FYI for those people with overheating issues with their VX

[eternal21]

Got the new fan clutch, fan blade and thermostat installed.
Merlin advised a redesigned OEM fan clutch is the only one available now, and requires a new fan blade as well. New fan clutch is now $250 and blade $100... OUCH! Old fc was around $70 IIRC....

If you order this part from Isuzuparts.com, you need to specify the part number. If you have the new fan clutch (part number 8-97349-761-0) DO NOT order online as they will send you the old fan (part number 8-97172-201-0, bottom picture above). When I had to call them after ordering online because they sent me the wrong fan, the guy I spoke to (Brian) said that the new fan doesn't even show as a part for the VehiCROSS. Just as an FYI, the redesigned fan part number is 8-97349-762-0, top picture above).

The old fan/new fan clutch are physically incompatible.

[evillecutter]

looks like it would push much more air

[evillecutter]

wondering about that odd blade gap too...

[samneil2000]

Maybe it's for room for an arm or wrench or something if you're workin on something around there???

[Scott Larson]

With the engine running, the fan better be pushing air towards the engine, otherwise you've got it on backwards. If so, I'm surprised you got away with it for even a day!

[89Vette]

That new, curved blade fan should be quieter too. Curved fans (like the SPAL type) are definitely the most quiet going. I'm going to convert my vette to a 3600 cfm SPAL-shaped unit.

On the VX, changing to an electric fan might make more sense. I saw on the vette forum, this variable temp control that looks promising.

OTOH, I know there's a thread on electric conversions (here) that I haven't looked at yet. But, I'm not having cooling issues at this point. Only wondered about a quieter fan someday....

[blacksambo]

Great info! Thx

[VX KAT]

First off....I don't know much about the cooling system, so some of my questions may be very elementary....

Taking VX on a trial run tomorrow to test for overheating. Going to be 103 air temp in Phoenix, and A/C will be running coldest setting and fan at highest speed.
It's about 200 miles round trip. About 3 hrs of it will be city driving around town doing errands.

• Today noticed I could hear kind of a whining/humming from the engine when A/C was on, and I had driver window down.
  It stopped when I turned A/C off.
  Heard it mostly when slowing for a light. It slowed as truck slowed.
  but never stopped completely...I assume this is the fan?
  I also hear a clicking sound and then a hum when I turn A/C ON... I assume that's the A/C compressor kicking on/off?
  
  
  
• Does the A/C control the fan clutch when it needs it? Since the fan obviously runs w/o A/C, I'm wondering if the A/C can cause it to speed up when it recognizes the need. Or is the fan just responding to the engine temp it's reading, regardless if it's the A/C causing the strain or any other factor?
  
  
  
• If the A/C fan speed is lower, is that a lower load on the fan clutch?
  
  
  
• I believe I should keep the A/C temp at the coldest setting, to keep the compressor working at as max as I can get it, correct?
  
  
  
• If I drive in D3 to keep the revs higher, trying to tax the engine even more, will that dramatically skew my test? Or can I go in D3 for a while, then go back to normal D4?
  
  
  
• I don't really want to turn off the engine to allow any cooling whatsoever, but, based on my Las Vegas trip last month, it really didn't cool off much, even after an hour. Is it negligible?
  
  
  
• There's a short stretch of Interstate 17 that raises over 2000 ft in elevation in just a few miles. Common area for cars and rigs to overheat. Will I tax the engine a bit more if I go up this steep section slower, which means less air flow into radiator?
  The right lane is often moving at only about 30 mph because of many big rigs.
  This steep stretch is on the return trip, so maybe it will reveal something.
  
  
  
• Any other TIPS OR SUGGESTIONS/DO's/DON'Ts to test for overheating?
  

p.s....Hubby is on stand by to come get me while roadside assistance is on the way, if necessary.

[tom4bren]

First off....I don't know much about the cooling system, so some of my questions may be very elementary....

Taking VX on a trial run tomorrow to test for overheating. Going to be 103 air temp in Phoenix, and A/C will be running coldest setting and fan at highest speed.
It's about 200 miles round trip. About 3 hrs of it will be city driving around town doing errands.

• Today noticed I could hear kind of a whining/humming from the engine when A/C was on, and I had driver window down.
  It stopped when I turned A/C off.
  Heard it mostly when slowing for a light. It slowed as truck slowed.
  but never stopped completely...I assume this is the fan?
  I also hear a clicking sound and then a hum when I turn A/C ON... I assume that's the A/C compressor kicking on/off?
  
  Bingo. Hopefully the humming is coming from the new clutch & will go away as it breaks in. Do take the time though to check to see if anything is rubbing. Double chech the shroud for any signs of contact with the fan blades (they change shape slightly as the fan is spinning & may contact while in motion but not at static).
  
