in my 87 e350, the factory temp gage usually reads in the a-l range of the word "normal" on the gage face, and according to what comes out of my heater, its pretty darn warm in there, though i have yet to get an accurate gage installed. last year i replaced the radiator, as it was corroded and leaking. that stopped it from overshooting the top of the gage to the point i stopped for fear of doing damage.
even still, i get up in the morning, fire it up, and after 2-3 miles it reaches the center of the gage, and a couple miles later its pushing the L. considering that i'd never heard the fan clutch lock up, i ordered one last week, and then had to figure out where to find a wrench to fit it. i found one today, and installed the new fan clutch in the oreilly parking lot with their loaner wrench. on the drive home, it got just as hot as it did before.
when i got home, the gage was reading fully on the L, i turned off the engine, jumped out, popped the hood, and found that 1) the fan spun freely when i hit it with my hand, and 2) the upper radiator hose was hard, indicating pressure, which means a good cap and a temp above boiling, which confirms the gage reading.

does it sound like i just got a defective fan clutch, or do y'all think there might be something else going on that i should look at?

 

If you haven't changed the thermostat, do that. Also while the cooling system is drained, install a mechanical temperature gauge. Also refill the system with long life coolant rather than the green stuff.

 

the thermostat is one of the few pieces i haven't replaced on my cooling system. the engine has about 50k miles on the rebuild, which was done by the PO, so i don't know if he used the proper thermostat or an off-brand. if it were an off-brand, would it function as it does or otherwise? i have replaced the radiator, heater core, all hoses, and added a second heater, leaving only the water pump and thermostat untouched.
for a little history, the PO rebuilt the engine, drove 5-10k miles, went out of business, parked it in his backyard for 3 years, and then sold it. i've put 45k miles on it since i bought it in january of last year, and never had good cooling, but also never boiled over.

FWIW, it doesn't always stay on the L, on a good downhill it might even hit the M of the gage.

 

I had the same problem with my 84, it sounds like thermostat along with a combination of a bad gauge...

 

ok, thanks for the info, i'll plan on changing that soon

also, i just stepped out to the workshop for a minute to look at the old fan clutch, mounted the wrench surface in a vise and warmed the hub with a propane torch until the bi-metal spring stopped adjusting itself, and through the entire range of movement there, the unit never locked up, so thats a confirmed problem. i think i'll go try the same thing on my new fan clutch (in position) with my smaller torch and see if it locks or not - unless you advise against it

 

My new fan clutch is very stiff to turn by hand, cold or hot.



And it works, I hear it!




But definitely install a real gauge, I wouldn't bother with a mechanical one, those are bombs waiting to make a hell of a mess in the cab. Go electric, just as good, and no mess if hose pops.

The gauges in these vans are totally worthless.

 

I think you're mistaking how a mechanical coolant gauge works. For an oil gauge, you're right, a tube goes from an oil gallery to the gauge, which is just a regular pressure gauge. Tube breaks, oil sprays out.

Mechanical temperature gauges have a sealed sensor at the end of the tube with a wire running through the tube. Something in the sensor expands and pushes the wire to change the gauge reading. I'd guess thats its probably like the wax plug in the thermostat, expands when hot, contracts when cool.

I prefer electric gauges though, easier to run and disconnect.

 

here is my temp gauge. works great and was like $20 from advance auto parts.

Engine Temp Light - Page 2

 

i haven't had the best experience on sunpro's electric gages, their quality control seems non-existent.
so i'll look into what i can find from a more reputable brand.

 

update: today i got a second fan clutch in, from the same parts store with a different manufacturer. i tested it by warming the bi-metal spring with a torch, and found that the warmer it is, the freer it spins. this test was done with the hex (wrench surface) held in a vise, and spinning the fan by hand. on BOTH replacement units, the warmer the fan clutch got, the freer it spun, and i reached temps up to 450* according to my IR thermometer. hell, it should lock up before it reaches 250!!
in all these tests, i found that both replacements will spin the fan 2-4 revolutions from a simple throw of my hand on the fan while hot, while the original will stop nearly as soon as i let my hand off of the fan blades, hot or cold. this seems to align itself with the fact that the temp gage is reading hotter on the new fan clutches than on the old one.
considering all this, i plan to take BOTH fan cutches back on warranty, as defective.
from there, i'm looking into an electric fan. someone please remind me, was the common electric fan from the aerostar of the windstar - i know if was one of those, but can't remember which

 

before you keep advancing with your troubleshooting, i had the same problem with my 86 truck, the gauge would always be really hot, but i notice that the ammeter gauge wasn't working properly, oil pressure seem not to be to active either, replace the voltage regulator on the back side of the instrument cluster, all of my "overheating issue" dissappeared. don't know if the vans have that on there cluster's or not. it was like a $20 part and the ppl i bought it off of never sold one before.

 

I'm sure you already know this, but if it is over-heating then it's surely also over-heating the automatic tranny, which is really bad.
Certain that the tranny coolant is running through the radiator too or does it have a dedicated cooler or extra cooler?
I would invest in a secondary tranny cooler- I get a new $40 one with every truck I buy ever since I lost two C6's to a over-heating truck, which killed the tranny's.
I've even thought about using an aux oil-cooler too...
Just a thought

 

paul, i recently replaced the IVR because i was getting occasional gage spikes across the board. that problem was only occasional and is now solved. the main problem is i'm still running hot and can't find a decent fan clutch. who makes a good one?
Linus, thanks for the input. while your words are obviously true, i never would have thought about it. the van already has an auxiliary tranny cooler mounted to the front of the radiator, so i should be covered on that side.

 

Do you know FOR SURE you are overheating?



The gauges in these vans are totally useless.



Step one, get a real gauge. Forget the fan clutch for now.





I always taught my '87 camper was always running hot as the gauges reads right in the middle, sometimes on A of NORMAL but now with a real gauge, it rides on 180* cruising, with the dash gauge telling me pretty hot.



And, about those "high peaks", what did you replace exactly to correct that? What's it called? Cause mine has the same problem. It only happens slow driving, or heavy traffic in very hot weather, or anytime the engine is working hard for a long time (climbing hills etc.) Makes all gauges read high, as you can see.


And I installed mine here, using a screw that holds that trim piece to hold it there. I didn't wanna drill any holes in the dash.

 

Just to be curious, which way are you rotating the fan clutch, and for how long each test. From what I've read on here, there is some kind of fluid inside that gets pumped around as the fan turns. When the bimetallic spring heats up a certain amount, it will close off some valve and the fan will lock up. I don't know if its an instant lockup, or maybe it takes a few turns (or a few hundred turns, how fast is it spinning at the front of the engine???)

Maybe you need to do your test a little differently. But x2 on getting a real gauge. Its on my list of upgrades too.