high volume water pump issues?

[rcravincase]

for a little background, the car is a 1986 Z28. TPI fueled 383, griffin 2 row radiator, derale 4000 cfm dual fan w/shroud, 160* t-stat, air dam is in place, radiator sealed agaisnt core support and open area between rad and grille filled in so air can only enter radiator. im running a high volume water pump, and i had heard from someone a while ago it can cause an engine to run hot by the coolant not staying in the rad long enough. my car will stay at 170 idling with both fans on when its 90* out. however, when cruising down the highway (75 mph, 2k rpms) with the fans off, it will run about 200-210* it cools off if i switch the fans on while driving. when i got home, i felt the tanks on the rad, and the cool side wasnt all that much cooler than the hot side, maybe only 30* i was thinking before it was a fueling issue, but there is no signs on of it running lean, especially at high rpms. should i go with a standard volume water pump?

[CarlC]

Flow is king when it comes to heat exchangers. The soak-time story is a fallacy.

[Randy67]

Carl is right, here is some more on it from Stewart components
http://www.stewartcomponents.com/tec...ech_Tips_3.htm

I ran my El Camino with just a gutted thermostat after having issues with thermostats not wanting to open until 240 degrees (more than one). It never ran hot, but would run cool in temps below 50 degrees when moving more than 40 mph.

With it heating up at speed, sounds like an airflow issue. Does the electric fan shroud block most of the radiator? Does it have any flaps to allow airflow at speed like some OE ones do?

[AM.MSCL]

for a little background, the car is a 1986 Z28. TPI fueled 383, griffin 2 row radiator, derale 4000 cfm dual fan w/shroud, 160* t-stat, air dam is in place, radiator sealed agaisnt core support and open area between rad and grille filled in so air can only enter radiator. im running a high volume water pump, and i had heard from someone a while ago it can cause an engine to run hot by the coolant not staying in the rad long enough. my car will stay at 170 idling with both fans on when its 90* out. however, when cruising down the highway (75 mph, 2k rpms) with the fans off, it will run about 200-210* it cools off if i switch the fans on while driving. when i got home, i felt the tanks on the rad, and the cool side wasnt all that much cooler than the hot side, maybe only 30* i was thinking before it was a fueling issue, but there is no signs on of it running lean, especially at high rpms. should i go with a standard volume water pump?

I had a 85 Camaro that I raced and it had a high flow pump in the beginning and the temps were higher then I liked. I replaced the water pump with a factory one and the temps dropped about 20-30 degrees so I truly believe high flow pumps can cause problems if you are running high RPMs most of the time while driving.
Ray

[John Wright]

pump turning in the right direction?
water pump pumping more water than can flow through the system....starving the suction side of the pump?

just some thoughts.

Flow is king when it comes to heat exchangers. The soak-time story is a fallacy.

I agree.

[BonzoHansen]

air dam under the nose is 100% required at highway speeds in 3rd gens.

[AM.MSCL]

air dam under the nose is 100% required at highway speeds in 3rd gens.

Mine 85 had the air damn installed

[rcravincase]

yea, air dam is installed. all the gaps along the side between the grille and core support were filled. a/c condensor was removed for the time being. i am using a derale fan and shroud, it has rubber flaps in the larger areas to open up at speed. im half temped to make my own, larger air dam from some sheet metal, but ground clearance is an issue and i know it will just get wadded up. both fans pull with enough force to blow fingers back. i got a water pump that is for clockwise rotation and running the 3 belt setup that was factory for 86.

i was thinking of going to a 70/30 water/antifreeze mixture and adding some water wetter. was also considering removing the trans cooler from the rad and having its own cooler, as well as adding an oil cooler. also has a 16 lb cap

[rcravincase]

any other suggestions?

[AM.MSCL]

Have you verified you do not have belt slip-age?

[rcravincase]

belts are all brand new and correctly adjusted

[Chad-1stGen]

Post up some pics of the radiator / fan combo? It would be fairly odd to me that turning on your fans at freeway speeds cools the car but with em off it runs hot. Sounds like the fan is resricting air flow...

[CarlC]

Try taking the fan out and driving it on the highway.

[chicane67]

First... make sure that the temperature sender is good. Next... make sure the guage is good and displaying the correct temp. Only use the fan when under 30 mph.

Next...

Ditch the 160* thermostat for a 180*... use straight water... and add a bottle of RedLine Water Wetter... for starters.

And make sure you have bled ALL of the air out of the system.

[Trevon]

With it heating up at speed, sounds like an airflow issue.

Its not an airflow issue over about 40 mph, thats a problem in the liquid flow. There should definitely be plenty of air flow at freeway speeds (my car is the opposite, gets hot at idle because I don't have a fan shroud and am not using the whole radiator to cool fluid, as soon as I'm going 40+mph it cools right down to 160)

[rcravincase]

i have seen terrible things done to engines by running just straight water. also because of where i live, i need to run at least 70/30 water/coolant as it occasionally gets to 0 during the winter, and the car isnt stored inside. i did notice when i started it yesterday, i got a bit more air to bubble out into the reservoir, so there may have still been a very small air pocket. the fan shroud is not easy to remove as i riveted it the rad. it did seem to run a bit cooler yesterday, but i kept one fan on the entire time, and ambient temp was about 85, maybe near 90. it never got over 195. here are pictures of my setup



this is the fan that i am using. http://www.summitracing.com/parts/DER-16927/ i am going to pick up some water wetter today and try that out. im also going to take out about 2* or 4* of base timing. i dont get any knock, but i did have the knock sensor desensitized, so there may be a tiny bit of ping i cant hear over the volume of the exhaust. i figure that will help more than it hurts. compression is 10:1, and i run 92 every tank

[Randy67]

Its not an airflow issue over about 40 mph, thats a problem in the liquid flow. There should definitely be plenty of air flow at freeway speeds (my car is the opposite, gets hot at idle because I don't have a fan shroud and am not using the whole radiator to cool fluid, as soon as I'm going 40+mph it cools right down to 160)

It can be an airflow problem above 40 if the airflow is being blocked by the shroud for the electric fan(s). Like Carl said, drive without the fans and if it stays cooler then the shroud/fans are restricting airflow unless they are on.

[rcravincase]

problem is i cant run without the fans. by the time i get to the end of my driveway, it would be well over 240* not the mention the few hours of work required to remove them. i think for now im going to try the purple ice i bought and drop the timing from 12* base to 8* and unshroud the fans as a last ditch effort. the rad is only a few months old, but as you can see in the picture, constant removal and installation has messed up a few fins

[Randy67]

Maybe you could add flaps like these: http://carphotos.cardomain.com/ride_...0120_large.jpg
to aid in higher speed cooling?

[rcravincase]

fan shroud is already equipped