Heating Up At Idle

[FrankieRider2]

This year my '93 Chevy has been really bad to heat up at idle with the A/C on; in the past it has been really tolerant about running with the A/C on. On the farm, it idles a lot during the day, and it just will not stay cool anymore for any length of time. 210 comes up fast on the gauge, and then the A/C will kick out as the temp rises....

On the road it still cools fine at speed, but is really quick to start heating up when under engine load (hills, etc.)

Anyone have any ideas.... I hate to take it to my dealer and ask for their "expertise"

Water pump.... radiator.... fan and/or clutch.... other ideas, anyone? I would sure appreciate any ideas that any of you might have for a place to start looking for problem(s). Thank you.

[Dvldog 8793]

Howdy
Sounds like your Radiator has lost it's cool. I would first try cleaning everything up front and flushing good. Also maybe replace your stats. I would think all this could be done in an afternoon for about $30.
Good luck and have fun!
Conley Janssen
USMC 87-93

[BuffaloGuy]

Hello Frankierider.
I'd say start simple and go from there.

Is the radiator clean inside and out? When was the last time you had it rodded out? It seems if I use our well water (which varies from location to loaction a lot) I only get about 90,000m until the radiator is plugged pretty bad. I tried only putting distilled water in it (the stuff you buy from the store) and it made a big difference.

If that's not it how about the thermostat? What temp and how long has it been in there? They are easy and cheap to swap out.

Perhaps the motor is all sooted up from idling so much. Diesels, and these especially, need to be run hard every once in a while to keep them cleaned out.

I heard of a diesel mechanic that when getting a big rig in that was not running right and was suspected of having been idled alot would use a home made motor cleaner.

After checking all the easy obvious stuff but before opening up the motor and incurring big expense to the owner he would insert a hypodermic needle somewhere into the intake side of the motor and run a hose into the cab. There he had a propane cylinder (the little ones you get at the hardware for a small torch) and would connect it.

Next, he'd take it out on the road and pour the coal to it preferrably with a load and crack the valve on the propane ever more while he watched the exahuast and coolant temps to be sure he didn't cook the motor. Story is that if the motor was sooted up loads of black soot would pour out and 1 bottle would do it.

Perhaps you can use this principle in some way to clean the soot out of your rig. Might just need a good heavy pull.

Have you got the '97 cooling upgrades? If not and all the above doesn't do it I'd do that next with a new 180F fan clutch.

Have you got EGT and Boost gauges?

Sorry for the long winded response.
Ken

[FrankieRider2]

Hey, no response is a long-winded one when it contains good information!

My dad has always marveled at the way my truck seemed to be unaffected by heat when using the A/C.... but he just got a 2001 F350 PSD, and now he's doing the bragging about not being affected by the heat when running his A/C. Just this week one day my truck reached 240 on the gauge and had only been idling for about 10 minutes.... :eek:

My truck's radiator was rodded and gone through last year, and the 195 'stat is two years old. I'd like to upgrade to a better than OEM or an aluminum radiator for better heat dissipation and resistance, but haven't seen one available.

I do not as of yet have the cooling upgrades; I was hoping to be able to get everything to make the swap when I bought... I'm no good at fabbing stuff. I need to be able to purchase a complete "turn-key" type installation that will not affect my truck's operation. I wish I was mechanically inclined....unfortunately I'm not.

I have heard some concerns, though, about the cold idle being affected with this series of cooling modifications on earlier 6.5 models. I really don't want to lose anything from my truck's operation due to a modification; besides, it gets pretty cold here in Arkansas sometimes.

I have the Banks Power Pack on the truck, so yes, I have the EGT and boost gauges.

[ucdavis]

Frankie,
With a 1 year old rodding & somewhat fresh stat, I'd start to suspect water pump vane cavitation. B4 opening that up, however, I'd double check radiator for bugs between ac condenser & radiator; lotsa guys marvel at the accumulation there when all else looks squaky clean. If that's okie-dokie, its gotta be somewhere else. Pinhole leak would be next to look for (allows coolant to flash off & escape w/out holding system pressure); check all hoses & use a coolant pressure guage to check if its holding pressure. then coolant flow is next up- meaning try a new stat (its cheap, fast & then go to water pump. Fan clutch could be bad, but I wouldn't expect enough heating to require the clutch at idle unless something else is wrong.
Good luck.

