How To Replace the THERMOSTATS on a MERCURY 135 BLACKMAX engine

[@ProWrenching]

thermostats (PAID LINK): amzn.to/46vtI6C DISCLOSURE: As an Amazon Associate I earn from qualifying purchases.

[@arkadiuszszczurowski4178]

Great content. I really appreciate your steady camera work and your direct and clear narrative with quality audio.

[@ProWrenching]

Thank you!

[@PKD253]

Thank you sooo much for making these videos! I just started working on my boat 2 days ago. I have a 93 Mercury 150 XR6 that I bought towards the end of last summer that worked great before I put it away for winter and I just un-winterized the boat and changed the water pump and its not peeing any water. All Im getting is air coming out the hole. I watched all the other videos you posted and those are going to help me so much to trouble shoot my issue. This is my first boat and Im not very mechanical but I think I can take care of this myself with the help of your videos. If you have any suggestions on why Im only getting air where its suppose to pee that would be great. But for now Im going to take off the thermostats and replace those and then replace the poppet valve. Ive already ran a wire through the tell tale but didnt help. Again thank you!

[@ProWrenching]

Great engine! I’m glad you’re finding the videos useful. It sounds like the problem started after replacing the water pump. I would remove the lower unit and check to make sure that the water tube is installed correctly.

[@PKD253]

@@ProWrenching Wow thank you for responding so quick. Ill pull the lower unit off again this weekend. And see if the water tube came off... When I did put it on it was very lose. I figured there would be some kind of seal to make to hold the tube in place but there wasn't one. Thank you sir!

[@PKD253]

@@ProWrenching I got it working yesterday. I changed the thermostats cause they looked bad. One was broken for sure. But they also were not the same as the OEM I was able to find at my local marine shop. I then ran wire through all hoses and confirmed no blockage. But still no water out of the tell tale and the block was still getting hot. I finally pulled the lower unit back off like you suggested and pulled the impeller off and greased it a lil more. Reinstalled and it worked. Boat is running nice and cool again. I cant tell you thank you enough for such amazing videos. I have no experience working on any kind of motors at all. I feel very accomplished lol Only thing left figuring out how to make my gauges work. Until then, its time to go fishing!

[@ProWrenching]

@@PKD253 Awesome! Glad you got it working!

[@stewpeterson3331]

Hey Pro Wrench -- thanks for taking the time to share all this helpful information on Merc 2 strokes. I've got a 1990 xr4 150. Ran great and then I let it sit for two seasons. Getting it back to snuff. No tell-tale stream. I've done the water pump. Doing stats and poppet next. QUESTION: Is RTV needed on the thermastat housing? Didn't notice you using any on your application. Another issue I've encountered --- I have trim adjustment controls on the motor (under the cowling) and trim controls on the throttle control at the cockpit. The controls on the motor aren't working. The trim buttons on the throttle control work fine (up & down). I noticed your trim solenoids are at the back of the motor near your coils. Mine are in the front of the engine near the carbs. Any suggestions or tests to see if it's a solenoid or the actual buttons on the motor cowling? Again, thanks for taking the time - Stew

[@ProWrenching]

I didn't use RTV- not necessary, although it wouldn't hurt if you wanted to use a little bit on the gasket. I wouldn't bother using it unless there was some extreme pitting and I needed a little help getting a good seal. For the solenoids, I would use a test light and test to see if you're getting power and ground to the solenoids. You may need to have a helper run the trim switch up and down to see if you are getting a power signal to the solenoids. If you have good power and ground going to solenoids and it's still not working, you're looking at a bad solenoid. Glad my videos are helpful- appreciate you watching!

[@ChristopherHargis]

Can you tell me what size bolts the thermostat housing uses on those heads in this video?

[@josemariatrueba4568]

I wonder why you found those washers instead of the thermostats or if the washers need to be kept inside with the thermostats. Water fliw diagrams showa bypass simbol labelling it "thermostat vent groove". Why having those washers with no rubber seals doesn't ause water leakages?

[@ProWrenching]

Some people remove the thermostats and install washers with a hole in it of a certain size that will restrict the water flow to the correct amount in the engine. The washers that I removed were installed in rubber gaskets so they would not leak.

[@josemariatrueba4568]

@@ProWrenching Weird. My second hand 1998 engine came without thermostats but with plain washers without any kind of rubber seals. I installed new thermostats and now temperature gauge reads 1/4 after several minutes idling. Thermostats take care of proper temoerature at low rpm with the assumption that poppet valve is closed while idling in order low water pressure is enough to send water through the whole engine. My engine gets too hot as soon as I pass 3000 rpm and I suspect that poppet valve is locked closed after 25 years running in salt water.. I think that my problem is that poppet valve keeps closed not allowing hot water getting out of the engine at high rpm.

[@ProWrenching]

@@josemariatrueba4568 That may be. You might want to check out my poppet valve video kzbin.info/www/bejne/bnqbhISVoq2thrs

[@josemariatrueba4568]

@@ProWrenching Thank you, I went there and left a comment because my 1998 Mercury 135 gets hot and alarm starts sounding as soon as I increase rpm to 3,000 rpm.

[@Mr22657]

Leave them out!They get clogged up and cooks the engine.Our lake will junk your engine if you leave them in