Blown head gasket??

[mapleleaf]

I dread starting this one, but I think I have to.... About a month ago I overheated my boat....New daddy brain...Left the fake a lake on and ran her around for long enough to see 210 on the temp gauge. Immediately shut her down, but ever since she's had an small idle surge. I haven't had her back in the water, but have been trying to tune her on the hose and I can't seem to get this resolved. On the hose, without any load, my temps and oil pressure seem normal. Prior to overheating I was trying to chase down a poor idle. I'm not an engine guy!

My plan is to do a short lake test this weekend and see what the temp does.... I cant get at the spark plugs for a compression test without removing the mani's at which point I'd be inclined to just do the head gasket's. I'm wondering what the other dead obvious signs of a blown head gasket would be? Could the idle surge simply be the carb that's been acting up all year?
Recent tune ups include: fuel filter (will do another this weekend ), points, cap, oil/filter, carb rebuild 2010 ( but did run the boat outta gas since I suspect picking up some varnish from the tank in the process)

Thoughts??

[lively]

white fog like smoke out of the exhaust indicates blown head gasket , loss of power w/ shuddering effect . lags during full load , backfires , there are several ways to diag this and 1 is the most important compression test through cylinder , another would be to pressurize the raw water pick up with a plug and a bike pump for a CHEAP WAY lol i have a auto one that i do coolant diags with and all you are looking for is bubbles or loss of pressure .. hope that helps

[wotan2525]

You may also see water or milk in your oil if your head gasket has gone.

[mapleleaf]

checked the oil a few times since, level hasnt risen and it looks clean, oddly I did an oil change just before the overheat. Exhaust on the hose has looked clean and I haven't seen any traces of anything but water on the road while its running.. I'm gonna throw her in the water this sat and hopefully get to the bottom of it, if it's not the head gasket, I'm gonna check timing and have the carb rebuilt. I was warned that the idle surge since the overheat could mean a blown head gasket....

[michael hunter]

At 210 I doubt you harmed the engine. The first things to go are the hoses and rubber parts. It sounds more like a carb problem maybe power valve?

[cadunkle]

230* is approx where damage will start to occur. Temp gauges will not be accurate if in pockets of air, so if water flow was the problem your 210* might be on the low side of what it actually hit.

I would do a compression test and if that indicated any trouble, a leakdown test will help isolate it further.

[bdumas35]

Idle surge can be the result of a lot of things but you may want to look for a vacuum leak.

[bdumas35]

Forgot to give you this link. Good Luck.
http://www.aa1car.com/library/vacleak.htm

[jet]

With points and an old carb (not rebuilt in the last several years) It will be VERY HARD to get it to idle smoothly. GET RID OF THOSE POINTS TODAY!! I had to adjust my points sometimes each time I went out on the water..because the LOBE that your points open-andclose on was wearing down therefore giving me a different spark on some of the lobes top-dead-center. I think its a 6-lobe if I recall and if some of them are worn you will get a good spark on this one and not a good spark on that one..making your engine run ruff! Which means YOU WILL NEVER GET IT SET RIGHT. Spend the $140 for the electronic points and end your frustration. You cant adjust the carb if your points dont have a baseline to work from. since my electronic upgrade several years ago It has started on the first bump of the key 100% of the time since installed and thats not a hold it down turn of the key its a .2 second bump and let off. BOOM Its running. sorry for the rant..I know what your going thru but this is one of those situations you cant get around. I also dought you hurt your motor, it would be very obvious with leaking water in the oil and from the motor if you had a gasket leaking. But you can rent the gauge you need from your auto parts store and do the compression check just to make sure. Goodluck man. Jet

[bdumas35]

Yeah Jet. Points suck. And then there were the dual points days. Whew.

[rludtke]

I agree with Jet, but I think a carb overhaul will also produce performance imporovements for less money (~$25). Look for my other posts about carb overhauls.

Ultimately I think you would want to do both: convert to electronic ignition, and overhaul your carb.

[mapleleaf]

Thanks Rick, I have looked through the carb stuff, I got another rebuild coming. And since I don't know how to adjust my points, elect. ignition too!!

[Ptownkid]

do the carb yourself...i'm about to tackle mine and have a step by step for a 4160

[mapleleaf]

im coming over......