overheating is back

[Scott Larson]

Stuck thermostat. Open or closed, it doesn't matter. If it's closed, water can't circulate. If it's open, water circulates too much, too fast and can't pull the heat away. The fact that it just suddenly started overheating is the clue IMHO. Faulty rad cap is also a suspect in this hot mystery

[gergmon]

Sue I've been having the exact same problem too. Only when I use the A/C does it start to shoot up after about 10 minutes. I look forward to hearing what you find out!

[IndianaVX]

Agree with Scott, you can have new radiator, shiney new cap, the prettiest new hoses, ect..... But if the thermostat isnt working right, none of that new stuff will cure your problem. Maybe it's just me, but I always start with the little (read cheap) stuff first. And these cheap things probably needed replaced anyway. Are you Loosing coolant? Also check the firewall between brake booster and fender for coolant. I've seen my truck spray coolant thru the resivour cap.

[VX crazy]

Mine does it too, and so did my other vx in the Texas heat with ac on in stop and go traffic, I just turn ac off and sweat til I start moving. Funny thing is the temp gauge in the truck says normal or tad over half when scan gauge says 210 , but after it gets just 6 degrees warmer the needle shoots way over, I have let it get to 222, too hot for me, no leaking coolant, coolant new in last yr and half and royalmpurple wetter always used too.

[eternal21]

Mine does it too, and so did my other vx in the Texas heat with ac on in stop and go traffic, I just turn ac off and sweat til I start moving. Funny thing is the temp gauge in the truck says normal or tad over half when scan gauge says 210 , but after it gets just 6 degrees warmer the needle shoots way over, I have let it get to 222, too hot for me, no leaking coolant, coolant new in last yr and half and royalmpurple wetter always used too.

Started happening to me, as well, even w/the upgraded fan. So I stuck on another 10" fan in front of the radiator. No dice. I think too much heat is getting trapped under the hood. To test my theory, I'm going to remove the hood insert, and drive around on Mon & Tues of next week when the temp is going to be over 100 degrees again. We'll see what she does. I saw another member had ordered a heat extractor and put it on his hood, and it looked pretty good, so I ordered the same one for $95 on eBay. If removal of the hood insert does alleviate the situation, I'll be putting on the heat extractor in short order.

http://vehicross.info/forums/showpos...2&postcount=17

[VX KAT]

Started happening to me, as well, even w/the upgraded fan. So I stuck on another 10" fan in front of the radiator. No dice. I think too much heat is getting trapped under the hood. To test my theory, I'm going to remove the hood insert, and drive around on Mon & Tues of next week when the temp is going to be over 100 degrees again. We'll see what she does. I saw another member had ordered a heat extractor and put it on his hood, and it looked pretty good, so I ordered the same one for $95 on eBay. If removal of the hood insert does alleviate the situation, I'll be putting on the heat extractor in short order.

http://vehicross.info/forums/showpos...2&postcount=17

"Bill" from Ron Davis racing also told me this the other day:

If you put a

2nd fan on the front side of the radiator, it blocks airflow and probably only about 30 percent of the airflow makes it through the radiator. Not a good choice.

[RickOKC]

Trying to find out if my fan blades are positioned more forward into the shroud than other VXs.

I didn't take any measurements, but the position of my fan looks the same. Hah, purple yardstick!

To test my theory, I'm going to remove the hood insert, and drive around on Mon & Tues of next week when the temp is going to be over 100 degrees again.

Unless something has been modified, that won't do anything - the hood is solid metal underneath the insert.

[VX KAT]

OK, gonna look into details of the Ron Davis radiator...gulp...and see what kind of moula I'd be talkin' here...gulp....also asked newthings for detail$.

After I faint, and dave revives me, I know I'll have to have my mechanic explore some of the "other" possible culprits.

Agree with Scott, you can have new radiator, shiney new cap, the prettiest new hoses, ect..... But if the thermostat isnt working right, none of that new stuff will cure your problem. Maybe it's just me, but I always start with the little (read cheap) stuff first. And these cheap things probably needed replaced anyway. .

Yeah, absolutely, going to have mechanic start next week picking off the possibilities (based on his eval and what he suspects). I'll also discuss various options with him re: radiator flush, alum radiator, etc...


1) Drove it for last 2 days up the big hill, with A/C, NO overheating at all... but AIR temp was at least 6-8 degrees cooler....can that small of an air temp variation 6-8 degrees (91 vs. 98-99) really make a big difference??

2) Talked to "Bill" today at Ron Davis Racing Radiators. He wanted to ask about some things about my VX before he finishes the design updates (from "newthings") on the aluminum unit.
He had me try some stuff:

• evaluating how far the fan blades protrude beyond the shroud (toward the rear of truck). The top of the shroud is a little deeper, for finger protection, but the sides are a little shallower.
  My fan blades BARELY break the plane of the shroud.....meaning, my fan blades are set well INTO the shroud. Bill said that set up moves LESS AIR.
  WHAT DOES EVERYBODY ELSES VX LOOK LIKE IN THIS REGARD??
  COULD THIS BE YET ANOTHER "HAND MADE" VARIANCE??