  
• Does the A/C control the fan clutch when it needs it? Since the fan obviously runs w/o A/C, I'm wondering if the A/C can cause it to speed up when it recognizes the need. Or is the fan just responding to the engine temp it's reading, regardless if it's the A/C causing the strain or any other factor?
  
  The fan should run all the time while the AC is on. The engine turns it on & off as needed with temperature. The fan is not adjusted for speed by the AC (it's either on or off). The fan speed will change with the engine speed though. In reality, the fan speed isn't being adjusted to run faster with the engine speed to pull more air - it's simply a matter of the fan being driven by the engine and spins at the respective speed.
  
  
• If the A/C fan speed is lower, is that a lower load on the fan clutch?
  
  No. AC is on or off just like in your house. It turns on to get the cabin temp down to a few degrees below what you set it for & then turns off. When the cabin temp rises a few degrees above the set temperature, the AC turns back on & the cycle starts all over. The cabin fan just circulates the air.
  
  
• I believe I should keep the A/C temp at the coldest setting, to keep the compressor working at as max as I can get it, correct?
  
  Yes but only around town. It sounds like your overheating issues are associated with the slow crawl rather than highway speeds.
  
  
• If I drive in D3 to keep the revs higher, trying to tax the engine even more, will that dramatically skew my test? Or can I go in D3 for a while, then go back to normal D4?
  
  With the engine running at higher RPMs, you would certainly be putting more stress on the cooling system. Just don't over rev your engine for long periods of time (remember that you've already experienced oil consumption at highway speeds that you don't on 'round town driving). Hate to see you blow your engine trying to test your cooling system.
  
  
• I don't really want to turn off the engine to allow any cooling whatsoever, but, based on my Las Vegas trip last month, it really didn't cool off much, even after an hour. Is it negligible?
  
  Turning off the engine is certainly the best bet if you're starting to run hot so that the engine will stop trying to dump more heat into the already hot system. It is however a 300 lb block of metal sitting inside a fairly closed chamber. It'll take a while for that heat to dissipate. Open the hood & it'll cool much faster.
  
  
• There's a short stretch of Interstate 17 that raises over 2000 ft in elevation in just a few miles. Common area for cars and rigs to overheat. Will I tax the engine a bit more if I go up this steep section slower, which means less air flow into radiator?
  The right lane is often moving at only about 30 mph because of many big rigs.
  This steep stretch is on the return trip, so maybe it will reveal something.
  
  I don't think you'll see much difference between going 30 mph & going 60 mph up that hill. When your cooling system is operating correctly, I'm guessing that the fan almost never turns on above 20 mph. The radiator fan on my Eclipse doesn't come on automatically anymore (I know ... I know ... I should fix that - I will when I get tired of procrastinating). As long as I'm moving at speeds above 15-20 mph, I don't have to worry about it. Unfortunately with my commute there is a lot of sitting in traffic so I just hit the AC or Defrost till the temp comes back down (fans still come on when compressor is on).
  
  
• Any other TIPS OR SUGGESTIONS/DO's/DON'Ts to test for overheating?
  

Pray

p.s....Hubby is on stand by to come get me while roadside assistance is on the way, if necessary.

See if your mechanic has a scanguage or a temp guage that you can borrow for your test. If I wasn't using my scanguage this weekend, I'd send it to you. Sorry!

EDIT: Of course everything I've said is completely inaccurate if it's your thermostat that's causing the problem.

[VX KAT]

See if your mechanic has a scanguage or a temp guage that you can borrow for your test. If I wasn't using my scanguage this weekend, I'd send it to you. Sorry!

EDIT: Of course everything I've said is completely inaccurate if it's your thermostat that's causing the problem.

THANKS Tom!
We replaced the thermostat at same time new fan clutch etc...OEM of course.
Ironically, I just bought a SG2, but it hasn't arrived yet. I decided I want to know the engine temp/coolant temp, and we want to know how the tranny is handling towing on our other truck. (It claims to come with a tranny cooler, standard). Oh heck, who am I foolin', I just wanted one to play with and learn all kinds of new useless info!
I'm running out of 100+ degree days, so I decided to try it now anyway.

[tom4bren]

I'm running out of 100+ degree days, so I decided to try it now anyway.

Boiling down the many words to few:

Drive it like you always drive it. It sounds like your trip will be challenging enough without trying to put extra strain on the cooling system.

Best o' luck & let us know how it turns out.

