140 * thermostat for 1996 5.7L

[Ed Harris]

I am looking for the correct part number to try a 140 degree thermostat in this engine. I have a 160 in place now but engine runs around 195 to 200 at ~3000 rpms. I am looking for it to run a little cooler since I have new risers, manifolds, impeller and engine water pump. I didn’t want to order the wrong one and it not fit. Engine serial number 0F 790518.

 

[tacx]

Bump, Anyone?

 

[Ed Harris]

Not much out there I guess. Going to buy one anyway and see how it goes.

 

[Boater31]

It sounds like you have a problem with water flow somewhere. Possibley a sticking thermostat, have you tested it in boiling water and see when it opens. If that's not it it's a flow problem and will need more trouble shooting. You should post serial number of the engine so we can look what tstat you should have. Around that year they switched to a 160. I think the general consensus is 140 in salt, and 160 in fresh. This is assuming you have a raw water system. Either way you temps should not be that high.

 

[Boater31]

Also look up service bulletin 95-13. Assuming you have a alpha 1 gen 2 it could be that problem to.

 

[Scott Danforth]

verify your gauge is accurate. use an IR temp gun

the most I ever saw on a 160 degree temp thermostat was about 170 and that was while boating in 90 degree water in the gulf of mexico

if the temp is still high after verifying it. you have a water flow issue somewhere

 

[Ed Harris]

I used an IR gun and could not find 190 anywhere on the cooling system. Ordered a new gauge anyway be cause the 23 y/o gauges are looking bad. Checked the tstat in boiling water with a thermometer and it opened at 160. Also ordered a 140 just to see. Thanks for the replies.

 

[Boater31]

Looks like you found your problem. It could also be the sender. Lots of post on here on how to test the sender or the gauge. If your 160 is fine I would keep running that, engine will burn cleaner and slightly more efficient. This is assuming you are not in salt.

 

[Ed Harris]

Update on the temperature. 140 stat came in and so did the new gauges. I started with putting it new gauges for oil pressure then the temp gauge. Fired it off, oil press was reading good and temp never got over 150 after about 10 minutes on the hose. Even upped the rpm’s and got to about 145 @ 2000. Leaving it alone and taking it to the river for a run.

 

[tacx]

I'm confused? Did you leave in the 160 stat or did you install the 140.?

 

[Ed Harris]

Left the 160 in. Taking it to the river tomorrow and see how it does under a load.

 

[Ed Harris]

Update. Went to the river Monday run down the river at about 4000 rpm’s temp stayed at 175. We are calling it good. 23 y/o gauges just needed updating.