Seafoarm Decarbonizing... Overheating WOT????

[ngentile]

Hi guys,

So I did the seafoam deep decarbonizing on my 25hp 1987 2-stroke Mariner #0B211923 hoping to increase compression (psi).


I did the whole 1 gallon of gas/oil mix and one 16oz can of seafoam in a small auxillary tank and threw the earmuffs on it and ran it on and off for about 15 min intervals a bunch of times.. Never overheated or anything just blew lots of smoke. Actually ran cool on low idle.

SOOO I decided to take it for a test run on the lake. Switched tanks over to my normal gas tank... used the same 12ft gas line... (probably should have drained the seafoam rich gas from the line before use).

I idled for a little bit and then attempted WOT and just before I got to full speed I had major loss in power... I cut the throttle and put my hand on the pee hole and it was really hot. Cut the engine kicked on my trolling motor and trolled back to the boat ramp.

When I got home I cleared the gas line and ran it with normal gas/oil/b-12 in the tank for a while as to clear any seafoam enriched gas from the system. I will test at the lake again tomorrow.


My questions are as follows:

1 - Would seafoam enriched fuel cause my engine to overheat at WOT? (1 can of seafoam to 1 gallon of gas mixture) (i think yes)

2 - Is a sudden loss of power at WOT a symptom of overheating??? Or phrase it this way - Could overheating cause a sudden loss of power when approaching WOT.

3- I added B-12 CHEMTOOL to my main tank. Do these fuel additives make my engine run hotter than norm? Will it hurt it?

4 - After a major Decarb is it normal to have a little less compression? At least untill all the carbon that's been knocked loose has worked it's way out of the system???

Thanks for all your help.

Nick

 

[latin monkey]

Re: Seafoarm Decarbonizing... Overheating WOT????

i think you probably blew the exhaust cover gaskets

 

[latin monkey]

Re: Seafoarm Decarbonizing... Overheating WOT????

also check the exhaust cover and baffle for holes or cracks

 

[ngentile]

Re: Seafoarm Decarbonizing... Overheating WOT????

Thanks for the quick response.. Don't think its exaust gaskets... I just put new ones in recently and did everything by the book. I did a very clean and carful job on those gaskets. There's no leaking or anything.any other ideas?

 

[latin monkey]

Re: Seafoarm Decarbonizing... Overheating WOT????

well, for the water to be getting hot like that i would think its a blown gasket or crack in the cover letting the exhaust heat it up. I saw your other post about the thermostat but i'm not sure if you have one but if you have good water flow out the telltale then it would be working anyway.

 

[latin monkey]

Re: Seafoarm Decarbonizing... Overheating WOT????

how much did the compression drop after you ran the seafoam and did all the cylinders lose some compression?

 

[ngentile]

Re: Seafoarm Decarbonizing... Overheating WOT????

1234

 

[Mi duckdown]

Re: Seafoarm Decarbonizing... Overheating WOT????

You should check compression. Again. Seafoam is not saviour for all problems.

 

[ngentile]

Re: Seafoarm Decarbonizing... Overheating WOT????

Compression dropped about 5-10 psi... Overall ran well.. Just problem going WOT. I really think it was the left over seafoam in the 12 ft line bc I didn't run it that long prior to the WOT fail. And this motor sips fuel.

 

[latin monkey]

Re: Seafoarm Decarbonizing... Overheating WOT????

let it idle for a while to burn off the rest of the carbon build up and if you take it out just run it at different rpm's but not wide open, if it starts to heat up then go back to idle and make sure it starts cooling down. check compression and make sure its not dropping more and let us know how it does

 

[latin monkey]

Re: Seafoarm Decarbonizing... Overheating WOT????

one more thing, another problem could be that some trash got to the carbs and is making it run lean. HOPEFULLY thats not the problem and its just the seafoam but pay close attention to the water temps

 

[herb boughn]

Re: Seafoarm Decarbonizing... Overheating WOT????

TOO MUCH SEAFOAM??? Think max mixture is 1 can per 8 gal. You may have damaged rings/cylinder walls. take a look.

 

[ngentile]

Re: Seafoarm Decarbonizing... Overheating WOT????

ok.. Just got back from the lake. Everything is normal except for the fact that it will not stay in WOT. When I start throttleing up I can plane out and go miles and miles... HOWEVER when I engage to full WOT it will go for about 5 seconds and then throttle down, then throttle up 5 sec and throttle down etc.

I took the cowling off and put my hand on the block/cylinder head - it was definitely getting hot at WOT - however i don't know if this was what it was doing before and it could be a carb issue.

Note this also - the water temperature at WOT was warm/hot. Almost to the point that I couldn't hold my hand in it.

My guess is it's overheating... may not have enought water circulating.. may be a clog?? don't know..

Any thoughts???

What would be causing a motor from bouncing up and down from WOT to mid throttle?

Many thanks.

