1988 25hp Johnson (Still need a little help)

[Pony]

I'm pretty much posting to see if my troubleshooting is correct here.

Today after running the motor for rought 5 minutes at WOT I retrieved the boat and then was getting prepped to go home, just happened to touch the block and it seemed rather hot. I could hold my hand on it for a good 10 seconds before it got uncomfortable. I could still keep it on longer (I know its been said here, just can;t for the life of me remember the amount of time a hand should be able to be kept on the block)......I was thinking about gettin some temp sticks. 163F is considered overheating correct?? I also am wondering, since the motor is still peein fine if the t-stat is stuck closed. Although at this point I am unsure as to whether its even running too hot.


Also at one point today the motor died on me. I had run it awhile, fished, run it, fished, run it, fished, and then I went to start it again. When I tried to increase throttle it died. Restarted to the same effect 4 times until I disconnected my hoses and then reprimed the system. It ran fine the rest of the day. Am I correct to assume that I had an air leak due to a faulty connection somewhere??....the tank is new as of today and its possible I didnt fully tighten a fitting. I ruled out carn problems as it ran great besides that, no matter the speed without a hiccup or a stall.

I'm beginning to think that it was just a fluke bad connection that got loose for whatever reason, and than the hot block is just me not knowing what a normal block should feel like.................as I said its still peeing a stream of water.

 

[SpinnerBait_Nut]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

Hey Pony, don't know how hot it was there today, but maybe a vapor lock or do outboards have them?

 

[Pony]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

Mid 80's at most.......I used it all day Sunday and it was 97 then. I too am not sure if outboards can vaporlock.........

 

[ob]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

vapor lock is a dynamic possibility on any carbureted engine.I don't think it was your issue though as most would occur in under hood temps in excess of 200F.Since you noted that you could rest your hand for several seconds on the block,I'd rule out the vapor lock and tend to lean toward a loose fuel connection.They happen.It happened to me once.Fitting was simply not pushed on to its locked position.Best advice from hear I can offer is to see if the symptom reoccurs with known sealed fuel connections and no other fuel/air line leaks.

My advice on determining the engine running temps ,since if yours is overheating it's likely marginal,is to get one of those 163 thermo melt stiks you mentioned above ,and check several locations of the heads and block after a warm up run.

 

[Pony]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

I will re-check and retighten all my fittings today. I used teflon tape when I did them yesterday.......The fuel line in new within 3 months, and it never had any issues with the old tank. I will start there.

I will get a thermo melt stick............Any chance they have them at an auto parts store??

 

[Pony]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

I should also add that I took the plugs out and they are not oily, but not clean like they would be if water was getting on them. The carbon is still on them. I have as a result ruled out a leaky head gasket...

 

[DJ]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

163F degrees is borderline, especially after a cooldown.

Check your fuel connections, as stated. A lack of fuel can cause heat by running lean.

Teflon Tape? You're inviting air leaks with that stuff.

 

[tashasdaddy]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

pony if you can hold you hand for a 4 count you should be ok, if not then you're hot.

 

[Pony]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

Dj I am not sealing the connections with teflon tape, I wrapped the threads in it before I tightened the connector to the tank.

I just bought a water pump kit, just because I am not sure when it was done last and its good practice anyways. I was looking at putting a new tstat as well as long as I am gonna put a new impellor in. On the iboats parts, what is the difference between the thermostat and the thermostat kit?? The kit is 2x the $. I'm looking in my manual..............Do I hae to remove the head on this to get at the tstat? I figure even if I am not currently oerheating, I might as well do the cooling system now just for peace of mind sake.

 

[tashasdaddy]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

peace of mine is always good.

 

[Pony]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

Sorry to bump this up....but........anyone know the difference between the thermostat and thermaostat kit? Does the kit just have the seal along with it?

 

[ob]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

One probably contains a new pressure relief spring and gasket.I'd get the kit.Those parts get pretty crusty over a period of use.Since I only install dealer cooling sysytem parts on my engine ,I can't speak for the other kits available.

 

[Pony]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

Thanks ob. Since I am thinking that the tstat is the current problem anyways I am gonna run to the dealer for it today so I can get one sooner and maybe put it in right away. I do still have a waterpump kit on the way, but since its still peeing I might wait till the end of the season to take care of that.

Getting some temp sticks too

 

[Paul Moir]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

Why would you buy temperature sticks when you've got a great excuse to buy one of those IR thermometers? They're getting pretty cheap now.
The only problem is they don't work on shiny aluminium unless you reset the emissivity constant.

 

[Pony]

Re: 1988 25hp Johnson

Re: 1988 25hp Johnson

Ok.......put new tstat in. First time I have removed a cylinder head water cover so hopefully its on correctly. Not leaking water anywhere . Seems to be running a bit cooler. I let it warm up for a good five minutes and could hold my hand on the cylinder head for 15seconds. One thing that I noticed that after a min or two after shutting it off (same amount of time it sat before at the lake when I shut if off) I could hold my hand hand on there forever. So hopefully I nipped this problem before it became one. Forgot temp sticks

I think I may add a temp sensor to the head.....anyone have a part # for that?? or a cost??

I used BRP dealer parts for the tstat, seal and gasket fwiw. Its peeing water like before, maybe a bit better.

 

[Pony]

Re: 1988 25hp Johnson (Still need a little help)

Ok, ran it again for a bit today to verify yesterdays results. Warm tell-tail stream is a good sign the tstat is opeing correct???

The water stream stopped for a second, but I think it was because the muffs were slipping off the intake, as soon as I moved it the stream was back. Still gonna put a new impellor in whenever it gets here. But am I right to assume that I have a stream and tstat working?

 

[ob]

Re: 1988 25hp Johnson (Still need a little help)

Hard to verify whether a cooling system is operating properly without running the engine up to speed in water under load.A warm tell/tale stream will at least tell you that the t/stat assy is restricting flow and throttling.what flow the pump is sending to the engine block while running on the muffs which get their supply from a pressured water source.What you can't tell by running on the hose is whether the spring loaded bypass feature will open fully at speed and provide adequate flow and then return smoothly back the its water throttling position once the engine slows down or whether the pump will move adequate flow without a pressured intake source.Always best to replace the components before malfunction occurs,for obvious reasons.

 

[Pony]

Re: 1988 25hp Johnson (Still need a little help)

thanks ob, thats kinda what i was thinking. Luckily the new water pump kit arrived today so I dug in.............

The old impellor............sadly enough..........looks to the original, as none of the bolts i removed had tool marks on them. The fins were very flexible, and one of them was looking like it was wanting to maybe come off soon. There were some tiny tiny pieces missing from it as well. Got the new one in with all the seals.......only problem is I now need a little nylon keeper on the shift shaft so that i can shift again. I havent started it yet, the neighbors hae a baby and its late, but I'm hoping this will be the real solution to a possible overheat.