2001 200 XL Carb Overheat

[dsiekman]

Rebuilt the carbs this spring and was going to put in today. Decided to run it one more time on the hose. Took a bit to get it started but once I did it ran fine. Let it idle maybe five minutes. It was “peeing” from the get go. Temp was up to 200. I remember more like 140-150 last year. What do you think?

Oil injection still in tact. I was getting some smoke so I assume it’s working

 

[Dukedog]

over heat buzzer goin' off?.. hose is not a good test of coolin' stuff.. needs ta be under a load in tha lake.. jmo.

 

[dsiekman]

I’m not sure the buzzer is even connected/working.

 

[dsiekman]

Found part of the problem. The tstats are packed full of corrosion and crud.

 

[dsiekman]

[No message]

 

[Chris1956]

You probably should inspect/clean/rebuild your poppit valve, as well.

 

[dsiekman]

So everything is rebuilt and back together. Same issue. I decided to use my laser thermometer to double check. Port bank was running around 165-170. Top cylinder on the starboard side was up around 195. Middle was about 185 and the bottom was 140??? Makes me wonder if it is even firing.

 

[Chris1956]

Well, if your poppit valve is working, and the 'stats are working and she still overheats, maybe you have a leaky head gasket.

 

[dsiekman]

Compression was 115 across all three on the starboard (hot) side and 105-115 on the consistent, cooler side. Are there any other signs of a blown head gasket? Should I do both sides?

 

[dsiekman]

Ok. Pulled the head tonight. The gasket (seal seems more accurate) was pretty crispy and torn up at the top. The hot cylinder had a clean spot on it, I assume from water infiltration. That said, the water jacket looked pretty clean to me. Any thoughts on what is causing my issue?

 

[dsiekman]

The gasket around the hot cylinder seems intact which is what I’m not understanding

 

[dsiekman]

I’m doing a little science experiment as well. I’m soaking the old tstat in coke overnight. After an hour I could already see some clean metal showing through. If it works I might soar the heads overnight.

 

[Dukedog]

did you do "complete water pump kit"?.. first thing ya do with an unknown heat problem.... no water pressure gauge other than "its peeing?"...…. pistons look normal maybe.. top a little on tha lean side for a production motor.. .can be caused by temp... perfect for a hot rod... no water intrusion.

pics of bottom that side and pics of all three on other side?

 

[dsiekman]

No, just an impeller. Housing and wear plate both looked fine. At the end of last season it was running much cooler.

I will try to upload additional pics. The site would not let me upload from my phone because the files were too big. I need to save them down and then upload. Should have them up in a few.

 

[dsiekman]

Let's give this a shot now that the file size has been reduced.

 

[dsiekman]

Dukedog, the cylinder you mentioned as running lean is actually the hot (middle) cylinder. The picture was just of the bottom two. The top cylinder is pretty wet.

I rebuilt the carbs this season, but I am 99.9% certain that all mix screws were backed out 1 3/4 turns just as they had been when I took them out. I can always check again just to be sure I didn't somehow screw that one up. If that was the issue I am going to be pretty irritated that I went to all this trouble just because I can't count to 1 3/4...

 

[Dukedog]

No, just an impeller. Housing and wear plate both looked fine.

those two items can be a problem.. they can both "look" perfect but actually are not..

WTF is that stuff in that one hole???

 

[dsiekman]

Not sure which hole you are referring to. The crap on the top piston - appears to be an oily sludge. The crap in the head bolt hole is part of the old o-ring gasket. It looks as though it was either in the way when it was installed, or it was crushed to the point of expanding into the hole.

By the looks of the o-ring above the top cylinder (where the tstat sits), it was pretty much done.

 

[Chris1956]

Idle mixture screws mal-adjustment will not cause an overheat. Partially clogged main jets will cause overheat or worse.

 

[dsiekman]

Good to know. The carbs were completely stripped, left to soak in a bucket of carb cleaner overnight, sprayed out with aerosol carb cleaner (I went through one large can cleaning the three of them), then reassembled with a new rebuild kit. Everything went back together nicely, so I am not sure how I would have picked up a clog.