[BuffaloGuy]

Been thinking about your problem today and I had another idea. I should have thought about it right away.

How's the fan belt and the tensioner? If they aren't doing their job a little slip would make a big difference and at idle and you probably wouldn't hear it squeal like you would at higher rpms.

I never heard of the a/c kicking off when the motor gets hot either. Maybe my '93 is supposed to do this and doesn't (of course, my a/c has been broken for 2 years now anyway but I don't remember this happening). If the belt is slipping running your water pump and letting your motor get hot then your a/c would be not working very well either (same belt).

Just a thought.
Ken

[FrankieRider2]

Ken -- The serpentine belt is plenty tight and the belt is only about two months old.... Goodyear Gatorback. There's no slack anywhere in the belt system.... I had to replace a crank pulley about two months back (new belt at that time), and all was checked out and found to be in good shape.

When the temp gauge gets to @ 230 or so, you can feel the A/C click out and the regular vent come back on.... it was just like you pushed the dash switch off. Yesterday was the first time I have ever experienced this in my truck since I've had it. And the outside ambient temp seems to not even be a factor, because the truck will heat up any time of the day if it's idling. That made me think perhaps this might be some sort of coolant flow issue.

But we used to have a '91 Ford Explorer that did the exact same thing under load.... the problem turned out to be a radiator issue on that truck.

ucdavis -- The radiator looks to me to be pretty clean and uncluttered. The hoses are both new this year and look to be in good shape. I'm not seeing any coolant loss, so it doesn't seem that I have a leaking problem to deal with.

I will try a new stat and see if that improves things (it's an easy swap).... but I'm leaning towards either the radiator or the water pump as the source of my troubles.

It seems that the cooling mod kit is readily available, but I've been looking today for a better quality replacment radiator (preferably aluminum), and haven't had any luck finding anybody local to me who could order one. Anyone have any ideas or advice on a source for a new 6.5L TD performance radiator?

Thanks to everyone for their replies.... I appreciate the advice.

[FirstDiesel]

I would vote for the radiator being the problem. 93 isn't exactly a new radiator and I've never really beleived that having them cleaned was anything more than a stop gap measure.

As for the A/C, I think it's 2 seperate problems. My guess is that the A/C system is slightly low on Freon and when you get the truck very hot the A/C is shutting off because the condensor is getting hot to and failing to cool the Freon enough. Your getting a low pressure indication and the system shuts off.

Fixing the truck overheating will fix the A/C problem but it's not the cure. The cure is to get the system checked for Freon levels.

[david]

Well i have not seen any talk about the clutch fan!!!!!!
It pulls air even at idle.
David :confused:

[vandej]

I was having a similar problem when towning my 10K pd fifth wheel. Oeverheated constantly. See the thread "Am I screwed?" My radiator "looked" clean, however I pulled it out anyhow. It was completely clogged. I could only see light through 1/4th of it. I have yet to pull my fifth wheel after spending 3 hours cleaning and flushing the system, however it runs 15 degrees cooler just traveling with no load. I would really recommend taking the rad out and cleaning especially with your truck being a farm truck. Mine was used by the previous owner as a plow truck.

later,
jason

[FrankieRider2]

Well, an update....

After a call to my local mechanic that I use, we have discovered that the fan clutch is basically "free-wheeling". After spinning it 3 times by hand, I figured it was time to chalk that up as a problem....

I have a new "Severe Duty" clutch on the way at $195.99. Even my GM dealership ($408) agreed that was the way to go, especially with a lifetime warranty on the part and considering the fact that my truck idles so much of the time around the farm.

As for the radiator, I learned today that Griffin does indeed make an aluminum radiator for the truck.... but it's $729.00. :eek: So it
looks like we'll be trying to take the one out that I have and do some more cleaning on it....

Thanks for the A/C advice as well.... I'll worry about that more when I can keep the temp gauge on the south end of the scale regularly. smile.gif

[FrankieRider2]

UPDATE #2 - Well, I replaced the fan clutch yesterday and it helped some.... but the truck still heats up while it idles. It just takes longer to do it now.

Guess I'll break down and take it to the dealership and have a cooling system test run on it.... I can't afford to keep replacing parts at random trying to fix the problem. Thanks for all the advice so far.

