PLEASE HELP! Blown U Hose From Thermostat to Circulation Pump Volvo Penta 3.0 GLP-C

[xpertgrafix2]

Recently I had the large u hose blow on my 2004 Volvo Penta 3.0. It's only been run in fresh water. I notice when I was doing maintenance on drive and engine, that when I ran it with muffs the U hose was swelling under pressure then it seemed to go back to normal when the thermostat opened. While running it in the lake later that day the hose finally blew. So, I took all hoses off the thermostat and ran water though all hoses. It did not seem to have any restrictions. So I pulled the thermostat housing off to replace the thermostat just in case that was the culprit. While cleaning the housing I came across a old piece of impeller lodged in the bypass hole. I had to take the allen screw out to get to it. My question to anyone who has come across this. Would that have caused enough back pressure to blow the hose?

 

[dypcdiver]

Couple of things to check,
1st make sure that the connection from T'stat to exhaust is clear at the manifold ie. poke some wire in the hole. Also whilst the hose is off check you have flow with the engine running (just for a few seconds).
2nd make sure the rubber hose on the exhaust has the clamp in the correct position and that the hose has not swelled up inside and blocked the raw water annulus

 

[xpertgrafix2]

Couple of things to check,
1st make sure that the connection from T'stat to exhaust is clear at the manifold ie. poke some wire in the hole. Also whilst the hose is off check you have flow with the engine running (just for a few seconds).
2nd make sure the rubber hose on the exhaust has the clamp in the correct position and that the hose has not swelled up inside and blocked the raw water annulus

I have good water flow everywhere. I was just wondering if a blocked bypass hole would cause enough pressure when thermostat is closed to swell and burst the u hose. If am a correct, there is always water running through the thermostat housing because of the bypass hole. If it is clogged, very little water is getting to the exhaust until the thermostat opens. Which I would think would cause a lot of back pressure because raw water pump keeps pumping water no matter what. Does that sound reasonable.

 

[Bondo]

If am a correct, there is always water running through the thermostat housing because of the bypass hole. If it is clogged, very little water is getting to the exhaust until the thermostat opens.

Ayuh,.... The exhaust should be gettin', 'n dumpin' water, whether the t-stat is open, or not,....

All of the water pushed by the raw water pump, is Not run through the block,.... only what's allowed by the t-stat,...

 

[dypcdiver]

When my bypass was blocked by a vane, the extra pressure pushed the T'stat open and kept the engine running cool ie. 120/130 deg once cleared it runs at 165 deg now.

 

[Pavpav]

So what was the resolution/cause for this?
I have exact same problem with my boat. The hose looked brand-new when I took it off during inspection this spring, and it burst yesterday when I brought the engine up to 4000rpm for a few minutes.

 

[GA_Boater]

So what was the resolution/cause for this?
I have exact same problem with my boat. The hose looked brand-new when I took it off during inspection this spring, and it burst yesterday when I brought the engine up to 4000rpm for a few minutes.

Stop posting in old threads!