'93 Ski Nautique 351 PCM Pro Tech Overheating
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=28337
Printed Date: May-21-2024 at 4:02am
Topic: '93 Ski Nautique 351 PCM Pro Tech Overheating
Posted By: tsassman
Subject: '93 Ski Nautique 351 PCM Pro Tech Overheating
Date Posted: November-13-2012 at 8:15pm
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I purchased a ’93 Ski Nautique (my first boat) a couple of months ago at a real good price. Before purchase we took a test drive and really the only issue was sporadic temperature readings. Boat owner said probably needs a new thermostat or gauge. I have all the original paper work from original owner with the original owner’s manual. Original purchase was in Dallas and I purchased it from a guy in Austin. As far as I know it has never seen salt or even brackish water. Don’t know how may owners it has had. Took the boat to marine shop for a complete checkup (I noted to have him check the temperature issue) and here is what they have done: 1) Battery – Check electrolyte level and specific gravity. Inspect case for damage. Inspect cable and connections. 2) Change engine oil and filter. 3) Change transmission oil. 4) Check and adjust engine alignment. 5) Clean and inspect ignition system. 6) Check and inspect cooling system, drive belt, and exhaust system. 7) Check electrical system for loose or dirty connections and damaged wiring. 8) Clean and inspect flame arrestor and crankcase ventilation system. 9) Check complete engine assembly. 10) Replace fuel filter. 11) Replace raw water impeller. 12) Checked all hoses and clamps for cracks and leaks. 13) Checked all temperature sensors. His notes on the temperature issues after all this was he tested the boat on the lake and it overheated. He then pulled the thermostat and noticed a large amount of rust in the thermostat housing. He pulled the thermostat, cleaned out the housing and installed a new 160F thermostat. Boat was them retested with the same result – overheating getting close to 200F. Technician then performed a raw water pump capacity test the result showing proper performance (5 gallons flowed in 15 seconds @ 3000 RPM’s) Circulation pump was now in question but mechanic contacted PCM support technician (Travis Snyder) to discuss issues. Both seem to think that the circulation pump could be weak but due to the manifolds and risers not overheating this is not the main issue. PCM believes that due to the rust issue at the thermostat and water jackets proper flow has been compromised. New circulation pump could possibly fix the issue, but may not be able to perform and better than a weak circulation pump to possible blockage in cooling water passages. He said the engine might have to be pulled and taken to machine shop to have cooling water passages cleaned out. Sounds expensive!!!! Any thoughts or suggestions on what course of action I should take next? |
Replies:
Posted By: Hollywood
Date Posted: November-13-2012 at 8:21pm
Bend over. You get what you pay for. ------------- |
tsassman wrote:Posted By: SNobsessed
Date Posted: November-13-2012 at 9:28pm
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You might want to try some lime-away type cleaner (acidic) - pour it in & let it sit for a few days, then flush well. Maybe even idle the engine (belt off) for a couple minutes to heat up that soup. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: tsassman
Date Posted: November-13-2012 at 9:40pm
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Thanks Chris for the constructive suggestion. I am willing to try just about anything to keep from having to pull the engine. I am in no hurry, just want it to be ready to ski with this spring/summer. Could you give any more detailed instructions on how to do that? |
Posted By: SNobsessed
Date Posted: November-14-2012 at 1:38am
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OK, I'll give it a shot. Mind you I haven't done this myself! Pull out the thermostat. Remove the pump drive belts. Drain the block, both sides. Pour your solution in. Some science needs to be done on the solution, commercial boiler lime cleaner? Maybe ask a radiator shop? Maybe just 'The Works' toilet cleaner (which is acid). Run the engine for a few minutes at idle. After a soak period, maybe a day, put the thermostat back in, hook the belts up & a raw water supply. Run the engine, catching the rusty crud coming out the exhaust, or run it on your neighbor's driveway when he isn't home (just kidding Ralph). This might be hard on the water pump, but your were thinking about changing it anyway. Keep in mind this may not be the real problem - you could have chunks of an old impellar stuck in a passage somwhere - I can't help you there. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: tsassman
Date Posted: November-14-2012 at 1:53am
| Thanks, I'll put it on my list of things I might try. Still open for more suggestions if anyone has any. By the way if indeed a piece of an impeller is restricting a passage. What would be the solution there? Has anyone had any experience with that? |
Posted By: tsassman
Date Posted: November-14-2012 at 1:56am
| Would you suggest that I change the water pump out first to rule out that as the issue. If it isn't not much lost there right. |
Posted By: SN206
Date Posted: November-14-2012 at 2:04am
Plenty of brackish water in North Texas. ------------- ...those who have fallen and those who will. |
Posted By: Dreaming
Date Posted: November-14-2012 at 3:21am
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Posted By: 8122pbrainard
Date Posted: November-14-2012 at 8:19am
