[79Rod]

the temperature grows quick from 150° to 230 and even higher (at idle and running) I notice that coolant droops to coolant reservoir (this coolant is cold). I disconnected the radiator inlet hose and saw that the coolant flow is intermitent....sometimes it flows, sometimes not
I pulled out the water pump, and didn't notice any impeller problem. I have a brand new radiator (used less than 5 miles) and also installed a third fan.
Last moth I swaped to carb, so I pluged the throttle body coolant hose and the hose that was near to the distributor (rear intake manifold side).
Brand new belt tensioner....
What could be happening? :huh:
help please

 

[vetteoz]

Last moth I swaped to carb,

So what controls the fan(s) now?
Do the fans run at all , at what temp?

I notice that coolant droops to coolant reservoir and saw that the coolant flow is intermitent....sometimes it flows, ..
What could be happening?

You don't state what year we are talking about?
These systems need to be " burped" to get rid of air; you have to hold revs @2K and pour coolant in then put cap back on before dropping revs
If you don't you get the situation you are seeing where the pump can move coolant out of the radiator faster than it can get back in so you end up with air in the system =overheating

 

[79Rod]

1990 L98.
the fans are conected direct to switch signal

 

[ndrewoods]

the temperature grows quick from 150° to 230 and even higher (at idle and running) I notice that coolant droops to coolant reservoir (this coolant is cold). I disconnected the radiator inlet hose and saw that the coolant flow is intermitent....sometimes it flows, sometimes not
I pulled out the water pump, and didn't notice any impeller problem. I have a brand new radiator (used less than 5 miles) and also installed a third fan.
Last moth I swaped to carb, so I pluged the throttle body coolant hose and the hose that was near to the distributor (rear intake manifold side).
Brand new accessory belt tensioner....
What could be happening? :huh:
help please

Here some cause of overheat:

• Bad Thermostat
• Cooling system leaks
• Leaky Head Gasket
• Fan Not Working
• Leaky Water pump
• Lower Radiator Hose Collapsing
• *Slipping Belt - Check belt tension and condition. A loose belt that slips may prevent the water pump from circulating coolant fast enough and/or the fan from turning fast for proper cooling

Your engine may not be overheating at all. Your temperature gauge or warning lamp may be coming on because of a faulty coolant sensor. Sometimes this can be caused by a low coolant level or air trapped under the sensor.

 

[79Rod]

I found this: hoses, radiator, pump, fans are Ok.
the intake maifold have blocked the water passages between heads.
The tpis big mouth intake dont have this passages blocked.
On many forums people said that this water passages are not used.....I dont think so....let me hear your opinions

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[84wannabez06]

overheating

I noticed that my x-ram manifold has those rear coolant crossover passages blocked but the new renegade has them cast in I think that running aluminum heads I would really want that extra balance to minimize hot spots

 

[HardcoreABN]

you do not need the front and rear, quite often the rear is blocked off anyway. Personally I prefer to use those anyway to help balance the cooling system and improve flow.

the front is deffinately used, that is where the thermostat is fed from. the coolant flow goes from the radiator into the water pump thru the large lower hose going to the water pump. from there it is pumped into the engine thru the holes on the front of the block that the water pump is mounted on. from there it goes into the heads then the intake manifold. it passes thru the thermostat (mounted on the intake manifold) and back into the radiator.

also, i cannot think of what coolant hose that is routed back near the distributor.

I am curious why you went to a carb over the tpi

 

[sdhd97]

Sounds like what happenned to me after I rebuilt my motor. I left my thermostat on the bench for 7 months and it went bad. I was overheating as well, so I changed my thermostat and all is good.

 

[79Rod]

problem solved....it was the water pump rotation

 

[vetteoz]

i cannot think of what coolant hose that is routed back near the distributor.

The Vette TPI intakes have a small bleed pipe connected to the heater return hose that GM engineers said is supposed to allow steam built up in rear of alum heads out and back into coolant system
Had mine deleted for years with no effect :thumbsup:

Steel line from intake goes to small spigot on heater hose at rear
(RHS in pic, large spigot is for oil cooler return )