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Discussion Starter · #1 ·
Hi

2003 astro cargo van 334000 KMS 2 wd

ok back story

about 2 years ago i blew the original engine , swapped it for a good junkyard engine out of a 2005 jimmy.

from day one that it was started it never heated up correctly or as the other engine did.
on a warm summer day its about normal a little lower on the gage than the other engine.

it does not overheat

on a cold Ontario day such as today it does not heat up enough.. its minus 11 C

if you cold start in the morning ..the gage comes up at about the same speed as before but levels off just a hair above the quarter mark. it used to go to about 100C and you could literally see the thermostat open and it would drop to just below 100C. not with this engine.

there's not enough heat coming from the heater or the engine.

with a scan tool .... driving at 100 KPH F 177

idling after a long drive ... 179 ....if turn off heater it may go to 185

I thought I might have made an error and changed the water pump and installed thermostat number 5 a genuine GM 195 stat ...that helped a bit.i tried AC Delco stats ..moterad etc no difference

replaced rad cap , coolant is at right mix and does not lose any.
the system does pressurize ..the rad hose is semi firm.

ive asked all kinds of shops and mechanics and no one can explain it or help ...any suggestions?

Alex







ive tried every way possible to bleed air out.
 

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Discussion Starter · #3 ·
HI
yes its all routed correctly , we totaled the water valve taking the moter out the front. it was replaced as was the temperature sensor.

so when the moter was first started for the first time it barely heated up at all....that was about spring 2020.
it stayed really cold. changed the thermostats several times .... no change.

i got pissed off and took the whole front of the engine back off .... checked eveything . replaced the water pump and the stat again, all the hoses and checked everything against the diagrams. it got better ....but still is not right.

alex
 

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Discussion Starter · #6 ·
Make sure you have the correct thermostat... and you have it in correctly.
(I remember one poster put his in upside down)
The later models use a "two valve" stat (with an important bypass).
View attachment 282230
Also one hose connects to manifold (send) and the other to water-pump (return)
ok...the engine is a 2005 even if the van isnt ...do you know a AC Delco number for that stat
 
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