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How to test radiator fan relay & motor functionality?

60K views 13 replies 4 participants last post by  flstffxe  
#1 ·
Hi there,

I'm hoping someone can instruct me on how to test my radiator fan relay(s) and the radiator fan motors as well to make sure they're working properly.

I can't remember the last time I saw or heard them running, and I did have a slight overheating scare on my last trip across the country in October:

My ScanGauge showed temp climbing up 200-208 deg F for some parts of the drive. Granted the car was LOADED to the point where the rear suspension was pretty saggy and I was cruising at 70-80mph in NV, UT, CO. At one point the ScanGauge read 210 and it freaked me out and I got off the highway and discovered a bunch of coolant around the thermostat housing & also that the overflow reservoir had emptied. I was thinking that maybe the coolant boiled over and bubbled some out of the overflow reservoir as that small hose is not sealed around where it goes into the reservoir. So I refilled the reservoir and wiped off all the coolant so I could keep an eye on things. No more coolant spillage/leakage for the rest of the trip, but temperature did continue to fluctuate between 195-205 until I got to Missouri or so, where the temperatures stayed down below 195.

So at this point I'm just trying to find out if it was a fluke because of the loading conditions (cargo, altitude, climbing grades) and because it hasn't really gotten quite that hot since (still getting to 190F while cruising STEADY at 50mph in 5th gear, even with 40F ambient air). OR if something in the system isn't working perfectly.

NOTE:
1) Thermostat was correctly replaced w/ OEM one (jiggle pin facing front & "spring side" into pump housing) when I did the timing belt ~7500 miles ago.
2) Water pump was replaced w/ NAPA Tru Flow part (cast impeller design) at timing belt change
3) Did a couple distilled H2O flushes then refilled with 60% distilled/40% Genuine Subaru Long Life coolant after timing belt repair.
4) Car doesn't consume any coolant
5) Engine Temp gauge on dash display would be pegged in the dead middle and wouldn't even start to rise a hair until ScanGauge temp displayed 205F+.
5) All summer I never saw the ScanGauge read above 188F, even going up the 7mi/3,000ft grade that I would frequently drive up @60MPH in ambient air temps of 85-95F, but not with huge loads.

I suspect one of these:
- malfunction w/ radiator fan relays or fan motors
- partial radiator blockage (hopefully not)
- malfunctioning radiator cap
- no real issue, just a fluke, and running a bit on the hot side of things :shrug:

Long story short: I want to test the rad fan relays and motors at this point, but I'm not great at interpreting the wiring diagrams in the Service Manual. :icon_redface: Engine is out of the car for other reasons (fixing a severe oil burning problem), so I can test the fan motors on the bench if it'd be easier.


Thanks for reading folks.
 
#3 ·
210 is not a high temp. It can easily go up to 220 in summer.

Once the engine is hot let it idle. The fans come on at I think 203F

Also if you turn on the a/c I think the fans come on. Not sure though.

Replace the cap with genuine Subaru. Make sure you add the conditioner to the coolant. I would highly recommend Subaru coolant.
 
#4 ·
...cruising at 70-80mph in NV, UT, CO. ...until I got to Missouri or so...
What route? I-15 North and I-70 East?
What gas grade? "Regular" or "Mid-Grade / Special"?
A/C on or off?

More later,
Jim / crewzer
 
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#5 ·
With a 50/50 mix, and at the elevated pressure (above 1 atmosphere, I'd assume) in the closed loop, the boil over temp must be quite a bit over 212, eh? I was freakin at 209 thinking 212 would be boil over.

Still though, it was odd, on long trips I'd never seen temps like that since I got the ScanGauge... even in Death Valley's 100 deg temps... but with a bit less weight in the car.
 