 

[latin monkey]

Re: Seafoarm Decarbonizing... Overheating WOT????

i would do a carb and fuel pump rebuild. did you check the compression again after you ran it?

 

[ngentile]

Re: Seafoarm Decarbonizing... Overheating WOT????

Yeah.. compression is fine. Like I said it gets to WOT no problem.. it just seems to be overheating and after 5-10 seconds of WOT it loses power and starts bouncing in and out of WOT at 5-10 sec intervals.

Do you think it's overheating??? Is "very warm/hot" water out of the pee hole normal? (tell you the truth i've never felt the water at WOT until this problem). The pressure from the pee hole seems to be full blast. (i've changed the impeller recently and checked all gaskets).

I have never done a fuel pump job..(replace gaskets and diaphram etc...) it's just that the loss of power at WOT and the bouncing seems all to calculative rather than just an intermittent problem.. that's what leads me to believe it's an overheating problem.

But heck.. I'll rebuild the water pump just to be sure.. I have the parts for it.

What do you think about the overheating? And if it's overheating what could be causing it? I have no thermostat in the engine (bc i'm in Florida) and engine block is almost room temperature at idle... Don't know what to do.

Nick

 

[starcraft1982]

Re: Seafoarm Decarbonizing... Overheating WOT????

The water is normally hot coming out.Just the way mercs circulate.You need to install a temp guage to catch overheating.If compression is good I would probably pull carbs,clean/rebuild them and for good measure,throw a new fuel pump kit in there,too.Seafoam could have broke loose some junk and partially clogged jets in carb or something.Clean it out,install a temp guage so you dont torch it,and run.If running problem persists,get back here and get more into it.good luck.

 

[ngentile]

Re: Seafoarm Decarbonizing... Overheating WOT????

Starcraft and Latin Monkey:

I've been reading non stop since I got home from the lake. It really must be the carbs as latin suggested and then Starcraft solidified it. My cooling system is in A+ condition... pressure is great.. It has to be my high speed jet and yes it was probably that potent dose of seafoam that knocked some stuff loose in the carb.

I'm going to rebuild the carb and fuel pump, test it, and get back to you guys. (which will probably be next weekend).

BTW - where does the temperature gauge attach to? My motor is a pull start. Does it go in line with the water hose? Or attach to the block? Is there a model you recommend?


Many Thanks to both of you.

 

[jtsailjt]

Re: Seafoarm Decarbonizing... Overheating WOT????

I overheated an engine once (alarm didn't sound) until it suddenly shut itself off. After a few minutes of cooling, it would turn over and start back up though. I had a mechanic take it apart and replace the overheat sensor and check the compression and condition of the pistons/cylinders and it checked out OK (about $1200). But then when I tried to run it at high throttle settings, it would start to overheat and sound the alarm so I immediately throttle back and the alarm would stop. The mechanic said that even though the cylinders and pistons seemed OK when cool and at low throttle settings, my initial overheat had slightly warped my cylinders so they generated more friction than normal and were causing the overheating when I tried to use more than about half throttle. Short of an entire engine rebuild, that engine was done and I sold it for parts. Hope that's not your problem but what you wrote sounds suspiciously similar to what happened to me.

 

[chum1]

Re: Seafoarm Decarbonizing... Overheating WOT????

warped cylinders that overheat at high throttle settings?....What?, I have heard of a choked bore and seen wash boarded cylinders from overheat but a warped bore? i could be wrong but you may have been taken to the cleaners.

If compression is good ,spark is good, its probably a fuel issue in the system, sucking air perhaps?

 

[jbjennings]

Re: Seafoarm Decarbonizing... Overheating WOT????

I don't believe B-12 chemtool in 2-stroke fuel is not good at all! Also, you cannot clean a carb whatsoever by adding carb cleaner to the tank, it just doesn't work that way. Cleaning a carb is really easy on a 2 stroke motor---don't be scared at all of trying it if you're even a little bit handy with tools.
Your indicator stream should not be HOT. It should be warm at most. I can hold my hand in the indicator stream on my '84 25xd mercury all day long and the faster the motor runs, the cooler it gets.
Get a $10 infrared temp. gauge at harbor freight and aim it on your cylinder head and other areas while running it with the cover off. I'm thinking it should not get over 140 degrees. ALso, I'm thinking on that motor that the water pump indicator stream will work fine with the thermostat boogered up, so if the temp. gauge shows it's overheating but you're getting good water pressure out the indicator tube, then check your thermostat.
Last of all, due to the way you describe your motor surging, it could be starving for fuel caused by a weak fuel pump, dirty fuel filter, and many other things. After you've checked to make sure your motor is positively not overheating, try pumping the primer bulb while you're running it WOT and see if it stops surging and smooths out. If it does, it's possible your fuel pump needs rebuilding or a dirty fuel filter, etc. Your tank vent could even be closed and cause a very similar situation to what you describe.
Good luck,
JBJ