Runnin hot...bah! - Page 4

phatdaddy · #1 12-01-2006, 11:15 AM

I had a similar problem on a 83 150 Merc. It turned out to be a broken ring in the middle port cylinder which is just below the temp sensor. I pulled the power head to check the gasket between the base. changed head gaskets and had the heads shaved, etc. While the heads were off ,I was looking up in the cylinders and noticed the ring gap on that piston was about 1/4 inch.
Good Luck.

TheTinMan · #2 12-01-2006, 05:36 PM

Quote:

Originally Posted by phatdaddy

I had a similar problem on a 83 150 Merc. It turned out to be a broken ring in the middle port cylinder which is just below the temp sensor. I pulled the power head to check the gasket between the base. changed head gaskets and had the heads shaved, etc. While the heads were off ,I was looking up in the cylinders and noticed the ring gap on that piston was about 1/4 inch.
Good Luck.

pd, did you have good compression?

TheTinMan · #3 12-01-2006, 05:38 PM

Quote:

Originally Posted by Seacrets

Are you getting water out the pee tube at 140-150.

yes, thanks.

phatdaddy · #4 12-01-2006, 09:32 PM

Tin,that was the weird thing, I did have good comp on all cylinders. A mechanic friend said the end of the ring must have broke off and passed out the exhaust. The wall of the cyl looked good. I had some other issues with the engine, so I just re-powered instead of going any further. One thing I did learn is to check your t -stats. I change mine every year w/ the water pump. I take a piece of string and put it in the opening of the t-stat and hang it in a pot of cold water. Put the pot on the stove with a frying thermometer. Turn on the heat and watch the water warm up, when the t-stat drops in the pot, that is the temp it is opening. I have found them to be as much as 20 degrees off. I also like to get two that open about the same time.

TheTinMan · #5 12-01-2006, 10:02 PM

pd, what about your water pressure?? I can't see that being high with a bad ring.

I just read the other day about that t-stat test...mine are new.

TheTinMan · #6 12-01-2006, 10:10 PM

I'm 90% sure it's an obstruction. I'm going to check the waterpump and housing...it's possible I cracked the housing (maybe over torqued) when installing the new impellor and I'm sucking air. If that's not it I'm going to remove the...what the hell is that cover between the heads called again???

I don't think it's a major engine problem....she runs like a raped ape! :o

phatdaddy · #7 12-02-2006, 12:59 AM

Tin , you're right, the broke ring would not have anything to do with high pressure. My pressure was 12 to 14 lbs @ 4000 rpm. The only symptoms I had were after running at 4500 rpm for 25 to 30 minutes, the temp alarm would go off, but the gauge only showed slightly above normal. I would stop the boat and turn off the motor. After 1 minute, I could crank it up and run another 25 to 30 minutes.
I would still test the t-stats, even though they are new. I've had brand new ones out of the box be way off . I've also had better results with OEM water pumps & t-stats than "will fits".

Kajun · #8 12-02-2006, 04:26 AM

i found this LU exhaust seal all busted up on mine...think this could cause my overheat alarm? i got one on order today but it wont be here till next week sometime...now i got to wait to see if the new water pump fixed it...or should i just put the LU on with this seal like it is and run it?

phatdaddy · #9 12-02-2006, 12:56 PM

Kajun, the mechanic thought that my seal was bad, he said the exhaust would pre-heat the water before it go to the block and cause higher than normal running temp and maybe overheating. Unfortunatly, my gasket was O K .

Tin, I might have missled you with my first post. I never did get the motor to run normal. I lost a season and spent $1,000 on "repairs". I did everything my shade tree experts suggested and finally took it to the local dealer. A week and $700 later he called and said he got it running "cooler". The only thing he noticed was the broke ring. By that time I had had enough, I loved the V-20 hull and wife said life's too short and she missed a summer on the water( She was a teacher then so we took it out 4 or 5 times a week), so I put a new motor on. That was 12 years ago, so I'm due to make that decision again soon. I don't think you have the same problem because of the high pressure symptom

kamikaze · #10 12-02-2006, 06:18 PM

Kajun:

Given the corrosion on the lower part of your engine bracket have you given any thought that you might be overheating due to salt build internally within the engine cooling jacket? I have used MST Flushclear
( http://www.mstguardian.com/Treatment.htm and found it quite effective at removing salt build up.

It looks like the company is having some trouble with an employee patent issue, but they might still be selling the stuff? It is rather easy to do with the lower unit already off, just mix the stuff up, fill a pressurized 3 gallon bug sprayer and connect it to water pump tube in the midsection with a rubber plug and fill the engine cooling jacket, let stand for 15 minutes and salts all gone.

Kamikaze