#6 ·
crewzer: North of Cedar City on I-15 it is 80MPH on the interstate now. And I had my scare, where the temp was 208 right after merging onto I-70E from I-15N last month. Pulled off at some old fort, at night, opened the hood and with my headlamp could see all the coolant there. So I slept in the car. In the morning when it was light out, I couldn't see anything wrong with the connections at the t-stat housing and lower radiator port, or anything weeping from the new water pump for that matter. Coolant was scattered throughout that area, a little on the Timing Belt cover and a little on the coolant reservoir. Had to have been a radiator cap malfunction causing it to bubble coolant out of the reservoir.

85 Octane in Utah and Colorado (atleast until Denver I think). It was my understanding that 85 octane substituted for 87 octane in the higher elevations of those states. FWIW, if there was any pinging, I certainly couldn't hear it.

A/C was off. At times, when ScanGauge was showing 200+, I would turn the heat all the way to hot and the fan on 2-3 to dump some extra heat from the coolant, then open the windows so it wasn't roasting in the cab.
 
#7 ·
Boilover is 265 so that's not an issue. If it wasn't a defective cap, you likely have a head gasket leak.. That is what typically forces the coolant overflow in the plastic container.
 
#8 · (Edited)
Fozzy,

Thanks for the extra info.

My ScanGauge showed temp climbing up 200-208 deg F for some parts of the drive. Granted the car was LOADED to the point where the rear suspension was pretty saggy and I was cruising at 70-80mph in NV, UT, CO. At one point the ScanGauge read 210
It's a long uphill slog along I-15 from the NV/AZ line (~1,800 ft elev.) to Cedar City, UT (~5,800 ft elev.), but then it's fairly level from there to Fort Cody (~6,000 ft elev.) at the I-15/I-70 interchange. It's another ~4,500 ft elevation gain (10,500 ft total) to Vail Pass on I-70 west of Denver.

The indicated temps were perhaps a little on the high side, but not too alarming, IMHO. We've had our '09 Forester (loaded!) and our '06 Honda up in these general areas for summer road trips in 2009, 2010, and 2011. We had no cooling system issues with either car.

The boiling point of healthy 50/50 coolant in a closed system with a healthy 15 psi radiator cap (2 atm total system pressure) is ~264F, give or take. At 6K ft elevation, I would expect the BP to drop to ~246 F.

However, if the coolant was weak, the radiator cap malfunctioning, and/or there as a leak that resulted in reduced cooling system pressure, then the BP would be lower. For example, plain ol' water in an open pot at 6K feet boils at ~206F.

Here are Subaru's thermostat specs for the '07 2.5L n/a EJ engine (same as yours?):

  • Start to Open @ 176-185F (80-84C); fully open at 203F (95C)

These specs have been changed for the new FB25 engine:
  • Start to Open @ 187-194F (86-90C); fully open at 203F (95C)

I recorded the following cooling system operating specs for my "old" 09 Forester with the EJ25 engine:

  • Low normal operating temp while moving: ~185 F
  • High normal operating temp while moving: ~194 F
  • Cooling fan cut-in temp when idling: ~212 F
  • Cooling fan cut-out temp when idling: ~204 F

The point of all this is that it does not sound like your car's engine got hot enough (212F?) to turn on a cooling fan. Accordingly, checking the fan relays and motors should perhaps not be your top priority.

3) Did a couple distilled H2O flushes then refilled with 60% distilled/40% Genuine Subaru Long Life coolant after timing belt repair.
This is probably not optimal. One issue is that the general recommendation is a 50/50 mix. Another issue is that any water left in the cooling system after the H2O flushes just served to further dilute the new coolant mix. For example, if there was just 1/2 qt of water left in the "drained" cooling system, then the resulting mix was ~63% water and 37% antifreeze. This is way below the typically recommended 50/50 mix.

The correct way to do this after the the H2O flushes, IMHO, is to pour in 3.5 qts of undiluted coolant into the ~7 qt system, then add Subaru's recommend/required coolant system sealer, and then add distilled water to complete the fill. This way, you'll end up with an ~50/50 mix.

