Evans coolant heat soak problem and solution
 

Running Evans for a week now with Fluidyne and new Mazda Thermostat with four 1/8 inches holes on the periphery of the thermostat.

Problem: car runs at 180 with A/C fan on no matter the condition (not boosting past 5 psi yet as I got only 130 miles on a Malloy reman). At shutdown, temperature at filler neck starts rising to 250 F within 15 minutes and then drops down to below 180 after 2 hours in 68 F weather. I saw this problem with standard coolant but not as high as 250 (more like 240).

Solution: VW has an electric auxiliary water pump that continues circulating coolant after shut down. The design allows coolant to flow by the mechanical water pump if the electric pump isn't working. Inlet and outlet are 5/8 inch (I think cause I haven't receive the part yet) with an L configuration. This would be perfect for connecting the outlet from the block to the heater hose connection at the firewall driver side. Running this with a 5 minute timer after shutdown.

VW did this to their VR6 only because of the packaging of 6 cylinders into the space of 4 cylinders leading to hotspot after shutdown. This caused cylinder head warpage without an auxiliary electric pump. They have this on the VR6 engine since 1993. Mercedes also do the same on their 190D series.

Anyone done this before?

oh yeah, it's $110.00 shipped from www.volkswagenpartstore.com


In the VR6 Passat, this electric pump runs at idle and low rpm to assist the mechanical pump and runs in conjunction with a fan after shutoff.

On the VR6 passat, normal coolant temp is 240 F in traffic. I almost jumped out of my friend's car when showed me what the digital gauge was reading. He said it's normal temp due to emission requirement. That's freaking hot for a piston engine!

The only thing I would be leary about is how restrictive the electric pump is when coolant is flowing through it, "like if you installed it into a heater hose to the heater core and the electric pump if off" as most cars have fluid flowing trough them constantly. other than that its a great idea.

Re: Evans coolant heat soak problem and solution
 

The car runs at 180 F no matter what the condition because it's supposed to. The thermostat doesn't even begin to open until 180 degrees so until the coolant reaches that point it's not even flowing through the radiator.

Yes, that is exactly why I'm running this pump. It's not mechanically connected to the motor so that if the motor is off, it's free wheeling. Otherwise, I could've used the electric water pump that drag racers use. But I chose this b/c of this free wheeling feature.

Re Damon B statement: 180 F isn't the problem, it's the heat soak that's the problem. Sorry, wasn't clear enough ...

Any idea what the current draw and the gallons/hour are on that VW pump?

No idea but probably less than 10 amps; Once I get it, i'll see what it will pump for 5 minutes to see what flow rate it's capable of.

If it's high enough, I might even have it as a supplemental pump during for hot track events. It seems that evans coolant likes high flow rate, it heats up and cool down very quick but doesn't have the thermal mass of water so more flow is better.

I don't know what the stock water pump flows at idle but the whole cooling system barely holds two gallons. Shouldn't take much flow to be useful for cool down.

uh, where in the hell would you plug it in?

You'd wire it to the battery through a relay and control the relay with a turbo timer for instance.

Still no idea on the current draw but the flow rate is 6 gallon per minute.

My radiator system has about 3 gallons, that means with a five minute timer, I'll be circulating coolant through the system 10 times.

Once I get it hooked up with a 555 timer into my heater hoses, I'll post some pictures.

Just for my edification, which way are you going to drive the coolant? From block, through heater core, into lower radiator connection, through radiator, into filler neck and through block until T-stat closes? Or the other way?

sounds like a good. keep us posted on the result.
andrew

Planning to install to pump in the same flow path as stock: pull coolant from radiator thru the block near the spark plugs to the heater core, back to lower radiator hose.

Pump is mounted near the starter and pumps coolant from the block near the plugs to the steel heater core pipe on the fire wall.

I need to wire in a timer for the pump.

Finally got a chance to test my set up which pulls water from the pipe coming out of the block next to the plugs, pumps it up to the heater core and back to the lower radiator hose. Flow rate measured w/o being under pressure is 6 gallons per minute.

Since my fans keep the temp at 185 regardless of outside temp and the temp inside the heated garage is about 60 deg, there shouldn't be any variation from what I saw in the last two weeks (185F rockets to 240F after shut down, back down to 185 after 30-45 minutes).

Note that I'm running Evans NPG+ which has different heat conductive characteristics (0.13 compared to 0.3 for water only and 0.2 for 50/50 mix).

With engine off, temp at 185, I ran the electric pump for 3 minutes. It kept water temp to 210 deg instead of 240. With the fan mod, it shoudn't even get to 210. However, I have the miniature sealed battery so I'm concerned about battery drain with fans and pump running for 10 minutes.

Lookin good, lookin good! :bigthumb:

a better point to hook it up to, would be the rear throttle body coolant return and the supply coming off the water pump housing

rob @ pineapple said that would work

Why is that one better?

I'm not clear on the supply side to the water pump? You mean the lower radiator hose with the small nipple for the heater hose next to it?

As for TB return line, well I bypassed the throttle body completely. The coolant comes from the top of the block near the ACV and now runs straight to the small pipes of the rat's nest (which goes to the Turbos).

The reason I picked this particular spot was b/c it was suited to the configuration of the pump with the 90 deg inlet and outlet. I just wanted hot coolant pump out of the block so that it forces coolant (some of it at least) thru the radiator.

To really force coolant thru the radiator, I would need to pump it out of the block from the pipe next the plugs and straight into the TB return line. But the rub here is that the pipe is a 5/8 in and the TB return is a 3/8. Plus there would be lines running everywhere including a T so that coolant could still flow through the heater core.

My configuration at least forces coolant thru the heater core and pulls some of the coolant from the lower rad hose thru the block.

As far as I'm aware, I think I'm the first to do this to an FD so if anyone tries something different with different results, please let me know. I waited for 2 years for somebody to do this but finally got tired of waiting.

:confused: :confused:

This is just weird. I have NPG+ and with my fan mods the neck coolant temp never rises over 220 even in 105 summer heat.
The temp rise at the filler neck (radiator inlet) after stopping the car is normal and by running the car in idle for a bit (or turbo timer) will drop the temp somewhat.
If your coolant temp is rising too much, there maybe an underlying problem with you coolant flow path. This could cause uneven cooling, and using the electric pump is simply masking a problem that could get worse.

I haven't done the fan mod b/c it killed my battery, several times.

With the fan mod alone, yes I'm seeing the same temp you're seeing.

W/o the fan mod or pump mod, I see 240.
With the pump only, I see 210 and I only have to run the pump for 5 minutes.