Episode VIII: Found the overheat cause; An explanation of outboard cooling 2002 Mercury 90 hp

[@garyradtke3252]

The poppet valve is actually to dump discharge water past the thermostat for high rpm engine cooling because the engine produces much more heat at higher rpm for more cooling and the thermostat is to limit water flow past the cylinders to force the engine to heat up at low speeds for smother operation and drivability. The poppet usually opens around 2000 rpm depending on the engine. The salt/corrosion build up between the poppet seat and the block can squeeze the seat enough to shrink the hole for the valve and bind it. This corrosion expansion can break housings and is what causes fasteners to seize in their holes.

[@ChristosChios]

Thank you very much for this precious information! I'am facing exactly this problem at high rpm and my mechanic could not realize what the problem is. Now I understand. This is exacly my problem. Many thanks again and again!!!

[@Jt-cc9qz]

Thanks for posting this video I have been trying to gain an understanding of the cooling system on a 225. Horsepower Mercury EFI it was really great to be able to see all of the channels in your outboard, and it really made it impression as far as replacing the poppet valve, job well done ! On my outboard, above the water pump, there is supposed to be a strainer before the water goes into the main block , was hoping find that more information on how to access it. Thanks for the video.

[@jleech]

This is truly a handy video! Just watching it over and over again to visualised my motor innards. Thanks heaps from Australia!

[@ChristosChios]

Thank you so much for your expanatory videos. I have this outboard and i don't mean to change it for a new one. I want to keep it as long as possible. Excellent job!

[@jolssonusa]

Great explanation. I had an issue with the tell tail only dumping cold water. Your video help me solving the issue. The previous owner had ran the outlet from the water jacket to the tell tail instead from the top of the power head. As you mentioned, no diagram in the handbook. Many thanks

[@RUDYAKAHALIBU77]

Question, when you remove the impeller housing I didn't see any nylon washers on your impeller or keyway on your impeller that's probably the reason why the water is not flowing because the impeller is not spinning.

[@robertrampolla2782]

Thank you for this video. There is very little info on these motors. I own a 2002 75 hp model so it is the same design and wanted to update my outboard this spring. You saved me some trouble.

[@SugaryPhoenixxx]

I don't actually own one of these motors I was just flipping through your channel & since I am a bit of a gear head I just checked this out. I am glad you posted your solution on KZbin because some day some guy is going to have this same problem with this same motor & he is going to google it & he will hopefully find your video! I know my ass has been saved a few times by KZbin videos of other people solving my problem for me! lol

[@michaelsweet1898]

today may be that day for me !

[@jamesrahn8339]

Heck ya that's useful! Thank you for posting this!

[@stevehillebrand6612]

Thank you very much. Your clips really helped me so much with my identical Merc. Would have loved to have you as my neighbour here in South Africa😜. Cheers

[@christopherderaps]

Outstanding video and instructional information. I'm having an issue with my bottom cylinder on my 90 and I noticed that when I removed the plugs to check them there appeared to be steam slowly coming out of that cylinder. With no head gasket on this block type, it can only be the exhaust plate gasket allowing water into the cylinder right?

[@TheFritz423]

Maybe. It's easy enough to remove the exhaust plates and check. Hopefully though it is just vaporized fuel/oil mix from lack of spark.

[@kriskoteles]

I am having the same problem but with a rebuilt powerhead I just installed, only turned it over to check if it will run and tried to dial in the idle and it cut off. Pulled the plugs and the bottom one had water on it. Did you figure out what it was?

[@christopherderaps]

@@kriskoteles I replaced the exhaust gaskets (which is basically the head gasket on this model) and after they were all done it still ran but bucked. Wound up giving up and selling it a couple months ago.

[@matthewstevenson1267]

I have a merc 200 2 stroke started getting hot out of the blue one day. I suspect a poppet has salt corrosion but definately glad I watched this, I'll replace the poppet seat and Tstats while it's apart

[@germancarfan360]

I have a Merciry Optimax 150 V6 2 stroke which is currently suffering with heating issues, Im getting a reduce throttle alarm then overheat alarm eventually. Ive just changed my impeller, which was faulty, but its still persisting with this alarm, my next port of call is change the poppet valve, have you done so already and dis it fix the issues?

[@matthewstevenson1267]

@@germancarfan360 yes. Didn't fix it. Pulled a head, not good news. Hope yours is a simple fix.

[@chrisduesterbeck2503]

Thank you! New to boat motors. Very helpful!

[@seanleonard2912]

I'm busy with a 2004 engine,just serviced the water pump and found tons of corrossion,now wondering if i should be looking to replace the termostat and popet valve? Thank you you video was very insightful.

[@TheFritz423]

Yes. Just understand that every fastener has a chance of breaking on an older engine, especially if it's been run in salt. If your poppet valve has a removable seat, I would clean out the corrosion under it and replace that as well.

[@seanleonard2912]

@@TheFritz423 ,thank you,I will be doing this.

[@x--LeethaL--x]

What was symptoms? Shut down after long use? Barely turn over until sits for a long while? Water in cowl?

[@byknutz]

Great info and thanks! So it was sending a long steady beep? I'll look for an update

[@RogersFixItBarn]

I think you got this whipped now to put it all back together

[@timduffy7]

Big help to me, Big thanks

[@noza6692]

Do you know the part number for the gaskets? one that square panel seems not listed in the catalog anywhere.

[@TheFritz423]

www.marineengine.com/parts/mercury_marine_parts/sn/0T428176/1090412ZD/3374_170

[@riccilong81]

Buy a can of Corrosion X. It's worth every penny. That stuff works great at protecting and penetrating corrosion and nearly vanishes it away. Also, Why didn't you use heat/penetrating oil on those bolts before you broke them?

[@joshuagreene9976]

Did replacing the poppet carrier fix your issue?

[@TheFritz423]

it wasn't so much the carrier as the aluminum corrosion underneath it that was pushing in on the carrier and making the poppet stick. That and the corrosion around the water tube were the main culprits.

[@EternalMaster12]

@@TheFritz423 my 2002 150hp mercury flows water on idle but no tell tale flow on full throttle. Do you advise buyin poppet valve and carrier? Or just clean around carrier and see what happens? Thanks for your vids!

[@germancarfan360]

@@EternalMaster12 Did you solve your fault in the end? poppet valve replaced?

[@ChienNguyen-xg1xf]

It is great video

[@pp-sw1lx]

remember .. 24c grease is your friend especially in salt water applications

[@raymondlamarr3251]

AT 210 IN VIDEO NO KEY IN KEYWAY IN THE WATER PUMP ???

[@mrmacias4217]

Hi👋