Running hot with electric pump on street

I've been fighting this running hot problem since before I re-built my motor. I'm starting to think it's the electric water pump that was on there when I bought the car. It only spins at a constant rpm, where a mechanical pump spins at engine RPM. I 'm thinking that the electric pump isn't flowing enough water when I'm running at 55-60 mph. What do you guys think?

are you running a thermostat? I had a heat problem with my electric water pump. Guys on here recommended putting a restrictor in the housing. So i gutted my thermostat and it worked fixed my problem ... hope this helps

if i had a street car with a bbf i'd run a belt and a stock pump.your not gona notice the power loss.a lot depends on the rest of your cooling system.

The rest of the system is a 4-row aluminum radiator and a Mark VIII fan pulling air through a full shroud. I'll try the restrictor set up tonight, but if that doesn't work,I'm going to put a mechanical pump back in.

Double check and triple check, and make sure the electric water pump is wired correctly and turning in the right direction. Apparently there were some wiring harnesses out there, where the blue wire and the black wire were installed bass ackwards, which when wired up accorrding to the directions, make the electric motors turn backwards.

Hope this helps,

Charlie

What Charlie said is true. And what Cool said is true also. IMO,I don't think the flow rate is the problem,as long as the water is moving good,the air flow through the radiator should keep the water cool. And also make sure the hoses are not colapsing when the water is hot.

Charlie hit it right on the head. I've quick disconnects on the pump leads and I swapped them while it was running with the cap off (inline filler cap) and the flow rate looked like it doubled. I took it out for a ride, but I still got up to 215* and this was after I pulled the thermostat and gutted it to make a restrictor. Maybe next, I'll pull the restrictor and let it run full flow. I thought I had this cooling problem beat. I had the block hot tanked and jet washed, added a 4-row alum rad, and put an 18" Lincoln Mark VIII fan behind it. The fan moves MAJOR air too. This is getting frustrating.

what is your timing curve ?

do you have a vacume advance?

My timing is mech. advance. Initial timing is 14 with total timing at 32*. MSD dizzy with black bushing and the 2 heavy silver springs. I can't see where I would have any vacuum leaks either. I only have 1 line running to the trans, and the other to the valve cover for a crankcase vent. The other open ports are sealed up tight. Should I close off the one running to the valve cover?

a friend of mine had a fox body with a bbf way back when it was a new idea and he bought a kit to install it.mounts,pan,headers......we worked about a year tryen to cool it but couldnt figure why it would set at idle all day at 190 but wouldnt go 5 miles down the road without blowen the water out.after he give up on it we found the header's made wrong and covered the ports up,kinda like haven the gasket on backward.i put it in my race car and never got hot.this may not be your problem but i'd never thought it coulda been his.let us know what you find.

Sometimes having too much coolant flowing thur the radiator is a bad thing. If the coolant doesn't stay in the radiator long enough cool down, the over all temps will rise. So you might want to put in a smaller restriction to slow it down some. It wouldn't hurt to give it a try.

I'm gonna have to look into that Cool. I've got D0OE-R heads on this, and if the headers were made for a different head, I could very well be covering up some of the port. That'll suck if I have to re-flange these things. Good thing is the place I used to wark has 5 laser burn tables. I'll just have to make a print that they can upload to the laser. The boss there owes me a favor for tig welding the water tank on his RV.

I found the exhaust ports partially covered on the bottom. About 3/16 to 1/4" of it is covered up. I'm going to use some transfer blue tomorrow to get a better look at how bad they really are. Tonight I just used a piece of cardboard bolted on to transfer the hole location, then overlayed it on the header to see how much it was getting blocked. I may be able to weld up the bolt holes and re-drill them in the right location to get things to line up better.

I think the water is not staying in the radiator long enough. Restrict it some more and see what happens...

jbozzelle wrote:I think the water is not staying in the radiator long enough. Restrict it some more and see what happens...

Agreed, if its staying at a constant high rpm and your just driving around town then the coolant doesn't have a chance to cool off and goes back in the motor without really cooling down.

Try putting a 180* thermostat on it if you have a lower temp one on it right now, it wont flow as quickly as lets say a 160* thermostat. Maybe that's not too true but I was told a 160* flows more frequently than a 180* thermostat.

Make sure you are running a high flow thermostat as well. They usually drill a small bypass hole it it as well (that is what Stewart calls their "modified" thermostat). You can just buy a Robershaw stat form a local supplier and drill your own 3/16" hole.

http://www.stewartcomponents.net/Merchant2/merchant.mvc?Screen=PROD&Product_Code=302&Category_Code=Therm



Stewart also has some tech tips here.

I've had 3 different thermostats in it (165, 185 and 195* and 2 different restrictors 1" and 3/4". All had the same results. I found that anywhere from 1/4 to 3/8" of the top of the exhaust ports are being covered up by the header flanges. I'm gonna scribe them out tomorrow and try to get a smooth blend into the tubing. I really don't feel like cutting the flanges off and re-doing them.

jonboyusmc wrote:I've had 3 different thermostats in it (165, 185 and 195* and 2 different restrictors 1" and 3/4". All had the same results. I found that anywhere from 1/4 to 3/8" of the top of the exhaust ports are being covered up by the header flanges. I'm gonna scribe them out tomorrow and try to get a smooth blend into the tubing. I really don't feel like cutting the flanges off and re-doing them.

I've ran the header gasket backwards where they cover part of the port and never noticed and difference in temperature but good luck. The one thing I didn't see mentioned was whether or not the head gaskets are on correctly. IIRC there should be a small tab out the back and it should be stamped "back" (at least on the Felpro ones I have used). If you put the gasket on wrong it plugs some coolant passages. It's been a few years for me so hopefully someone will correct me if I am wrong.

One other thing, I noticed you said you had a 4 core aluminum radiator. The aluminum units just come 2 core but they are usually 1" or 1 1/4" thick cores. Was the radiator new when you put the motor in or was it from before the rebuild? The reason I ask is when you take them out for an extended period of time (like while you rebuild your motor or car) any scaling or crud inside will dry up and when you fill it back up and start circulating all the scale/crud comes off and plugs up the radiator. One of my friends (mechanic for 30 years) said he has seen it so many times that it is there SOP to have the rad flushed every time they do a motor job.

The head gaskets are 100% for sure on right. The original builder of the motor had one on backwards. Also the the radiator is a true 4-row. It came straight from the manufacturer and is rated at 950 hp. This whole build is brand new everything, thats why I'm baffled about the heat issues.