j498

iTrader: (10)

2000 Trans Am
ls1 6sp
Stock

I had to get a new water pump due to a leak on mine. The new water pump is a Gates (45002) older Ls1 style pump, while the leaking pump that was already on the engine is an ls2 style pump and thermostat housing (it was replaced at some point).

Does anyone know if the Ls2 style thermostat and housing (Thermostat separate from housing) will work properly on the old Ls1 style pump (calls for the thermostat/housing unit - 1 piece) ? I could not find anyone with the specific problem when searching.

The ls2 thermostat and housing bolts up fine to the older ls1 style pump, however the ls1 pump seems to have a wider mouth for the housing. The gaskets are also different, not sure if this is only due to the different housing/thermostat designs or a difference between the ls1 and ls2 pumps themselves.

Has anyone specifically run this combination specifically without problems?

JakeFusion

iTrader: (7)

Yeah, they changed the pumps in 2004 and the thermostat housing.

Here is a pic for those who don't know.

j498

iTrader: (10)

... I already know this.

I'm asking if anyone if anyone has used the Ls2 housing on an LS1 pump.

MikesTA2002

iTrader: (1)

i just ran into this problem i ordered a hypertech 160 stat for my 2002 trans am.. pulled a 2 piece housing and thermostat from the pump and tried the 160 didnt fit! i thought the company sent me the wrong one sent a pissed of message but turned out i had the new style ls2 pump they put in now for replacement ls1 cars, i ordered a 160 ls2 gto 04 corvette 2 piece stat fit perfectly, so the ls1 stat wont fit into the new style water pump hope this answers your question before u start taking it off. so not the ls2 housing will not work on an ls1 pump. when i tried putting the ls1 1 piece housing into the ls2 style pump the inside prongs on the stat where too large

MikesTA2002

iTrader: (1)

joecar

I had to file the ears on my LS1 thermostat so it would fit in my LS2 pump...

but the OP is asking the reverse: yes, the LS2 thermostat fits in the LS1 pump.

therabidweasel

iTrader: (5)

The ls1 tstat does fit in the stamped together ls2 pump that folks use with fast 102 intake. At least it did on mine.

j498

iTrader: (10)

Update.

I measured the Ls2 and Ls1 pumps closely. The LS1 style pump has a slightly bigger opening where the water neck part of the thermostat bolts to the pump. While the LS2 style thermostat and water neck fit in and bolt up to the Ls1 pump, I'm not sure the gasket will be fully seated, it seems like the gasket would be on the edge of the thermostat housing opening on the pump, barely fitting.. At least on the parts I have. The replacement pump was made by Gates, who knows there may be some variation between different manufacturers, however it was marked "made in china".

Anyway, I ended up just buying the old style thermostat. I didn't feel like taking a chance using questionable parts. Really tired of making a mess of coolant on my garage floor.

jbmart7735

I know this is an old post, but FWIW, I can verify that using the LS2 style thermostat and water neck on the LS1 pump will leak. The seal doesn't cover the opening completely, and when the system builds pressure it squirts pass the seal and leaks. I learned the hardway.