Re: Yamaha 4.3L Sterndrive Overheating
Yep I just got myself a 1992 Rinker 186 with the Yamaha 4.3L Stern drive and the seller told me the same thing, I had to check to make sure I didn't start this thread.
It is deceiving as most of my friends I/O and outboards have the impeller in the out drive or lower unit, this doesn't, don't try and unbolt it, you will find gear oil and not an impeller.
Also be aware that since the impeller for the raw water is inside the boat with the engine, when using muffs, be sure to put pressure on them and push the water all the way up to the impeller, as you can read on other posts, it only takes about 30seconds of dry run to destroy the impeller.
This engine has 2 pumps, the raw water pump, and the main circulating pump. The Raw water pump is located, if looking at the front of the motor, at the bottom right corner and is driven by belt. This pump does contain a rubber impeller and is supposed to be replaced at least every two years, and they are getting harder to find.
Mine would run all day on muffs, no issues, put it in the water and it would over heat. Here is what I finally had to replace and do in order to get it running properly, today was the first time out with it after working on it for 2 weeks and it finally ran like a dream.
Replaced the Raw water impeller, seller said it was just done, but after inspecting it, it was destroyed and needed to be replaced. He probably had it replaced but ran it on muffs with out pumping water up to the impeller.
Took off the exhaust manifolds and risers to find that someone before me had not put the riser restrictor gaskets with weep holes back on and tried to use some type of sealant to put it all back together.
The Exhaust hoses, 4" up top and 3" after the elbo were worn out and leaked.
The thermostat was stuck open.
Got new gaskets for the risers, thermostat gaskets, Impeller, Exhaust hose 4" and 3".
Filed the risers and exhaust manifolds with a flat file to make the surface smooth again. A recommendation for the boards, and it worked great, found out that someone tried to use a high speed tool and slightly warped the plates, it looked like it might have been leaking.
Did a compression test at this point as it was real easy to get to the plugs with the exhaust manifolds removed.
Also checked and then had to replace the bilge pump and float switch, it seemed to be easier to do it before I put the exhaust back together.
Put everything back together with the new parts.
Finally it will run like it should and stay cool.
I ended up spending about $500 on parts over all, and learned that no matter what the previous owner thinks they know, they don't really know much or want to tell you everything that might be wrong.
I used a local boat shop that knew a little about the Yamaha Stern Drive, and I was recommended to CaptKen in Florida as well, he is a wealth of information and has a lot of the parts for the Yamaha, if he doesn't have it he can get it.
I can?t really tell if the previous owner did the work on this boat, but I can?t image that an experienced marine mech would do such sloppy work, and I also cannot image that the boat ever ran cool since this sloppy work had been done. This reason and the fact these Yamaha stern drives are becoming harder and harder to find parts for might be why I got such a good deal.
Over all the boat is nice and in really good shape otherwise, even with the added expense of the parts, I feel I got a good deal. I will be out with the boat all week coming up.
PurSid -
1992 Rinker 186 w/ Yamaha 4.3L Stern Drive
