I'd guess everyone here probably knows that I've been having some minor problems with engine temps out here in the southern California desert.

With summer daytime highs in the 120's, my little PV544 just wasn't up to staying cool if I had to sit in traffic more than a minute or two. I believe that the Volvo temperature gauge is pessimistic, reading 'Hot' when the car isn't actually anywhere near boiling. I'd prefer a pessimistic gauge that reads high to an optimistic one that reads low - at least where engine heat is concerned!

When I got the car it had an aftermarket temp gauge installed under the dash because the capillary tube was cut off the stock temp gauge. A quick look through eBay got me a good temp gauge, but it's always read at the high end of the middle range, and when stopped in traffic, the needle would practically shoot up to the max.

Monday I received a 13-1/2 inch stainless steel flex fan, and it took me only two days to get it installed. Luckily, the fan hub was far enough from the radiator so I was able to get the fan off without too much disassembly!

ANYWAY, I finally got the thing back in, torqued down, and I gave it a test drive for about an hour.

The driving temp indication is now about 1/8 lower than with the old 4-blade stock fan, and it only got up to the old 'normal' reading at the top of the normal range while sitting at idle for 5 minutes.

So far so good. I think I've beaten that problem into submission!

Steve,
That's great. Congratulations. I've experimented with Volvo fans from two-bladed through five-bladed and never noticed any difference in their effectiveness. So I would have been skeptical about the mechanical Flexfan if anyone had asked me. Good to know it does the job. About the hub: I had one break up on me, possibly because I had the belt too tight, but in the process of replacing it learned that metal fatigue in the hubs is not uncommon and that Volvo became aware of that and made later hubs with a more rounded edge where the cone meets the flat front . Mine is a "62 and had the earlier type with the sharper edge. Unfortunately I don't know what year they changed.
Bob S.

The hub on my 1975 B20 engine appears to be the later model. And you're right about the side pull from the alternator being the cuprit. Sometimes owners will over-tighten a badly worn(shiny, slick) belt to keep it from slipping.

Better to replace worn belts with the tooth-tye that grip better with less tension.

After living in AZ for twenty years, I know desert heat and just can't imagine driving a PV544 with no A/C and little or no insulation in the roof and sides in the summer heat. I would overheat a lot faster then the car. You must be one of those tough individuals who can withstand the brutal summers or your PV has A/C?.
When it comes to heat, I am a whimp and basically hibernated in air conditioning from May through October.
Good luck with the new fan.
Dennis

I'd love to get AC installed, but the only complete setup I've seen so far was over $400 with no guarantee that it was any good.

My Dad gave me a complete small AC setup he removed from his Datsun pickup, but so far I haven't been able to locate it in his shop. I'm sure it's out there among all those racing parts, somewhere!

The heat doesn't bother me - it's a DRY heat, Ya know! Thank God for wind wings, though! The air flow helps make it bearable.

To tell the truth, I rarely drive very far in town in the summer. That's what our newer cars are for. I like to use the PV for short road trips, which usually take me up into the mountains, to the Sequoias or Lake Tahoe, etc.

Just a note: I have a tiny Cushman van I like to drive around town in (60+ mpg)and I installed a misting system like they put on patios in that. A windshield washer pump and large reservoir, running to two misting nozzles above the windshield. Really gives me a chill!

That's interesting! You're not talking about an electric fan, are you?
Did you use the original fan hub? I heard more than once that the original fan hub is not very strong and even may collaps occasionally. Wouldn't that risk be higher in your case now that you've put an heavier load on that hub? (if you still use it, that is)

We've had a lot of PV544's over the years, never heard of a water pump hub going bad, as in breaking. The shaft seal, perhaps - which would cause a leak. If your fan is properly balanced there should be no additional load on the hub.

The side pull from the alternator or generator is much more load than the fan.

This stainless fan (yes, it's a mechanical 'flex' fan) actually weighs 4 ounces less than the stock Volvo 4-blade steel fan. It's 13-1/2 inches in diameter, which is 1/2 inch larger than the one I took off. I think I could have put in a 15" fan without any clearance problems.

I used to see flex fans made of all aluminum - or even fiberglass, but I think stainless steel is a far better material.

Where did this miracle worker come from and what modifications are needed to install? Seems my 544 runs warm even in the mid-west during spring.

No brand name on it, but it hase a set of shiny felxible wings riveted to a stiff center. All stainless steel. Very strongly built, compared to many other flex fans I've seen. The center is blue, wings are bare metal.

I did a search on eBay for 'flex fan' and looked for anything in the 13"-14" size in good condition, good seller feedback, etc.

It took me about a month to locate one, under $20 shipping included.

I hunted through as many auto parts websites as I could find, but no one seems to sell fans this small. Which is odd, considering how many small engines there are these days!

I'd have liked to installed an electrical fan but the stock water pump hub is too close to the radiator in the back side, and the hood spring is too close to the radistor on the front side. With a little work I could have moved the radiator back about an inch, so I could have used an electrical fan.

This flex fan was easy, quick, cheap and effective.

Compared to the stock fan (sorry, I should have taken pictures before I installed it!) the wings are pitched more, and are larger, besides having two more blades.

