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  #11  
Old 03-01-2014, 02:06 PM
lake weir skier lake weir skier is offline
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Originally Posted by mikeg205 View Post
I wouldn't put that 160 t-stat in. I did that in my 1995 5.7 MEFI 1 - the heat soak temps will get higher than expected by the ECU and cause hard hot starts - even though the engine runs more efficiently at a bit higher temp - the hard hot starts are very frustrating especially when changing riders.

Larry (engine nut) is a great resource to have at Indmar.
I talked to a guy (not Larry) at Indmar about it months ago, I’ve spoken to Vince at DIM about it, and I’ve read a pretty large volume of varying opinion on here about it. It seems people who have tried going from a 143 to a 160 degree thermostat have had differing experiences.

Since I’m on inland lakes in central Florida that get pretty warm, and especially after reading BrianM’s argument against moving to a higher temperature thermostat based, at least in part, on being on very warm lakes in Louisiana, I asked Vince about that. I even had in-hand historical temperature data for my primary lake collected by the water authorities here. Vince, who says he’s talked to engineers at PCM about the issue (he seems to deal with them more than Indmar), told me he has a 160 degree thermostat on his personal boat and that when he was pulling his son in very warm lake water based on a lake water sensor on his boat, he had no problem. That was in 95 degree water if I recall correctly.

It seems if I experience the problem you describe I could just go back to the lower temperature thermostat. I won’t be very tolerant of hard hot starts because I had my fill of them with a starter last year that caused hard hot starts that turned into hard cold starts and then no starts. I had it rebuilt.

Somebody please correct me if I’m wrong, but I think I’ve read the relevant threads in the past few months and I don’t recall that Engine Nut (Larry) has ever weighed in here publicly about this going to a higher temperature thermostat thing. Has anybody ever asked him about it publicly or privately? Anybody know what he thinks about it?
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Last edited by lake weir skier; 03-01-2014 at 02:08 PM. Reason: Spelling
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  #12  
Old 03-01-2014, 02:19 PM
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Quote:
Originally Posted by lake weir skier View Post
I talked to a guy (not Larry) at Indmar about it months ago, Iíve spoken to Vince at DIM about it, and Iíve read a pretty large volume of varying opinion on here about it. It seems people who have tried going from a 143 to a 160 degree thermostat have had differing experiences.

Since Iím on inland lakes in central Florida that get pretty warm, and especially after reading BrianMís argument against moving to a higher temperature thermostat based, at least in part, on being on very warm lakes in Louisiana, I asked Vince about that. I even had in-hand historical temperature data for my primary lake collected by the water authorities here. Vince, who says heís talked to engineers at PCM about the issue (he seems to deal with them more than Indmar), told me he has a 160 degree thermostat on his personal boat and that when he was pulling his son in very warm lake water based on a lake water sensor on his boat, he had no problem. That was in 95 degree water if I recall correctly.

It seems if I experience the problem you describe I could just go back to the lower temperature thermostat. I wonít be very tolerant of hard hot starts because I had my fill of them with a starter last year that caused hard hot starts that turned into hard cold starts and then no starts. I had it rebuilt.

Somebody please correct me if Iím wrong, but I think Iíve read the relevant threads in the past few months and I donít recall that Engine Nut (Larry) has ever weighed in here publicly about this going to a higher temperature thermostat thing. Has anybody ever asked him about it publicly or privately? Anybody know what he thinks about it?

The issue I believe dependent on the ECU calibration - Indmar and PCM will have different calibration files for the ECU.
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  #13  
Old 03-01-2014, 02:35 PM
lake weir skier lake weir skier is offline
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Originally Posted by mikeg205 View Post
The issue I believe dependent on the ECU calibration - Indmar and PCM will have different calibration files for the ECU.
The guy at Indmar said it wouldn't hurt to go to the higher temperature thermostat but the "fuel table" in the ECM assumed a 143 degree thermostat as originally installed. I mentioned this to Vince at DIM, who was unswayed by it and insists it's a good move knowing what boat I have and it not being used in salt water. I'm really out of my depth on this technical issue and can only count heads of apparently knowledgeable people.
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Last edited by lake weir skier; 03-01-2014 at 02:37 PM. Reason: Clarification
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  #14  
Old 03-01-2014, 02:38 PM
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Vince told me the same thing.... after the 160 installation - hard hot starts - returned to 143 - all problems went away. I did like the way the engine ran at 160 though.
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  #15  
Old 03-01-2014, 02:47 PM
lake weir skier lake weir skier is offline
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Originally Posted by mikeg205 View Post
Vince told me the same thing.... after the 160 installation - hard hot starts - returned to 143 - all problems went away. I did like the way the engine ran at 160 though.
Really? I wasn't expecting I would notice the performance difference. What difference did you notice in how the engine ran?
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  #16  
Old 03-01-2014, 03:20 PM
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Originally Posted by lake weir skier View Post
I contacted Engine Nut at Indmar to confirm I received the correct engine overheat switch and to learn the specs for it. He responded they only have one such switch -- Part No. 654004. That is the part number for the new switch I received. He says the problem is the information in the Clymer manual is incorrect. He says the contact point for the switch is 225 degrees F, not between 190 degrees F and 200 degrees F as stated in the Clymer manual.