[BuffaloGuy]

Yesterday I talked to my local radiator man. $65-80 to clean, rod and repaint the radiator. That's money well spent.

If I were you I'd do a new thermostat first (cheap).

If that doesn't do it then I'd get the radiator rodded out. (don't go to the dealer for this!) Actually they are very easy to take out yourself. Just remove about 6 or 8 bolt right on top of the support that the hood latches to and then remove 2 bolts per side down halfway on the fan shroud (a long extension works great for these).

Then after it's drained and the hoses removed it just lifts straight out. You never need to crawl under it to get it out. While you have it out make sure you check the oil cooler and the A/C condenser to make sure they are clean too.

If that doesn't do it then all you have left is the water pump or being carboned up (see above solution). Water pumps are not bad to do either.

If you don't use your truck hard I wouldn't spend the bucks on the '97 cooling upgrade or any other bells and whistles. Sounds like it mostly idles around the farm with little load. Right?

That should do it.
Ken

[FrankieRider2]

Ken, thanks for the reply.

I removed the radiator myself last year when I had a small coolant leak on the RH side tank, and, no, it wasn't hard to do at all. I went ahead and had the radiator gone through at that time top to bottom; all total for the repair and the cleaning was about $100. But should it need the same thing again so soon?

I've been looking for a lower temp thermostat (180 or so), but haven't been able to find one anywhere. I'm sure that the info is here on this site somewhere, but I guess I'm notlooking in the right place or not doing my searching properly.

I pull show cars and my trailer pretty often (5500-6000 lbs.), and I'd like to be able to pull our 32-ft. dual tandem gooseneck trailer when I need to as well for farm work (hay, equipment, etc.). So I figured that the cooling mods would be beneficial for doing that. Do you disagree?

My truck is indeed a driver for most occasions, but I need to be able to use it hard when the situation requires it.

[ucdavis]

Agree on usefulness of cooling mods. I wouldn't burn too many calories on 180 tstats; once stat is open & engine temp increases you don't get any benefit from the lower opening threshold. If I found 180s, I'd go for it, but if not I'd just try a fresh stat.

[BuffaloGuy]

No the radiator should still be fine. That is unless.... Did you mix well water with the antifreeze or use deionized water? I can imagine that the wrong kind of well water could plug it up in a year.

Syphon off a little antifreeze until you can see a few of the cooling ports in the radiator. Do they look clean? If they are corroded and gunked up you may have not gotten a good job for your $100 or perhaps the water you used had a little of mineral in it.

Then again, if it looks clean I'd go for a new thermostat. It took me a while to find them too. I finally found them at a Carquest but like ucdavis said the lower temp wont help after it's open anyway.
Ken

[markelectric]

Have you pulled the top shroud and looked DOWN between the radiator and AC coil? I dont recall you saying you had. You will be suprised how much garbage collects there. None of that crap is noticable thru the AC coil. If there is much, you may want to pull the radiator and use a power washer. DONT bend any fins. Just a thought.

[FrankieRider2]

Well, here's the latest poop....

I got my truck back today from my Chevy dealership after they ran a cooling system flow check on it (cost - 1/2 hour labor charge $20.00). The water pump is flowing fine... there are no leaks in the system... but the radiator is showing some restriction according to the GM tech.

The radiator shop I normally use quoted me a cost of $195 to rod out the radiator and go through it completely. Last year I paid about $100 at a different shop, but I'm wondering how good a job I got if the radiator is restricted again with a year's time? I did not use well water when the radiator was refilled, and I have not added any water or coolant since then. I plan on replacing the thermostat when I deal with the radiator problems.

The expression on my usual radiator guy's face leads me to believe that I didn't get too good a job for my $100....

And to top it all off... I can get a new radiator for just over $300 from O'Reilly's.... GM wants over $500 for a new one. Ideas or thoughts....?

[rustypig]

You can get the Robert Shaw brand, high flow style thermostats from autozone. I recommend the 180's if you tow. You may notice a slight drop in mileage (diesels run more efficient around 200 degrees), but I feel it's worth it. I feel these rigs (at least mine) suffer from an overall heat soak problem when run hard ie...tranny fluid, coolant, engine temp, a/c condenser, tranny/oil coolers, intercooler etc, etc, all add heat and the overall frontal opening for airflow on GM's is a disadvantage.

