Overheating issue

[dumbucket1]

Put a replacement305 in my 87 silverado. Used heads, intake, and water pump from bad motor. All hoses get hot except upper radiator hose. I changed the thermostat with a new stock replacement. The bad engine didnt have overheating issues. Any ideas?

[Lt.Del]

did you check the head gaskets to ensure they are the right ones, meaning they didnt cover up any antifreeze holes on the block or heads? Same with intake gasket? 

t-stadt going in the right way...spring side down into the intake?

Whenever I'm putting a new engine in, i ensure the water pump is new....nice insurance for a new motor, while you have everythng off.

what kind of fan do you have? 

[gold84gmc]

the radiator isnt clogged is it?

[gold84gmc]

wait nevermind about the radiator being clogged because the coolant goes into the radiator through the upper hose....like SgtDel said make sure your head gaskets are the right ones

[dumbucket1]

Hmm block is a 79 model year but used heads, intake, etc from 87 motor bought head gasket kit for 87 model year motor. Put gaskets on same way they came off. Fan is stock clutch fan. Im suspecting bad thermostat out of the box since upper radiator hose stays cool. Will do the boil test tomorrow.

[dumbucket1]

Wait just realized put straight water in just in case there was leaks. This be the culprit?

[Lt.Del]

straight water will not be the culprit....water transfers heat better than antifreeze.  Antifreeze is mixed so it wont, well, freeze....and its anticorrosive qualities.    straight water should be fine short term.   

Take the t-stadt completely out of its housing.  Put the hose and housing back on withou t-stadt.  See if it then overheats.

[dumbucket1]

Ok it does not overheat with the thermostat removed and I put the thermostat into a pan of boiling water and it opened up so im not sure whats going on

[gold84gmc]

did the upper hose get hot/warm?

[Lt.Del]

Ok it does not overheat with the thermostat removed and I put the thermostat into a pan of boiling water and it opened up so im not sure whats going on

run if for a few days without a thermostadt and watch the needle.   Ensure the water pump is pumping the coolant around.  If it runs fine, just get a new t-stadt next week.  At least you have narrowed down the problem.

[gold84gmc]

Ok it does not overheat with the thermostat removed and I put the thermostat into a pan of boiling water and it opened up so im not sure whats going on

run if for a few days without a thermostadt and watch the needle.   Ensure the water pump is pumping the coolant around.  If it runs fine, just get a new t-stadt next week.  At least you have narrowed down the problem.

he tested the thermostat and its good so he doesnt need to get a new one

[Lt.Del]

he tested the thermostat and its good so he doesnt need to get a new one

Really?  Oh, I read the post.  How about the part where he said when it was in, it overheated?  When he removed it, it didn't? 

my diagnosis?  Thermostadt.

[dumbucket1]

Im just going to exchange the thermostat for a new one. For some reason or other this one was not opening in the engine.

[Lt.Del]

make sure it is for the correct 'intake' since you have half '87 and half '79.  It might be that it cannot open because it may be binding or something--even though only a small part of it actually moves open.   Just an idea.

[ccz145a]

upside down?