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Re: tough one: overheating on the highway [Re: flypaper] #1719505 01/03/15 04:34 AM 01/03/15 04:34 AM
Joined: Feb 2003 Posts: 16,133 Mesa, Arizona D dart4forte I Live Here
dart4forte I Live Here D Joined: Feb 2003 Posts: 16,133 Mesa, Arizona	Are you running the stock electronic ignition? If so you may want to try a new box. I had a high speed overheating problem this summer. Kept chasing after dead ends. Well a friend told me he had the same issues before and he ended up changing the box. Solved the problem. Turns out the box was leaning out at high RPM. I changed mine, problem solved. When those Mopar boxes are new things run great but they go away things can haywire.

Re: tough one: overheating on the highway [Re: flypaper] #1719506 01/03/15 11:27 AM 01/03/15 11:27 AM
Joined: Sep 2007 Posts: 14,889 up yours Supercuda About to go away
Supercuda About to go away Joined: Sep 2007 Posts: 14,889 up yours	Quote: a few thoughts i have is what kind of water pump did you use? some hi volume pumps will push the water way too fast thru the radiator,not giving the water enough time in it to be able to cool down. DO NOT listen to this type of "advice". It is wrong and illustrates a completely ignorance of thermodynamics. They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.

Re: tough one: overheating on the highway [Re: smos001] #1719507 01/03/15 11:41 AM 01/03/15 11:41 AM
Joined: Feb 2005 Posts: 28,312 Cincinnati, Ohio Challenger 1 Too Many Posts
Challenger 1 Too Many Posts Joined: Feb 2005 Posts: 28,312 Cincinnati, Ohio	Quote: Might be leaning out as you press into the higher speeds. Does it miss at high cruise? faint lean miss? a lean miss also cause a slight hesitation as you press on the gas at a stop sign. You may have to rejet the carb a little. Vacuum leak? Do not discount the 2 guys who suggested this. I third this suggestion.

Re: tough one: overheating on the highway [Re: Challenger 1] #1719508 01/03/15 04:45 PM 01/03/15 04:45 PM
Joined: Jan 2003 Posts: 512 Niwot, CO Formerly denn... dynorad mopar
dynorad mopar Joined: Jan 2003 Posts: 512 Niwot, CO Formerly denn...	I second the idea of using a IR thermometer to help you troubleshoot. Harbor Freight has them for not much money.

Re: tough one: overheating on the highway [Re: dynorad] #1719509 01/03/15 09:38 PM 01/03/15 09:38 PM
Joined: Jan 2003 Posts: 3,575 The Netherlands BigBlockMopar master
BigBlockMopar master Joined: Jan 2003 Posts: 3,575 The Netherlands	Underhood airpressure might cause air to have hard time entering the enginebay at speed through the radiator. I know you mentioned air flaps are presents but maybe a front airdam has been left out perhaps? Specially since the car is fairly high overal with a lot of groundclearance causing turbulence under it. BigBlockMopar.com

Re: tough one: overheating on the highway [Re: flypaper] #1719510 01/03/15 10:05 PM 01/03/15 10:05 PM
Joined: Aug 2014 Posts: 45 Delaware G GeorgeH member
GeorgeH member G Joined: Aug 2014 Posts: 45 Delaware	Had a old dodge van I had a similar issue on. Turned out the heat riser spring was weak and not opening up fully.

Re: tough one: overheating on the highway [Re: GeorgeH] #1719511 01/04/15 02:14 AM 01/04/15 02:14 AM
Joined: Jan 2008 Posts: 4,254 Canada WO23Coronet master
WO23Coronet master Joined: Jan 2008 Posts: 4,254 Canada	Pretty sure he mentioned he has headers

Re: tough one: overheating on the highway [Re: WO23Coronet] #1719512 01/04/15 02:28 AM 01/04/15 02:28 AM
Joined: May 2007 Posts: 952 Queens, N. Y. FASTBACK340 super stock
FASTBACK340 super stock Joined: May 2007 Posts: 952 Queens, N. Y.	I sure hope we find out what the cause is as the remedies are all over the map�. `68 Barracuda 340-S