Putting my hand behind the stock fan with the engine at idle, I could barely feel any air movement. This fan really moves some air! I plan to add a fan shround to increase its effectiveness. All I need for that it to find the proper material (stainless steel or aluminum sheet, 12 gauge or better).

The only kind of warm running a better fan (mechanical or electrical) will fix is the stopped/stop-and-go/very slow speed sort of overheat. If it overheats or runs hot when the car is moving then you have a coolant flow problem, not an airflow problem.
--
I'm JohnMc, and I approved this message.

I have "solved" overheating on a couple of my volvos by soucing and installing the correct thermostat. I notice that if I go into a modern parts shop and ask for a thermostat for a B18 engine, I'll normally get offered a 190-deg thermostat. I like the 170's best for Denver driving. Also have a 160-deg, but that runs too cold in the wintertime.

John: Absolutely correct. If your engine is getting hot while running at 30 mph or better, look for system problems. Luckily, mine only gave me fits when sitting in traffic for several minutes.

Also, I changed to a 180-degree thermostat last year, which helped some. Much cooler than that and I believe the efficiency of the combustion process would start to deteriorate.

Hi,
I really hope you left your fan clutch on. The fan will pull the pump apart at speed and tear into your radiator making the road much harder to negotiate at speed with all that steam shooting up and scrap metal flying about.

I speak from experience. When I was 19 (long long time ago) this happened to me while I was passing a big rig going down Donner pass at 90mph. Lots of fun!

-Ted
'74 144GL (it happened to my old '73 142GT)
'59 PV445

"FAN CLUTCH" on a B20? Sure, (Ahem!) I left it on, just like it was on (NOT!) when I started.

This is a flexible-bladed fan, which flattens out somewhat at speed, putting less stress on the hub than a fixed-blade fan would. At lower RPMs or at idle, it pulls the maximum amount of air through the radiator.

I've had to remove the clutches from almost every Dodge product I ever owned just to keep them on the road. Except for a litle more noise at speed, there was never any problem with the hubs after many thousands of miles.

Now hold on a minute. I thought the reason they called it a flex fan was because it flexed and flattened out the pitch at high RPM. With the engine running at idle RPM, the pitch increases and provides more airflow across the radiator. I also thought the flex design was specifically designed to be used without a clutch or on vehicles that never had a fan clutch anyway.



--
Volvo Farmer:

21 Volvos '58-'91

445-544-122-144-1800-240-740

sorry, no FWD

You're right. See above post...

I've had a 13" flex fan bolted right on the water pump on one of my motors for -- um -- ten years at least, and there's never been the least problem with it. Can't imagine why there would be unless the fan was unbalanced or something.

I 80 from Truckee to Reno is very steep. I was going very fast and I stomped on it. The water pump pulled apart. Beleive me it will pull apart if there is enough forward force. It is a pressed fitting. I have no idea if the fan was out of balance. I just know that the incident scared the hell out of me and could have killed me. After what happened I decided that like wearing a seat belt having a fan clutch is a good idea. It was like "oh yeah now I know why Volvo put that funny thing on there."

After owning well over 100 vehicles, I've only had problems with the clutched fans, never the direct drive ones.

I think your incident was one of those happenings that are so rare as to be almost unheard of. I suspect our water pump was already defective, probably either worn out or corroded until the metal was too thin to support the pull of the fan.

Does anyone else know of un-clutched fans exploding the water pump?

I would roughly estimate that at 3,000 ROM the fan would put around 10-20 lbs. of pull on the hub, certainly not enough to do any damage.

Let's hope no one else has this problme, I can see how it could cause a lot of trouble, even an accident.

The nearest experience I had was in a Ford pickup with a replaced radiator. The radiator mounts weren't tight and the suction of the fan pulled the radiator back and the fan chewed right through it!

The stock thermostat was 170F. These are basically unavailable, so most suppliers will sell you the 180F unit as a "correct" replacement.

Interesting...mine had a 190-degree thermostat in it. Now I'll see if I can find a 170. Thanks!

Is this what you've got?



http://www.flex-a-lite.com/auto/html/1300-series-flex.html

Yep...the blue one. Flex-A-Lite part #1313. And it IS sharp!!

I think mine is exactly like that (blue too), except that it was sold as some other brand at the time. I have a nice scar on one knuckle from getting sloppy working around it once...

That will happen! I see the Flex-a-Lite page says it MUST be used with a fan shroud.

I suspect that's not so much for the additional cooling as to help keep fingers out of the fan!

I'll be making up a shroud soon anyway, so I guess I can overlook that warning for now. ;-D

Will you be looking at shrouds from other cars, Volvo or whatever, or are you planning to fabricate one from scratch?
Bob S.

From scratch. This should be a very simple job, as the radiator is very small and I can easily reach everything. For the fasteners to hold the shroud together I'll be using aluminum rivets and washers, which will hold the pieces together very tightly, and by using a washer on the back side of the rivet, they can't pull apart.

I'll be making a two-piece shroud, so I can slip the bottom half into place by rotating it around the fan, then screw the top half to it, and then mount everything to the radiator mount.

I'm taking off a week to go over to Las Vegas, but the many little tasks will continue when I return.

I promise, I DO have a very nice digital camera, and I always intend to take piz as I go along, but somehow I end up too tired to bother. Hopefully I'll feel better when I get back, and I can upload some pictures about all this. ;-)