Alternately, you could just pour in an entire gallon of undiluted coolant, then the sealer, and then top of with water to end up an ~57/43 mix of coolant:water, which is below the typical 60:40 mix limit and should offer a bit more cold weather protection.

I'd also check the radiator for any blockages, both internal and external. It's also worth checking the A/C condenser to make sue it's not externally blocked (with bugs, leaves, too many bent fins, etc.). And, considering the info above, it's probably worth confirming that you have the correct thermostat.

5) Engine Temp gauge on dash display would be pegged in the dead middle and wouldn't even start to rise a hair until ScanGauge temp displayed 205F+.
Sounds "normal", unfortunately, as the temp gauge operation is not linear. I'll let you do a forum search on that popular issue. :mob:

Short version:

  1. Check for minor leaks / do a pressure test
  2. Check for correct coolant mix and for sealant
  3. Check for correct thermostat temp spec
  4. Check for radiator- and condenser blockages
HTH,
Jim / crewzer
 
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#10 ·
Thanks for the great responses.

@ adc: The head gasket, and mating surfaces didnt seem to show that there was coolant getting terribly close to getting in the cylinder. Compression was fantastic (205psi all around, dry, on a warm engine). Car also wasn't previously consuming coolant and didn't consume any more coolant after that incident. It's all academic anyway since I'm in the middle of a teardown & rebuild and new head gaskets are in order.

Once I re-assembly my engine which is in the midst of a rebuild, I'll fill with 50% Coolant, add 1/2-2/3 bottle of Redline WaterWetter, then top off with distilled while burping the system.

Is the cooling system conditioner really still recommended? The engine will have brandy new Cometic .040" HGs on it and I'd prefer not to have all those gelatinous brown particulates that the Suby/Holts coolant conditioner creates in the coolant to bugger things up.

Any reliable way to check for blockages in a radiator? Feeling for hot/cold spots doesn't seem too scientific. Will most radiator service shops run a flow test on the rad? How much could that end up being for a simple test?

The 2005 Suby factory service manual gives different temperatures for the thermostat.
Starts to open: 169F-176F
Fully open: 196F

I believe the part number for the one I bought was 21200AA071. I'm going to try to test it myself as described in the service manual, since it is basically brand new, before reaching for a new one.
 
#11 ·
You really shouldn't need water wetter. I would not go with a high pressure cap bc it allows a higher pressure in the coolant system. The conditioner won't cause any problems (IMHO). It is recommended.
 
#14 ·
Shouldn't need, but I can say it does work. I am all for keeping coolant temps around the thermostat setting. If you can aid heat transfer and keep the temps lower why not.
 
#12 · (Edited)
Any reliable way to check for blockages in a radiator? Feeling for hot/cold spots doesn't seem too scientific. Will most radiator service shops run a flow test on the rad? How much could that end up being for a simple test?
in the "good ol' days", I always checked for clogs by running my hand over the fins after the engine had warmed up. IR thermometers are now a good way to go. I have an inexpensive one from Radio Shack.

It seems to me that you could use this technique with the radiator out of the car. Hang the room-temp radiator, block the lower pipe, fill it with cold water, and scan it with an IR thermometer. Any internal blockages should show up as relatively warm.

The 2005 Suby factory service manual gives different temperatures for the thermostat.
Starts to open: 169F-176F
Fully open: 196F

I believe the part number for the one I bought was 21200AA071.
Looks like Subaru went to the hotter thermostat for MY2006. The -071 has apparently been superseded by the -072. So, what are the -072 specs, and which thermostat do you actually have?

The coolant temps reported when using the colder thermostat may be cause for concern. So, I think my original short list still makes sense, especially item #4.

HTH,
Jim / crewzer
 
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#13 ·
The coolant temps reported when using the colder thermostat may be cause for concern. So, I think my original short list still makes sense, especially item #4.

HTH,
Jim / crewzer
Yea and actually the hotter temp stat really only serves to allow the engine to warm up hotter at low load conditions. In summer and going up hills really the radiator size determines the temp
 
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