308 Engine Cooling

I went with a billet (sp?) pump that was custom made by a guy in Washington State. Search this forum for the thread. Once installed, my '77 308 never overheated. It seemed to push a lot of water!

 

Granted, it's still cool here in NJ, but I just pulled my radiator for a pin-hole fix and power-flush. I'm told there wasn't much gunk out of the flush, but I swear I'm running 200 now where I use to run 220-240.
It may also be due to some debris I cleaned out of the fins & general area, new foam insulation around the radiator (I didn't have any before), or a fresh 50-50 antifreeze mixture (the old mixture was very green and I suspect not diluted properly)

I had a Large Muffin fan on the oil cooler...that didn't help at all.
Next step for me is going to be Haydens.

 

220 or more I think is too warm for that car... ensure your water pump is in top condition... and also ensure you dont have any air bubbles in the system... that said.. there is not much you can do to the std system... they were must not designed for today's traffic... I run H2O and watter wetter and that helps... I have seen others fit an auxillary fan to the oil cooler ... Ron Reineke has suggested bigger fans that push more air... the kinds of fans that hot rods use... flat fans... may also be a fix.
good luck!

 

The stock water pump will work fine if all else is in working condition. Before you start changing fans and such You need to service the cooling system by doing the following:

1) Replace Thermostat
2) Have the radiator cleaned (not just dipped but where they remove top and bottom and "rod" out the core)
3) Change Fan switch in Radiator to a 180 degree switch (do a search for Fan switch for source)
4) And lastly add new coolant and properly bleed cooling system. (use distilled water)

This should give you a cool running 308.

And verify that your gauge is correct by using a digital IR Temp gun:
Measure temp at coolant pipe on drivers side of engine to the left of oil filter it should read what guage reads (or close too). I replaced my sending unit and guage now reads 30 degree's higher then actuall temp (new sending units need to be calibrated to the old guage by a shop like Palo Alto Speedo). There's nothing worse then trying to fix a temp problem that really does not exist.

I run Nicks Forza Ferrari Advanced Water Pump but I have a modified engine that use non water coolant (Evans) and that water pump is a better choice for that coolant. If you water pump does fail I would highly recommend Nicks pump rather than rebuilding old pump.

 

And for what it will cost, try fitting a new expansion tank cap, to ensure the cooling system is operating at the correct pressure.

(Low pressure will encourage boiling of coolant, air bubbles, cavitation in the pump and may spoil circulation a little).


I've also wired an over-ride switch to my fans and LED idiot light to indicate when they are operating. This means I can turn the fans on before the temperature starts to climb. I have a proper circuit diagram at home, but I won't be there until the end of the work week! So I've attached a rough version instead. It is very simple, nonetheless...

One side of the relay coil is live (with ignition on), the other goes to the radiator temperature switch and then to ground (earth). Joint off the ground side of the fan relay(s) and run wire to one side of the new switch. Run wire from other side of switch to ground. (DO NOT cut or disconnect the original wire).

Now the relay will trigger the fans when either the raditator temperature switch makes (due to temperature) or whenever you close the new switch... best of both worlds?


Yours,

David
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I'd have thought that it'd be chucking coolant out at those temps so my first question would be as to whether the gauge is accurate. If it is then you need to get it fixed because running at those temps won't be doing your engine much good.

So, are your radiator fans cutting in & if so at what temperature? They should be at around 190.

If they are cutting in at 190 then odds are the gauge is right & you have an issue with either very low coolant level, a bad water pump, a blocked radiator or a bad/stuck thermostat. I'd check the coolant level first, then replace the thermostat & then look to the other two if that doesn't cure the thing.

If the fans arn't coming on at all then the temp sender (for the fans) located at the radiator may be at fault - or it may just be that your temp gauge is over reading horribly & there is really nothing wrong!

A few temperature readings with one of those hand held laser things (from the expansion tank, the radiator & the engine block) would also help you to identify what's going on.

I.

 

coolant or no coolant your temp should read normal at around 190 deg. F
Check your radiator fan switch make sure its turning the fan at the corect temp. Also you might have air in your water system this will defenitely increase the temp try to bleed the air out.

 

250 is too hot !!!!!!!!!!!!! bleed the cooling system. use the heater and make sure to open and close the heater valve several times. then bleed the system again. i have NEVER in the Georgia heat had one of these cars that would read over 210.
230 + means something is bad wrong. my cars were stock other than new foam and water wetter mixed in accordance with the directions. i see no reason to go changing a bunch of stuff on the car. its over 120 + here in the summer with the high humidity.

 

I still find it difficult to believe that these cars have overheating problems unless maybe you live in parts of the country that have 90* weather on a constant bases. This 3L motor has a 19qt. cooling system . As I recall all of my Vette's and Jag conversions had 19qt capacity cooling systems and with a 5 or 6 L motor. I've never had a overheat problem with these engines either.So I guess either I have one of the rare cars or there are problems with other cars here on the board. I use 50/50 antifrz and change it every 2 years. My waterpump blew at the normal unacceptable milage of 35K and was replaced. I have a 185* tstat and during normal highway driving in the winter or summer in the New York area my gage never gets past the 1st mark even with the AC on. In city traffic on a 90*+ day the needle moves toward the 195* mark at which time the fans turn on and in about 3-4 minutes the needle moves back and the fans turn off. In fact with the AC on and 1 fan on the temp goes up but usually not enough to turn on the 2nd fan. So I guess something is wrong with my car. So for all who have rodded the rads did you see what kind of crap came out and also have you done a power clean of the block. Also if you restored the cooling system to orign. did it perform as designed. Enjoy the ride