Moparts Tech Archive
Motor General
Temperature Q's
Running Hot on freeway... Temp problems.Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-02-2002 06:35 PM
Getting ready for the trip up for the Woodward Dream cruise, and of course, I have a last minute problem. When cruising at 60-70, the temp gradually is going up to the 200-210 range and staying there. Just got back from a freeway cruise and it stayed at 210* until I got back down on surface streets, where it cools back down to the 180-190 range.
493 w/E heads- all fresh
New flow-kooler water pump
Radiator is factory 3 row 26" that was recored 3 years ago and I had it rodded and checked last week and it is perfect.
Brand new HD thermal clutch on an 8 blade factory hd fan w/shroud.
Huge trans cooler that is NOT in series with the radiator, should remove some of the load off the rad.
New hoses and the bottom(suction) has a spring in it to stop collapse.
Had hi-flow Mr. Gasket 160* thermostat in it, replaced it with 180*, no difference.
Fresh fan belt with proper tension.
Running A/c seems to make no diff at hiway speeds.
This is getting aggravating! Granted, it is close to 100* today, but the car will run cooler in traffic than on the hiway! This led me to look for hose restriction, clutch fan problems etc. I have a new Auto Meter temp gage in conjunction with the factory gauge in my 69 RR and they agree, 210 on the auto meter is near the last hash mark of the normal range on the factory gauge, and 180 is near the center. At this point, I am willing to try just about anything! HELP!
Lee.
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70dart360
Moparts Member
Posts: 782
From: Hampton, Ga
Registered: Jun 2002
posted 08-02-2002 06:40 PM
Sounds like a stopped up radiator but you have eliminated that problem, Maybe the water pump is pushing water too fast at higher speeds?Not allowing it to stay in the rad. long enough to cool it?
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blowncuda
Moparts Member
Posts: 2757
From: Fairfield,CA
Registered: Nov 1999
posted 08-02-2002 06:41 PM
Lee-Do you think it is possible that you are moving the water to fast with the Flow Kooler at high way speeds? I had the same problem with mine on the highway. It would run 200-210 when I had the flow kooler on. Removed it and put the stock(aluminum replacement)pump bak on and now the car is back to running on the thermostat on the highway. Just a thought.
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Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-02-2002 06:50 PM
Thanks for the replies. The only thing I have not replaced at this point is the pump. I thought that if the water was circulating too fast, that a higher thermostat would keep it in tha radiator longer to allow proper heat exchange???. Hey, I have the factory iron A/C style that was on the 446, I will try that next, just thinking that I might be missing something! I am not comfortable with cruising at 210* Does not leave much room!
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Brian
Moparts Member
Posts: 1402
From: Houston, Texas
Registered: Nov 1999
posted 08-02-2002 06:50 PM
Flow-cool pumps blow! I agree that it maybe pushing to much water to fast. I dumped mine for a STOCK six blade. Then again, 200-210 ain't bad for the weather we're having today!
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Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-02-2002 07:06 PM
OK, I am going to put the stock pump on. Just what temp is too hot? I am guessing about 225? Don't want to take any chances with the new stroker/alum heads!
[This message has been edited by Lee446 (edited 08-02-2002).]
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blowncuda
Moparts Member
Posts: 2757
From: Fairfield,CA
Registered: Nov 1999
posted 08-02-2002 07:08 PM
IMO where it is running(200-210)is not a problem as long as it does not continue to climb. If it stops there it is fine. IMO 230 would get me concerned.
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ScottG
Moparts Member
Posts: 247
From: MariaStein,Ohio,USA
Registered: Jan 2001
posted 08-02-2002 07:57 PM
I Have heard some guys say that high flow water pumps can cavitate the water in the pump, and the water will not flow! If you are using your stock pully with that pump, it might be spinning to fast at higher speeds. If it stays cool in traffic you have got the hard part done. I would put the stock pump back in! Just my 2 cents! Scott!
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Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-02-2002 08:42 PM
OK, I put the stock pump back in and there is not any discernable difference! She runs up to 210* and sits there. It just makes me a little nervous, as I am setting out soon for a 3000 mi. road trip. My 446 with iron heads always ran below 200 at speed with all the same equipment. With all these changes I am making, I am just running water, which according to nascar, removes heat better than any glycol blend. Anti-freeze just ups the boiling point, does not actually affect temp... right? When I quit swapping pumps, thermo, etc. I will run 50/50 with some water wetter when I am finished dumping it on a daily basis. Anyone else? Lee.
