mn_vette

If you pull the thermostat you see the radiator bypass hole directly below the thermostat hole. This hole gets plugged when the thermostat warms up and moves the plunger downward. There is some kind of hard plastic gasket that lines that hole and mine deteriorated and came out. Is it really needed? And if so where can I get a replacement??

Snuffy

I haven't seen mine (1988) for a while but I think my thermo opens upwards. I wouldn't think that leaving that hole open would hurt anything. It is always safe to have flow from the pump through the rad as opposed to no flow.
I have known some people to just remove the thermostat altogether. It takes a little longer to warm up but in normal operation a car engine is always circulating coolant.

mn_vette

Sorry, forgot to mention this is for an LT1. The plunger definately opens down. This secondary plunger fills the hole that causes the hot side and the cold side to mix inside the pump.

SJW

This is correct, and is not well enough understood by many. The LTx engines use a dual-function thermostat. Half of it is a conventional thermostat that opens (downward) to permit flow of coolant through the radiator. The other half is a bypass/recirculation flow shutoff valve, that closes (also downward) to seal off recirculating coolant flow when the thermostat opens to allow flow through the radiator.

Installing an incorrect-for-the-application thermostat into an LTx engine will guarantee an overheating result. Leaving the thermostat out completely will have the same effect. In either case, much of the coolant that should properly be directed through the radiator after warm-up will instead be recirculated -- uncooled -- through the engine.

With respect to the original question, I don't recall seeing any such plastic seal in my water pump, or on my thermostat. When I get home tonight, I'll have a look at the pump/'stat I removed from my car, if I can remember to do so, and let you know, if nobody else steps up with the correct answer before then.

Be well,

SJW

Red Dwarf

This article seems to have some explanations..

http://www.theherd.com/articles/lt1_cool.html

mn_vette

Anybody else know if where I could get a new hard plastic washer for the waterpump bypass spot??

SJW

Lemme check the pump/'stat I removed from my LT1 when I did the Opti a coupla years ago. It may take me a few days to get to this, but if what you're seeking is in there I'll let you know. If you still need it at that time, I'll send it to you.

Be well,

SJW

redrose

really good, has a couple small errors