Overheat - now top speed reduced

[SuperDave]

I had an overheat on my 20i this past weekend due to burnt impeller. Temp guage showed 220-230 when alarm went off.

Replaced impeller and everything seems to run fine. Only issue is it seems my top speed is down. Last week top speed was around 46mph and now its 41.5 or so. RPM's are at about 4600.

I have not done a compression check yet but I can't believe 220-230 would cause any major issues.

Any thoughts/experience out there?

Thanks,

Dave

[chpthril]

230F is hot for a boat, but not hot for an engine. Don't know why your top speed is down.

[spharis]

You are probably fine. Are you burning oil?

[Domsz06]

when i overheated I also had fuel pump/fuel filter/ and fuel/water separater issues. Lack of fuel could kill your top speed.

[spharis]

You may want to pull a couple of plugs and have a look as well. I had an instance of some rough running, and reduced top speed, and when I pulled a plug, the ceramic was warped indicating a very lean mixture. I am jetting up my carb before this weekend. I am trying to figure out if it is because I had a clogged fuel filter (which I replaced) or if the addition of the inline and the fuel flow pickup are causing the problem. I think the carb just needs rejetting though based on the way the boat starts, runs, and never bogs.

If you do pull a plug, snap a photo or two and post them up. Some diagnosis can be made from that.

[SuperDave]

thx

Thanks guys, I check those things out.

My biggest worry is head gasket. I'll pull the plugs and check them out and do a comp check as well. Changing the fuel filter is probably a good idea too.

It's fuel injected so no options for adjusting mixture but it could be leaning out on lack of fuel like you said (clogged filter).

[Domsz06]

your head gasket shouldn't be a huge problem. it didn't get that hot.

[Tequilasun]

I'd be very surprised if it was a Head gasket.

[SuperDave]

head gasket

I agree. I'm sure the speed issue is just coincidence to the heat issue and I'm just being paranoid.

[Armstrong6]

Dude, you could have a potentially serious problem. These are open water cooled systems. What that means is when water is not under pressure it boils at 212 degrees F. Your car is different because it is under pressure and has anti freeze, which increases the boiling temp to around 260 degrees. If you were seeing 220 to 230 you may very well have a problem with head gaskets or other areas. I would definitely take it to a service shop or at least discuss it with a qualified mechanic.

[Domsz06]

I would not be as concerned. The water in your system is still under some pressure. Plus your temp gauges are only accurate to around +-10-20.

I had the same problem in mine over 200 hours ago. It's fine now. I even had to limp back in gaurdian mode.

I would check your oil, check your compression and if the compression is fine, and the oil has no water in it, your head gaskets are fine.

I'm sure sp or chpthril will chime in on here and say something similar.

[spharis]

Armstrong you are correct. However you are missing one thing. The system is open which means when/if water was to boil, then it would have room to expand right out the exhaust. You aren't as likely to blow a head gasket, or warp a head like you would in a car. In a car or a closed system, then steam has no where to expand...something has to give.

[Domsz06]

good call sp, I forgot about adding that.

[chpthril]

Armstrong you are correct. However you are missing one thing. The system is open which means when/if water was to boil, then it would have room to expand right out the exhaust. You aren't as likely to blow a head gasket, or warp a head like you would in a car. In a car or a closed system, then steam has no where to expand...something has to give.

also keep in mind, with an open system you are always replacing the hot water in the engine with cooler lake water, where as in a closed system, if you can't cool the coolent in the system, it will just get hotter because the same water just keeps getting circulated.

I have seen many a car come in with a bad radiator fan motor and the engine temp up around 280-300 and leave with no problems. It's the ones that come in with leaks that have no coolant in the engine

Dude, fix the cause of the hi temp and you are good to go