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Thunderstruck
Moparts Member
Posts: 1235
From: Killeen, Texas, by God!
Registered: Aug 2000
posted 08-02-2002 10:03 PM
Ok, first your fan is not needed above about 30 mph, so if your low speed cooling is ok then it ain't the fan. Also, the AC not making a difference kinda rules out the airflow as a problem.
Next, usually high road speed cooling issues are water flow related, low road speed cooling issues are airflow related.
Sounds like your thermostat is not opening enough. Pull it, put it in an old pan and use a thermometer so VERIFY when it opens and eyeball it to ensure it is opening all the way. Also, make sure you did not put it in backwards.
Steve
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Paul Fancsali
Moparts Member
Posts: 818
From: Pittsburgh pa USA
Registered: Nov 2001
posted 08-02-2002 10:13 PM
I see nothing wrong with a 210 temp esp on a 90+ degree day the motor will run fine. Run a antifreze mixture of 1 gallon and the rest water.that should keep it in line
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Jeff
Moparts
Posts: 1474
From: Staten Island NY
Registered: Nov 1999
posted 08-02-2002 10:26 PM
One other possibility,
MAYBE the car is leaning out on the highway?
then when your back to street driving it richens up and cools it down?????????????
just a thought.
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Brian
Moparts Member
Posts: 1402
From: Houston, Texas
Registered: Nov 1999
posted 08-02-2002 10:59 PM
You Big Block guys make me sick! Inside of 90 minutes Robert changes the pump, takes it for a spin and reports back the results!
The Wather pump on an A/C small block is an all day afair! I'm pushing about 200 at cruise this time of year. How about distilled water and water wetter?
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440trk
Moparts Member
Posts: 2156
From: Harrisburg,Pa. USA
Registered: Nov 1999
posted 08-02-2002 11:09 PM
What PSI Radiator cap ya runnin?
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fox
Moparts Member
Posts: 487
From: auburn Il USA
Registered: Sep 2000
posted 08-02-2002 11:16 PM
I think you are running lean! increase the jets by 2 sizes and it will go away.
I have been there!
You may want to check total timing- keep it under 50 degrees.
fox
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TJP
Moparts Member
Posts: 4051
From: Omaha, Nebraska
Registered: Jan 2000
posted 08-02-2002 11:23 PM
Make sure your ac condenser isn't plugged up with bugs etc limiting the air flow through it and the radiator. Make sure something hasn't found it's way in between the two
(shop rag etc).
Verify your temp guage with a digital thermometer.
Also make sure you are not over advancing the motor at hiway speeds.
And last make sure all of the hood seals etc are in place. if not they will let the air go over the top rather than through the core
ANd i agree as long as it doesn't go any higher 210 would be ok. But if it runs cooler at lower speeds that would indicate inadequate cooling for some reason. Happy hunting and keep us posted
Tim
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Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-03-2002 01:03 AM
Total timing is 36* all in by 2500-MSD billit dist. Thermo's both opening in the pot at correct temp. I have two seperate temp gauges and they agree. A friend has a Stant rad pressure/cap tester and the cap checked out at 16# and the system holds pressure. My lift-off hood is sealed between the core support and hood with armorflex(damned good thought though!) It had passed my mind about rejetting the center carb on my six-pack, that is a good suggestion, wont take long, and may make a diff. Two sizes it is! 210 in and of itself is a liveable temp, I am just not happy with it that high, I keep feeling that it does not leave me much breathing area out on the road. If I knew for sure that I could drive all the way to Michigan and back and never exceed it, I would'nt worry! I thank all of you for the excellant suggestions, I'll rejet and report back tomorrow. Lee.
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HemiDoug
Moparts Member
Posts: 450
From: Bowling Green, KY, USA
Registered: Apr 2001
posted 08-03-2002 01:15 AM
You will get better cooling performance with 100% water than with an antifreeze mix. Dump in a bottle of Water Wetter and go. I doubt if it will freeze in Detroit in the next couple of weeks...
