Glowing exhaust during engine break-in.

[zzambucca]

During the break-in of my freshly rebuilt stock engine, the exhaust started glowing red, and then the engine overheated and started pukeing coolant from the overflow hose. It was about 20 minutes into a 30 min. run at 2000-2500 break-in. I ran it for 15 mins at 2000, then when I raised it to 2500 for the last 15 mins. it only lasted about 5 of it. I let it cool down, and tried it again, but still it only lasted 10 mins at 2500. Radiator was just flushed, engine was hot tanked, water pump is new, initial timing was set to spec, mechanical fuel pump is older, full fan shroud, and new radiator cap. Carb is a Edelbrock. The rear cylinders seemed to glow more than the front, so I am thinking lean caused by vacuum leak. I checked, and no leaks from hoses or at carb base. The intake was a little loose, so I retorqued it. I am hoping this was the cause, but I am taking thoughts. The carb might be dirty, and leaning out, but its weird that only the rear cylinders are lean. Dual plane intake would have opposite cylinders glowing if one barrel of the carb was clogged/dirty. Possibly ignition timing at 2500 is wrong, I only checked initial at idle. Probably too retarded, as burning in exahust, not in cylinder. Did not seem like fuel delivery or fuel level issue, as it did not sputter, or miss at all. Engine sounded good and steady. Any thoughts?

[ibstrokin]

Is there any possibility that the thermostat did'nt open, causing it to overheat?

[zzambucca]

Possibly, but it was new. I did not test it before I installed it.

[Rob]

I had a similar thing happen with my first engine build, did you check for good coolant flow through the radiator while it was running?

[Paul408Notch]

Could be too rich, too lean, not enough timing, etc...

What kind of distributor? Maybe it's not advancing enough at 2500. Could need a new spring kit.

[theyallslow]

I also think that it may be a coolent flow issue. but there are also to meny variables for me to know for sure. if need be I will be Talode to help...

[zzambucca]

I didn't have my laser temp gun, but there was a noticable difference in temp from the upper hose to the lower by touch. Possibly not enough to keep it cool, but there was a difference. I do not have my adjustable timing light until next weekend, so all I can really check is initial timing. Vacuum advance was not connected at any time. The weights and springs are good, as far as they snap back and no binding. Could be wrong springs. I have an exhaust leak between the manifold and the down pipe, where blue flames were shooting out, so I cannot put my wideband O2 sensor on it until I fix that issue. I am going to change the oil again, and let it idle to see how well the fan is pulling air. I might go back to a direct bolt on fan, instead of the fan clutch if its not pulling enough air.

[zzambucca]

OK, initial timing was 8 BTDC, and at 2000-2500 RPM it was 18 BTDC. Total advance is only around 22 I think, but I don't have my other timing light back yet. The fan clutch is working great, and there is plenty of airflow. I richened up the idle mixture half a turn on both primaries to bring the idle vacuum of 17 to 19 inches. Vacuum guage shows constant, not bouncing or anything. I pressure tested the radiator cap, and it tests out at 15 Lbs. I pressure tested the radiator, and found 2 small leaks at the heater hose nipples. I have to order a new fitting, the other was just loose. It was a slow leak, dropped from 15 PSI to 0 in over 2 minutes. I let the car idle, and after about 5 minutes, it started spitting coolant. I felt the lower hose, and it was extremely hot. I felt the top hose, and it was alot cooler. I am wondering if the thermostat is not opening. I will be replacing it with a cooler thermostat when I replace the fitting. I think the thermostat in it is around a 195. I am replacing it with a 180. We shall see if that helps. I will work on it when I find time.

[331TwistedWedge]

im guessing your thermostat isnt opening, i have had new ones do this to me ...... i have had the headers glow on me as well, it was timing issues ... just my experiences, hope this helps ........

[Paul408Notch]

When you replaced the water pump, did you get the correct one? Reverse rotation if you're running a serpentine setup.

[theyallslow]

I think this is the 283 cid, 62 impala. I dont know if there is a difference with the serpentine or v-belt.

[Paul408Notch]

Ahhh... thought it was a Ford motor.

[zzambucca]

Its all the same. It is the correct rotation water pump.

[G93T]

Your headers will not be glowing red hot if it was something "coolant" related, water pump, etc. It has to be something related to timing...

[theyallslow]

i think that we had too much timing, and then we had a rev flow water pump fan on a 62 pump, so it was not kooling it at all.

[zzambucca]

Yeah, the fan was a reverse rotation from a serpentine belt engine, so it was pushing air into the shroud. I put a temp gun on the radiator while running, and only saw a 10 degree difference between top and bottom, so I put a high power carpet fan aimed at the radiator, and the temp change was a huge difference. I now knew it wasn't the radiator, but airflow. I felt for air behind the fan, and felt alot of air, which didn't make sense. I felt for air between the shroud and the radiator, expecting suction, but felt air being pushed out. I turned off the engine, and checked rotation of the belts and the fan, and found it to be wrong. The air was being pushed into the shroud, and then pushed BACK between the gaps of the shroud and fan tips. The timing was a little off, but not a cause of the issue. Car is now off to the exhaust shop for a new dual 2.5 exhaust system.