Engine Getting Hot

[jschildm]

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]

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]

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]

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]

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]

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/...ight=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]

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]

MCX? what does manual say?

Below manual says 143 and 160.

http://www.mastercraft.com/files/man...ammyDuvall.pdf

[jschildm]

I believe it is the MX Plus Engine.

[jschildm]

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.