He says if the ECM detects an engine overheat condition via its dedicated temperature sensor, it will enter a power reduction mode to protect the engine. I had read on here about a ďlimp mode,Ē but I didnít know if I my 1994 had it. Apparently, it does. Considering I also have a temperature gauge with its own sensor, he points out the engine overheat switch is a third line of defense and not a big deal.

Given that and since Iíve run the boat for about twenty hours since buying it without getting false positives on the engine overheat light, it seems my old engine overheat switch is probably acceptable even though, at 212 degrees F, it closes somewhat lower than the spec contact point. Iím planning to soon change from a 143 degree thermostat to a 160 degree thermostat I have in hand. Hopefully, I will still be okay with my old engine overheat switch.

I first contacted Engine Nut Thursday afternoon and immediately received a reply that he was in the office but busy teaching service school through Friday. He then answered me about a half hour past midnight last night (Friday night). Pretty impressive service.
I don't kow if MC parts still use the same prefix they did in 2000, but if you have an Indmar part number, put 81 ahead if it and you'll have the MC P/N e.g., 81654004.

The events during overheat have been discussed to death here and it has been posted many times- DO NOT THINK YOU CAN LIMP A BOAT HOME. This is called RPM Reduction Mode and it's only intended to allow the boat/boaters to move out of the way of impending trouble, not to limp it home. These don't have a radiator, so this mode is almost always the result of a raw water pump impeller failure or some kind of blockage or a broken belt. That being the case, if it enters this mode, shut it down, immediately and let it cool down. While it's cooling down, open the motor box and look for obvious problems. If possible, find and repair the problem but DO NOT RUN THE ENGINE!

Any engine with injection has this mode.

As Mike posted, don't use the 143 degree thermostat. This engine calibration calls for 160 degree thermostat, so use that. If you use a cooler one, it will run richer and you'll waste fuel, but it won't help, especially since you weren't actually overheating. If you were, the engine would run rough and not exceed 2000 RPM, even at WOT. The recommended procedure for shutting the engine off after a hard run is to idle for about a minute. If you're picking up a skier, you probably don't need to be there instantly- they're not going anywhere. If a boat is moving toward the downed skier, it's better to block them with your boat, anyway.

If your overheat light comes on, it's from heat soak. If it happens while the engine is running, you have other problems.
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  #17  
Old 03-01-2014, 03:22 PM
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Originally Posted by mikeg205 View Post
Vince told me the same thing.... after the 160 installation - hard hot starts - returned to 143 - all problems went away. I did like the way the engine ran at 160 though.
Did you test the ECT when it was hard to start, or was this after it sat and heat soaked? Did you try opening the throttle a bit while you cranked? I don't remember if you described this problem here.
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  #18  
Old 03-01-2014, 03:56 PM
lake weir skier lake weir skier is offline
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Quote:
Originally Posted by JimN View Post
I don't kow if MC parts still use the same prefix they did in 2000, but if you have an Indmar part number, put 81 ahead if it and you'll have the MC P/N e.g., 81654004.

The events during overheat have been discussed to death here and it has been posted many times- DO NOT THINK YOU CAN LIMP A BOAT HOME. This is called RPM Reduction Mode and it's only intended to allow the boat/boaters to move out of the way of impending trouble, not to limp it home. These don't have a radiator, so this mode is almost always the result of a raw water pump impeller failure or some kind of blockage or a broken belt. That being the case, if it enters this mode, shut it down, immediately and let it cool down. While it's cooling down, open the motor box and look for obvious problems. If possible, find and repair the problem but DO NOT RUN THE ENGINE!

Any engine with injection has this mode.

As Mike posted, don't use the 143 degree thermostat. This engine calibration calls for 160 degree thermostat, so use that. If you use a cooler one, it will run richer and you'll waste fuel, but it won't help, especially since you weren't actually overheating. If you were, the engine would run rough and not exceed 2000 RPM, even at WOT. The recommended procedure for shutting the engine off after a hard run is to idle for about a minute. If you're picking up a skier, you probably don't need to be there instantly- they're not going anywhere. If a boat is moving toward the downed skier, it's better to block them with your boat, anyway.

If your overheat light comes on, it's from heat soak. If it happens while the engine is running, you have other problems.
I have previously read your warning not to try to limp home in the so-called “limp mode” and have planned to heed that warning if the situation arises. Thanks for the reminder. Fortunately, the lakes I’m on are small enough I could paddle in if I couldn’t fix things on the water. I wouldn’t like it, but I could.

