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Hi Guys,

I think I may have a problem with my 1999 Volvo Penta 5.0GL in our Sundowner 205

When we took it out in the summer we had a good run through after acquiring it in the winter season.

Firstly when we took it out of the marina we started hearing beeping, looked down and saw the engine was over heating, ahh what do we do??
So we turn the engine off and let it cool down and then turn it back on after about 10 mins and slowly idle it back in, then as we were coming in the engine temperature suddenly dropped and then it clicked that as we had the thermostat changed it must have been closed and opened on the way back. But anyway we go and in and have a good check and everything seemed fine.

So we go back out and throttled up a bit more to get it moving and after about 5 mins I smell a burning smell and looked behind and saw smoke bellowing out of the engine bay , the 4 letter word beginning with S was shouted and turned the engine off yet worked out it wasn't a fire as the automatic extinguisher hadn't gone off. So we leave it a bit and open up the cover to find one of the rubber hoses connecting the exhaust riser to the exhaust tubing almost melted through. So we slowly make our way back and back in the marina have a feel around, touch the left riser, my hand was almost singed through a glove and the right one was way cooler. So figured we had a water flow problem so left it and took off the riser, no water was getting through to cool it, so then clean it all out and take the elbow joint off the exhaust manifold, ah its clogged there lies our problem, cleaned it all out and it was fine after that with a new rubber tube.

Yet as the week went on we ran into troubles that when running at idle for more than 10 mins the oil pressure went way up and the temperature up with it, so we run it up with no drive and it cools down, all the oils are right and the water pump is working ok, so anybody got any ideas?

We are planning on taking it do a dealer during the winter season to have the engine out and outdrive off for a full service and check but anybody got any ideas in the mean time?

Rob

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Rob Sherry
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1999 Sundowner 205

Rob,

From your description, I assume the following points:

* The water elbow at the exhaust manifold was clogged, you cleaned it out.

* The riser was clogged, you cleaned it out (adequately?).

Now, did you also remove the exhaust manifold? You may have the water passages in the manifold clogged as well.

Is the left side riser still hotter than the right side, or do they seem pretty much the same?

And ..... is the right side actually passing enough water? You should be able to rest your hand on a properly flowing riser. The right one is likely clogged as well, just not as much as the left one. It may be time to replace both manifolds and risers.

I am questioning your note about the oil pressure going up as the temp goes up. Is this what you meant to say? Is the oil pressure actually rising as the engine temp goes up, or is the pressure going down?

In through all of this, have you checked the raw water pump impeller?

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Gordon Arnold
New Hampshire

2003 268 Vista ..................................................................Prior: 97 245 Sundowner

Yes we did try and clean the manifold out in situ, but we tried to take it on and didn't want to risk shearing the bolts off in the block so we did the best we could.

They seem pritty much the same now but it is a fair point that they should be replaced, I think we are planning to have the whole engine broken down, seals and cylinders replaced and all relevant parts replaced.

Sorry I obviously didn't explain myself.

When idling for longer than about 10 mins the oil pressure goes DOWN and the temperature goes up and the only way to cure it breifly is to power up the engine out of drive to get a decent pressure and the temperature come down, we have been suggested that the water pump may be duff and that the engine is heating and thus the oil thinning out but I cant see the oil pressure rising that much just due to the water pump?

The oil pressure also fluctuates wildly in use in that when you power up, it goes up high (still in normal range but only just) and then when you come back down to near idle it drops again? We have been suggested that it may be the oil pressure relief valve?

Rob

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Rob Sherry
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1999 Sundowner 205

I'd look into changing the raw water impeller and if this is a salt water boat, raw water cooled, it may be time for new manifolds/risers. See how the temp is after you do that, it should be stable at 160F with the standard Volvo thermostat. In salt water you really have to consider changing the manifolds and risers at about 5 years or so. If they rust through you can get water in a cylinder and if they clog you get the overheating of the exhaust, which is dangerous. IF the rubber hose on the exhaust melts totally through you can get water in the boat.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

From memory, on a raw water cooled VP small block V8 there are 2 cast in outlets on the thermostat cover, one for feeding cooling water to the left and one for the right manifold. I changed from raw water cooling to closed cooling on my previous VP V8 engined '99 boat after 1 seasons use in salt water ( it had 2 seasons use in fresh water before that). The cast iron thermostat housing and thermostat was in a horrible state after only 1 season in salt. Those 2 outlets do not have a very big ID when new, on mine they were pretty clogged up with rust, one a lot worse than the other. It could be worth your while checking that these 2 outlets (and the hoses from them) are not full of rust build up/ debris. Such a restriction would severely restrict water flow to the manifold.

It's not at all unusual for engine oil pressure at idle to drop if an engine is overheating; the oil does a lot of heat transfer, in a boat it's quite restricted in it's possibility to lose that heat as it's in basically a closed box (unlike in a car where's there a lot more air movement around the engine)

Graham