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Water pump


jonlabree
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Jon, what you are suggesting might work to cool the engine better but from my experience with race cars, cooling the engine depends more on getting the water cooled down to a lower temperature while it is in the radiator than flow through the system. I have actually known of people that removed the thermostat from the engine thinking they would get more coolant flow, and thus more cooling, to find it had the opposite effect. With too much flow the water doesn't stay in the radiator long enough to be cooled properly before it is returned to the engine. The best way to cool the engine is to install a larger radiator (more cores) and/or increase the flow of cool air across the radiator. No mater how fast you circulate water through the engine it will not help much unless you can adequately cool the water down in the radiator.

Sorry that I couldn't answer your question about over driving the water pump. I don't know anyone who as done that. Usually on a high performance (high RPM) engines you use an under drive pulley to prevent over speeding the alternator, and other accessories, and to cut power loses from driving them.

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All I can say is that I have "fiddled" my TranSport the same way as the cars and made a round trip to Tallahassee on 90+ degree day, air on all the way, and a Reatta on a dolly on the way back. Temp gauge never went above 185F.

Now the TranSport has an "L" 3800 and a larger radiator than the Reatta but if I were concerned, I'd add a good oil cooler rather than trying to overdrive the water pump.

Back in the day when I raced small block 'vettes in SCCA B/P I did not have a thermostat. I did have a washer with a 7/8" hole in place of the thermostat.

Be aware that if the coolant sensor registers below 146F, the TCC will not lock up.

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Both fans are working properly. The Radiator is new, oversize and aluminum. All hose’s are new, and it has a new 180 thermostat. The pump is the only thing that I have not changed. That is coming shortly. I have a new one. The temp still runs in the 200's on a normal day. I am in the prossces of making a new aluminum pulley for the w/pump that is 1/4" smaller. (that's 10% increase in the speed) I may be over reacting because of a bad pump, but I don't think 10% over speed wil hurh it even if the pump is bad.

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Do you have any means to turn the fans on earlier ? The stock programming does not turn the LO fan on until over 200 and once hot, the 3800 is hard to cool down.

My experience with the 3800 is that the standard equipment is enough to keep it under 190F at all conditions as long as the fans are on at low speeds (under 50 mph). It really wants to run less than 90F over ambient temperature. On mine (several), 179-183 is typical when moving. see 190 briefly at stoplights with the a/c on a hot day but then te HI fan kicks in and it comes back down.

Since you have a supercharged engine, the PROM must be special. When are the fans set to kick in ?

BTW if you spend a lot of time at high rpms (over 2500) I'd be looking for underdrives, not over. The cooling system efficiency peaks at a specific flow rate.

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Have said before, the factory considered anything under 230F to be OK. Long experience has shown me that running 180-190 instead of 210-220 makes everthing under the hood last longer.

Picked 180F for three reasons

- thermostats are available/inexpensive (I like STANT SuperStats)

- is high enough for burn-you-out heat even at 0F

- is high enough for the computer to be "all-in"

Been working for me since 2001 in Reattae, decades longer in other cars.

One note: cheap thermostats open slowly. The set point is where they begin to open but it may take 10-20F for them to fully open. My observations with the Stant is that it goes from full shut to full open in about 5F

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First of all, Are you guys getting the temp readings from the stock gauge? If you don't have an accurate gauge on the engine your readings a all bogas. The stock gauge is useless and should not be considered at all.

My added gauge reads accuratley and it shows 220% on a normal ILL., day at normal speed.

When I stop and shoot my temp gun at the thermoustat housing it reads 225%.

The chip has been modified by Ryan at Sinister Eng. so the fans are coming on at a lower temp.

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I have a couple of IR guns as well, and if the gauge reads rong (can see the thermostat open if watching ED04 during warm up), it gets replaced. +/- 2-4F am not concerned about but if a temp goes over 190F, I find out why and fix.

Personally, I have had a lot more oil pressure senders fail than water temp.

Wish I knew how to paint, people seem more concerned about shiny than how well it runs.

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Nice looking work. I have not checked the water temperature with a mechanical gauge or IR gun but I don't get any indication the engine is hot even with an intercooler, oil cooler and trans. cooler directly behind the grill. These items get all of the air first and completely cover the grill area. I will have to check with a second means to see if there is indeed a discrepency between indicated and actual. I do have a new water pump installed but the drive is all stock. The ceramic coated exhaust system under the hood does reduce the "feel" of heat under the hood.

