New 455 Engine Overheating

Listen guy, you are putting words in my mouth and it's extremely frustrating. I never made mention about any mechanical knowledge you may or may not have, because frankly I couldn't care less. I left an opinion to the OP about an agreement with others on a potential timing issue, backed up by a personal experience I had, not you. Meanwhile you probably sit there and pick your boogers and flick them at the same computer screen you use to portray your yourself as an internet tough guy. You crack me up dude. Focus on writing useful info for the OP instead of a di@k measuring contest with your own agenda. Oh..wait...sorry if I was abraisive here. It wasnt my intention...

 

Overheating going down the road is really the most unlikely thing; the fan is redundant or even a hindrance. I think in a previous thread we generally accepted that at 35 mph there is something like 28,000+ cfm of air going through the radiator. A fan and shroud are totally unnecessary on a roll. At a "stop" and idling (with no load) you'll eventually need a fan and shroud - guaranteed! And at virtually every engine condition other than WOT, or off, or rubbish you'll have some level of vacuum pulling (especially at idle assuming no ported and/or switched vacuum) on the canister helping to ensure that fuel burns in the chamber and not down in the cylinder.

If you overheat on the roll your radiator is FUBAR or your VA 'aint cuttin' it, or both. Finally, if you overheat on the roll and then come to a stop and idle it will continue to overheat. Just sayin'.

 

BadBrad,
I agree with your post. A little more detail from the original poster would help. If the idle over heating issue is happening after driving then it would make sense due to stored heat in the system.. If it's happening just by starting and letting it idle then that's a whole different scenario. Overheating at speed could be caused by several things..timing. Lean cruise air fuel mixture. Radiator, plugged exhaust. Etc etc

Duke350, your post said everything I need to know about you..Good day

 

I determined that in my case the dual electric fan setup I was using actually blocked some of the air flow and contributed to the on road overheating.

 

One thing that is actually overlooked on a roll is the air dam under the radiator that is designed to create a zone of low pressure under the shroud so the air on the highway doesn't just dam up under the hood and stall flow. That being said, the dam on my Skylark has been broken for over a decade and I have yet to run into a cooling issue, even with outside temps hovering around 120F, but the little air dam mounted under the radiator of most cars is there for highway speed cooling purposes.


With the information provided I personally would be doing this:
Check the cooling system is full, with no air bubbles creating false readings at the sensor.

If there is an actual difference in the exhaust note between the two banks of cylinders (not casual observation), or actual noticeable quantity difference of flow between the two exhaust pipes.
Install a temp sensor you can rely on, or using the laser one. My experience is with the laser one is the thermostat housing will be about 10F over its rating and the waterpump body will run right around the thermostat temp. If it's over heating the waterpump body, IMO, is a good place to check engine temp on. Its what the block is getting and running, its a good place. If you have a temp gun, checking exhaust temps will probably show a bank of high temps with a plugged exhaust. My experience is the outer cylinders run cooler than the inner ones by a bit. Can't give exact numbers because they are rpm, fuel amount and timing dependent, and all three of yours are likely different than mine.

The radiator cap is at least an 8lb cap and is actually holding pressure at its rating (a decent auto shop should have a tester if you do not, of course if they want to charge more than $5 to test it, it may be worth while to throw a new part at it). When I worked at a dealership, I saw several cars come in that were overheating from simply the cap not holding pressure and I've had my car piss a bunch of coolant into the overflow bottle from a cap that only held 4lbs pressure.

And not to get too deep into the tune, but my cars run about 10F hotter at idle when just running 1 point more richer on the AFR. Idling at 15:1 AFR versus 14:1 AFR. And I use more advance to warm the engine up faster when cold and down around 12 timing at idle once warmed up (this is all EFI system controlled). At idle, I've never observed less timing as detrimental to cooling (going down the road is a different story).

 

Check this out - Lean of Peak - Lean mixtures at cruise might not be so bad. http://www.gami.com/articles/frugalflyer.php

 

This is way out in the weeds. Lean at cruise airplane engine conditions are far far far different than lean at cruise car engines. The short of it is aircraft and marine engines are constantly loaded up hard, even at cruise, where an automotive engine is barely working at cruise. Lean combustion always burn hotter, its just what it does, and the old racing adage, lean is mean, applies, you can make more power lean but you run the risk of burning your valves or melting some pistons (assuming no detonation). In an airplane, the risk of running lean is frying some valves (particularly the exhaust), where as in an auto, running lean down the highway at cruising load, the engine will mis-fire before something is hurt, and also, the engine actually will typically run cooler IF there is enough ignition advance to make sure the fuel burn is doing work. If it's lean and not enough timing then it's just generating heat with no work being put towards turning the water pump, etc, and that builds heat in the system (and is hard on the exhaust valves).

