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Mercury XR4 150 overheating

C

Crunch

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Hello OB277288 Mecury XR4 150. I have over heating problems thats driving me up the wall. I did a breakdown on the engine upper and lower to clear all passages, replaced gaskets and impeller. Still over heating. Replaced head gaskets as well. Compression check was 119 on all cylinders. She spits water like a champ and at high rev shoots like a garden hose. I even replace the poppet valve. Now heres the deal on the hose at home she doesnt over heat. I take her to the lake and at idle or low speed its only takes a few minutes to over heat like 8 minutes. I drove her this season like this and made due, but now shes overheating at higher rpm... I have the oem manual and read so many things it makes my head spin. I payed 3k for her year before last and hate to give up on her because of so much invested already.

She has the small gear case still btw. I replaced the prop with a new one that came with a plastic ring, the old one didnt have it. I used the ring on the prop btw. Other then that she starts every time and screems WOT, runs a lil rough at low speeds.

Any suggestion will be welcome. I cant afford to put it in the shop atm because I just spent 6k on my dogs vet bill im flat broke.
 
Just changed out the Temp sensor and took it to the dock. It sat and idled for 10 minutes before doggone heat alarm went off again. Tell tale was pushing out water the entire time. How long can 2stroke xr4 150 idle before alarms go off?
 
I replaced the impeller and pump housing gaskets and metal plates it all came in a kit. I guess im going to try and flush the system and run without thermostats to see if it helps with cooling.
 
While checking the popit..... This is important...... make sure the plastic seat that sits in the adapter plate is seated all the way.... Inspect it closely. The outer surface should be a hair below the aluminum.... Corrosion pushes the out. This will cause an overheat.
 
Morning,

When I first bought the engine it seemed to work properly on the engine stand that the man had it on. I mounted it on the boat and ran it again on muffs and everything seemed fine. I then went on vacation and when I put it into the water and drove for a bit it began over heating. While on vacation I removed the thermos made sure all the piss lines were clear and ran it again on the water. This seemed to help but still would over heat after awhile. I discovered the piss stream would stop then it would over heat, so vacation was over. I came home replaced the poppet valve and all seemed fine while running on the muffs. I then went to another lake and low and behold the piss stream stopped again. I was now convinced I had some kind of blockage. Over the winter I tore the entire engine down cleaned all passages inside changed the impeller with a kit and all respective gaskets. In the spring I took it out and yay it didnt over heat I could drive all day and the pisser stream never stopped and was strong. But... I soon discovered that I couldnt idle around for more then 8 or 9 minutes before the engine would overheat. So I was ok with that for this vacation trip. Drive around have fun get to where your going and park.

I then went to another lake just recently and it started over heating not only at idle but at higher speeds now. I checked to see if the pisser stream was running and yes it is.
 
I checked the poppet plastic retainer ring like you said and it was 1/32 raised above the aluminum. I tried to seat it further but to no avail. I removed the thermos ran it on muffs no problem. I then went to the nearest docking ramp and popped it into the water and idled there for 25 minutes no problem. I even ran the engine part open for about 5 minutes still no over heat. I know I didnt fix it correctly but it seems to be working now. I will be taking it out on a few more trips this summer with the thermos out. I know it isnt good to run without the thermos but thats in colder water from what I understand.
 
Need t-stat or restriction washers...cannot run with empty t-stat housings. Running it like this will cause you to search for rebuilding advice or a different motor!
 
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