My engine woes and quest for repower.

[CPlay]

Oct 2020: One of my 2009 Tohatsu MD115A outboards on my Tomcat 24 developed an overheating problem. After performing the usual water pump replacement and thermostat check I discovered problem was more severe than my casual mechanic skills wanted to tackle. I took the boat to the only Tohatsu mechanic in area.

This is when I began to realize the demands Covid put on boating industry. After boat sat at mechanics for a month, shop started on my engine by performing a compression leak down test and informed me that compression was poor and it was not worth trying to fix this 11 year old saltwater engine. I will note that engine has only 1K hours and runs strong. Repair was going to be difficult due to some disassembly would be required. I believe that due to shop being so busy they did not want to tackle a difficult repair when they had a huge backlog of routine (easy) jobs. I can't say that I would do any different if it was my shop.

I brought boat home and continued to to work to resolve the overheating issue. Lots of de-carboning spray that I believe caused the leak down test to indicate poor compression and also could cause overheating. (I run these 2-stroke engines too slow.) Flushed engine with vinegar. Checked temp sensors. Sealed pump housing to riser tube to ensure no leaking. All this was to no avail and I decided the the next step to diagnose issue would be to remove exhaust manifold. 25 bolts that I knew would break and require drilling and tapping. I decided this was not worth it as all that work would likely only reveal the issue and more work and parts would be required to actually fix. Time for new outboards.

Calling around in November to various repower dealers revealed just how busy everyone was. Nobody was really trying to sell new motors. I felt like I was watching an old Red Green show episode. "Sure we can sell you new motors, if we have to, I guess." They could order but it was long wait times for motors and/or high installation price. No dealer would offer anything for my remaining good engine. They would just remove and dispose of.

I decided I wanted new Mercury 90s but investigated others also. The following are just my research and opinion. I hope I don't offend anyone here.

Mercury 90s or 115s. 5 month wait time. Could order in November but delivery would be mid April. One dealer wanted 50 percent down and the other 10 percent down. Really? 50 percent down payment and wait 5 months?

Honda 90s. Available and good motor but by far highest price (too high in my opinion) and small displacement.

Tohatsu 90 or 115s. Available in February. Too new design. Too heavy.

Suzuki 90s. These were my 2nd choice. Good price. Lightest. Good dealer/ customer interaction. Was told wait time was unknown. Probably a month or 2. I decided I really preferred the Mercury higher cu in displacement.

Yamaha. Not best at anything. Not lightest, cheapest, or most displacement.

I ordered the new Mercury 90s the first week of December.

I believe the issue getting the Mercurys is that Mercury has contracts with lots of boat builders. 2020 overwhelmed boat dealers with orders and boat dealer contracts come ahead of repowers.

I just find this interesting that the wait time for a 90 hp motor from a U.S. company is 5 months. It's not like I am trying to buy quad 400s that the boating publications would have you believe that without, you don't have a real boat. Although who knows, maybe 400 hp are more available as I would assume profit margin goes up with engine size. I usually try to buy from U.S. companies when I can, and I believe the Mercury 90s are currently the best engineered 90s, but I bet this unavailability has persuaded potential Mercury customers to the competition. I checked last week and was told mid April is still the estimated delivery.

In the meantime, I hooked a Harbor Freight purchased 12 volt water pump into the flush port and put the pickup hose into water. I found that this extra water flow keeps the engine running like a champ. A temporary and dubious fix but 12 hours run time so far on this arrangement.

If you had the patience to read this far I hope you found this tale entertaining.

-Jeff-

[easy does it]

thank you, I found that very helpful and interesting, i have to admit the last paragraph was the punch line!

[thataway]

Had anyone checked the water pump and also pulled the thermostat? Those would be the first place to check. The water thru the hose, bypasses the water pump.

Also, in the future you might see what Marc Grove at Wefing's Marine in Apalachicola. Marc was a C Dory dealer. (Although your 24 could have been sold be one of several dealers in the SE).

Good luck on the reposer. It has not been all that unusual to see outboards overheat with salt in the passages. There are several cleaning methods. I am a little surprised that the mechanic had not explored those avenues.

[Schuster]

It appears that you have narrowed the problem down to an easy solution. Either your waterpump impeller is faulty, your waterpump housing is faulty or you have a blockage of salt in the intake line somewhere. I'd start with the blockage idea first. Use a product that dissolves salt and let it soak. I'm not sure if Salt-Away works or not for this sort of think. Good luck.

[srbaum]

CPlay,
I'd bet that there is a blockage in the water pump supply pipe. I have had this before in several friends outboards and cleared it by removal of the lower unit, hooking a water-hose to the powerhead flush port and ran water through it for a few minutes. When the lower unit is off, you can also run a snake up that tube (coat hanger wire works). Also, I have removed the thermostats and their housing to allow water to flow out of this area and caught a few bits of sew shell, by doing this, that otherwise caused blockage in the cooling system.

[CPlay]

I appreciate the suggestions. I would love it if I could have one of those head slap moments and say "That's it! I can't believe it was that easy". I think I tried all of these suggestions though. I tried 2 different pump impellers. 2 different pump housings. The passage from water to the pump is clear. I did run a wire up the the tube from the pump to the bottom of the block. I forced water from household hose up the tube and also down from thermostat area. I ran vinegar thru system. I am pretty convinced that I either have a corrosion blockage somewhere in the block or a corrosion hole that is allowing water to exit to the exhaust passage (shortcut) without flowing where it is supposed to. I am the 3rd owner of these engines (and the boat) so I have no idea what the level of care was prior.
I am actually looking forward to the new 4-stroke Mercs. I know they will be quieter and hopefully more reliable. The Tohatsu 115s have proven to be pretty good engines the 4 years I have owned them and more power than I need, but quirky/idiosyncratic (new lower unit due to broken gear on one, new fuel pumps, propensity of one of them to vapor lock, leaking fuel air rail on one, always appeared to have low water pressure).
-Jeff-

[kaelc]

Glad you are still running strong! We just rolled over 1000 hours prawning after Christmas and hope to go a long way with our Honda 150. A good friend decide to repower as well, twin 250 Suzuki’s and kicker and a guide I fish along side did the same. Their twins were just delivered, I think most supply chains are getting caught up, after the Chinese manufacturing lock down last spring. Hope the install goes well and you get a good price for your good engine!