Re: tough one: overheating on the highway [Re: FASTBACK340] #1719513 01/04/15 12:26 PM 01/04/15 12:26 PM
Joined: Jan 2003 Posts: 1,381 Youngsville, NC D dem440c OP pro stock
dem440c OP pro stock D Joined: Jan 2003 Posts: 1,381 Youngsville, NC	Quote: I sure hope we find out what the cause is as the remedies are all over the map�. holy moly you aren't kidding... you guys have a LOT of great ideas. A lot of them I have tried already and I've been taking notes on some things to try that I haven't done yet. - full length headers, 2-1/2" duals through Flowmasters exiting in front of the axle. I'm pretty confident there is no exhaust restriction. - gonna try the idea to remove the fan and see what happens. Only problem there is I have to drive 25 minutes to get to a highway, guess I'll bring tools and see what happens. - I haven't mapped the timing yet to see exactly what the distributor is doing as the RPMs increase, I can do that. It runs perfect so I haven't been thinking in that direction but it wouldn't hurt to see what it is doing. - pulling freeze plugs is gonna be a sucky job but I agree that the symptoms would line up with that cause so it should be explored. Man, that is gonna take me a whole freakin' weekend to pull all that apart and then get new plugs back in... sigh - changing the ignition module is easy, I have a box full of them. I'll try that just because it is quick and easy. - someone mentioned air baffles, I have all the ones in place that cover the gap between the core support and the radiator. What else should be there?

Re: tough one: overheating on the highway [Re: dem440c] #1719514 01/04/15 12:44 PM 01/04/15 12:44 PM
Joined: May 2007 Posts: 952 Queens, N. Y. FASTBACK340 super stock
FASTBACK340 super stock Joined: May 2007 Posts: 952 Queens, N. Y.	Might be easier to pull the water pump and use a bora-scope and peek in through the timing chain cover openings first. Freeze plugs are a chore on an educated guess. `68 Barracuda 340-S

Re: tough one: overheating on the highway [Re: FASTBACK340] #1719515 01/04/15 02:02 PM 01/04/15 02:02 PM
Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska R RapidRobert Circle Track
RapidRobert Circle Track R Joined: Nov 2003 Posts: 36,040 Lincoln Nebraska	that if you do not post the solution (when you find it) that there might be a cyberspace lynching . Recently a member lost his life cuz he DELETED his thread . On the timing, in your driveway just run it up to the same RPM you are at on the highway when it is getting hot & see what you get with your dialback or make some marks. 0.0632683" around the circumference is 1 degree on the dampener or can use the tab as a ruler. 2&1/4 (2.246") is 35.5 deg which should get you close to what you have tho the can will kick it higher above that live every 24 hour block of time like it's your last day on earth

Re: tough one: overheating on the highway [Re: dem440c] #1719516 01/04/15 03:41 PM 01/04/15 03:41 PM
Joined: Jan 2003 Posts: 3,575 The Netherlands BigBlockMopar master
BigBlockMopar master Joined: Jan 2003 Posts: 3,575 The Netherlands	Quote: - someone mentioned air baffles, I have all the ones in place that cover the gap between the core support and the radiator. What else should be there? I don't know what came stock on your car as I don't have any experience with these models. But if you're adventurous you could take a trip simply without the hood mounted and see if the issue remains. BigBlockMopar.com

Re: tough one: overheating on the highway [Re: RapidRobert] #1719517 01/04/15 03:49 PM 01/04/15 03:49 PM
Joined: Jan 2003 Posts: 727 Ottawa, ontario D dd340 super stock
dd340 super stock D Joined: Jan 2003 Posts: 727 Ottawa, ontario	Quote: that if you do not post the solution (when you find it) that there might be a cyberspace lynching . Recently a member lost his life cuz he DELETED his thread . On the timing, in your driveway just run it up to the same RPM you are at on the highway when it is getting hot & see what you get with your dialback or make some marks. 0.0632683" around the circumference is 1 degree on the dampener or can use the tab as a ruler. 2&1/4 (2.246") is 35.5 deg which should get you close to what you have tho the can will kick it higher above that This made me think of something, can you duplicate the overheating in 1st or 2nd gear if you hold it at the same rpm as you run at highway speeds? If the engine doesn't heat up in the lower gears this would seem to eliminate the water pump and pulley possibilities. I would be interested to know the results of that.

Re: tough one: overheating on the highway [Re: dd340] #1719518 01/04/15 04:08 PM 01/04/15 04:08 PM
Joined: Jan 2003 Posts: 43,522 Round Lake Beach, Illinoisy Rhinodart Rhinotruck
Rhinodart Rhinotruck Joined: Jan 2003 Posts: 43,522 Round Lake Beach, Illinoisy	I still have not read if you checked or replaced your cap... The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it. JB Rhinehart, Realist A-Body's RULE!

