When I ramp up to 4k rpm the temp hits 180 degrees

[Jquest]

Ok...a while back I hit a sand bar. I took it to a guy. They fixed it. Well....it still started to heat up (close to 200). The great people of this forum gave me advise. I ran it hard without STats. Thinking a saltwater flush would work. I put the tstats out on the water and it came back in at 160 constant. Ok....took it out this weekend. IT ran around 160 and jumped to 180 when I gunned it. I'm thinking something was not right with the impeller. To have peace of mind...I dropped the lower unit and took it apart. The thing is brand new. Got a new set of gaskets and put it back together. Now....sense I have the lower unit off....I was thinking of using a pressure cleaner. I was thinking of connecting it to the uptake port where the water pump tube connects to and cut loose. After I take out the STats of course. My engine is a Johnson 150 2stroke 25", 91. It doesn't have a pressure relief value like the crossflow models. ONly the springs that unseat the tstats to allow more water flow. The reason why I'm asking about this is...I think I might have some obstructions in the heads. I don't want to have to take them apart yet. I'm thinking that without any tstats and a pressure cleaner...I can practically remove any and all sand deposits that might be stuck in there. Can I damage anything by using a pressure cleaner,going up her shaft?? Any and all comments would be gladly appreciated.<br />Sincerely, <br />Frustrated. <br />By the way...the telltail has a good flow coming out of it when I'm out on the water and the tstats are brand new.

 

[ob]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Too much pressure can blow the seal on the waterpump discharge tube at the powerhead.I'd just use city water pressure ,which is still higher than the engines normal pressure,and see if you can flush some crud out of the T/stat ports.Flush in both directions being careful with the water around all ignition components.<br /><br />If your water pickup sucked in a lot of sand it could have grooved out the impeller cup as well and decreased the output of the waterpump.<br /><br />I notice you mention in your topic title that when you get the rpms to 4000 that the temp comes up to 180.Is the engine capable of 5500 + at wot?Just trying to insure that the engine isn't over propped causing a cooling issue.

 

[Jquest]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Thx for the quick reply OB. YEAH... it can go up to 5500. I usually don't go up that high. Around 4 to 4,5k the boat moves pretty good. . I guess when I get home today...I"m gonna flush it for a while and then put back the lower unit. See what happens. I'll let ya know. Thanks for you help!

 

[Dhadley]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Are your t-stat assemblys white or black?<br /><br />BTW -- work on the set up when you get this fixed. We need that motor in the 5800 range with an average load.<br /><br />Good luck!

 

[Jquest]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

they are white. 5800rpm That's a bit quick with my boat. I know my setup can do that without problems, but I don't like to dog my engines. Do I need to get the rev up once in a while to clean it out???

 

[Dhadley]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

The old white t-stat assembly has three little "legs" on it that get hung up in the rubber seat. Get 2 new style black ones and I think your problem may disappear.<br /><br />5800 is your target rpm with an average load. Anything less and you start to lug it. 2 strokes dont like to be lugged and will revolt. <br /><br />That doesnt mean you cant cruise all day at any given rpm. You just need to be capable of 5800 with an average load to insure the motor isnt struggling all the time.

 

[Jquest]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

The old white t-stat assembly has three little "legs" on it that get hung up in the rubber seat. Get 2 new style black ones and I think your problem may disappear.<br />

I"m not sure what you mean buddy. THe white T-stats are cylinder types( looks like they are made out of porcelin or some heat retardent compound. Anyway...they are pretty smooth going into the rubbers seats. WHere are the legs that your are mentioning? A pic would be great if possible.

 

[Dhadley]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Oops! Never mind! I was talking to someone on the phone about a V4 looper and still had that on my mind.<br /><br />On your t-stat assembly, if it has the small holes on the bottom they have been known to plug up. We have cut the bottom off so its one big opening. Small debris can pass freely then.<br /><br />Sorry for the confusion.

 

[Jquest]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Thanks for the tip buddy. I had been wondering about cutting the bottoms off. I thought the holes were a little small and restrictive. Also the thing with the debris.....yeah..a couple of sand particles and BAM!!! Your pluged up again.

 

[Dhadley]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Try that and let us know. There are a couple of other odd things that can cause what you see but lets look at that first. Mine are cut for just that reason. We do a lot of fishing in shallow and grassy waters here.

 

[WoodsJ]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Jquest,<br />Something you might also try is a product called Salt-Away, since the motor is used in the salt water this will help to clean out all the passages of any build-up.I use this regularly after the first few times I used it I noticed a difference in the cooling of my motor(88' 120 Rude)<br />Jonah

 

[Dhadley]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Jonah, did it seem to work?

 

[jim dozier]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

After you have checked out the cooling system if it still overheats at higher rpm it is possible that you are venting exhaust gases into the coolant through a leaking head gasket. The head gasket may have started to leak because of the overheating episode that started when you sucked up the sand. Check the compression. You may ultimately have to pull the head.

 

[Dhadley]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

Those motors have O rings instaed of head gaskets. They've proven to be quite good at still sealing even after a severe overheat. But it might still be a good idea to do a compression check.

 

[Jquest]

Re: When I ramp up to 4k rpm the temp hits 180 degrees

well....finally got it. It turns out to have been the seats where the t-stats go into. I was looking at them two weeks ago and saw that it was a snug fit when I pusted in the t-stats.<br />I went down to my Johnson parts place and bought two news rubber seats. Took of the heads(only way they come out), popped the old ones out and put in the new ones. Put everything back. When I put the t-stats back in...they would slide out of the holes. Had to hold them with the springs. I guess since the old material was swollen...with all the bumps and boat jumping around...it was causing the t-stats to get stuck in there and they weren't unsitting themselves as the water pressure came up. OH well..problem solved. I have hope thread helps someone else with their overheating problems and johnson two stroke engines. 8^)