Will Not Reach Normal Operating Temperature

[454cid]

NO! This is a 4.3L VIN W CPI Engine. The thermostat mounts in the front if the intake. It does not have a recessed groove that the O-Ring fits in like the '96 up, where the thermostat mounts in the top of the intake. The rubber thermostat gasket is beveled on the sides, which fits in the hole of the intake. Which I believe the paper gasket seals the thermostat housing to the intake.

Ok, found one on ebay to look at..... I forgot about that one, since it was never offered in the GMT-400.

I just watched a old video on Youtube on it, and that guy used both gaskets... not sure why on that though. Are you getting the thermostat into the groove in the middle of the rubber o-ring? That is the same as the newer engine, even if the beveled outside profile is not.

 

[jswiftsr]

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For those that are confusing the thermostat installation in the 4.3L (L35) "W" Engine with the '96 and up 4.3L, here is a diagram I found in my Service Manual. It does show the beveled rubber thermostat gasket and the paper gasket between the thermostat housing and the intake surface. This is the way I have mine installed with a AC Delco 24505924 thermostat. Which I don't see how the coolant could be bypassing the thermostat. That is why I may have concern that the intake may be cracked somehow internally from running the previous engine very very hot and pouring cold water in it to get it home. The engine I have in it now is a different long block with the old intake off the other engine. However it has relatively good compression and does not lose coolant.

 

[FarmerPhil]

There is only one possibility. The heater hoses are incorrectly routed. The coolant has to be bypassing the thermostat by pushing coolant through the heater core and into the radiator. You could test this by pinching off the heater hose and watch your temperature rise.

you’ve added a lot of insight in my personal thread - and this issue I can relate to. Which hose is the heater hose? (350 v8)

 

[jswiftsr]

I am wondering if the regulator on the spider may be defective? If the diaphragm in the regulator was not leaking gas straight into the intake....but maybe not regulating fuel pressure to the poppets....could this cause a rich condition, not throwing a code but running a rich mixture, thus causing cylinders to have low temp? Hence 40 degree less overall engine temp?

Or maybe egr slightly open....but again not throwing a code, cause low operating temp?

 

[Schurkey]

Run rich that long, the catalyst would have melted.

EGR at idle would make for rough idle.

 

[Hipster]

I am wondering if the regulator on the spider may be defective? If the diaphragm in the regulator was not leaking gas straight into the intake....but maybe not regulating fuel pressure to the poppets....could this cause a rich condition, not throwing a code but running a rich mixture, thus causing cylinders to have low temp? Hence 40 degree less overall engine temp?

Or maybe egr slightly open....but again not throwing a code, cause low operating temp?

I've already said in a previous post that with an incomplete combustion event the temps the block sees will be lower. Whether that be leftover unspent fuel cooling the chamber or a dead cylinder and it has nothing to do with the temp of the flame front or the temp at which combustion happens. You can foul a plug one time and it won't come back or it fires intermittently. Random misfires brings the condition of the ignition components into the equation, possible over-fueling/bad regulator? Unfortunately we live in an age where new doesn't mean it's a good part.

You have to get it running right before concentrating on the temp it's running at.