another overheating thread

[geek]

Well, I took my new Tige out for a week on Lake Powell. The trip was wonderful, I will post pics once my wife gets them all loaded to the computer.

The first 3 days the boat ran perfect. Everything was spot on, but the last few days, my boat would slowly heat up to nearly 200 degrees. This would happen once during the first run of each day. I would shut off the engine once it got that hot, and let it sit for about five minutes, then start it and let it idle. The temperature would quickly drop to around 150 and stay between 150-175 the rest of the day. I initially thought that there might be a problem with the thermostat sticking in the morning and once it opened, everything would be fine.

Been home a week now and decided to take it to the local lake just to see if the problem would still be there. It did the exact same thing, except this time it seemed to have an abnormal amount of exhaust coming out while surfing. Once again, it heated up after running for about 30 minutes, then I let it sit for a short while, and it stayed between 150-175 the rest of the day.

So, since my wife wants to take it out again this evening, I decided to tear into this thing to see if I can figure out what is happening. I took the cover off for the impeller, and it looks perfect. I can't see any problems and all the teeth are there. I decided to change the thermostat, so I removed the housing and pulled the thermostat, it looks like it is in good condition, I picked up a replacement at a local marine shop and will install the new one. Since I have it mostly torn apart, I think it would be a good idea to try backflushing the system and see if I can get anything out of it. But I am unclear as to which hose I need to disconnect to force water through.

This is a Marine Power 5.7, I assume I need to push water back through the transmission and there is a hose that runs from the thermostat housing down to the Jabsco pump, then one that runs back to the transmission and then I assume to the scoop that picks up the lake water. Is this where I need to backflush?

I will be heading home to reinstall the thermostat housing in a few hours, so I am hoping someone can point me in the right direction. I would also love your opinion as to whether or not you think I am on the right track in pinpointing this heating problem.

Thanks.

[duffymahoney]

Mine sometimes jumps to around 200 when we are surfing. I also have the same engine. I thought it was normal! It usually stays around 175 or so. Let me know what you find out.

[ajholt7]

Take the hose off that goes from the impeller housing down to here

and flush it through that hose. You may also want to take the hose off of each side of the cooler to make sure it is clear.

[bigdaddy_houseboater]

I pull the hose connection to the inlet of my sea pump and flush back to the street from there with a garden hose. If you dont have a strainer... get one.
Sherwood Sea Strainer, www.iboats.com

[geek]

OK, this is what I have done.

Put the thermostat housing back on the engine with a new thermostat. I removed the inlet hose from the Jabsco pump and stuck a garden hose on it, flushed the hoses. The water immediately came out the thru-hull pick up. I was watching it pretty closely and not much debris came out. There was a few grass blades, but that is about it. Then I moved the boat to another location so I could crawl underneath and checked to see if there was anything lodged in the brass pickup. Nothing that I could find, so I hit it one more time with the garden hose. This time, nothing but water came out. I let it run like that for a few minutes, so I am now convinced there is nothing obstructing the lines to the pump.

I am taking the boat to the lake this evening, so I will keep an eye on the temp and post back in the morning.

Thanks.

[bigdaddy_houseboater]

OK, this is what I have done.

Put the thermostat housing back on the engine with a new thermostat. I removed the inlet hose from the Jabsco pump and stuck a garden hose on it, flushed the hoses. The water immediately came out the thru-hull pick up. I was watching it pretty closely and not much debris came out. There was a few grass blades, but that is about it. Then I moved the boat to another location so I could crawl underneath and checked to see if there was anything lodged in the brass pickup. Nothing that I could find, so I hit it one more time with the garden hose. This time, nothing but water came out. I let it run like that for a few minutes, so I am now convinced there is nothing obstructing the lines to the pump.

I am taking the boat to the lake this evening, so I will keep an eye on the temp and post back in the morning.

Thanks.

Perfect. If it heats up... then you got shiit lodged somewhere in the water jackets of the motor. Any other issue would be catestrophic.

[geek]

Ran the boat for 3 hours last night. Pulling wakeboarders, skiers and surfers and the temperature never went over 155 the entire night. The boat ran absolutely perfectly all night. I am quite sure this bad boy is fixed.

Thanks for the suggestions.

[bigdaddy_houseboater]

Ran the boat for 3 hours last night. Pulling wakeboarders, skiers and surfers and the temperature never went over 155 the entire night. The boat ran absolutely perfectly all night. I am quite sure this bad boy is fixed.

Thanks for the suggestions.

Was the thermostat... They tend to stick.

[duffymahoney]

What thermostat should I get?

[bigdaddy_houseboater]

The stock is a 140 deg. on mine. I have a MP 315 ('07 20i). Some are 160.. either is fine.

[duffymahoney]

I mean where do I get it? Standard chevy 350 one from like napa?

[bigdaddy_houseboater]

Duffy,
Most NAPA's wont have a 140... but they will have a 160. Take your old one with you. Get the same one. If you have never taken it off and cant figure out how to get it out of the housing, there is a little round (pipe shaped) PVC retainer that holds the thermostat in the top of the housing. It has to come out to get the thermostat out. I mess with mine quite a bit lately, because I am dealing with a ton of debris in our lake right now. I bought a 160 from iboats.com
Here's the 160 on iboats... but its a mallory which all auto parts stores have.. typically.
http://www.iboats.com/mall/partfinde...n_id=789039743

[geek]

I picked mine up at a local marine shop. I own several auto parts stores and the closest I had available was a 160. So, I decided to go with what it had stock, which was the 140 degree. The part number I got was a Sierra 18-3551. I paid about $18 for it which is frustrating because the 160 degree equivalent is only a few dollars at just about any auto parts store. I think I am going to get after some of my manufacturers to see if any of them supply a 140 degree thermostat, then I will buy a few hundred and sell them off at 300% gross profit and still be less than the marine shops.

[bigdaddy_houseboater]

I picked mine up at a local marine shop. I own several auto parts stores and the closest I had available was a 160. So, I decided to go with what it had stock, which was the 140 degree. The part number I got was a Sierra 18-3551. I paid about $18 for it which is frustrating because the 160 degree equivalent is only a few dollars at just about any auto parts store. I think I am going to get after some of my manufacturers to see if any of them supply a 140 degree thermostat, then I will buy a few hundred and sell them off at 300% gross profit and still be less than the marine shops.

lol... the 140 is only 9 bucks at iboats

[duffymahoney]

I thought marine power said 160 was the correct one? My lake is pretty cold. About 65 now. What one should I get?