and it does. That's why it will create more HEAT than the stock pump...it does more work. The opening in the thermostat will only allow so much flow before it starts to cavatate. If you have a Hi-flo pump, you NEED a T-stat with a larger opening...or no T-stat at all...to get the 'extra' flow provided by the new pump.
As mentioned, if you aren't racing the car or doing some long high speed running, you really don't need a hi-flo pump. It's just another of the expensive 'go faster' parts that speed shops sell to folks who don't need them.
As mentioned, if you aren't racing the car or doing some long high speed running, you really don't need a hi-flo pump. It's just another of the expensive 'go faster' parts that speed shops sell to folks who don't need them.
Safety Car
Joined: Sep 2005
Posts: 4,203
Likes: 643
From: Orange County Ca
Thread Starter
Instructor
Joined: Dec 2012
Posts: 107
Likes: 4
From: AZ
I got the "high flow" pump because it was the least expensive US made chrome pump for my car. I will eventually go aluminum when I built a 496 for it next year, but I wanted it to be a little shiny for a car show I got coming up. I got the 160 degree RobertShaw thermostat and will install it this weekend. I will also re-glue the foam insulation back on top of the radiator (between radiator and hood). I've talked to a tech and Summit and we discussed the whole situation and particulars. He said they sell a lot of Tuff Stuff and have never had one run hotter, but they do recommend the high flow thermostat to go with it and he was familiar with the C3 and said to make sure that the foam insulation was in place. He also brought up the inlet hose spring and I know mine doesn't have one, so it is something else I will have to find. I didn't see mine collapse but it was idling at the time so it may only be collapsing when it's reved up.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
With your car completely warmed up and sitting in your driveway, have someone rev the engine while you look at the lower rad hose from below. If you see the middle of that hose 'suck inward' (collapsing), that is your problem. That hi-flo pump can't do its business if it can't get any water to the input.
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
Several guys here are correct pointing out that a hi flow pump does not run hotter. (The additional friction created by higher flow will increase coolant temps but minimally). I use a Moroso LOW FLOW pump on my 383 just to save a few hp in pumping effort and a few pounds in iron vs aluminum. I have no cooling problems.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 107
Likes: 4
From: AZ
Quick update: I ended up buying flexible stainless upper and lower hose kits for the radiator (one of the belts was rubbing on the lower hose and cutting a groove in it). I got the thermostat and now just need time to work on it. I'm off on vacation next week prepping for local car show (Midnight at the Oasis) that starts Thursday, so I will work on it Monday and Tuesday (also need to buff out some swirls in paint lol). So Wednesday, I will take it for a cruise around town to burn up the 91 pump gas so I can fill it up with 100 race fuel for the Thursday and Friday night cruises.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 107
Likes: 4
From: AZ
Update: survived the cruise without overheating. Got to about 208 or so, but didn't boil over. I think I have another idea of what may be causing my issues. My waterneck and upper hose sit higher than the radiator. Might be an air pocket trapped up there. I ordered a waterneck with a radiator cap on top. I am also wondering if the radiator might have gunked up from sitting empty for a couple of months while I had the engine out.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Update: survived the cruise without overheating. Got to about 208 or so, but didn't boil over. I think I have another idea of what may be causing my issues. My waterneck and upper hose sit higher than the radiator. Might be an air pocket trapped up there. I ordered a waterneck with a radiator cap on top. I am also wondering if the radiator might have gunked up from sitting empty for a couple of months while I had the engine out.
Engines don't have "air pockets" as that is a myth some moron started a long time ago and it still persists to this day. If you're not running the stock 7-blade clutch fan you will have heating problems. If your cooling system holds pressure your bottom hose will not suck shut once the cooling system is pressurized. Hoses "sucking shut" only happens when the engine is cold and suddenly revved high.
Drifting
Joined: Feb 2005
Posts: 1,879
Likes: 38
From: Los Gatos CA
To diagnose heating problems, there are 2 things I look at. At freeway speeds, you have plenty of airflow across radiator, so suspect blocked radiator, too small radiator or radiator efficiency. Around town, if she runs hot I suspect airflow issues. I like thermo clutches and AC type fans. This assumes all components are in good working order. My guess, based on your 1st post, is airflow. One more thing: in sunny CA, I run a weak antifreeze water mix. Water transfers heat well and is less viscous. Just my 2 cents...
Last edited by Jeff_Keryk; Mar 6, 2016 at 12:17 AM.