Excaliber engine running temperature

markn

Have an Excaliber Chevy in my 196. Has 450 hours on it. Typically let the engine warm up to about 130 before driving to the course. (about a 5 minute run). If we immediately start skiing, the temp never goes above 145 degrees. After skiing, we shut off the engine and after restart, she goes up to 155 degrees. I put in a new thermostat....same result. Had an on water service call with new plugs, distributor, fluids and another new thermostat. Service guy's computer showed a 3 degree delta from gauge/computer. Went out today....never got above 130 degrees. Mechanic was baffled, but I am betting a fellow baller, much more mechanically inclined than me, might have some insight. Thanks for the help and best wishes to all for a Merry Christmas and happy, HEALTHY, and prosperous New Year.

Orlando76

Im confused, you’re worried your engine runs well below normal and ideal temps?

markn

It is my understanding it is hard on an engine to run too cool as well as too hot. I realize the computer compensates for operating temps as it warms up, but 30 degrees below normal operting temps does not seem right. Nothing about which to be concerned? Thanks again for the input.

Jody_Seal

Yes you might want to replace your thermostat. Excalibur needs a little more heat to properly run. 160-170 or they seem to want to run rich.

markn

@Jody_Seal thanks for the response. I have replaced the thermostat twice with the same result. Possible to have 2 bad thermostats 3 months apart?

Jody_Seal

No but possible for the bypass hole in the housing has enlarged itself..

Gloersen

if new T-stat still yields "low temp", faulty sending unit?/gauge?
Sending unit ohms ought be 99 at 175 F

dvskier

@markn Jody knows what he’s talking about. Similarly I have a 2004 SN 196. My engine was running cold a couple of years ago. I changed the thermostat with a new 160 degree thermostat and it fixed the problem. Are you replacing the gaskets on the housing?

markn

@dvskier yes sir, you are right, Jody does know what he is talking about...awesome mechanic and not too shabby in the driving department either!! Yes, with both thermostat replacements, the housing was cleaned and new gasket installed. @Gloersen we checked the guage vs. the computer and they were within 3 degrees, so assume the sending unit is ok. Thanks to all you guys for the responses and help. Hope I am not making too much of this. Just want to take care of this old 196...she is a beast and make it last another year or two.

Gloersen

^^ the temp sending unit provides data via the harness to the ECM and thus the Diacom temp reading. If the sending unit has gone awry ($15 replacement part) the ECM will receive faulty temp data as well as an errant temp reading displayed on the dash gauge. If Diacom = gauge reading the dash gauge is ok.
Easy enough to put an ohm meter across the two leads (2 wire snap in connector) after engine is at operating temp (should be ~140 ohms). If the coolant temp at the sending unit location is actually 130°F after "warm" an ohm reading of ~220 would be expected. IR temp gun will help dx; if it reads~160°F and ohms ~220, then consider faulty sending unit.

Gauge readings with resistor level:
220*=70 ohms
200*=90 ohms
160*=140 ohms
120*=250 ohms

markn

@Gloersen Dang, this is one sharp group of engineers/mechanics and skiers. Thanks for the info on the sending unit. Of course, you are assuming I have an Ohm meter....sounds like a need to go buy one! Thanks again to all for the help. You guys are the best.

Jody_Seal

Or you can go get a cheap infrared thermometer and read it at the sending unit casting.
Their cool to have even for other uses.. checking beer can surface temp you know!

markn

@Jody_Seal Now that I have for checking tire temps at the track. Great I dea. Will check it out today......and check the temp of my next bottle of Syrah or Malbec or Dogfish Head ale. Thanks.

Jody_Seal

@markn
Check out the oyster city Hooter brown. That is if you can find anywhere that far south of apalachicola..

DW

@markn - on your first run v second run 10 degree increase in water temp, probably due to oil temp difference which will be higher once you have run the boat at speed. Also, inlet water goes through trans cooler (that oil also warmer for second run) so it gets heated a bit before it does its job in the engine. The step change to running cooler subsequent to some fiddling, may have to do with something that got changed or adjusted before / after. Did your lake water temp cool off a fair amount, many times if the inlet water is cold the engine simply does not heat up the water to operating temps.

On a separate note, you should borrow a pyrometer with a probe to compare tire temps, you are only getting a top surface temp that changes fast with the infrared gun, you really want a deeper down temp to accurately understand what is happening. I have a couple of guns and they are not that accurate so proceed with caution, unless you have a really good one.

kurtis500

From the information provided it’s hard to really know where the problem is. First, what does the manual say is the ideal operating temperature? Second, after many years of racing and building my own race motors I can say 130f is well below normal OPERATING temperature. Extended operation at that low temp will effect the heads, valves and cylinder bores over time. Dyno results have shown this numerous times and the motor is down on hp when it’s too cold. Engines will run at low temp as they warm up but hundreds of hours at 130 has side effects. Based on your description of the temp going up after shut off I’d say you have too much cool water flowing somehow.

