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jschildm
08-20-2012, 09:41 AM
I have 1998 Prostar 205 with the regular 350 Chevy motor. A couple weeks ago when I took it out we were heading back to the boat ramp and the temp gauge shot up fast enough it caught my attention. I stopped and checked the impeller, it looked fine, so I put it back in and we idled back to the ramp, and the temp never went back down.

I did some searching on here and found that in addition to the impeller, I should also check the screen on the front of the transmission cooler. I pulled the hose off and there was some stuff in there, but I wasn't sure if it would be enough to cause the issue. I took it out yesterday to test it out, and it warmed up just like normal, and about the time the gauge got to 160, it went up really quickly again to 220+.

I checked for leaks and didn't see any, but the hose that comes from the front of the cooler to the bottom of the RWP has rubbed on the alternator and either has a hole in it, or is very close to having one, no leaks that I noticed though. I am looking for some advice on troubleshooting I should do now to get to the root of the problem. I am ordering some hose to replace the damaged one from SKIDIM as we speak.

My thoughts are air getting in through this damaged hose, t-stat, RWP, or Circ Pump. Its worth noting that I was getting on it pretty hard when the problem first showed up, so I also thought perhaps head gasket, but it still runs just fine. What steps should I take to continue troubleshooting and not throw parts at it?

Sorry for the really long post, just trying to give all of the details I can. Thanks in advance for your help, this website is a great place for advice and information.

Jerseydave
08-20-2012, 10:24 AM
I would suggest removing both hoses from the trans cooler and back-flushing it with a garden hose. Then replace that hose that has been rubbing and install a new t-stat.
Make sure you have no weeds in the pickup at the bottom of the hull and maybe even flush that out with a garden hose as well.

LYNRDSKYNRD
08-20-2012, 10:41 AM
Mine was acting in a similar fashion and it turned out to be the sending unit. My boat has a carbed 351 but it sounds exactly like my issue.

homer12
08-20-2012, 10:43 AM
I was thinking t-stat. My knowledge is far less than others here, but I think you can search to find how to troubleshoot the t-stat. That would be my next step.

LYNRDSKYNRD
08-20-2012, 10:46 AM
True it could be t-stat too I ruled that out by pulling mine while I was on the water but always a good place to start.

mikeg205
08-20-2012, 10:52 AM
pull the t-stat..a and use see if you have good water flow. use this demo from Cantrepeat..

http://www.youtube.com/watch?v=qHR9bbPbwmM

Should cost about 10bucks to make...

this thread has parts list from EastTx... http://www.mastercraft.com/teamtalk/showthread.php?t=46244&highlight=fake+lake

If you're running fine and don't have nay blow by...you may be ok..IMO... you could also do a leak down compression check to give you piece of mind.

jschildm
08-20-2012, 12:45 PM
I don't think its the sending unit because it did seem as though it was warmer than normal when I had to idle back. That is certainly not fool proof, but does lead me to believe something else might be the issue.

I'll probably go ahead and get a t-stat while I am at it. For 12 bucks it won't hurt to replace and have a back-up if that's not the issue.

Right now its in storage, but I will try and drag it home this week to test out. On a similar note, while searching this issue it seems the boat might be running a bit cool (until this happened). The temp gauge generally stabilized around 140 degrees, and I had never seen 160 until this happened. Is that cooler than it should be? I believe it should have a 160 degree t-stat, correct?

mikeg205
08-20-2012, 01:30 PM
MCX? what does manual say?

Below manual says 143 and 160.

http://www.mastercraft.com/files/manuals/1998_OwnersManual-PS190-PS205-XStar-SammyDuvall.pdf

jschildm
08-20-2012, 01:43 PM
I believe it is the MX Plus Engine.

jschildm
08-21-2012, 09:13 AM
I pulled the boat home last night, but didn't have a lot of time to mess with anything. I did pull the thermostat out, and was moist on top, and appeared to be dry as a bone under it. This is the first I have had it off, so I don't know if this is normal or not. I might try running with a fake-a-lake tonight with the t-stat in and everything like it is now to see if it is sucking water. If it still gets hot (hopefully I can run it long enough to find out), then I might try taking out the t-stat and see what that does.

JimN
08-21-2012, 09:20 AM
I have 1998 Prostar 205 with the regular 350 Chevy motor. A couple weeks ago when I took it out we were heading back to the boat ramp and the temp gauge shot up fast enough it caught my attention. I stopped and checked the impeller, it looked fine, so I put it back in and we idled back to the ramp, and the temp never went back down.

