Tried EVERYTHING but Volvo Penta 230A overheats

[dc10tech]

Hi all,

I sure hope someone here can help me out. My 91 Glastron Volvo 230A is overheating at high RPM? I know, this again?! I?ve tried everything guys.

1. I changed out the impeller.
2. I removed the exhaust manifold to inspect it. Found it practically brand new. No rusty chunks inside and the zinc plug looks ok. These exhaust manifolds don?t have risers, so I flipped it upside down and stuck my water hose in the intake hole and watched as the manifold filled up. No water ever entered into the exhaust ports. Not even a trickle. The water filled up the water jacket and started pouring out of the end where it ejects out the exhaust pipe end as per normal.
3. The thermostat seemed to be working well but just to be safe I popped and locked it in the open position.
4. I flushed out the heat exchanger. Removing the line that leads to the exhaust causes it to instantly drain. There is no restriction. I placed a water hose in it at high power and the thing drains water out really fast. It even looks nice and clean inside. The cooling lines that run to the engine seem good too because when I flush that out it also drains like a champ.
5. I replaced the gasket to the water neck on the outdrive.
6. The outdrive water neck was slightly corroded, so I sanded it down lightly to make it smooth and applied a thin coat of sealant around the neck so it would mate well with the S hose. That failed miserably too
7. I considered that the problem may lay in the seals of the outdrive. Some have found the plastic bushings around the water tube (where the pivot yoke is) to break or develop pin holes that cause air to be sucked in. I can?t afford an outdrive rebuild, so I drilled a nice hole in the bottom of my boat and installed a water intake strainer bypassing the entire outdrive system and gooseneck and plumbed it straight to the impeller intake side.
8. No, there is no water in the oil
9. Yes, it actually is overheating. It is not the temp gage. I know it is because it will lose power and the heat exchanger overflow and cap will start spewing yellow coolant steam

None of this helped in the slightest. The boat idles fine all day long but put it up on plane at anything above 3000 rpm and it shoots up to 250 degrees in under a minute. The engine sounds strong. Starts up real nice and easy, though it takes 1-2 minutes to warm up and stay running at idle (it's carbureted). This has always been a freshwater boat. One friggin time I took it to the salt and while cruising at 4200 rpm I heard the rpms drop and the engine lose power. When I checked the gages I saw it was very overheated and I shut it down to let it cool. A few minutes later it started right back up again but has never ran cool again. Only other thing that was done was that one time the points broke inside the distrib? I replaced them and the condenser. What in the world is left for me to try? I?m about to get laid off and I just need to sell it. I hate selling it broken when it?s a strong running boat. I don?t think I?ll get much for it and this is not the time for me to take a loss this big. What a waste.

Any suggestions would be immensely appreciated?

 

[dennis461]

No Title

Did you try this? You'd be surprised how a small gap in the wrong place destroys a pumps ability to pump.
Look at the gap in my old pumps end plate.

On My boat, I connected a clear plastic hose to the water pipe that runs to the exhaust header. It runs down low in the bilge then up over the transom. I can look at it while driving the boat and see how good the pump is working. Once I saw the water level go DOWN while on plane, I knew this was not an engine problem

 

[dc10tech]

Thanks Dennis. That's an awesome find but I just looked and mine and it looks fine. Nice and flat across the face. I just can't seem to find what the heck is causing this. I'm going insane.

 

[dennis461]

Do you have the right gaskets on the pump? Too thick will cause loss of suction.
What kind of through hull did you use? It has to scoop up water, a simple pipe sticking down won't work on plane.

 

[Glastron_V210]

The only suggestion I have is to get an infared laser temp gun and whenit get warm, shoot different parts of the engine from the intake tract to the outlet. This may tell you where a blockage may be.

Have you run it on a hose? Lots of throughput water?

Reread your post...heat exchanger...you're fresh water cooled?

If so, do a coolant system leakdown pressure test. I've seen engines (sorry to say this) with blown head gaskets/cracked heads where the cylinder compression leaks into the coolant system, causing a vapour lock. You may very well have had an initial overtemp due to some reason (I've seen where a piece of plastic or weeds will cover the intake port, shut off the engine, it disappears and solves the problem) which did in the head gasket and now you're seeing similar symptoms with a different cause.

I'd put a pressure guage on it and see if the pressure in the cooling system comes up BEFORE the temp increases.


Chay

 

[jerryjerry05]

No Title

It's overheating in the water.
There is a connector #28 on the drive that can suck air once it's up on plane.
Check it. Also the #23 the seals can go bad and suck air.

If these check out??
Then the manifold(even though it seems good) or the heat exchanger.
You flush the oil cooler?
One more,the water pump. There is a cam in there #5 that wears down, it can cause that problem too.

The startup: they are cold natured and that's normal for the 4cyl.

 

[dc10tech]

OK!... thanks for the suggestions guys. I think I got it licked. Tried many of the things you guys talked about. Went to the lake for an all day test extravaganza with tons of tools and supplies. As I said I had already changed out just about everything there was to change. I did go out and get a clear water hose to have a visual of what was going on. When hooked in to the outdrive water intake, I did see more bubbles up the pipe than when hooked to my new thru hull intake strainer on the bottom of the boat that bypasses the outdrive completely (by the way... I highly suggest this mod rather than tearing apart the outdrive to fix seals). Plugging the hole at the bottom of the of the outdrive improved that significantly till there was little difference between the strainer and outdrive, but still the strainer WAS better. I took laser thermometer reading all over the place and saw no significant temp increases. After a couple of hours of timkering and getting nowhere and screaming to the heavens, I removed the heat exchanger (radiator) cap and saw the antifreeze fizzing... not bubbling... fizzing. The water temp was through the roof. It was not a bad indication. At that point I got mad and decided to just floor it for about a minute with the cap off. The wife started yelling that it was doing a strange splurtting from the open hole and so I returned to idle instantly and received for my reward a giant volcano of hot antifreeze. When I shut down I looked in the engine compartment and found about 1/2 a gallon of coolant in the keel and the heat exchanger (radiator) bone dry. Luckily I brought supplies for every eventuality and filled the thing with fresh distilled water and antifreeze... IT TOOK MORE THAN 2 GALLONS!!!!! It just kept sucking it up! I came to the conclusion that there was an air pocket trapped in the cooling system somewhere and that was affecting my cooling. Basically I was cooling with steam in some parts of the engine. I ran the boat for 4 hours afterward and it never went above 205... for my boat... that's what it seems to run at. The only time it went higher is when I was on wide open throttle (4500 rpm or more) for more than a couple of minutes. I think that's normal right? I mean, what engine wants that much power for too long? What do you guys think? Problem Solved?

Thanks for all the great suggestions. I was about to give up on it and sell it as is.

 

[jerryjerry05]

If it runs at more than 180 it's too hot.
If it did the same thing in my car???
I'd say the radiators shot.
So you have 3 things you can do.
Replace the manifold or the heat exchanger or maybe the circ pump.
My first guess would be the heat exchanger, even though you say it was flowing ok.
You can't see inside it or the exhaust manifold.
They are both probably 24years old and one or the other needs replacing.

You test the thermostat?