SAN GT40 Running COLD???

[h2ohangtime]

Hope you can help with this one...I'm sure it's less of a mystery than I'm making it out to be.

Since I bought my 2002 SAN GT40 in October, it has run at ~140* and not any higher, according to my temp gauge. Additionally, we've seen some small plumes of white steam coming from the exhaust, both while on the lake and in the driveway with the Flush-Pro attached. The exhaust has also smelled a little like gas, I've seen a slight sheen in the water, and the boat has idled a little rough, which to me means that it's running a bit rich.

After putting these all together and doing some more research, I decided to try swapping out the thermostat on the off-chance that the previous owner had replaced it with a 143* instead of the 160*. After popping off the housing, I discovered that the existing stat was in fact correct and looked to be functioning properly. I went ahead and replaced it anyway and ran the boat in the driveway for 20 minutes. It still did not get above 145*. I didn't see any steam and the gas smell decreased slightly, but it's not completely gone.

Does anyone have any idea what's going on? I've always read that normal operating temp for the GT40 EFI is 160* or so--is there a possibility my engine just runs a bit colder? I want to make sure that I'm not wasting gas and potentially causing damage to the engine by having it run this way.

Any help you can provide is appreciated...thanks!

[83ski2001]

temp

i am having same problem. my boat when i pull out of water you can see a rainbow in the water behind it. no fuel in the bilge i have checked for leaks. but mine is running even colder. like 120, it never goes above that. i feel like my guage is wrong though as when i open the hatch it seems warmer in there than that. i am going to pull the stat tomorrow and see what it looks like. its run like that since last year. the prev owner said it always was like that when he had it too. any ideas?

[skijones]

Pick up an infared temp gun. You can get them for less that $20. Best place to check temp is the oil filter.
This will tell you if your gauge is correct.

As for the sheen, I would not worry about it. These boats are set up to run a little rich, and a little gas on water is very noticable.

[h2ohangtime]

Thanks skijones...I'll look into that. I assume a discount tool supplier like Harbor Freight is the best place to get one of these IR thermometers?

[nsteffens]

I have the same boat and just checked it today when I had it out. The temp was at 140. You should be fine.

[h2ohangtime]

Thanks nsteffens...I appreciate the temp check! I'm starting to believe that I'm totally over-thinking it, but I'm still new to the boat game and have only had our SAN for about 8 months, most of which the boat spent in the garage.

[jjgag60]

Running rich

The fuel injected 02 Gt-40 is not designed to run rich. In most case they run on the lean side because of the computer. You should pull your spark plugs and check them. They should be the color of a brown paper bag or in some cases you can still see the original white. Mine ran to rich and it caused gas to wash the cylinder walls and then contaminated the oil and i lost a main bearing. We have four or five sensors that help with the fuel mixture.You should have them checked out. If your plugs are the correct color, and you are smelling gas i would fix it, and I would buy a "Halon" extinquisher in case you need to use it. The normal extinquishers will cause all kinds of problems if you have to use it around your EFI and computer. You can download the Gt-40 manual and it give spec on what each sensor should be doing.

[h2ohangtime]

Thanks jjag...

I haven't pulled the plugs this time, but I did a couple months ago (when the problem still existed) and they were all a tan "paper bag" color. I'll dive into the GT40 manual as well...

[intrlaz]

My guess would be its a gauge or sensor issue. My 02 with the GT-40 ran right at about 140, and since then installed a new engine (zr6) which runs at the same temp on the gauge.