Hot Nailhead

[kilkm]

I'm looking for suggestions to solve the cooling problem with my '62 Electra. The 401 run cool as can be running down the road, but when left to idle for extended periods of time it gets hot. This winter I took the radiator out and had it rebuilt with 4 cores, I installed a 160 degree thermostat, and added a 7 blade clutch fan and ensured I had a good tight fit with the shroud. I also sent the exhaust manifolds to Arizona and had the "Jet Hot" high temp coating applied to reduce external temperature and also proved for smooth flowing exhaust gases. I also completely removed the air conditioning. (Car is an Electra Convertible and the add-on A/C unit was never used anyway.) I Thought this would take care of the problem but it didn't. Going down the road the motor only runs slightly over 160, but when left to idle in the driveway for 10 minutes or so it climbed to over 215 and was still going up when I shut it down. I did note that when I raised the idle the temp started to drop. Apparently the water pump is not pushing enough water at idle to keep this motor cool when idleing is necessary for extended periods. The water pump on this engine appears to be fairly new, is tight and doesn't leak. Is this a common problem with these engines? This restored 62' beauty is in several parades and events during the summer hot weather and this is a problem. I inquired to Edelbrock about their high volume water pumps as a replacement, but they do not make one for a buick 401. A friend of mine suggested putting a smaller pulley on the water pump so it turns faster at idle. Sounds like it could work to me and was wondering if anyone has tried this. Anyone else have this problem with the old Nailheads or have any suggestion to cure this problem?

[Ron Green]

Before I would start changing a bunch of stuff I would pull the water pump and check the blade condition. They maybe eaten up and simply replacing the pump may solve your problem. On many of the replacement pumps they now attach a plate to the back of the blades of which helps to push a little more water through. A high volume pump or different pulley could easily push to much water through the radiator not allowing the fluid time to cool. Also pressure check the radiator cap and verify you have the right pressure cap. If this isn't holding pressure that could be your problem.

Sounds like you did everything right. I had a 67 GTO that gave me fits trying to keep it cool, even a custom built 5 core radiator didn't do the trick. Your engine may have some crud in it and a good back flushing with the right professional equipment could help considerably. Recommend using a 50/50 mix of antifreeze as that will help to raise the boiling point up a hair. I assume your radiator shroud is fitted correctly?

[RocketDude]

I would be taking another look at the clutch fan. An inproperly operating clutch fan will cause exactly what you're describing. when it has good air flow from driving down the road, but heats at idle, the clutch may not be allowing the fan to provide enough air flow. Just because the blades are moving, it could be slipping and not moving enough air. When you rev it up, the fan locks up and supplies the proper air flow. Fans provide the air neccessary to cool at idle, but if it isn't locking up properly at idle, you won't get enough air flow.

Just another area to look at, in addition to above suggestions.

good luck

[jrbartlett]

I agree -- check the fan clutch. I've had -- and solved -- exactly the kind of problem you describe on my '66 Riviera.