Tim, You mechanic did a RWP flow check and it was good so I would say you can rule out impeller pieces blocking passages. Shoot the area around the temp gauge sender with a IR heat gun and make sure it's not a gauge sender issue. Has all the gauge wiring been checked for loose and or corroded connections? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: M3Fan
Date Posted: November-14-2012 at 10:18am
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That boat shouldn't have the 160 t-stat. A 160 T-stat will put your temp at around 180 or slightly above which may be what you are interpreting as an overheat situation. It should have a 140 t-stat. ------------- 2000 SN GT40 w/99 Graphics/Gel 2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
Posted By: JoeinNY
Date Posted: November-14-2012 at 11:33am
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Thier reasoning for dismissing the circulating pump is backwards, and therefore the conclusion is suspect. Intermittant block temp, with a known good RWP, with good temp at both manifolds and risers would be a result of a bad circulation pump. Could also be rust mind you but I have seen some pretty cruddy blocks cool just fine, and a very fresh and clean one with a bad circ pump (loose impeller) cause the exact behavior you are experiencing -- eventually leading to a valve sticking, breaking, dropping. That being said - as mentioned if an engine is running hot always always check your timing with a good light and make absolutely sure it is correct. If I was really worried about rust with the water pump off I would pull the core plugs off the side and blow a bunch of compressed air everywhere i could reach and see how much comes out. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Hollywood
Date Posted: November-14-2012 at 12:13pm
Pete, who's to say it isn't pieces from a previous impeller? ------------- |
Posted By: 65Cuda
Date Posted: November-14-2012 at 12:33pm
| you probably already checked this, is there blockage in the exhaust line that is not allowing water to flow freely? Chack passage from exhaust manifold to stern. |
Posted By: TRBenj
Date Posted: November-14-2012 at 1:13pm
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There is not enough information given about the nature of the overheat in order to give you very good advice. There are a LOT of things that can contribute to running hot. If you could tell us exactly how and when it tends to overheat, then we can provide better advice on what to troubleshoot. Specifically, does the temp creep up at idle (especially after running hard), or at speed? Regardless of the mode, circ pump failure and corroded cooling passages are possible, but pretty far down on the list of likely culprits. Its likely to be something much simpler, with a pretty straightforward solution. ------------- |
Posted By: Bri892001
Date Posted: November-14-2012 at 1:23pm
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Some good advice so far. Also, lets see some pics of the motor. Curious about a 93 Ski Nautique with a GT-40 engine. |
Posted By: tsassman
Date Posted: November-14-2012 at 3:31pm
When I pick it up this weekend I will ask the tech. about the plugs and timing. |
Posted By: tsassman
Date Posted: November-14-2012 at 3:34pm
As stated at top all wires and connections were checked. I am planning on buying a IR gun to test it when I get the boat home this weekend. Thanks. |
Posted By: Bri892001
Date Posted: November-14-2012 at 3:47pm
I agree with M3Fan on the Thermostat. A 93 era boat would typically have a 140 (143 actually) T-Stat. If someone did actually retro-fit a GT-40 Fuel injected engine in this boat, it may then call for the 160. |
Posted By: tsassman
Date Posted: November-14-2012 at 4:04pm
You are correct. My mistake and I have edited my post. It is a PCM 351 Pro Tech. Thanks for the catch. I just got off the phone with Karen( great help) at SKIDM.com(Discount Inboard Marine)and she informed me that they went to the 160F in '94. She says that I should have the technician put a new 143F back in, not that the 160F is bad just to help with the cooling issue. She also said that the typical running temperature for this boat is 180F -185F. Also, she said that 190 is typical. When is gets close to 200 is when you have problems. |
Posted By: kapla
Date Posted: November-14-2012 at 4:53pm
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is a carb or efi engine? I believe the 143 is correct for a carb engine and the 160 is correct for the efi engine. as far as temp readings I would be friggin nervous if my engine ran at 180-190 degrees... Mine runs 160, virtually all time... ------------- <a href="">1992 ski nautique |
Posted By: Hollywood
Date Posted: November-14-2012 at 5:23pm
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Time for a new marine shop. Verifying the proper, functioning thermostat should have been pretty high up the diagnosis list. Then again, posting accurate information helps too. ------------- |
Posted By: Munday
Date Posted: November-14-2012 at 8:24pm
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I think I would verify the temp gauge first, and check the dash ground. If that was all good then I'd replace the stat again with a balanced stat. Then I would go for the acid soak. All the heat is produced in the head area, so I think a couple of applications of acid soak might clean things up. Bob ------------- If the only tool you have is a hammer,everything starts to look like a nail. |
Posted By: jimsport93
Date Posted: November-14-2012 at 9:08pm