 

Hello Huckleberry. How are you filling and topping off your cooling system??Also, you may want to check to see if your water pump impeller didnt move, or is in the correct place. I had a new water pump do exactly what your engine is doing.Never noticed it on the dyno.

 

I am not sure that I filled the cooling system up correctly. How do I make sure that I don't have any air pockets? I jacked the front end up and took the cap off just to see if I saw any bubbles but no luck.

I have a n e 8 lb cap on the radiator. I will check idle timing this week to let you guys know.

How do I check to see if the pump impellors are moving? By taking off the hose?

I have access to a temp gun. Where should I measure temps?

Thanks so much for the ideas guys.

 

Those Air pockets in a Radiators after being filled is a huge problem! Don't they make a pressurized (tool ) that you seal on radiator opening were cap goes . and pump by hand! they seem to work?

 

One of my heater hoses goes to the intake manifold, and I simply remove that hose while filling up the radiator until water comes out the port on the intake, then pop the hose back on. Since I started doing that a few years ago I've had no problems with air in the cooling system. I even stopped drilling the hole in the thermostat.

 

There you go Larry getting all scientific on us.:grin: Seriously though the biggest causes of over heating is lack of airflow, stuck thermostat or to small of a radiator. If you have a sufficient size radiator, water circulation and airflow it will cool a lean running or mistimed engine all day long. It may run hotter but won't over heat if the system is up to par. The cooling system in my 53 is on the edge but still doesn't over heat because of timing. It will run hotter yes, but doesn't actually over heat.


Bob H.

 

Duke, I used TA 1607 stock bore cast pistons. TA calls them 10:1 but I am pretty sure that we calculated around 9.5:1 when we built the engine. The dyno run was at 20 deg advance as I just didn't know where to set it at the time and never thought that 34 deg total would be for best power. If I had it to do over again, I would do the dyno run differently. Oh well, you live and learn. No idea what the power is at 34 deg now but I expect that it has increased over the 20 deg run. Hope this helps. ~ Eric

 

Alright guys, I have checked for the air lock. I removed the center of the thermostat so effectively a big hole right in the center of the thermostat. There is no difference in how it heats up and continues to over heat. Regarding the plugged exhaust - Since I have run it on the road (about 25 miles total), couldn't I expect that anything (mouse's nest or something) in the exhaust might be blown out by now? Other than taking the exhaust apart, how could I find a restriction? So now I need a bit more advice. I can remove the engine and the builder has agreed to tear it down and check everything out again for free or I can add the TA high performance water pump. Or there might be a third option that you guys suggest. I will try to check the initial timing with and without vacuum advance tonight. What are your thoughts?? Thanks again, Eric

 

Latest news: Set the timing up as advised (14 deg initial advance and 34 deg total advance) and that did not improve the overheating issue. I took out the center of the thermostat and that did not improve the overheating issue. I put in the new TA Performance high performance water pump and that did not improve the overheating issue. Next, I will check the coolant for exhaust gasses. Should have done that first I guess. Live and learn.

 

Reg 4 core copper/brass rad, stock clutch fan, stock fan shroud, stock air dam, stock thermo with 1/8in hole in the top to burp, you should never have an issue... [ other note, a rad can get fouled with oil or other that cats the inside with an invisible film that blocks the thermo heat transfer, had a heater core like that, only changing it got me heat ]

 

Eric,

I had a '70 Stage 1 that had original exhaust on it at 30 years old. It started running weaker and weaker and the temp gauge kept rising. After chasing my tail, I replaced the original exhaust and the problem went away and the car ran great. I had sort of a wheezing sound with my car. People said a failed double wall in the head pipe was likely the reason. Maybe something changed when you dropped the head pipes? How old is the exhaust system?

I've also been bit by the different water jackets from 70/71 to the 72-76 designs.

Best of luck.

 

Brian, Thanks for the suggestion. Current exhaust is 2.5" with flowmasters that is approximately 3 years old. However, I still run the factory exhaust manifolds, which I would love to replace with shorty headers one day when my wife will let me. I still haven't checked for the restriction in the exhaust but hope to do that when I get a free weekend. Thanks again. ~ Eric