I did some searching on here and found that in addition to the impeller, I should also check the screen on the front of the transmission cooler. I pulled the hose off and there was some stuff in there, but I wasn't sure if it would be enough to cause the issue. I took it out yesterday to test it out, and it warmed up just like normal, and about the time the gauge got to 160, it went up really quickly again to 220+.

I checked for leaks and didn't see any, but the hose that comes from the front of the cooler to the bottom of the RWP has rubbed on the alternator and either has a hole in it, or is very close to having one, no leaks that I noticed though. I am looking for some advice on troubleshooting I should do now to get to the root of the problem. I am ordering some hose to replace the damaged one from SKIDIM as we speak.

My thoughts are air getting in through this damaged hose, t-stat, RWP, or Circ Pump. Its worth noting that I was getting on it pretty hard when the problem first showed up, so I also thought perhaps head gasket, but it still runs just fine. What steps should I take to continue troubleshooting and not throw parts at it?

Sorry for the really long post, just trying to give all of the details I can. Thanks in advance for your help, this website is a great place for advice and information.

Replace the gasket on the raw water pump. If the other one wasn't replaced along with the impeller the last time, it can't do its job. Also, make sure the hose clamps are tight on the raw water hoses. Make sure the hull fitting for the raw water is clear, too. People toss all kinds of garbage into the water and plastic bags can be sucked into the grate.

coz
08-21-2012, 09:20 AM
I stopped and checked the impeller, it looked fine,

The impeller can look fine but if the splines have broke free of the fins it will spin with the shaft and the impeller wont move. Did you give a bump to see if it's turning? I had this happen twice, just a thought.

jschildm
08-21-2012, 10:06 AM
I have inspected and cleaned the path to the water pump, so I think its clear. I am going to back flush tonight just to be sure. The gasket was replaced with the impeller, but when I looked at it last night, I did notice I had kinked it putting it back on when I checked it on the lake, but I don't think it was like that when the symptoms first occurred. It still seems to be in decent shape, so I put it back on making sure it was flush between the pump and cover plate.

I did turn the boat over with the cover off the impeller, but I didn't pay attention to whether or not it was turning. I will do that tonight as well. Hopefully tonight I will get to the bottom of the issue, and then it will just be waiting for parts to arrive.

CantRepeat
08-21-2012, 10:23 AM
I have inspected and cleaned the path to the water pump, so I think its clear. I am going to back flush tonight just to be sure. The gasket was replaced with the impeller, but when I looked at it last night, I did notice I had kinked it putting it back on when I checked it on the lake, but I don't think it was like that when the symptoms first occurred. It still seems to be in decent shape, so I put it back on making sure it was flush between the pump and cover plate.

I did turn the boat over with the cover off the impeller, but I didn't pay attention to whether or not it was turning. I will do that tonight as well. Hopefully tonight I will get to the bottom of the issue, and then it will just be waiting for parts to arrive.

How do you intend to back flush it and what do mean by this?

JimN
08-21-2012, 10:45 AM
I have inspected and cleaned the path to the water pump, so I think its clear. I am going to back flush tonight just to be sure. The gasket was replaced with the impeller, but when I looked at it last night, I did notice I had kinked it putting it back on when I checked it on the lake, but I don't think it was like that when the symptoms first occurred. It still seems to be in decent shape, so I put it back on making sure it was flush between the pump and cover plate.

I did turn the boat over with the cover off the impeller, but I didn't pay attention to whether or not it was turning. I will do that tonight as well. Hopefully tonight I will get to the bottom of the issue, and then it will just be waiting for parts to arrive.

Do you ever beach the boat? Does the water have extremely shallow areas, with a lot of sand and/or silt?

Open the petcock/remove the knock sensor and make sure the water rushes out. If it dribbles, remove the petcock and if it still dribbles, use a wire to clear out any sand/silt that may be in the way. If the wire won't go in easily, whatever is in there will need to be removed.

jschildm
08-21-2012, 10:58 AM
By back flush I just mean using a hose to run water from water pump back out the intake at the hull.

While on vacation we did park the boat for a week at a friends lakehouse in a cove that had some debris in it. I will check the passages to make sure water comes out. I hate beaching it, it makes me paranoid, so I don't do it, haha.

Thanks again for everyone's input.

jschildm
08-22-2012, 09:40 AM
Had some time to try and get to the bottom of it last night. First thing I did was pull the cover off the impeller and bumped the engine. The impeller was turning as it should.

Next I looked at the t-stat a bit to see if I saw anything awry (I didn't but have no idea what I am looking for). Put the t-stat back in and cover back on the water pump. Hooked it back up and started it using a 5 gallon bucket.

The water pump instantly started sucking up water, so I had that one scratched off the list. I finally got it up to temperature but couldn't get it hot. Stopped and pulled the plugs on the block and water came freely out of both, so the passages weren't blocked.