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Tim, I know it sounds kind of simple, but have you tightened all the hose clamps (with a nut driver) and made sure the raw water strainer is tight (and the gasket is in proper order)? Got the same engine in my 93 Sport and it will do the same thing after multiple hot and cold cycles during the season. Tightening down everything brings it back down into the proper temp range. I know the shop checked for hose clamps and cracked hoses....but did they actually tighten everything properly? I have worked in the boat business around a lot of technicians and sometimes they miss the obvious. Especially with the large punch list of things to go over. Just sayin! ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2798 - 93 Sport Nautique |
Posted By: TX Foilhead the 2nd
Date Posted: November-14-2012 at 9:15pm
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I'm goning to take this down a whole mother road here, sorry for the new name, I can't seem to get logged in as myself. So we've got the water flowing and the ProTec isn't going into limp mode, and the point everyone missed is the manifolds aren't hot. So the problem is the gauge not the cooling system. It's always a god idea to have an IR thermometer around, pick up a multimeter while you're at it. First thing I would check is the voltage your getting at the battery, the to the dash, and finaly to the gauges. Before my last rewire when I added the buss under the dash I was getting 12.5 volts at the dash, but it dropped to 10 by the time it got to the other side. This caused havoc with the PP and most of the gauges were off too. I was running 180 to 190 most of the time. Once I got the wiring fixed I've got 12.4 everywhere I look, 13.7 with the boat running and everything on (lights, heater, blower, and bildge pumps). Its now running 155-160 with the 160 Tstat just as it always has. Another possibility may be the kind of thermostat. I have had issues with the cheap basic thermostat from the autoparts store opening slowly and causing the temp to rise to uncomfortable levels. I had to watch this happen in a pot on the stove to figure it out. The auto tstat would begin to open at the appropriate temp while the PCM one would go full open at the right temp. The auto tstat was closed to 200 before it fully opened. I'm in the group that says 160 is OK, I've been doing it for years, makes my heater work better and even in 90 degree water in August my boat stays below 170. I know everyone here screams about it, but I run almost identical temps to them. |
Posted By: SNobsessed
Date Posted: November-14-2012 at 9:16pm
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Hmmm, might have to pull the engine. A nice slow-season job. But that would be milking the customer . . . ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: TX Foilhead the 2nd
Date Posted: November-14-2012 at 9:27pm
| I forgot to add, look at that receipt carefully and decide if you still got a deal. Then, come here next time you have a problem and get it figured out then fix it yourself so you never have to get another receipt for having your boat fixed. |
Posted By: tsassman
Date Posted: March-12-2013 at 2:28am
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I also posted this on planet nautique so I will give the same update here. After having done nothing to the boat since my last post(working alot) and waiting on someone to help me I took it upon myself to pull it out of storage to my house. As noted in my previous post the Houston service tech said he changed the thermostat. I am a below average mechanic and am leary about messing with engines. I took a chance and hooked up a homeade water supply system to my boat to check temperatures myself. I bypassed the water strainer and verified that I was getting water through transmission cooler. Learned a lot about how to do all this on these forums(thanks guys). Without the boat running I was getting water out the rear exhaust. Feeling safe to start the engine I did and temp gradually started climbing till it got to close to 200F and this is where I shut it down. I did during that time rev it and water shot out of the rear exhaust. Going through the overheating steps at SKIDIM this told me that the water pump was good. I decided to pull the thermostat myself and leave it out and check temp again. Started engine and temp never rose above 115F. WOW. This does tell me that I am getting water through the jackets doesn't it? I did this several times with the same result. Called the shop where the service was done and just so happen the tech who performed the service had to step out. Talked to the owner about what I had found and he verified that from what it sounds like the thermo is bad. As noted in my previous post the tech suggested that I have a machine shop pull the engine and clear the water jackets. He quoted me a price from someone he new at aroung $3,500 for the whole job. I will be ordering a new thermostat tomorrow or might even go to Houston(75miles away) and pick one up myself. I could understand that the orginal thermostat was bad but he installed a new one(or so he said) and when I found out he put a 160F in instead of original 143F I had him change it out. It still overheated after all this. |
Posted By: TX Foilhead
Date Posted: March-12-2013 at 3:28am
| It's really not that hard, you just saved a couple of years worth of gas. UPS will bring that thermostat from SKIDIM to your door a lot cheaper than 150 round trip. |
Posted By: backfoot100
Date Posted: March-12-2013 at 5:59pm
