• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

240 E fan only runs for 3 seconds at a time, temp gauge hot

2turbotoys

Salaminizer
Joined
Nov 13, 2007
Location
Reading pa
I have been trying to pin down what is going on with the cooling system in my 79 242 for a while. Replaced almost everything. The temp gauge goes almost all the way to the red when in slow traffic, so I thought the e fan wasn't working. It does, but only for about 3 seconds at a time. 30 seconds later it will do it again. It is an 850 fan, mounted in a 240 shroud, factory fan relay setup.

This happened before, so I installed an Autometer gauge in the glove box and it never went much over 210 degrees. I wanted my regular gauge back so pulled the Autometer out and hooked up the stock gauge. That would only work intermittently, so I just replaced it with another unit. This one goes very high as I mentioned, then back down to the N when at 50 mph or so for a few minutes. Do these not have the compensator thing which keeps the needle steady on the N?

What I did so far (for various reasons but this is the state of the cooling system):
New water pump
New thermostat
New radiator
New thermoswitch
New temp gauge sending unit (can you test these?)
Solid state voltage regulator for cluster
Replaced temp gauge with another one to see if that was the problem

Maybe there is no problem as the Autometer gauge read ok temps, but why does the fan not stay running for more than 3 seconds? This is sitting in the driveway watching the gauge and fan.
 
I did not, what would be happening in there to shut the fan off? I don't think there is any thermal protection. I can do that though.
 
Possibly the relay kicking on, heating up, and expanding the solder. Go in with both flux core solder and an additional tube of flux if you can. I can't think of anything else that would cause that except a problem in the ECU.
Does the 850 fan run at a higher wattage? It could very well have revealed a problem in the relay's solder.
 
It has no connection to the ECU, it is a K Jet car converted to Megasquirt. Megasquirt only runs the injectors, no timing. The fan circuit is only the fan, relay and thermoswitch. As far as wattage, the 850 fan is an old school solid upgrade, but I have never read anything about the wattage. E fans in general use a ton of current to turn on though.

I do have a few relays, I will restore one with the solder gun.
 
Barton claims the 850/940 fan pulls "lots of amps" when starting a high speed spin, if that helps. I assume he means relative to the other electric fans he's worked with.
 
Where’s the fan temp switch located?
SAAB T in bottom radiator hose with quality Volvo/Saab/audi NLA Made in W. Germany 77-82?C or 82-87?C switch or switch in passenger radiator end tank?
Temp switch in top radiator hose or crappy China temp switches will do **** like this.

Fan does draw a lot, Denso 100A / good belt grip or Bosch 100A helps but even then it’s a lot for the redblocks/v-belts.
Still, efan, even with the larger radiator, never really worked that well on the last of the USA market redblock cars. non-A/C euro market cars don't use that POS.

Restore to stock tropical clutch fan? :lol:
It basically does the same thing as switch in top of passenger end tank mechanically: top of radiator at t-stat temp but not totally heat soaked but measuring temp of heat exchanger output.

Have a Saab T and a thinning stash of made in W.Germany lower temp on-off no fuss switches. The nissens 3 rows will accept that brass screw-in switch on the passenger end tank, Volvo radiators that take the push-in switch w/rubber bushing you can use the 88-92?C Volvo Regina temp switch for 1992+ 740/940 regina cars.

Biggest problem with the SAAB T is having to splice the hose and that it's mild steel/most car crusty if someone doesn't change the coolant. That said, sensor at the bottom/well submerged even if there's a slight coolant loss (or you install the coolant float sensor like the 7/9s have? connected to a dash warning lamp with something better than avg TB lowered lowlife amateur-hour/OE eurotrash biodegradeable 80s volvo wiring) and coolant drain for the radiator without making a mess/having to pull the radiator is a nice side benefit.
Stainless MBZ 7mm drive clamps are nice?
Screw is mild on them IIRC?

No compensator, sender and gauge rarely fails on 73-80 cluster.
 
Last edited:
Interesting symptom. The fan runs for 3 seconds, then is off for how long? You need to do some electrical checks and stop throwing parts at it. If you ground your fan thermostat line, the fan should run. I agree (above) pull your fan relay(s) and have a close look.


-L
 
I agree with K-jets, if the switch is near the top of the radiator it will cycle like this, when I moved it to the Saab tee in the lower hose it worked much better. It also came on earlier. I'm running the fan off my microsquirt now.
 
It has no connection to the ECU [...] The fan circuit is only the fan, relay and thermoswitch.
Ah, at first I thought "e-fan" implied ECU control. But what you've got is wonderfully old school.

All you need to do is figure out whether the thermoswitch is flaky (meaning the relay is doing exactly what it is told) or else the thermoswitch is telling the relay to function but the relay won't comply.

Or the third option: control is good but the fan won't comply. Is there a thermal circuit breaker built-in to the fan motor, to protect from abnormally high inrush current? In which case, can the bearings be cleaned and lubed? I'm totally guessing, but this scenario fits pretty well with the symptom of running for 3 seconds.
 