The 180 just allows a full open position sooner (obviously) and gives more of a cushion. It also helps keep tranny temps in check (in radiator cooler). I think it can help with stop/go or slow speed driving like farm work.

[HowieE]

Before you pull the radiator again look at what is in front of it. Take a look at my web site, noted below, and see what may be between your oil coolers and the AC condenser.

[FrankieRider2]

I bought some Prestone HD radiator cleaner to run through the radiator.... will this even be worth my time? My AutoZone says they do not sell Robert Shaw products anymore, so that avenue for a thermostat is no longer here locally. Kennedy Diesel advertises them, I may go that route if I decide to get a 180 degree unit.

I will double check for debris in front of the radiator and condenser, but I got a larger problem right now.... on Friday night my light switch fried and now I have two melted wires going to it that will have to be repaired.

I got the HL switch harness back through the dash, but I can't get the wiring down far enough from up under the dash to replace the burned wires myself. As far as I can see and/or unwind the harness wrap, the wires are still burned and melted together.

So it looks like a Monday morning trip to the Chevy place again.... AARRGGHH!

[FirstDiesel]

2 words

New radiator. Whby keep spending money on an old unit??

As for the light wires, the cure is a Kennedy Lighting harness. When you see the difference in the size of the wires and understand that GM foolishly draws all the power for lights through the light switch you'll understand why the wires fried.

[jeffreydmet]

Just a word of caution for anybody replacing thermostats. Be sure to get the high flow variety. I recently replaced mine because they weren't keeping my 99 K3500 up to temp with what NAPA listed. When I took a trip to the mountains I had severe heating problems. I had to cut the guts out of the thermostats to get enough flow. When I got back I found out that the GM stats have a much larger flow area.

[debles99]

I would agree that it's probably rad related, although maybe not INSIDE the rad.......

When I bought my 98, the first day I had it home, it was idling in the driveway for about 10 minutes. When I went back out to the truck, the temp gauge was pinned and there was no AC. When I started moving down the highway, the AC would work and the temp would come back down.

My uncle, who runs an AC repair shop brought his gauges and tested the sytem, the pressure were insane. Looking around, he took a piece of Kleenex and stuck it in front of the rad while I revved the engine to about 2000 rpm. The Kleenex fell off the grill instead of being sucked against it. We pulled the rad out and found that it was 100 % plugged with crap. We pressure washed the rad and the AC condenser and the tranny and oil coolers, put it all back together and the AC pressures were factory perfect, and the truck would idle at about 180 degrees with the AC running full time without cutting out. Now I run covers on my bumper vents made out of screen from an old satellite dish and keep a bug screen on the rad all the time. I see guys here running in the summer in bug season with no screens at all and can't imagine how they are not melting the engines down. Even with the screens, I take a hose and flush out the fins about every other month, trying to keep them as clean as possible.

Good Luck


debles99
98 Chev 3/4 ton Xcab 4x4

[cruzer]

FrankieRider2, I just replaced my rad this spring.
The 1st thing I found was every rad I could find was going to be Aluminum w/plastic tanks. The 1st rad I got was a oem replacement from Delphi, I took 1 look and could tell it wasn't going to cool properly. The inlet & outlet were smaller than my original & it came with adapters to go over the necks,Plus it had one large 1 1/2"core in it. I found a company on the internet, I think it was the radiator barn, but I really can't remember. It was the cheapest who carried a Visteon Rad. They shipped directly to to my address. It was a direct factory replacement it has 2 1" or 1 1/4" cores in it(can't remember") and it works great. With the cooling mods, 20"fan, fan clutch and rad running 75mph w/7500lb trailer on back of truck in the hills of KY It run around 195* it went over 200 only a couple of times & not more than 210*. The rad looked identical to may old brass 1 except alum/plastic. I think it was around $450 w/shipping. I flushed the system and use dex-cool And DISTILLED water.Investing $195 to rod out an old 93 rad my not be worth it. Just my .02cts.
Be sure to maintain the cooling system properly. I neglected it for yrs and paid the ultimate price.

Correction: the new rad was around $350

[ 09-25-2003, 09:49 AM: Message edited by: cruzer ]