Fan clutch...I think

[Portland Suburban]

Ok, here is the deal. I bought this suburban just about three weeks ago. Upon its arrival, we found that it did not want to cold start. Tests and inspection showed dead glow plugs and fried solenoid. Hmm. Ok, that is fixed now but...it runs to cold and has really lound fan noise at speed.

So...glow plugs are still firing intermittently even after driving for about 30 minutes in 40f weather. I pulled the solenoid controller after a while to stop this. Water temp is around 130-150 as indicated by dash temp gauge.

Now, here is what I think happened. The Clutch fan is spinning up when it is not supposed to. More or less, it spins with the engine. It is therefore keeping the motor too cool which causes the glow plugs to fire too long-which just killed the stock plugs. I have the glow plug issue fixed, but I think the clutch fan needs to be replaced.

I have pull tested the clutch fan and it sort of moves when the engine is off-but not much. I found a clutch fan at autozone for $200. Is this my best course of action? Are there any other tests I can run?

On a side note, I did run a search before writing this post and it was helpful, just not conclusive.

Thanks,
Chris

[bmiszuk]

Chris, what year is the Suburban? Do you have any history on it?

If you're not getting close to normal operating temperature, I would suspect the thermostat. You can change the thermostat without a lot of trouble. Just drain a little antifreeze out of the radiator and change the thermostat out. I use silicon to seal the thermostat housing. If you are going to keep the Suburban or if the antifreeze looks brownish, I would dump all the antifreeze, change all the hoses, perhaps have the radiator checked, and change the thermostat. An $8 thermostat is cheaper than a $200 fan clutch anyway...

I don't quite know what you mean by the "pull test" for your fan. But the fan on my 83 Suburban can be moved by hand with the engine off. Does yours spin? Is there any looseness in the shaft? I suppose it's possible that it's bad and is spinning when it should be freewheeling but I don't know enough about them to say for sure. In my limited experience, my cooling problems have never been fan-clutch related.

Bob

[Portland Suburban]

Ok, let me elaborate. My coolant is green and I almost positive that my fan is spinning when it is not supposed to. Why The outside temp here is 45 and the engine temp is less than 150. The fan also spins at cold startup and sounds like a tubine at slow speeds. On the freeway you can barely talk because of the fan noise. I know how this thing works as I drove heavy duty trucks for quite some time. While it could be the thermostat, how would it affect the fan clutch?

On the test, it takes quite a bit of effort to turn the fan and it does not spin freely at any temp. While I don't want to spend $200 needlessly, I think this is it. As for history, it is:

1982 3/4 ton suburban
6.2L

[NH2112]

If the thermostat is operating as it should, the fan running at engine speed won't result in too-low water temp. Why? Because the t-stat will close more often and for longer periods of time, restricting flow through the radiator, to keep water temp where it's supposed to be. I'm going to say you have a bad t-stat as well. Your fan clutch may well be bad, but it's not what's keeping your water temp low.

[Portland Suburban]

Good point about the t/stat. However, with the fan turning all the time it will be pulling cool air through the oil cooler and the radiator at full speed cooling the water and oil-prematurely. Won't this have an effect on the overall engine temp?

So, should I run a 180 degree or 195 degree thermostat for maximum heat?

[BobND]

If it is a 1982, with the original-type controller, there is s bi-metal switch/heater in the GP conroller that is heated up by current from the alternator after startup, and will "lock out" glow plug operation after a minute or two, whether or not the engine has warmed up.

If there is a internal problem with the alternator, a bad connection between the alternator and the controller, or a defect in the controller, the original GP controller will continue to cycle the GP's, long after the normal interval.

These last several years, the replacement controllers look identical, but have a tiny solid-state electronic board in them, rather than the bi-metal strip switches and heaters. They are "flaky" as hell, and I've never had much luck with them.

(This is the 6-pin controller that has a pipe thread on it that screws into the blocked water port at the rear of the LH cylinder head.)

What I have done, is replace them with a newer-style combination controller/relay mounted where the solenoid used to be, on the LH fender.

I install Dr. Lee's glow-extending resistor, and 60G GP's. They start better than new that way.

Obviously, the fan should slow down a few seconds after a cold start, as the silicone oil in the fan clutch gets to where it needs to be, and if the fan races all the time, it's a bad fan clutch, or the fan and fan clutch are mis-matched.

However, with a good thermostat, the engine should still warm up, and even if it doesn't get above the 150 degres you mention, the GP's should NOT continue to cycle.

Here, in northern ND, on my 1984 Sub, I remove the fan and clutch from about this time of year, until the end of May. Even then, on really bitter days, a LOT of the radiator can be covered without causing overheating.

This will be the 4TH or 5TH winter I've done this.

I would not recommend this for everyone, but I'm the only driver, and just use it as a parts runner.

I drilled and tapped the water crossover manifold for a temperature switch for a car with and electric fan that turns on at about 215 degrees. This operates a relay, and cuts power to the IP, should the engine overheat. Typically, I can go all winter with no fan, without overheating, and when the weather gets mild and the unit shuts down a time or two, it's time to put the fan back on!

[Portland Suburban]

BonND, thank you very, very much. I so much appreciat that info. Your check is in the mail. tongue.gif

[Portland Suburban]

Okay, so I went by the chevy dealer today. Here are the prices:

Fan Clutch $140 (dealer)
Fan Clutch $200+ (Schucks)
1985 glow plug controller: $160

The fan clutch will be on order from the dealer and the glow plug controller...well, I think an off switch will work for now on the glow plug solenoid.

[NH2112]

$160 for a glow plug controller? I've seen them for $30 on eBay, and I know it wasn't THAT long ago that I got one for maybe $60 at the dealer.

[Portland Suburban]

Maybe $140-but I know it was over $100. Maybe because I wanted the new and improved 85 controller?

[Portland Suburban]

Just in time for Christmas....

http://cgi.ebay.com/ebaymotors/New-diesel-glow-plug-controller-85-93-GM-6-2L-6-5L_W0QQcmdZViewItemQQcategoryZ33693QQitemZ80043588 64QQrdZ1QQsspagenameZWD1V

[Lightyear]

That price is about what I paid at my local GMC shop for a new Delco gp controller. But I've also paid over $100 at a Chevy dealer...also here in GA. Go figure.

[NH2112]

Originally posted by Portland Suburban:
Maybe $140-but I know it was over $100. Maybe because I wanted the new and improved 85 controller? That's what I was driving, an 85 w/6.2l. I know GM jacked the prices of lots of parts WAY up (73-87 doors went from like $130 to $400+ overnight) but I didn't think glow controllers did it too.

[NH2112]

http://cgi.ebay.com/ebaymotors/CHEVY-6-2L-DIESEL-C2500-C3500-PICKUP-GLOW-PLUG-CONTROL_W0QQitemZ8015347600QQcategoryZ33693QQrdZ1Q QcmdZViewItem

[britannic]

NAPA sells that controller as Echlin Part # AR145, normal retail is $92.00, but you can get a discount if you have AAA membership or some other affiliation supported by the store you visit.

[jaymanaa]

Napa also has the fan clutch (made in usa) for 74 bucks. Bought one today, mine was locked up but my t-stat still kept engine temp at 180 in 30 degree weather.