Where’s the fan temp switch located?.

It is a new Volvo radiator with the push in thermoswitch. I used this before in my old 740T, and it worked well, but maybe it doesn't in a B21?

Never gonna put the mechanical fan back in haha.

I do have one of those SAAB T's, I can try that. Anyone know the part # of the thermoswitch or year/model to order it? I forget what car I got that from, many years ago.
Edit: found the switch, but appears to read 115-110, which is really hot
Edit #2 haha, BECK/ARNLEY 2011545 is an 82 deg C switch, BECK/ARNLEY 2010809 is a 92 deg C switch. What is the better choice? I think the 82 deg C one, I ran the car without a thermostat for a while and it ran fine.

The relay is doing exactly what it is told, if you complete the circuit with a screwdriver on the thermoswitch terminals the fan will keep running until you remove it.
 
Last edited:
Air bubble?
Leak?

I’ve had air bubbles on bcp headed B21s that don’t come out as willingly moreso than small water pump pulley 700Turbo/their heater core path.
If there’s a leak or bad expansion tank cap, sometimes the switch/all else is good, but switch barely submerged, switch turns on fan, coolant shrinks/switch ceases to be submerged, fan turns off.

Air bleed on t-stat oriented right & all?

Don’t know what else to tell ya.
Have replaced a few 88-92?C regina switches that failed in '92-'93 e-fan 7/9 cars that ate the headgasket + heater core on regina 940s along with the radiator end tank (taking too long to turn on the fan) just after replacing the HG, expansion tank cap (deformed/valve stuck shut) :lol: made a mess but didn’t overheat/caught it quick. Don’t miss coolant spills/toxic fluids & surprises as a mechanic.
Quite the 1-2-3 knockout.
Block per stealthfti (same experience here) always shows signs of running too hot on the OE E-fan cars.
Regina less-so (ish)...switch is more conservatively placed/temp range like the clutch fan cars/less reactive like the ECU temp sensor location in the head that the ECU doesn't kick on until the aaaaaabsolute last second, nearly stalling the poor overburdened redblock in the heavy fat lazy american 7/9 barge.
 
Last edited:
Barton claims the 850/940 fan pulls "lots of amps" when starting a high speed spin, if that helps. I assume he means relative to the other electric fans he's worked with.

A lot of amps compared to a belt driven fan :) (wrote that in context of dealing with heavy amp spikes).
Not really a lot of amps compared to most electric fans nowadays.
Dave
 
Alternators are only ~50% efficient (at best at perfect/ideal ~2500-3k RPM engine cruising economy speed), why make the electricity go thru shady un-fused/circuit breakered euro-trash car wiring going under an oil-leaky tractor motor to then drive the fan brushed DC motor non-variable speed/pitch fan that's ~80% efficient on the motor on a small/marginally sized radiator requiring more belt tension with a small alt pulley/large reflected moment of inertia & shady/sketchy redblock accessory brackets/bushings, again?

Granted, typical of the swedes/british/anglos, they didn't really design the clutched fan right either;
RPM too high, on the undersized water pump bearing, same blade as a nissan truck with a wider radiator but lighter duty, super annoyingly noisy (blade pitch/symmetry more than anything there/low bid Aisin part).

Look under the hood of the Toyotas (Toyota got the controlling share in Aisin) & their heavy equipment & thus got to source top-shelf Aisin stuff 4-ch33p with legendary Japanese quality control; fan's quiet and efficient on most all of them/never have problems with it/never leaks oil at the clutch hub hardly (Landcruisers & worked real real hard forklift in a hot warehouse getting slammed around full speed on/off the gas lifting shipping containers or something crazy heavy or same motor in the Toyota 4x4 van with a really ****ty undersized little radiator with the front diff blocking all the airflow, sometimes :lol:...BRUTAL though...).

Same with the AW-71 trans in the volvo; turbo-volvo is the highest HP application for that trans & everything about the volvo adaptation of it is totally half-ass & a mess & over-stressed/miserable to repair/leaky compared to the ~98HP stuff they put the AW-71 in otherwise and 114Hp they put the weak AW-70 in in the volvo. low bid, **** adaptation/design. Typical of volvo cars. :roll:

IDK if I missed something, or you had a calibrated temp gauge in the 7/9 car you had when it was working "fine", but all the 7/9 cars except the very very early ones with VDO instrument cluster the temp gauge is just a gauge-shaped warning lamp more-or-less;
indicates the coolant isn't yet warm~150F or so/don't beat on it/flog it brutally
or you overheated it, with whatever damage that did long or short term/probably too late. :lol:

Might have worked about as well/badly in that car more-or-less (tho no 3sec on/off?), but if you were using the OE gauge, you probably wouldn't have had clue 1/inspector clueseau/clue-zero, necessarily?

Never gonna put the mechanical fan back in haha.