[frankd14321]

I started having overheating issues this summer. I live in the desert at 4,000 ft elevation and it gets to 120 degrees here sometimes.. So i expect some overheating in most cars.. But this was quite often. So I drained, flushed the radiator... put 20% anti freeze and the rest distilled water and redline water wetter. Now my overheating problem is gone. I'm still going to look into new fans though, after 12 years I doubt the OEM fans are spinning at the same RPMS.

For those of you who are against running mostly water, this is the same setup I use in my 400+ hp ls1 Camaro and my 500+ HP 2Liter Turbo Evo boosting 35psi. Also my cars are all garaged and the weather never gets much below freezing here.. And I typically change the radiator fluid in the winter to about 40% anti freeze.

I also realize many of you live in colder places and cannot run this setup, and some of you may be doing this already and still having issues... But i'm just sharing.

[IndianaVX]

Well, replaced the thermostat today, flipped my fan over to the correct side (again, never had an overheating problem since it was off last dec when I replaced head gaskets.

So, the original topic being bad radiators, but bad because of cracks. Should I suspect the radiator, even if there are no cracks? What is the process of deciding wether a radiator is good or bad? Just elimination?

The truck today, on start up after thermostat replacement, I had the heat on high while I filled the raidiator, the gauge read halfway, but I had no heat. So I drove it around the block a couple of times, gauge still pointing down halfway (normal position) then all of the sudden, I had FULL BLASTING HEAT! so drove a bit further, and the gauge started creeping up to the hot mark turned around to drive back to the house, ( this whole time I have heat on high) and the gauge starts to creep back down and staying at the normal position. So I continue driving a bit more, but I turn the heat off, and temp gauge starts to climb again, turn heat on high, gauge goes down to normal.

Does any of this sound like a reason to suspect the radiator?

[VX KAT]

My test run today was kind of inconclusive....

• Normal with full A/C all the way down, 80 miles at 70-75mph, air temp 104, full sun, in Phoenix.
• City driving, stop/go, for about 20 minutes ->normal
• Turned off while in restaurant 45 mins
• Sat in car 5 mins, full A/C full, waiting for steering wheel to cool down --> Normal
• Minutes later, driving around shopping center slowly --> Started to go up, between 70-75% of dial.
• Continued slower city driving a few miles, --> Stayed around 70%-75%
• Stopped for 25 mins, engine off
• Started up and was at 65%
• Freeway at 65mph for a few miles --> Normal
• Stopped for 30 mins, engine off
• Started up and was at 65%
• Highway for 80 miles, 65mph --> Normal within a few mins
• Climbing the steep elevation part of route--> Normal for 2/3 of 4 miles
• Went up to 65%
• Returned to normal remainder of highway drive
• Full A/C, coldest setting, entire trip
  

IMPRESSION-

• It didn't act inconsistent like last trip....it went up when you expect it could/would.

• Didn't go as high as last trip, despite higher air temp and more city/slow driving

Thoughts?? New fan clutch, fan blade, and new thermostat...did they help?
.
.

[VXorado]

My test run today was kind of inconclusive....

• Normal with full A/C all the way down, 80 miles at 70-75mph, air temp 104, full sun, in Phoenix.
• City driving, stop/go, for about 20 minutes ->normal
• Turned off while in restaurant 45 mins
• Sat in car 5 mins, full A/C full, waiting for steering wheel to cool down --> Normal
• Minutes later, driving around shopping center slowly --> Started to go up, between 70-75% of dial.
• Continued slower city driving a few miles, --> Stayed around 70%-75%
• Stopped for 25 mins, engine off
• Started up and was at 65%
• Freeway at 65mph for a few miles --> Normal
• Stopped for 30 mins, engine off
• Started up and was at 65%
• Highway for 80 miles, 65mph --> Normal within a few mins
• Climbing the steep elevation part of route--> Normal for 2/3 of 4 miles
• Went up to 65%
• Returned to normal remainder of highway drive
• Full A/C, coldest setting, entire trip
  

IMPRESSION-

• It didn't act inconsistent like last trip....it went up when you expect it could/would.

• Didn't go as high as last trip, despite higher air temp and more city/slow driving

Thoughts?? New fan clutch, fan blade, and new thermostat...did they help?
.
.

Sorry I missed this thread & your question Sue. I may have mentioned before on an earlier thread but an OEM fan clutch with the original fan blade fixed my over heating issues. My engine temp acted exactly like yours until last April when I picked up an OEM fan clutch. I was cranking the A/C on Cliff Hanger while you were on Top of The World and my temp never moved from the normal operating temp.

I previously tried several aftermarket fan clutches, electric fan, & the coolant temp sensor Wintermute mentioned (agree it's very easy & cheap to replace).

My suggestion... try running your new OEM fan clutch with the original fan blades. You should be able to hear the fan slighlty more than the engine during accleration -at least that's how my setup sounds.