Re: tough one: overheating on the highway [Re: Rhinodart] #1719519 01/04/15 04:40 PM 01/04/15 04:40 PM
Joined: Jan 2003 Posts: 3,049 Bowling Green, KY C cudaboy master
cudaboy master C Joined: Jan 2003 Posts: 3,049 Bowling Green, KY	Quote: I still have not read if you checked or replaced your cap... Its in there. Changed twice. Dennis

Re: tough one: overheating on the highway [Re: Supercuda] #1719520 01/04/15 05:07 PM 01/04/15 05:07 PM
Joined: Dec 2003 Posts: 22,696 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,696 Bitopia	Quote: Quote: a few thoughts i have is what kind of water pump did you use? some hi volume pumps will push the water way too fast thru the radiator,not giving the water enough time in it to be able to cool down. DO NOT listen to this type of "advice". It is wrong and illustrates a completely ignorance of thermodynamics. However "way too fast" condition can promote cavitation and/or hidden hot spots, But then I am one of the "unlearned brethren" that thinks a well performing cooling system at highway speeds has little use for a fan. Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: tough one: overheating on the highway [Re: RapidRobert] #1719521 01/04/15 05:55 PM 01/04/15 05:55 PM
Joined: May 2007 Posts: 952 Queens, N. Y. FASTBACK340 super stock
FASTBACK340 super stock Joined: May 2007 Posts: 952 Queens, N. Y.	Quote: that if you do not post the solution (when you find it) that there might be a cyberspace lynching . Recently a member lost his life cuz he DELETED his thread . Especially when the suggestions for repair run the entire spectrum of anything/everything that could possibly affect the cooling system. Let's have some fun�.. Lottery anyone? `68 Barracuda 340-S

Re: tough one: overheating on the highway [Re: FASTBACK340] #1719522 01/04/15 06:46 PM 01/04/15 06:46 PM
Joined: Apr 2005 Posts: 4,916 new berlin wisconsin M Mr T2U master
Mr T2U master M Joined: Apr 2005 Posts: 4,916 new berlin wisconsin	I am surprised no one mentioned weak fuel pump. if it cuts out at higher rpm's it can make it run lean. of course if it's lean at the top end it usually surges. perception is 90% of reality

Re: tough one: overheating on the highway [Re: cudaboy] #1719523 01/04/15 06:53 PM 01/04/15 06:53 PM
Joined: Jan 2003 Posts: 43,522 Round Lake Beach, Illinoisy Rhinodart Rhinotruck
Rhinodart Rhinotruck Joined: Jan 2003 Posts: 43,522 Round Lake Beach, Illinoisy	Quote: Quote: I still have not read if you checked or replaced your cap... Its in there. Changed twice. Dennis OK, didn't want to wade through the whole post again. The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it. JB Rhinehart, Realist A-Body's RULE!

Re: tough one: overheating on the highway [Re: dem440c] #1719524 01/04/15 08:16 PM 01/04/15 08:16 PM
Joined: Jan 2003 Posts: 15,311 Omaha Ne T TJP I Live Here
TJP I Live Here T Joined: Jan 2003 Posts: 15,311 Omaha Ne	Quote: Quote: I sure hope we find out what the cause is as the remedies are all over the map�. holy moly you aren't kidding... you guys have a LOT of great ideas. A lot of them I have tried already and I've been taking notes on some things to try that I haven't done yet. - full length headers, 2-1/2" duals through Flowmasters exiting in front of the axle. I'm pretty confident there is no exhaust restriction. - gonna try the idea to remove the fan and see what happens. Only problem there is I have to drive 25 minutes to get to a highway, guess I'll bring tools and see what happens. - I haven't mapped the timing yet to see exactly what the distributor is doing as the RPMs increase, I can do that. It runs perfect so I haven't been thinking in that direction but it wouldn't hurt to see what it is doing. - pulling freeze plugs is gonna be a sucky job but I agree that the symptoms would line up with that cause so it should be explored. Man, that is gonna take me a whole freakin' weekend to pull all that apart and then get new plugs back in... sigh - changing the ignition module is easy, I have a box full of them. I'll try that just because it is quick and easy. - someone mentioned air baffles, I have all the ones in place that cover the gap between the core support and the radiator. What else should be there? At this point I would 1. verify the timing 2. verify the pulley sizing 3. look at lean condition due to jetting or a vacuum leak. 4. pop a freeze plug What intake / carb setup are you running ?? www.tandmautomotive-omaha.com

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