The all-join-in/circular-around camp song & TB jeer?
See ya next year (if that's going to be a thing)?
Requests?
kumbaya?
Camptown ladies?
<iframe width="560" height="315" src="https://www.youtube.com/embed/OFykFC6W9tQ" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

'least I don't gotta travel for that nostalgic campfire smell eh?
Who needs beautiful late summer PNW vacation? :rofl:
 
Last edited:
Much truthiness.

More truthiness.

Never gonna put the mechanical fan back in haha.

:nod:

Can't possibly be one of the kewl kids with a tropical clutch per Volvo's reccomendation.

Just look at Dave Barton's e-fan adventures hundreds of hours and dollars and he's still not completely happy with the results?

That said unless you don't have anything else better to do why not put in a 66% less efficient e-fan that runs most of the time?

Or simply buy a more modern car with better sound deadening and a quieter fan instead of installing earrings on a sow's ear?
 
Last edited:
I have converted several of my Volvos to efans, never had a problem until now. I'll sell my last metal fan to the kool aid crowd, just found the adapter for it. Hanging a few pounds of metal off the waterpump isn't the best idea, pretty much every manufacturer gave that up a long time ago.

The cap is now bad, in the start of this it seemed fine, but now whistles and leaks a little. The thermostat is installed correctly, valve at the top.

I know it was working well in the 740T, for 14 years, checked with an Autometer gauge more than once, and it cycled like a normal fan does. It didn't run that often, just when needed. And I showed that car no mercy, it had a much bigger turbo and all the stuff to go with it. You could hear the fan turn on and even feel hot air blowing out under the car.

Ken, you know I own 2 modern Volvos as well as the old ones.

Appreciate the help guys, I will replace the cap, if that doesn't help I will put my Saab T in.
 
^Metal fan on a 240 :lol:
That's british junk/non-thermostatic/no need to run that on the SOHC 4-cylinder.
Rarely if ever fails on the bright side, just keep your fingers away/keep adding fuel to spin it minus T-stat. :lol:
Debatable on B20/run it if you can't find the rare USA-market flex fan in perfect shape/works.

Plastique with the Aisin thermostat goodie 1981+ style.
Wear part yeah, but so's an alternator/fan motor.
Take care/keep your fingers off it/motor mounts good and shroud in place.
No more (if any) power if in good repair (clutch & blade is any good).
But this is TB and everyone loooooves the E-fan mod.

Every single 1992+ 7/9 turbo car w/e-fan the engine pulled apart showed evidence of running on the ragged edge of cooked.
No thanks.
It's a brick shaped longitudinal motor car that's electrically/engine accessory mounting challenged, T-static mech fan fits/works.

That said, if it's just an N/A clapped out low-friction volvo tolerance/quality control loosey/goosey 200K+mile B21F N/A, test your push-in switch with either the el-cheapo meat thermometer (or your autometer gauge/sender since you got 12V+DC there already from the battery maintainer/little battery for testing the switch anyway right?, your choice) and ohm beeper/test light that draws 5-20W of current thru the switch with some just under 200F water from the electric kettle that slowly cools for your switches on/off points a few times?
Or your https://www.vestaprecision.com/prod...MInJuIw4bl6wIVcz2tBh1PGwA5EAQYAiABEgLKu_D_BwE
$$$ restaurant precisely temp controlled consistent meat cooker/precisely temp controlled pot for casting metal dental teeth/jewelry?
Don't do it with the wife around in the case of the former/make suuuuuuure to get all that ethylene-glycol residue out before you return it to the shelf...:lol:

BTDT a bunch of times/catch a ****ty switch a few times.
Find the air bubble/fix the cap?
No need to install a foreign part (SAAB T) to solve this IMO/don't fire the parts cannon just yet eh?
Either you have an electrical problem or a blocked passage/air bubble/bad cap or something like that.
Coolant mixed ok?
IDK if the OE volvo black caps are still any good.

Some tempermental/less that forgiving cars rely on steam pockets (Hitler's Revenge VW/Audi comes to mind) and the cheaped out german/EU mandate recycled plastique failing in any way will make the entire cooling system cease to function, or plastique water pump impeller, or plastique reservoir built into radiator....or soon to be entire plastique engine???
 
Last edited:
Kjets, can a clutch fan be installed on my car? I've thought about putting one on, but the electric fan seems to be connected to the ECU and I don't want to upset it by cutting its fan control.
 
It was stock, so not sure why that's funny, but no worries about my fingers because I won't reinstall it. It makes a better garage decoration than the intended purpose. I don't have a plastic one, and certainly wouldn't spend money on getting one since I have 4 more e fan setups lol.

Alternator upgrades are easy and pretty cheap.

Anyway, this thread was about figuring out my e fan, I have already said I will not revert to the old style fan, there are several reasons why people put efans in, performance is one of main reasons. When you have that tiny amount of power, rotating mass on the engine is a bad thing.

I swear you guys will want me to put K Jet back in the car next, but that also will not happen lol.
 
Back
Top