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  • 3 weeks later...
For all of the na-sayers. The new smaller water pump pulley keeps my temp down one whole mark on the GM gauge. And it looks awesome.
As you said before, "First of all, Are you guys getting the temp readings from the stock gauge? If you don't have an accurate gauge on the engine your readings a all bogas. The stock gauge is useless and should not be considered at all."...

So for all us naysayers, tell us how much difference it made in degrees with the mechanical gauge you added to your car. I'm sure it does look good.

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"one full mark" - which one ? Midpoint is about 182F so if running close to 180F it could go either way. The real test is coming off the Interstate to a long stop light on a 90+F day with the a/c on. ED04 is the real answer.

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No just it is hard to tell what changed. I am assuming you have a 180F thermostat which is very near the break from a 11 o'clock reading and 12 o'clock. OTOH straight up (12 o'clock) can be anything from 182f to over 200f before it goes to the 1 o'clock mark.

With reprogammed fan set points mine can go from no fan to lo fan to hi fan without any change in the "gauge". ED04 is the only way to tell what is really going on.

BTW mine turns 10% faster at idle because I increased the warmed-up idle speed from 625 to 700 rpm to spin the a/c compressor a little faster at stoplights.

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if you can get a temp drop from the smaller pulley it raises a question is there another car pulley out there that's that much smaller that can be made to fit on the reatta's water pump without too much mods since the rest of us dont have access to machining equipment but can get to junkyards. Also if youre getting too hot have you tried running an alternate trans cooler to keep tranny heat from the coolant, draining and correctly running a 50/50 mix of a good quality coolant and distilled water then add a bottle of royal purple addative to it (it dropped temps in my hyundai about 10 degrees) and it may sound obvious and kinda stupid but mine kept overheating when i had a blown head gasket. It ran fine but the high temp combustion gas would get in the coolant and make bubbles which made hot spots and warmed the coolant too much

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Personally I have never worried about it, my cars sit very close to the 180F thermostat opening, with only brief spikes in unusual conditions (like a stop light coming off an interstate). I have found that if you keep the engine cool to begin with, it is easy to keep that way and a 3800 is a lot easier to keep cool than a SBC.

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right after rebuilding mine, meaning new everything, 180 degree thermostat, perfect coolant mix, no trash in the block, as in cooling system is all new and PERFECT working order on a 56 degree day mine rose up to about 196 sitting in the parking lot at my shop and was still rising steadily when I shut it off. Within a minute it went from 188 to 196

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If you had a 160 degree thermostat it would do the same thing. If you had left it running long enough it might have gotten as hot as ~230 degrees before the fans would have kicked on and cooled it back down assuming you still have the stock ECM programming.

Thermostats do not limit how hot the engine can run... thermostats determine the bottom limit of how cool it can run on a cold day.

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Oy. The thermostat determines when water is allowed to flow throught the radiator. Before it opent it just circulares in the block and heater. The idea is to minimise the time when the engine is cold/inefficient.

The radiator is a liguid/air heat exchanger. In order to exchange heat, the air must be moving. This can either happen because the car is moving or because the fans are on. If stopped and the air is not moving the coolant will get hot regardless of the thermostat setting.

The General does not even turn the LO fan on until well over 200F so for a stopped/idling car to get from 180F (thermostat opening) to 196F is just because the air is not moving.

When I diddle my 3800s it is two-fold, the thermostat is lowered to 180F and the fan settings are lowered by changing the PROM programming. LO fan comes on at 185F or with a/c and HI at 189F. On a long 90+ day stoplight I may see the temp on my 88 rise to 189-190 for a moment but then it comes back down to 185-186 .

You must have both - open thermostat and airflow across the radiator - to stay cool.

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i guess im used to newer cars. I forget GM engineered the reatta to run hot. When temps are under 70 degrees you never see the fans come on newer cars because they tend to stay at operating temp at idle just fine when outside temp isnt so high.

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im holding off until my engine is completely worry free until i spend money on interior, paint and ECM flashing (not necessarily in that order) I wouldnt mind buying a new ECM (ACDelco is $200 and aftermarket is $100) and have it reflashed to keep from putting the car down for a month to send it off and have it sent back.

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You do not need a new ECM, just the PROM "diddled". The latest 1990 FED PROM from GM is a 16148013 code (ED99 8064) . 1989 is 16141300 code 1094. These are still listed several places (1) (2). - make sure you compare the total with shipping.

Edited by padgett (see edit history)
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