I had been running of the hose that goes from the front of the cooler to the RWP. I pulled the hose off at the thru-hull fitting to make sure there wasn't something in the cooler blocking it. It again instantly started sucking water again. I was again unable to get it hot. The needle ran exactly where it usually did.

Seems to me that one of two things are happening:
1. The boat isn't under sufficient load to overheat (it still got hot just idling back to the ramp)
2. Tinkering with t-stat/hoses/etc made whatever wasn't function start to function again

Hose and t-stat should be here Friday, so I will probably go ahead and replace them and take it out again. I hate to complain that my boat wouldn't overheat, but I was hoping it would, and then when i pulled out the t-stat and ran it; it would cool off ... I guess thats the engineer in me wanting to KNOW what the solution was.

On another note, the t-stat in it now is a 143 degree and the one I ordered is a 160. The manual lists both and skidim made it sound like either was OK, and the 160 might use slightly less fuel, so I will probably stick with it, at least to see how it does.

jschildm
08-22-2012, 11:10 PM
Does anyone have thoughts on what I am missing or things I have missed before I put the hose and new t-stat in it and take it back out to the lake? Thanks for everyone's input so far, you have helped me check many things I hadn't thought of.

jschildm
08-22-2012, 11:12 PM
thoughts on what I am missing or things I have missed

I am good at English ..........

mikeg205
08-22-2012, 11:17 PM
Had some time to try and get to the bottom of it last night. First thing I did was pull the cover off the impeller and bumped the engine. The impeller was turning as it should.

Next I looked at the t-stat a bit to see if I saw anything awry (I didn't but have no idea what I am looking for). Put the t-stat back in and cover back on the water pump. Hooked it back up and started it using a 5 gallon bucket.

The water pump instantly started sucking up water, so I had that one scratched off the list. I finally got it up to temperature but couldn't get it hot. Stopped and pulled the plugs on the block and water came freely out of both, so the passages weren't blocked.

I had been running of the hose that goes from the front of the cooler to the RWP. I pulled the hose off at the thru-hull fitting to make sure there wasn't something in the cooler blocking it. It again instantly started sucking water again. I was again unable to get it hot. The needle ran exactly where it usually did.

Seems to me that one of two things are happening:
1. The boat isn't under sufficient load to overheat (it still got hot just idling back to the ramp)
2. Tinkering with t-stat/hoses/etc made whatever wasn't function start to function again

Hose and t-stat should be here Friday, so I will probably go ahead and replace them and take it out again. I hate to complain that my boat wouldn't overheat, but I was hoping it would, and then when i pulled out the t-stat and ran it; it would cool off ... I guess thats the engineer in me wanting to KNOW what the solution was.

On another note, the t-stat in it now is a 143 degree and the one I ordered is a 160. The manual lists both and skidim made it sound like either was OK, and the 160 might use slightly less fuel, so I will probably stick with it, at least to see how it does.


I got the 160 t-stat from SkiDim and had warm start problems after a few minute heat soak. Dropped back to a 143 t-stat and the problem went away. Guess it's a function of how the ECM is programmed.

jschildm
08-22-2012, 11:31 PM
Interesting ... I will definately keep that in mind. On another note, I see you are in the Joliet area. A buddy of mine is going to be moving up there around the end of September, so I might be up there for a visit sometime. Maybe I'll look you up if it happens to be boating season. What engine do you have?

mikeg205
08-22-2012, 11:45 PM
5.7 indmar...need a new pic have a new alternator now.

jschildm
08-24-2012, 03:44 PM
Parts are out for delivery now. Planning on putting those in and everything back together, and then take her for a test drive this weekend. I am hoping the 160 degree t-stat isn't an issue, since it would start at 220+ while malfunctioning. I will update with results and more questions, depending on the outcome. Thanks again for everyone's input.

jschildm
08-25-2012, 05:59 PM
Got the new t-stat and hose in yesterday. Took it out today and all was fine .... until I started to get on it some. The temp gauge did the same thing it did the other times. I decided I was going to replace the impeller since I had one, and it was the last easy solution.

Sure enough, it worked like a charm after that. I got on it pretty hard with no issues. It started raining so we didn't get to run it that long, but I am pretty confident it was the solution.

I suppose this is a perfect example of why I should have put the spare impeller that I already had in the boat in there the first night it started acting up. Live and learn I suppose. I at least now have a spare t-stat and fixed the hose that was just waiting to get a hole in it.

Thanks again for everyone's insight on this issue! Next weekend will be the big test because I plan on 4 long days of boating, weather pending at least.