I’m a little confused by some of the rest of your post. Mike didn’t advise me to use the 160; he advised against it. Said he tried it and went back to the lower temperature thermostat. Vince at DIM encourages me to switch to 160. However, if the “engine calibration” calls for 160, as you say, then why are there so many indications the boat came out of the factory with a 142 thermostat? I base that on the owner’s manual specs for my 1994 Mastercraft ProStar 190 saying the 350 TBI has a 142 degree thermostat, a former Mastercraft employee who was around twenty years ago and now works for Indmar telling me the boat was “born” with a 142 degree thermostat, and a dealer I bought the boat from installing a 142 degree thermostat (they say, I haven’t checked it yet to verify that’s what they installed) after I directed them to install whatever Mastercraft recommends before I took delivery of the boat last year.

EDIT:

Additionally, back in 2005 Engine Nut of Indmar advised a 1994 TBI owner he had a 143 degree thermostat and in 2007 he advised that Mastercraft/Indmar TBIs take a 140 degree thermostat. So again, how could it be that my 1994 stock TBI is calibrated for a 160 degree thermostat?

TBI engine sensors on 1994 Prostar205 (See Post No. 2)

Thermostat (See Post No. 3)
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Last edited by lake weir skier; 03-01-2014 at 05:54 PM. Reason: Additional information found
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  #19  
Old 03-01-2014, 09:16 PM
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Originally Posted by lake weir skier View Post
I have previously read your warning not to try to limp home in the so-called ďlimp modeĒ and have planned to heed that warning if the situation arises. Thanks for the reminder. Fortunately, the lakes Iím on are small enough I could paddle in if I couldnít fix things on the water. I wouldnít like it, but I could.

Iím a little confused by some of the rest of your post. Mike didnít advise me to use the 160; he advised against it. Said he tried it and went back to the lower temperature thermostat. Vince at DIM encourages me to switch to 160. However, if the ďengine calibrationĒ calls for 160, as you say, then why are there so many indications the boat came out of the factory with a 142 thermostat? I base that on the ownerís manual specs for my 1994 Mastercraft ProStar 190 saying the 350 TBI has a 142 degree thermostat, a former Mastercraft employee who was around twenty years ago and now works for Indmar telling me the boat was ďbornĒ with a 142 degree thermostat, and a dealer I bought the boat from installing a 142 degree thermostat (they say, I havenít checked it yet to verify thatís what they installed) after I directed them to install whatever Mastercraft recommends before I took delivery of the boat last year.

EDIT:

Additionally, back in 2005 Engine Nut of Indmar advised a 1994 TBI owner he had a 143 degree thermostat and in 2007 he advised that Mastercraft/Indmar TBIs take a 140 degree thermostat. So again, how could it be that my 1994 stock TBI is calibrated for a 160 degree thermostat?

TBI engine sensors on 1994 Prostar205 (See Post No. 2)

Thermostat (See Post No. 3)
You're right- I read that post and replied after about an hour, so....

If you want to find out which your engine was calibrated for, call MC and give them the engine serial number. If you can't find that, the hull ID will work.

If you're in a cooler area, you can use a 160 degree thermostat without hot start problems- it's warm/hot places that have problems but realistically, letting the engine cool down a bit before shutting it off usually eliminates it, anyway. If it's hard to start when it's hot, just open the throttle a bit and it will usually fire right up.

I'll have to check my notes re: thermostat temperature.
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  #20  
Old 03-02-2014, 12:04 AM
lake weir skier lake weir skier is offline
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Originally Posted by JimN View Post
You're right- I read that post and replied after about an hour, so....

If you want to find out which your engine was calibrated for, call MC and give them the engine serial number. If you can't find that, the hull ID will work.

If you're in a cooler area, you can use a 160 degree thermostat without hot start problems- it's warm/hot places that have problems but realistically, letting the engine cool down a bit before shutting it off usually eliminates it, anyway. If it's hard to start when it's hot, just open the throttle a bit and it will usually fire right up.

I'll have to check my notes re: thermostat temperature.
I donít know what things might have been like for others or in times past, but my experience with Mastercraft in the six months I have owned a Mastercraft is they have helped with a replacement trailer plate and hull color lookup based on hull id, but they beg off of engine questions and send me to Indmar for that. Thatís what they did when I called them months back about the thermostat issue.

I did call Indmar back then. I had forgotten until you mentioned it just now, but they did ask for the engine serial number before answering what thermostat my engine took. I remember because I remember the guy remarking it was unusual I knew what the first two letters stood for (think I learned from a post of yours). So the Indmar answer, based on my engine serial number, is my 350 TBI started its life with a 140 something thermostat. This jibes with what Engine Nut posted here in 2007 about TBIs generally (link in my previous post).

Having established that, I would think the issue would be, what is the best thinking now on what should be put on such an engine with twenty years of additional information and any relevant local factors such as ambient temperature.

Iím in central Florida, equidistant between the coasts operating in a county that has been known to compete in the summer with Death Valley, California for the hottest temperature nationally. My primary lake is mostly fed by rainwater directly and as runoff and gets little to no cool spring water. We have much cooler spring fed rivers in this county, but I donít use them with my boat. Guess that means you think I would be at higher risk of a problem by moving to a 160 thermostat, but none of this deters DIM from recommending a 160 thermostat.

I wonder what are the implications of sticking a 160 thermostat in an engine such as mine that was otherwise set up for a lower temperature thermostat.
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