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.

I gotta agree...something else is going on here.
This is strange...

OK, I tested my set up with the fan mod.

Pulled into garage at 195, shut the car off with fan mod going and pump going at the same time.

Within 3 minutes temp rose to 210, stabilized for 1 to 2 minutes and then went down to 180 within 5 minutes. My suspicion is that it's the turbos that are causing the high temp spike after shut down. With coolant circulating, this would show an immeadiate decrease in temp.

I need to datalog this heat soak after shut down and plot it over 20 minutes to see the total effect. Will do this later and report back.

any more info on how much of a difference your setup is doing?

does this mod work even if you do not have your temperature control turned to full heat in the cokpit. I would think that this route would be bloced by a valve if the control was not turned to full heat to open it. Am I right or is hot coolant always flowing through the heater core and we are just opening an air control damper when we turn the temp control.

Also, how did you wire in a timer. I was thinking about doing it this way or just using a temp sensitive relay that was tapped into the Thermostat housing. This way if the temp never got above 200 lets say, then the pump won't come on. Any body do this or tap into the stock fan temp sending unit. This one will bring the fans on at 225 and could also trigger the pump. I heard you can change this out for one that comes on lower like 205 deg.

I just started searching but this seems like a good place to ask

Mike.

See my answers in the other post.

As for the timer, I'm not running a timer. Running a fan switch relay available from Summit Racing for $40.00. The relay comes with an adjustable sensor probe. The probe could be inserted into the fins of the radiator but in my case, I just taped it with alumninum tape to the filler neck as this is the hottest spot (due to the turbos) and wired the relay to turn both the fans and pump on.

Poman..

Would you recommend this MOD. For FD's that
have regular coolant/water mix???
This mod would be great for any kind of heat soak
Evans NPG or regular coolant. right????

Since you are in DC.. If I bought the parts..
Think you could install it for my FD??

thanks

BTW any side effects or problems since this mod?

Yes, I would recommend it. However, you need to get silicone heater hoses for connecting to the pump.

Re: side effects - if you're running a small PC680 battery, it might drain it if you have both the pump and the fans running after shutdown. I haven't had the problem even though I'm running a 1/2 sized battery.

Re installing: sorry, can't help you there but any good mechanics should be able to do this.

I had noticed this too. My temps spike up after shutdown but I saw it on my PFC instead of a separate boost gauge.

Even with the fan running, I was seeing an increase up to around 100 deg C with a normal operating temperature of 86-87degC and ambient air of 64 deg C. (sorry running off PFC so all temps are in celsius)

What I did was after I had idled the car for two mins, I turn it off and watch the temp rise keeping the fan on. Then I fired her up briefly for about 30 seconds just to get the pump going. After two-three repetitions, the temps stay at around 87 deg C with the motor off.

Maybe I can build an independent circuit that will operate, based on temp readings, the fans and the pump in a cycle as to avoid battery drain.

I do ^^^ that as well but just only after spirited driving and if I have the time, I only do it once though, not start-off-start-off cycles.

I shut off, put he switch in ON and wait for the fans to come on. Pop the hood open and let it vent for a while, then fire her up for a few secs, shut off and wait again; everytime I do it the fans stay off so I don't rinse and repeat.

I don't have an aftermarket temp gauge though, I go by the fans. I do have a miata thermoswitch so the fans turn on at 207 F instead of 221 F.