Overheating Volvo Penta 140

[flotsam123]

Has anyone any ideas on this?
I have a Volvo Penta 140A which starts and runs perfectly until I put it into gear. Within a few minutes it starts to overheat. If I slip it back into neutral it cools down but overheats again when I put it into gear again.
I don't see how it can be the thermostat. Perhaps the impeller struggling under load? Could it be weed around the propeller? The inlet on the outdrive is clear and there is no blockage in the filter in the heat exchanger.
I'm lost.

 

[scottie]

Fresh water pump.
Oil cooler prone to blockage weed and or crustations

Not a oheating problem but check s water pumps for leaking on to cam belt pulleys

 

[Peanuts]

Hi

I had a pair of these in my Sunseeker for 18 years, so what would I be looking at.

Well first of all I have some questions for you, how old is the exhaust manifold? I used to remove mine every year, back flush and soak in an oil bath. If you don't clean them out you are looking at about 5-6 years before they corroded out in the elbow.
The problem with the corrosion is at number 4 cylinder where it eats away around the exhaust port, Volvo have a mod that inserts a ring into the cylinder head, this can be done in situ without having to remove the head.

Whilst the manifold was off I removed the oil cooler, first job removing all the bits of shell on the inlet side then after that de-scaling the tubes.

I would of course have checked the impeller and the water filter gauze as this is basic stuff. My next move would be to check the points and timing - an easy job to do.

Hopefully this should give you something to go on, let us know how you get on.

If you require a list of all the engine spares crossed over to car spares numbers let me know and I will forward on to you.

Steve

 

[flotsam123]

Thanks so far
Additional information.
The engine is a recently installed reconditioned unit. Exhaust manifold is almost new. The oil cooler is certainly a possiblity but would weed have got past the filter so easily? Points are fine but I haven't checked the timing.
I am trying to understand why it runs perfectly in neutral?

 

[rafiki_]

Could the heat exchanger be silted up?

 

[Peanuts]

You say it is a newish reconditioned engine, I assume it has been running OK without this overheat problem?

Regarding blocking of the oil cooler, I was always amazed at the amount of bits of barnacle shell that made it's way pass the strainer filter and wedged itself in the cooler tubes, a WD40 spray can tube (the tube you can put in the spray head) was just the right size to poke the stuck bits of shell out from the other end.

Forgot to mention, although hanging over the engine and the exhaust manifold this can be done on the engine, just by removing the cooler end caps, (not the best of jobs) and using a mirror look under the cooler to see if blocked, otherwise it's remove the filter, then the large nut and end caps then off with the cooler body. You will probably need to slacken (or remove) the 2 x 10mm head bolts under the manifold where the cooling pipe goes into it and until swung out you won't get the bolt out that goes through the cooler body. Hope that sort of makes sense!!

Forgot to mention I did once have a problem with a thermostat, can't remember the symtoms though - age related sorry.

As always let us know how you get on.

 

[oldgit]

"Exhaust manifold is almost new."

The exhaust manifold and the riser are two different things.
This riser is a example of corrosion that can occur.Until it was stripped off(whereapon it fell to bits) blockage was not obvious.

 

[A_8]

How about a broken or not correctly seated seawater intake tube, the one that goes into the outdrive.

 

[Peanuts]

"The exhaust manifold and the riser are two different things."

Completely agree, however on this engine the manifold and riser are a one piece casting.

"How about a broken or not correctly seated seawater intake tube, the one that goes into the outdrive."

Once again I agree with this, especially if still the aluminium one, they normally corrode up on the inside face, restricting the flow but as always I have suggested the areas to look at that gave me the most problems. I only chaged one of these but have changed many exhaust manifolds of this type due to corrosion.

 

[flotsam123]

Thanks for all your input. There are certainly plenty of ideas.
I have had oil coolers to bits in the past and I hope that isn't the problem, although it is possible.
The intake tube sounds good although I don't see why it would work ok in neutral if there was a problem there.
The engine has run well in the past but I have not had that much use out of it. It is only a recent problem.
I suppose the heat exchanger could be full of sucked-in rubbish. That's something I hadn't thought of.
I will also check the impeller.

As a matter of interest if I disconnect the intake hose inside the boat or remove the impeller, does the water in it drain out of the sterndrive or is more drawn into the boat? I've never disconnected this with the boat still in the water. I don't want to sink!

Thanks again for all your ideas.

 

[Peanuts]

Hi

You are OK to remove the impeller whilst on the water but I would not be looking at removing the inlet pipe, although it is not as low as on a 290 transom shield I still wouldn't be doing it, unless you want to be checking your bilge pumps!