• moving the OEM main fan blades manually, feeling for resistance, when cold and when hot.
  We found it spun pretty well, even easier when engine was warm
  

• We checked to see if all bolts holding the radiator were tight and flush, with no spaces - checked ok.

• Dave and I already confirmed the A/C fan comes on appropriately.

• He asked if everything appeared to be OEM...he STRONGLY recommends ONLY OEM parts such as the blades, shroud, etc... He feels they're properly engineered for the vehicle, have certain tolerances, and are more durable in general.

• [*He advised the OEM mechanical fan can move MORE AIR than a twin electrical fan set up can, so he recommends we keep the OEM....and make sure it's functioning optimally.
  Is there a spec on the fan blade placement?.....gotta look that one up in the big manual.

Any comments, input????
.
.

[Triathlete]

Sue...your vx is just too clean. The dirt keeps the sun from heating things up...see, there is a method to my madness!

[Zu4two]

Sue, I looked at my fan last night and it's relation to the shroud. Mine protrudes about 3/4" at the top. I don't know how you would modify that clearance, maybe someone put washers in-between the fan and the clutch. You mention that the fan moves easier with your hand when warm? When it gets Hot it should actually be harder to move since the thermostatic clutch should be engaging. Of course this is when measuring resistance with the engine off. It is not recommended to check this with your hand while the engine is running

Have you checked to make sure you don't have wax residue clogging the radiator fins from your incessant detailing? All kidding aside, a good power washing of the radiator might rid it of excess dust and grime that builds up after time.

[Y33TREKker]

...All kidding aside, a good power washing of the radiator might rid it of excess dust and grime that builds up after time.

I saw the same thing discussed recently on one of those half-hour automobile repair television shows.

They suggested holding a flashlight or worklight behind the radiator and looking to see how much light shined through to the front, because over time, road debris can accumulate between the radiator fins (and any other fluid cooling coils/fins in that area - like trans cooling coils, a/c condensor coils, etc) which can restrict air flow and significantly reduce cooling capacities.

And seeing as how the VX front end is just a straight shot right into the grill, it's not hard to imagine how a lot of road debris could find it's way into our radiators. Sometimes if we're lucky, it's checking the simple stuff that pays off.

[VX KAT]

Sue, I looked at my fan last night and it's relation to the shroud. Mine protrudes about 3/4" at the top. I don't know how you would modify that clearance, maybe someone put washers in-between the fan and the clutch. You mention that the fan moves easier with your hand when warm? When it gets Hot it should actually be harder to move since the thermostatic clutch should be engaging. Of course this is when measuring resistance with the engine off. It is not recommended to check this with your hand while the engine is running

Have you checked to make sure you don't have wax residue clogging the radiator fins from your incessant detailing? All kidding aside, a good power washing of the radiator might rid it of excess dust and grime that builds up after time.

I'm going snap some pics tomorrow of the fan blades. I'll post them for comparison.

"Bill" also described how the "oil" in there should actually get thicker when hot, so it should be harder to spin the blade by hand after it's been warmed up. It was kind of a subjective assessment by Dave and I but it appeared to spin a little easier after engine was up to temp.....AND ENGINE WAS OFF .

I got in touch with the VX owner on ebay that had purchased the FFD twin fan set-up and was so pleased with it. He's somewhere in TX and has had overheating for a while, with A/C on, in stop/go traffic, on high air temp days. He installed the twin fan set-up but it didn't help problem. When he contacted the company, they realized he should have been sent the "extreme" package, which is a SINGLE 17" FAN, and that solved his problem. This is consistent with what "Bill" told me.....a single larger fan can move more air than the smaller electronic fans.

Here's pics of the guys install: I thought the FFD set-up was in addition to the factory fan, and would be mounted in front of the radiator, but these pics appear it replaced the OEM.

[eternal21]

I got in touch with the VX owner on ebay that had purchased the FFD twin fan set-up and was so pleased with it. He's somewhere in TX and has had overheating for a while, with A/C on, in stop/go traffic, on high air temp days. He installed the twin fan set-up but it didn't help problem. When he contacted the company, they realized he should have been sent the "extreme" package, which is a SINGLE 17" FAN, and that solved his problem. This is consistent with what "Bill" told me.....a single larger fan can move more air than the smaller electronic fans.

So everyone has a little history

http://vehicross.info/forums/showthread.php?t=20464

[Scott Larson]

Nothin' that a good pressure washing can't fix...

[gergmon]

I'll give that a try. Same with me Sue, doesn't overheat when the A/C isn't running. Thanks for the tips.