[nabatta]

I recently installed a new Chevy 350 crate motor into my 1988 3/4 ton truck. I have a heating problem that I cannot seem to pinpoint the problem. With the new engine, I added headers, Edelbrock Performer intake, new water pump and hoses, alumimum undersize pullys (crank, H20, & alternator), and a hypertech thermal chip with 160F thermostat. The engine currently has over 5000 miles and it gets hot (220 F) whenever I travel at speeds greater than 70, pull my 3500lb boat, or just idle for a while. Some fixes tried was install a 6 core radiator, seal (caulk) all openings around the radiator shroud, add water wetter, install a mechanical H20 guage to verify operation of OEM gauge, and installed a 6 blade fixed fanblade. None of these have worked. Any suggestions? <img src="confused.gif" border="0">

[wrenchturner]

Sounds like youve pretty much replace everything the only other thing I can think of is maybe a higher pressure radiator cap and you might try some synthetic oil it helps to reduce heat.hope this helps

[4 Jaw Chuck]

Change the thermostat, if it doesn't get better then change back to the regular pulley's.

[willys36@aol.com]

There are usually two problems; air flow or water flow. Sounds like you have the air flow maxed-out. If you have factory shroud, big fan and clean radiator core, that's as good as it can get. I suspect your water side is the problem. If your crank pulley is a lot smaller than stock pump may be going too slow. Only reason to use non-stock pulley sizes is to reduce power consumption in a drag race - no consideration for heating problems. The new pump you have may also be 'high performance' reduced water flow and not move enough fluid. The other common water flow problem is a defective thermostat. I suggest you try fixing things one at a time. First take out the thermostat. If it still overheats, put the stock water pump back on. Finally, put all the stock pulleys back on. I would bet that this procedure will pinpoint your problem.

[Jim Weeks]

I have a few more things you might try to locate the overheating problem.

1. You did not mention your anti freeze water ratio. Water absorbs more heat than anti freeze so use about 20% anti freeze to 80% water in summer and about 50/50 in winter, depending on how cold it gets where you are at.

2. Go to the auto parts store and look up the correct presure cap for the radiator, and use that. Many people will use their old cap or replace it with the same thing that was on it before which may be wrong.

3. If you have any metel coatings on the rubber hoses take them off.

4. Undersizing your pulleys is a big no no. Put the stock size pulleys back on.

5. Recheck your timing. When you rebuilt the motor you should have checked to see that the vibration damper was correct while you had the heads off. Also vacuum advance is best for a cool running engine.

6. With the engine cold, take off the radiator cap, top off the radiator with water so that it is as full as it will go. Start the motor and let it run for a few minutes. Check to see if you have any bubbles in the radiator. If you do, more than likely you have a leaking head gasket near an exhaust valve. This can also be caused by a cracked head or block, but mostly the head gasket. You can have perfect compression and still have this happen so this is important to check and doesn't cost you anything.

7. When you find the problem, let the rest of us know what the solution is. Hope this helps you out.