guys have a 350 chevy in a 51', old motor went away and replacement motor is a 93' short block with 75' vintage heads that we installed and motor get hot. using thermal device to check block it says 160 plus heads are 160. the car has brand new 3 core radiator,2 electric fans,new water pump. checked tailpipes for vapor none! checked radiator for bubbles none! head gaskets were installed correctly with embossed side up. new thermostat and manifold is stock 4v GM! Car runs great but gets hot. Engine is .030 over, changed the timing nothing different. WTF am i overlooking? can block have crack and show no bubbles in cooling system or vapor out tailpipe? bring on the ideas cause this has me stumped!
My question as well. What does hot mean? If you are looking that the heads and they are 160 degrees and it is not bioling over I would have to say it is time to take a look at the gauge.
160 is actually borderline too cold for a Chevy SB.I have read a couple articles on optimal engine temperatures. Tests show 180 degrees is just hot enough to burn off contaminates in the oil. 165 degrees is too low and 195 is acceptable but doesn't quite create the optimal heat range for air/fuel mixture, power wise and breaks down the oil faster than 180. Better check your gauge.
thanks to 55dude and all of you for trying to help me out here. I should mention that when I checked the block and heads for heat and came up with 160-180, that was with it idling .. idling it runs about 185.. but when I say HOT, I mean boiling over HOT! only happens when you pull a hill. I'm thinking some blockage in the engine water jacket..here is a rundown of whats been done rebuilt and checked heads "check" two new 180 degree thermostats tested "check" new rebuilt engine that runs great with 30k on the rebuild "check" new 2 row radiator with TWO new electric fans "check" no water in the oil "check" no bubbles in the water "check" no pressure buildup in the radiator or the crankcase "check" third new temp gauge "check" didnt trust the gauge so checked it with a laser temp sensor.. it gets HOT!! boiling over HOT! flushed engine no rust or buildup of any kind. flushed very clean "check" head gaskets installed correctly "check" tried with timing advanced etc "check" no difference runs great until you pull a hill and then it climbs right up to 212 at which point I coast it down and cool it off so I can get it back to the barn without overheating..
If you could post some pictures, it might help. Maybe the radiator is too small...maybe the fans are not really doing much... it would really help to see what you actually have.
Ken, I'm wondering about a two row radiator also. But 212 is only marginally hot. Are you running a pressurized cap on the radiator? It seems odd that fiddling with the timing doesn't affect it. Stupid question but are the fans running in the right direction? Are you running pushers or pullers and is there a shroud? Lastly, do the water passages in the vintage heads match the block passages? All are dumb questions but you've already checked the obvious.
make sure the water pump is rotating correctly and double check fan direction. when it heats up is the temp in the radiator the same as the block?
Are The fans on the front or the backside of your rad? and are they turning in the correct direction. also make sure that your intake gaskets were not put on back wards. some of the later 350 intake gaskets only had a 1/4" hole in them and if you put them on back wards you will over heat under a pull.one more thing if at 212 it is pumping water out of the rad cap Check your cap presser and make sure that the cap is seating on the rad.I have came across some after market rads that took a spacial cap to seal off the rad. Good Luck.
Are you using a coolant recovery tank with the proper cap, or are you just using a radiator that has the overflow tube dumping out the excess coolant? If the latter, you cannot fill the radiator completely up and expect it to not puke some coolant when it gets up into the 210-220 range. A system like that needs to be filled, and then let it puke out what it doesn't want. If you continually top off the radiator, it's going to blow coolant every time it warms up.
Not likely a two row radiator is going to cool a late model small block unless you are talking aluminum two row. You said two new t-stats are we talking the 3 dollar stats? Have you checked them in a piot of boiling weater to see at what temp they open? Put one in a pot, drop a candy thermometer in it and turn on the gas. or you could go high dollar and spend about 11 bucks on a fast acting T stat. They will also have weep holes drilled in them for cooling under load. New water pump or new rebuilt water pump? Are you sure it is actually moving water or is it just stirring it. open the radiator and wait for the stat to come open. Your radiator should be roiling if you got a good pump. At what temp do your fans come on? Are thay actually comming on and do they spin fast enough to move air? I lost my second fan once and didn't know it. In 100+ temps at idle I got up to 135 (couldn't get around the car in front of me). I checked it later it was comming on and you could hear it but it was spinning at about half the speed of the good fan. That should keep you busy for about an hour or two let us know what you found out.
What lb. radiator cap are you using? There are a number of sbc overheating threads lately, probably because of the records temps, but most of them say 212 is not big disaster, especially if you're using a 15 lb. cap., where the puke point would be 257 degrees.
considered getting a YET larger radiator but this one is way bigger than the one I took out which cooled my other engine just fine.. hummmmm
no not dumb questions Steve.. and I appreciate all the input.. I may not be able to address all the comments at this time but .. yes the fans are turning the right direction..I know.. at this point.. we grasp at straws dont we! haha.. the heads are good but I AM considering a shroud.. I have 2 16inch fans.. not room for them both on one side or I would be pulling.. as it is.. I'm pulling with one on one side of the rad.. pulling with one on the other side of the rad.. I'm cooling the total surface of the radiator. I'm about ready to pull the intake and check the intake gaskets.. if there is a right/wrong way to install them.. possibly got switched .. (i had help haha thanks a bunch.. gonna read the rest of the replys..
fans are turning correctly but I'll check to see if there is a discrepancy in temp.. twixt the rad and the block when she heats up.. thanks!!
hey sure preciate all the input.. I've boiled the stats and checked them with a termometer.. I have also watched the water in the radiator to make sure the pump is actually "pumping" checked the fans .. yes they are blowing HARD.. I set them to come on just after the thermostat opens and I've double checked all this to make sure it is really happening.. and not just in my mind...where a lot of things take place! haha l've checked all the obvious stuff..
Ditto.... also, just make sure that the water pump isn't just warn out.... I had all the same issues on a 327 in a vega and after spending way too much time and money, i realized that the impellers on the water pump had just gone away... $20 water pump and it stayed at 180 all day.
it is an aluminum 2 row and much larger than the one I took out.. which by the way cooled my other engine just fine.. oh well.. back to the drawing board.. haha
I hope the fans are set up so one is pushing, and one is pulling. I would remove the fan from the front of the radiator, and only have one on the back. Pulling.
Do get a fan shroud as you mentioned. This will force more air to pass through the radiator. (anything else restricting the flow of air?) Check timing again. (What carb and such are you running? Vacuum lines set up right? What distributor? Vac advance?) You say you've got one of those laser temp guns? I'd check the temp on the exhaust tubes about 1in away from the heads. (See if you've got a cylinder or two generating drastically different temps from the others) Check radiator for clogs, corrosion, etc. After all that if you're running hot....may be time to start going through the motor looking for clogged water passages.
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