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re-carbed, and now over heating? engine degreaser? water pump fail?


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hey fellas,

I just finished putting Therputic Z Carbs on my 71 240 the other day...cranked right up but engine began smoking so I shut it down.

I've put a lot of time into engine degreaser and wiping it off with a rag (not hosing off) all over the block / engine compartment. in some cases it has air dried in hard to reach spaces...

I did forget to re-add cooling system fluid that I lost during carb removal...it took about the entire upper portion of the radiator to fill back up.

engine began smoking again after restart , also ruptured the thermostat housing gasket which began leaking coolant...

I tested the thermostat and it opened very slowly in boiling water, but ran motor without it after replacing gaskets. Seemed to work for the brief time I ran it but did not verify with a long time of running at idle.

today I put a new thermostat in (180degree?) and filled cooling system back up, even jacking up the front end two feet...but motor started to smoke (white coming off the block)...I shut it down and felt the thermostat cover but it was cool...top of radiator cool.

I let it set for a few minutes and restarted until it smoked a little then shut it down....I was hoping to bump the temp up little by little to get the thermostat to open and I believe that has happened, being how the top pf the radiator got warm.

Is that the best indicator the thermostat has opened?

Is the engine degreaser partially to blame for white smoke coming from areas on motor? (not exhaust)

the engine temperature gauge initially did not even read warm when I overheated the motor... but today with the three brief periods of running the motor ( two minutes?) I got the gauge to read a quarter inch under half way point. top of radiator was warm.

what's the pressure I should feel on the upper radiator hose? it felt warm but not much more pressure than when engine off...

there's no pulley fan, and the electric fan has never worked to my knowledge, but the Z ran fine prior to the carb exchange, and I've tested the electric fan by a straight battery connection so it will work...but currently I'm worried if thermostat is taking too long to open while rest of motor is burning off degreaser or melting...

also I have yet to tune the new Ztherapy carbs...so could they be running too lean at first?

Edited by bounce

I will remove radiator cap, turn on heater and run zee Z with front jacked up this afternoon to purge air if there is any.

still would like input on pressure / resistance to squeezing on upper radiator hose with thermostat open/ closed. ?

I'll check oil to see if I put water into it now that I've overheated at least once (when thermostat gasket failed)

How can you be sure the engine was overheating ? did the radiator boil over ? If you put engine degreaser on the motor that will certainly cause smoking but only for a few seconds till it burns off. Did you just replace the carbs or the whole intake ? does your intake manifold circulate water though the carbs or just the intake ? Not sure I understand what sqweezing the radiator hose is going to do besides burning your skin off.

The symptoms you mention (cold radiator and hot engine).

sounds as though you have an air lock in your block.

This is what I did, and it seemed to fix the problem.

Loosen the hose clips on the hose that runs along the right side of the block, then start the engine. With

engine idling, grasp the front hose clip area of the hose, and give it a few twists. You will probably see air

bubbling from around the hose. don't forget to top up the radiator as you go, then tighten the hose clips.

I have had to do this a couple of times after draining the water.

The smoke you mention, at a guess, would be the degreaser burning off .

Edited by olzed
How can you be sure the engine was overheating ? did the radiator boil over ? If you put engine degreaser on the motor that will certainly cause smoking but only for a few seconds till it burns off. Did you just replace the carbs or the whole intake ? does your intake manifold circulate water though the carbs or just the intake ? Not sure I understand what sqweezing the radiator hose is going to do besides burning your skin off.

squeezing upper radiator hose to identify pressure / open thermostat.

No I'm not sure the motor over heated...but when I was monitoring the smoke coming off the motor the thermostat housing gasket let go, spilling coolant.

the degreaser I used was thick and goopy and did settle into areas where I suppose would take a little longer to burn off than normal?

never boiled any water.

I did the carb swap with Z Therapy...plus fuel bar. Intakes? I don't know...everything from the spacers was replaced. water does still circulate through the carbs.

I'm thinking there was or still is an air lock...

thanks for your response

Edited by bounce
The symptoms you mention (cold radiator and hot engine).

sounds as though you have an air lock in your block.

This is what I did, and it seemed to fix the problem.

Loosen the hose clips on the hose that runs along the right side of the block, then start the engine. With

engine idling, grasp the front hose clip area of the hose, and give it a few twists. You will probably see air

bubbling from around the hose. don't forget to top up the radiator as you go, then tighten the hose clips.

I have had to do this a couple of times after draining the water.

The smoke you mention, at a guess, would be the degreaser burning off .

loosen clips, twist hose so that it kinks on itself, squeezing itself? or is it supposed to rotate completely? I'm not understanding fully but I'll look at the hose today for sure...

close enough I reckon, gauge never left the cold peg when I thought I smoked it.....when the thermostat housing gasket puked I thought for sure I was over heating...

update: smoke dissipated eventually, never did/ could get any more water in the radiator.

I eventually got the engine hot enough to push water out the top of the radiator with the cap off....put the lid on it and kept an eye on the temp gauge....

turned on the electric fan and the gauge maintained the pictured reading below...even on test drive for half mile at 55mph..

gauge240Z.jpg

I don't recall it being this hot prior to the carb change..perhaps I'm still lean? I think overheating issue is over, false alarm, I'm a newb, scared and don't have money to make stupid mistake repairs...

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