hey guys, im stumped. I have installed a new water pump, new radiator, running with no thermostat, and my 305 tbi is still over heating. My timing is off to where the car is backfiring, but it should cause this big of a overheating probblem should it. I drove it maybe 6 block then back home.. and its boiling hot. I was thinking that maybe im running the wrong water pump, the original motor ran with a serpentine system, and this motor that i put in was running off a diff type of pump.. since it was not running on a serpentine system. could it be that im running the wrong pump.

My other suspect is that the heater core was leaking inside the car so i bypassed it. so the line from the back of the intake is now running to the radiator.

 

first off the timing will cause more heat. second if you ordered a water pump for the serpintine set up it is wrong. third with no thermostat it is not keeping the water in the radiator long enough. all to gether and that is most likely the problem. does it have the air dam?

 

Agree-- one92rs--quite a combination going on--

Where in NM?

 

If you kept the serpentine and put on a standard rotation pump, that is your problem. Serpentine belt setups run reverse rotation due to the belt routing.
It (water pump for serpentine belt) is irrelevant of the motor it's on.

Reverse rotation just means the pump is meant to move water the same even though the pump is spinning the opposite direction of the crank (as opposed to traditional v-belt, standard rotation).

The timing way off (retard, assuming it's backfiring through the exhaust), no bypass and no thermostat isn't as huge of a problem but, it's not helping solve the issue either.

 

does running serpentine make a difference on cooling or is it better for cooling?

 

well see when i bought the motor, it had a v style set up and a longer pump. now what i did was switch the serpentine system off my old motor on to the swap motor. it seemed to be easier as far as with the harness. so now this motor has the serpentine system. the pump that i got was just the cheapy at autozone, i asked for the pump for my 91 rs 305 tbi. This car stock should of had the serpentine system right..?

The timing is off. it starts to back fire after about 5 min of just idleing.

CAN either the reverse of standard pump fit on the serpentine system. cause
I dont think the pump that was being ran with the v system would of fit with the serpentine system.

Im in Las Cruces NM

 

well if the pump was ordered for the 91 rs it should be the correct one. the cooling system could have an air pockets in it to. why is it backfiring?

 

Backfiring possilby cause you plug wires are mixed up.

 

Yes. Fix your backfiring issues and I bet your cooling problems go away. A poorly running engine will burn more fuel for an equivalent amount of power to an engine in tune. Most of the heat that an engine creates is a result of the oxidation of hydrocarbons.

 

Did you remember to "burp" or "purge" the system to let air out of the system?May want to think about a t-stat.

I've been to a few concerts in 'Cruces.I used to live in El Paso.
This time of year I REALY miss the South West!!

 

how do you burp these engines, I had a 98 z28 and I knew how to burp the ls1 but kinda lost on these 305's. Im learning as I go

Ill get the timing set and see how much clears up.
How to on burping this 305 would be apreatiated.
Will add the stat.. what temp do you guys recomend.. its bone stock

 

Iv'e never had to burp mine,always seems to get the air
out on it's own...Before you install a thermostat,run the
engine with the radiator cap off and look for coolant
circulation to make sure there is not a circulation prob.
The reverse rotation pumps have a different bolt circle
for the pulley so if the serpentine pulley fit you should
have the right pump. 195 thermostat will be best for a
stock engine,with a thermostat in place the bypass is
important to let heated coolant flow past the thermostat
and allow it to open.

 

'Burping' is intended to ensure there isn't an air pocket behind the t-stat that prevents hot water from reaching the t-stat spring and warming it so it will open. I've always drilled a small hole in the side of the stat when installing a new one.

If running without a stat doesn't allow the water to stay in the radiator long enough, is it staying in the engine longer? Is the water circulating so fast that it doesn't warm up from engine heat or is it not cooling down once it warms up (since it must stay in the engine longer)? Perhaps the extra heat generated by the additional minor losses and dynamic head losses of the faster flowing water causes the overheating problem?

 

Ive been having an overheating issue as well. I talked with TPIS and they said to pack the cooling system. With rad cap off run it up to operating temp and then bring the rpms up to 2k rpms. This will pull the coolant level down a bit and you can fill it up and put the rad cap on real quick. That will ensure there are no steam pockets that would allow overheating.
I live in Florida and everyone should know that we have 90 degree weather in Oct, which is kind of rare, but anyways, I believe this brought my temp down a few degrees. I also installed a dual fan setup and that made a few more degrees difference. If I baby it around town I can run at about 190 in the hottest part of the day. Morning and night it cools way down.
I would disagree that 195 is best. If everything is working right then a lower temp stat should make the car run cooler; thats the whole idea of a lower temp stat. You can run without a stat and it should run at 180 but if you live in the south during the summer your done, too hot.

 

The bypass is important? That is an interesting thought, I was just wondering about this. I disconnected my heater core, should I have the radiator line that was going to the heater core go straight to the front of the intake where the other heater core line used to go? Or is it ok to just plug them both off? (How they are now)

 

if you have a bypass hole drilled in the thermostat
flange,you can plug off the heater hose fittings,if not
should run the heater hose from the water pump to
the intake manifold fitting,this allows coolant to
circulate in the block,carrying heat away from hot spots
and circulating around the thermostat's wax chamber
so it can sense the coolant temp and start to open
when the coolant gets up to opening temp. If there is
no bypass or hole in the thermostat flange,circulation
is blocked and the thermostat will not open untill hot
coolant finds its way to the thermostat,at which time
there may be areas of very hot coolant in the heads
or other parts of engine(temp gauge will get up to
220-240*,then suddenly drop way down as thermostat
finally opens)

 

So, on my set up, with the heater core busted, I have the hose from the radiator that before went to the heater core, now goin directly to the back of the intake. where it used to run to the heater core..that should be ok..right?

Thanks for the advice on how to burp the car, Riverdog.

 

drill yourself an 1/8th inch hole in the t-stat and your motor will purge air by itself, as well as letting steam pockets as they form purge out of the heads fast.