1974 85 hp evanrude question

[kirmy22]

New here hope you all can help. Just bought this boat and motor the guy that had it said when he bought it he took it and got it tuned up and serviced, took it to the lake and headed out, about 10 min. into it an alarm went off and it died he and his wife ended up rowing it back to the dock and his wife said sell it so now I have it . havent tried to start it yet he said it starts and runs great till it gets hot. so Im guessing it the water pump, any ideas. Repair manuel is on its way. any input would be great , thanks.

 

[emdsapmgr]

Re: 1974 85 hp evanrude question

You are going in the right direction. On any engine which is new to you, it's good to replace the impeller. That way, you know that this critical item will not fail when you are out boating. I'd also pull the thermostat housing apart and replace the thermostat (called a vernatherm on that engine.) You can have a great water pump, but if the vernatherm is stuck shut, the engine will overheat at idle. Also, check the nylon pressure valves to make sure they are not deformed. When that engine starts cold, you will get a little exhaust out of the two exhaust relief ports at the top rear of the midsection. After a minute of running, the thermostat will open and you will get a fine water mist along with the exhaust. You can see water droplets on the palm of your hand. That's normal.

 

[ezeke]

Re: 1974 85 hp evanrude question

Since the engine died during the overheat, it's a good chance that the head gasket on one of the cylinder banks is damaged.

You would be ahead of the game if you purchased a model-specific service manual for your motor. They are available from the publisher at http://www.outboardbooks.com/index.cfm?fuseaction=search.main or you often find them used on Ebay: see http://cgi.ebay.com/ebaymotors/1974...50119883605QQptZMotorsQ5fManualsQ5fLiterature

 

[F_R]

Re: 1974 85 hp evanrude question

Since the engine died during the overheat, it's a good chance that the head gasket on one of the cylinder banks is damaged.

You would be ahead of the game if you purchased a model-specific service manual for your motor. They are available from the publisher at http://www.outboardbooks.com/index.cfm?fuseaction=search.main or you often find them used on Ebay: see http://cgi.ebay.com/ebaymotors/1974...50119883605QQptZMotorsQ5fManualsQ5fLiterature

Agreeing and adding to what ezeke said, since that motor overheated to the point of siezing and quitting, the head gaskets and exhaust cover gaskets are certainly damaged and must be replaced. Failure to do so invites water intrusion into the powerhead where it doesn't belong and will finish off the job of destroying it.

Once you get the exhaust covers off, you will be able to see the sides of the pistons and rings. Rarely do they survive without scuffing. That is where you have to decide what to do with it.

I suggest you buy a complete water pump kit from a dealer. It will include a new plastic housing with stainless steel liners as used on newer motors and is far superior to the aluminum housing used originally on yours. We had many failures with the old pump and many burnt-up powerheads.