You said you have an 8 bladed fan and a fan clutch. When you are moving at highway speeds, the fan can actually block airflow through the radiator, and 8 blades will block the most. Can you get your hands on a MP 5 blade fan to try?
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MY340
Moparts Member
Posts: 2071
From: missouri
Registered: Mar 2001
posted 08-03-2002 09:19 AM
Lee, To me your clutch fan is operating just like it's supposed to to do. I have a truck that runs the same way. Warmer on the highway when clutch disengages so to speak and cooler around town when it's engaged. I run 180 thermostat too. Waterwetter or Royal Purple Purple Ice may help alittle otherwise you'll probably just have to live with it. Have you ever thought of moving to Alaska?
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Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-03-2002 09:35 AM
Doug, Yeah, I replaced my 5 blade MP clutch fan with the 8 blade unit when this problem popped up, it had always been fine before. I am hoping that since I had never rejetted my center carb since going from a 440 to a 493, that it might be a bit lean at cruise. I know the idle mixture is spot-on. If that does not do it, I'm going on the trip as-is!
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blowncuda
Moparts Member
Posts: 2757
From: Fairfield,CA
Registered: Nov 1999
posted 08-03-2002 12:15 PM
Lee-What does the temp do at the track? Does it shoot up alot,ie 20-30+ degrees during a run and the cool back down almost immediately on the return road?
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1/4 mi Keith
Moparts Member
Posts: 439
From: Newberg (South of Portland), OR
Registered: Feb 2000
posted 08-03-2002 03:31 PM
As a few others have mentioned, try a bottle of Red Line Water Wetter. You may still have a problem somewhere, but the water wetter should drop the temp by about 10º. If you were going to drive it as is, at least the water wetter will give you a little improvement.
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Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-03-2002 03:48 PM
Blowncuda, now that you mention it, last week when I went to the track, it would be about 160* staged, then by the end of the run, it would be close to 190. I also noticed that within about 15 minutes of just sitting(after a run,not a hood-up cooldown) You could fire it up and it would be back near 160 again. That is when I decided to go ahead and replace my bottom hose with one that had a spring in it, thought the hose might be collapsing under high rpms. Are you on to something? Keith, when are ya coming back?
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blowncuda
Moparts Member
Posts: 2757
From: Fairfield,CA
Registered: Nov 1999
posted 08-03-2002 05:53 PM
Dont know that I am on to anything but here are a few things. Not sure 160 to 190 qualifies but here goes. A sharp rise in temp(follwed by very quick cool down)can be caused by a few things. One would be a very lean condition. Two Detonation,this can lead to sudden temprature rises, and third can be caused by a bad head gasket, not as likely but I have seen it happen.
Just some ideas and not sure they apply to your car as these would more than likely show up as sudden spikes in temp when making a pass. I have seen cars go from 160+- to 210+ in a pass and then as soon as they hit the return road be back at 180. I might start with the fuel mixture as IMO it may be the culprit especially given the carb arrangement on your car. I am sure you have watched the plugs for signs of detonation. I have seen this same thing happen when a head gasket starts to let go. Given this some rise in temp while making a pass is obviously going to happen. What I am referring to is sudden increase and then decrease in temps over a fairly large span,say 30-40 degree. Just some food for thought.
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Lee446
Moparts Member
Posts: 1095
From: Houston,Tx.
Registered: Dec 1999
posted 08-03-2002 07:33 PM
Well, the preliminary results are in. I changed back to the 160* hi-flow thermostat, while I was under the hood rejetting. Took her out for a run using the same route and speed as all previous runs. I went into my center carb to rejet and found that I had, at some time in the past, gone up from stock 63 to 66 jets. My kit seems to be missing size 68-69 jets, so since 67's wernt much of a change, I went with the 70's. It appears that it was lean at cruise and the bigger jets seem to have accounted for an approx 10* drop in temps. The car is now running closer to 200 than 210. Jeff, and Fox and Blowncuda win cigars! I would not have thought that a 350 cfm center carb would need a 70, even with a 493 under it, but it does. A big thanks to everyone for your help! B/C, I was starting to worry about possible head gasket problems, when we pressured up the system and it did not bleed down, I felt the gaskets had integrity. Have you ever seen one that passed the test with a bad gasket? I suppose if it was blown between two cylinders and not into the cooling passages??? Anyway, thanks for all the help! Lee.
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