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Something just doesn't sound right here. Two brand new stats of different temps and both bad?????? What are the chances of that? I would confirm that the stats weren't installed upside down and when you get the new one put it in a pot of water on your stove and heat it up to verify that it does open at 143 before you install it. ------------- When people run down to the lake to see what's making that noise, you've succeeded. Eddie |
Posted By: N2Deep
Date Posted: March-12-2013 at 9:12pm
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Or take the one out that is in there now and put it in water on the stove and see if it opens. Could tell ya if the thermostat is good or bad and it could be something else. ------------- 1991 SN pulled by a 2010 Tundra |
Posted By: Gary S
Date Posted: March-12-2013 at 9:20pm
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And the best way to test either one is to suspend it in the water.If it sits on the bottom you will get a false reading due to the contact to the hotter bottom of the container. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: dochockey
Date Posted: March-13-2013 at 1:10am
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OK Tim lets back up a step or two When running your boat in your drive you need to do the bucket method. this method tells us that your impeller is pulling water through the system. did you check to see if your impeller was good or are we taking the word of the mechanic ? get the new thermostat and report back you don't need a mechanic you have us! ------------- 1989 Teal Ski Nautique 1967 Mustang Harris Float Sunfish |
Posted By: tsassman
Date Posted: March-13-2013 at 4:40am
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I ordered a new 143F from SKIDIM today along with several other items and spoke extensively with Vince(great help). He indeed said it probably was a faulty thermo, but still could be a number of other things. I couldn't wait so I drove to Houston to pick one up from Palmer Power. I spoke a good long while with the manager there who also was very helpful. I showed him the old thermostat that I took out and he confirmed that it was a 160F. Remember in my previous post that when I found out the tech had installed a 160F I had him change it back out to the original 143F which he said he did. Obviously he LIED. Well I got back home and immediately installed the new thermostat. Hooked up the water supply and started the boat the temp. rose to 140-150-160 all the while I had my hand on the top of the thermostat housing to see if I could tell a temp. change. At 165 I started to feel a difference, at 170 it stopped rising and dropped back down to 160 and stayed there. I let it run there at about 1,000 rpm for about 5 minutes feeling spots on the engine, checking water flow out the back. I felt safe to rev to about 1,500 with not much change. I decided to install my fresh water strainer back inline, had to go to local auto parts store to obtain new o-ring. I installed the strainer along with reconfiguring my water hookup. I this time used a 5 gallon bucket to let the water hose fill the bucket and let the motor pull the water from the bucket. With the bucket full and water running over I started the engine. Same result with the temps and felt good suction from the hose connected to the engine. At 1,000 rpm and water on all the way, the bucket would still run over. At about 1,500 the bucket would stay level with the top, at 2,000 the water level in the bucket starts to drop fairly quickly. I feel pretty confident I have solved the issue, but the true test will be getting it into the river(hopefully tomorrow evening, have to work). Another step I want to verify is test the engine areas with thermo gun(hopefull tomorrow or Thursday). On and by the way I still have yet to recieve a call back from the shop where the original service was done(imagine that). |
Posted By: tsassman
Date Posted: March-13-2013 at 5:07am
Here are some pics of my boat the day I dropped it off at the service center. I believe I am very close to solving the mechanical issue.  
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Posted By: SNobsessed
Date Posted: March-13-2013 at 12:20pm
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Good to hear of your progress. Sometimes the cause is right in front of you, but mixed in with extraneous information. Your boat looks great. Have you considered replacing the side graphics? ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: dochockey
Date Posted: March-13-2013 at 2:46pm
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Tim Ive been in your shoes nothing more frustrating than when the boat give us touble. ------------- 1989 Teal Ski Nautique 1967 Mustang Harris Float Sunfish |
Posted By: tsassman
Date Posted: March-13-2013 at 5:05pm
| Will be replacing decals in the next couple weeks. One good thing about the whole process is how much I have learned about my boat. This is my first one. |
Posted By: bhectus
Date Posted: March-13-2013 at 5:39pm
+1 that's the first thing I thought about. upside down. ------------- '02 Ski Nautique 196 w/ 5.7 Apex bowtie - Sold '87 Barefoot - sold '97 Super Sport Nautique - originally custom built for Walt Meloon '97 Ski Nautique '83 SN 2001 |
Posted By: tsassman
Date Posted: March-13-2013 at 8:52pm
| Can't confirm anything what the original service tech did concerning stat replacement other than the 160F that I took out(it was installed correctly) which should have been a 143F. All I know is that when I replaced the 160F to the new one it seems to work like it should. |