Engine running too COOL?!?!

[Rock_Toy]

So, last time I took the boat out, she was running at 200+ degrees. Raw Water Pump was bad so I rebuilt it. I figured that I should also replace the thermostat so I got a new 160* thermostat and replaced it. Now, the boat won't even hit 160* in cold Tahoe water. I am running between 110 and 140 degrees. Anyone have an idea? I am going to pull the thermostat tomorrow and make sure that its not stuck open....that's the only thing that I can imagine. Does running the motor at 120* damage it? I would prefer cool to hot but.....is that reasonable?

[peteb]

RE: Engine running too COOL?!?!

Rock_Toy
I would call your service dealer for CC that you trust. If you dont have one call the guys at Midwest Correct Craft and go over your item with them. I use them for parts and they have been great on helping me solv problems even though they are not in my area. There number is 260.833.2226.

Good luck.

[tski97]

RE: Engine running too COOL?!?!

I would not be suprised with 140 in cold water. I am not sure if it causes problems but the cold water will cool the engine quick. What was the wate temp in the lake?

[Laketexoma]

RE: Engine running too COOL?!?!

You are fine. Mine always run cooler in the winter due to the colder water. The only issue is it might burn a little more fuel. Mine always seems to run richer in cold water. I guess its the computer trying to warm the moter up.

[Rock_Toy]

RE: Engine running too COOL?!?!

OK, so I put her in another warmer lake on Saturday and got the same results. Won't go a degree over 140. The thermostat is a 160. Just doesn't make sense to me why the motor won't heat up to at least 160 i the thermostat is closed. Brand new one. Anyone have any ideas? The motor runs like a champ other than the gauge reading low. Could it be a bad gauge or sender?

[SNMike]

RE: Engine running too COOL?!?!

It's fine Rock! I have 160 stat's in all my show cars and the temp gauge needle barely moves from dead cold. The water temp where you are, coupled with the 160 stat, it's all normal. Not to worry sir. Enjoy!!

Mike

[LakeaustinSN]

I am actually dealing with the same issue on my GT40 (I regularly run in 80+degree water) but on our last outing my temp wouldn't get past 110F. I didn't think it was a temp gauge or sender issue as the risers and engine felt cooler than usual. I pulled my old thermostat, held it upright and filled it with water. It looked closed, but I noticed a slow steady drip leaking through. I believe that under higher pressure when running, this was being forced open or allowing enough water through to over cool the engine. I just picked up my new thermostat, did the same test and no water dripped through after 5 min. I just installed it and will be testing later this week.

[TRBenj]

That does not sound like normal behavior. Ive got a 143 stat in my boat and run 150-160 all day long. A 160 stat should have you running closer to 180. I would try not to run the engine much cooler than 140.

Its probably just a bad stat- either stuck open or opening to early. Throw it in a pot of water with a thermometer to test it- or just get yourself a new one (or both).

Which engine do you have, by the way? A carb'd 351w would take the 143 stat, the 160 is really meant for the EFI engines.

[Rock_Toy]

EFi GT-40. Its a brand new Thermostat from White Lake. Guess I should pul and test it just in case. I agree with you in that its not normal. There is no way that the motor should be running less than 160 with circulating cold water. It must be open....

[ally606]

I've had exactly the same problem with my '97 GT40 EFI. So far I've replaced the sender, replaced the gauge. metered the sender wire for a higher than normal resistance (note a high resistance on the sender wire will reduce the temp reading on the gauge) and checked the supply and earth to the gauge. All fine.

I spoke with my local dealer and he advised there was a problem with a batch of thermostats he received so he's sent me a new one to try out. If that doesn't fix it then I don't know what else to change/inspect/meter... Next step, I'll get my hands on one of those laser thermometers to see what temp the waterpump housing reaches.

The water I run in is cold, the last time i checked on the perfect pass it said 10C (about 50F) o that is possibly a contributing factor.