Overheated

[ArtJ]

Thanks Art, I will look into the Flushing Kit.

I suggest using the deluted muriatic acid per Moyers instruction sheet.
If you are going to this much trouble, you want to be sure to clean it
out thoroughly the first time.

Art

[Seabee Chief]

Update

Well, we when down this weekend, started the engine and brought it up to op temp around 150-165 and started closing the by-pass. The temp was slowly rising so I completely closed the by-pass. She was still running hot @ 190-200 @ 1200 RPM. We must have clogged jackets in the engine. So I bought a MMI Flush Kit along with a new impeller, thermostat housing and gaskets. The old housing is badly detererated and may not be making contact with the top of the thermostat. I'm tired of loosing weekends on the dock.
Very frustrating, but we will get there.
This weekend I will start point to point and look at where the blockage may be. But it must be in the Block.

Chief

[hanleyclifford]

Have you inspected the water outlet fitting on the manifold for clear flow?

[rigspelt]

And the raw water entry to the exhaust dry stack? But you mentioned in your original post that you were going to check all the hose connections for a blockage.

[hanleyclifford]

Checking hose connections is not enough. The fittings must be removed and cleaned and a probe run into the casting. It is possible the manifold itself is blocked. I have cleaned some manifolds from engines that had been running that I couldn't believe would pass ANY water.

[Seabee Chief]

Guys,
Thanks for the feedback. I intent to do a full strip down of the hoses and fittings this weekend. Last weekend we were getting water out of the exhaust, but it was infrequent with the by-pass closed. Which leads me to believe not enough water is flowing through the engine. This problem really started rearing it's ugly head when the surface temp of our water got to about 70 degress. Yesterday I recieved the flushing kit, impeller, gasket, new hose and a new thermostat housing. Wow is that what the inside of the housing is suppose to look like! Ours is completely corroded and rounded off on the inside. I will be changing everything out and see if it will make a difference. Then I will perform the flush once I confirm good flow to the T-fitting. Another thing is that my by-pass is an old gate valve that may have a bad washer in it and is not completely closing flow. I will inspect it and may replace it with the small shut off included in the flush kit.
I'll keep you advised.

Chief

[roadnsky]

...Another thing is that my by-pass is an old gate valve that may have a bad washer in it and is not completely closing flow. I will inspect it and may replace it with the small shut off included in the flush kit.
I'll keep you advised.

Chief-
One more piece of unsolicited advice...
Gate Valves have no place on a boat. REPLACE it. (IMHO)

[sastanley]

Chief, what jerry said. Hopefully the boat itself doesn't have any left either, but that was standard practice in C-30's back in the day. If there are any left, they need to come out on the next haul out. dbschulz and I are talking about that offline now. It was a few days work..probably one weekend if you went at it full on. I suggest backing plates 5200'd to the hull & marelon seacocks & thru-hulls fittings

How'd the bypass for the engine get built with a gate valve??

[Seabee Chief]

Ball Valve

Jerry & Shawn,
Thanks for the advice. I believe this is the only ball valve on the boat. Ken from MMI said that some people did this years ago, so it proably is shot. All the thru-hull valves are ball valves and are in great shape. I will change out this by-pass with a ball valve this weekend.
Thanks again,
Chief

[Seabee Chief]

Update and success!

Guys here is an update to hopefully a resolved issue.
I purchased a new MMI bypass kit to replace the old ball valve bypass on the engine and replaced all the hoses. The old hoses were dry rotting.
Then I removed the thermostat and checked it in boiling water. (just purchased) Then I poured a couple cups of Muratic Acid into the head then re-assembled the housing less the thermostat. Started the engine and put the inlet hose into the gallon jug of Muratic Acid. Ran the engine until the jug was empty and shut off the engine. Waited 20 mins then started the engine.
WOW! We captured what came out of the exhaust in a bucket. You couldn't believe the rainbow of colored crud coming out of the exhaust. And I never saw so much water come out of the exhaust. During the whole time the bypass was closed so all the water went through the engine. After running the engine for 10-15 min more, I opened the bypass to bring the engine temp up. She ran cool as a cucumber! I used a laser temp gun to check the head temp. Cylinders #1 & #2 stayed around 100-120 deg and #3 & #4 were around 130-140 deg. It never got hotter. I figured when under load the engine might warm up more, then I can close the bypass if needed. The water temp coming in is around 62 deg. I didn't have time to take her out yesterday for a sea trial. I will do this next time I get down there. Thank you for all your advice and MMI for stocking these parts.
Just one question: Is there any problem with an engine running too cold?

Chief

[Administrator]

Did you use the muriatic acid straight, or did you dilute it with water beforehand?

Bill

[sastanley]

Chief,
Good news! To answer some of your questions:

Yes, running an engine too cold results in more internal deposits..like salt & stuff..you need the cooling water running thru the motor hot enough to keep deposits from forming.

I have a suggestion about the bypass...don't think of it as only open or closed. I have mine somewhere in the middle to keep an engine temp of 160-165. I think with it closed all the way, the engine simply runs too cold, but left open and the engine temp fluctuates quite a bit. If you adjust it while the engine is running you can see almost instant changes in the gauge reading.

I'll echo Bill's question..you should dilute the muratic acid, if I recall about 3:1 with water. Good thing you didn't leave it in for long!

[Seabee Chief]

Acid

Bill & Stan,
With the speed the engine was overheating, I knew I had serious blockages.
So I did use it straight out of the bottle, but only for this time.
I hope I did not cause too much internal damage. All I know is the exhaust would only spurt out a little water every 5 seconds and now it has a heavy spurt every 5 seconds with a smaller one between. Water is flowing like a brand new engine. I'll have to cross my fingers!
Now I know the jackets are clean and will maintain them with the recommended maintenance. I plan on doing the power flush this Spring.
During the diagnosis of the overheating problem, I started installing the MMI alarm kit and snapped of the nipple for the oil pressure sensor. It came out with an easy-out, but I do not want to touch any more fittings until next year
Got to get a few more sails in this year.
I wouldn't recommend anyone using the acid straight but this was an extreme case. This motor sat idle with no maintenance for 4-5 years.
Thanks again for all the advice,

Chief

[sastanley]

Chief, If you had the original oil pressure nipple, those are prone to failure. If you got it out clean (with the easy out ), now all you need is a proper tap to clean the threads for a new pipe nipple (brass!!) - I had to do this with my stbd aft block drain two years ago, as the nipple was epoxied to the block There are lots of pics floating around here of that, I won't repeat them. Check out my "old boat, new owner thread.."

[Seabee Chief]

Nipple

Thanks Shawn,
Will do.
Chief