Wish

Not a thread steal, just 2 quick questions. Ideal operational temp(s) for a GT40 is?? Also it’s a 160f thermostat correct?

dvskier

@Wish i believe the ideal operating temp for a GT-40 is 160, as such it uses a 160 degree thermostat. I had 97 SN with GT-40 for 7 years and it was solid at 160.

markn

OK, just returned from skiing. Started boat and warmed up to 131 degrees. Skied 10 passes at 34 mph. Temp never read above 131. Turned off boat while my wife got ready to ski. Started and temp went to 160 degrees. Skied and drove home.....back down to 131 and once in the boat house, lifted motor box and I could put my hands on the mainfolds. After all that run time, I could hold my hands on it. Did try to shoot the temp sensor and it read 140 at the probe. Water temp in lake has cooled to about 60 degrees surface temp. In the summer, it ran about 145 to 154 tops. Do I need yet another thermostat? Maybe go to 170?
@DW thanks for the insight on the tire temp measuring. Ball of Spray is a veritable font of info!

kurtis500

@markn what does the manual say is the proper operating temperature?

One more question, did you install the thermostat upside down? Some are able to be installed both ways and the direction of water flow will hold open the thermostat. Again, depends on what thermostat you use

markn

@kurtis500 legit questions....particularly with my mechanical skills! I replaced one thermostat carefully reinstalling just like the old one. A pcm certified mechanic installed the most recent one, so I have to assume it was installed correctly. I intend to check manual and verify flow direction/orientation. Thanks again for all the info and suggestions.

JackQ

Put the thermostat in pot with water and heat it up, watch to see at what temperature it opens up. Use to put in boiling water (212) when investigating if thermostat is failing to open. 140 degree thermostat is for raw water cooled motor to reduce corrosion, 170 for fresh water(heat exchanger) cooling. As Jofy said, the engines wear less and are more effective at 170-190.

Gloersen

What was the dash gauge reading when you used the IR temp gun to shoot the temp sensor (stated as 140°)?

Jody_Seal

Actually my raytec seems to coincide within a degree what either the gage or diacom/EEcom reads when checking Temps at sending unit bosses or manifolds. It comes in real handy when trying to find a misfire or a poor performing cylinder.

Another thing the boat has a seacock, turn the flow down and see if you can influanced water Temps on the engine. Again at 135 degrees that engine still thinks it is in warm up mode and running rich.

Rednucleus

How long have you owned this boat? Sounds like you are saying it's never run 160?
I helped change a thermostat in an Excaliber, and the housing split in two and looked like there were two different spots you could install the 'stat. Maybe yours is similar and it's in the wrong location?? BTW this was in a 2014 SN 200

markn

Thanks again to all who are willing to help with this issue. Update: In checking water flow (I am ashamed to say) one issue was the belt was on incorrectly. Before correcting belt configuration, could not get temp above 131 this morning...even when closing water inlet valve for a minute. Changed belt orientation and temp on guage read 140 and remained. Drove the boat to add heat. Temp guage remained at 140 steady. After shutting off and restarting, temp went straight to 140 and remained steady. Have owned the boat since 2004, but a new engine and tranny went in in 2016 and it did run around 160. Based on all the help and input, it appears the temp sensor is bad and reading 20 degrees below actual? I assume the belt orientation was also an contirbuting issue...dang, what a gomer.

Gloersen

if your IR temp gun reading on the base of the temp sensor (CTS = coolant temp sensor) is reading higher than the dash gauge, then clean the connector plug contacts on the CTS, be sure its plugged in well. CTS is just a thermistor; bad lead contact (loose or slight corrosion) increases resistance (higher ohms) and a false lower reading (and ECM data input) than actual coolant temp.

Even if actual operating coolant temp is indeed 160°, the ECM will detect the errant ~130° and as @Jody_Seal stated the ECM will cause the injector gap to be too great (running too rich when actually engine now warm). If the raw water flow is actually too high for some undisclosed reason; as stated already that's not good long term for proper oil flow, operating efficiency, and engine life.

Cheap part from Skidim CTS; in general not advocating throwing parts at a an undiagnosed problem, but for $17 it may save some troubleshooting effort.

DW

@markn - To your belt comment, what specifically are you referencing that the belt was on incorrectly? If I understand your comment, are you indicating one or more of the pulleys was then spinning in reverse to what is correct? If yes, which one(s) as that may indicate you will want to do a little more investigation on the effects of that.

markn

@DW Was lucky the rotations were still correct despite the wrong belt installation. @Gloersen took your advice and removed the temp sender, cleaned with wire brush and brake cleaner. Cleaned all connectors and made certain fitting was tight, started boat......140 degrees. I have ordered a new sender from Nautique and it should arrive Tuesday. Will install and report back. Sincerely appreciate all the technical expertise on this site from you guys. I am not much of a mechanic....I just want to ski!

Clydesdale

@markn i have a couple meters here at Swiss if you want to borrow.

markn

@Clydesdale Thanks for your kind offer...but you are assuming I would know how to use them! Ha. If after the new temp sender installation the problem remains, I will take you up on your kind offer...as long as you agree to let me take you out for a set or two in gratitude....or at least a pntoon booze cruze.