Volvo penta 3.0GS high water pressure in U-shaped water hose

[jnthn]

So, i bought the boat last year with twin 3.0GS/SX volvos. boat was running fine but decided to remove manifolds and risers for inspection. i decided to change everything and bought new volvo penta risers, manifolds, gaskets, thermostats, water pump impellers etc. i assembled everything and assembled the restrictor plate the oppsite way it was marked on as instructed on here, i drilled a tiny 2mm hole in the thermostat to avoid air locks etc.
now the problem is that after all this i m seeing there is way too much water pressure in the U-shaped hose. Engine temperature is steady at 160'F but feels there is something wrong in the circulation. i found a lot of posts of people having this issue but no answers. thanks by the way, problem is on both engines.

 

[dypcdiver]

Several posts about just this problem, try a search. But frequently it is due to the exhaust hose being over tightened and or not mounted correctly and restricting the exhaust water annulus.

 

[Fun Times]

Four possibilities come to mind for possibly having high water pressure bulging up the circulating pump hose like that on the 3.0's.

1) the restrictor plate (and/or gaskets) for the riser is installed incorrectly...Hopefully you didn't read an incorrect old topic as there are a few out there that I do seem to recall reading that indicated some seemed correct as the poster said he was able to over come the bulging hose while other topics seemed to contradict other topics with no end resolution....
http://forums.iboats.com/forum/engin...and-shoots-off

2) There is a very small hard to see/find bypass hole inside thermostat housing that has been known to collect debris causing circulating pump hose bulging/bursting or pulsing .
^, While this topic is a different engine size, the photos at the bottom may help give a visual of the general area of where to try and look on your thermostat housing...
http://forums.iboats.com/forum/engin...oesn-t-warm-up

3) Blockage found inside the exhaust rise top plug like explained on post # 20, http://forums.iboats.com/forum/engin...61#post5357061

4) Bad circulating pump.

After much testing on an OMC Cobra 3.0 bursting water circulating hose, the result was, I replaced the water circulating pump and it seems to have done the trick.

OMC Cobra 3.0 bursting water circulating hose

 

[jnthn]

Could.it.be from low water pressure on the hose?? Also manifold is getting very hot too

 

[dypcdiver]

"Also manifold is getting very hot too" Signs of a reduced flow of cooling water, Fun Times has given you a lot of good pointers as to where to look.

 

[jnthn]

Sooo, the pipes now have 0pressure )) it was the rubber pipe between riser and exhaust. I was clamped too low therefore i was clamping on the last parts of the riser instead of the upper part.
But the manifold is still very hot. The riser can be felt by hand ok no problem but the manifold is still very hot. Does water flow in the manifold with the thermostat closed?? I cannot feel water flow in the small 90degree bend pipe between manifold and the thermostat housing!!

 

[dypcdiver]

T'stat open or closed there should be water flowing, Pull the hose off the elbow and start the engine and have a look at the flow.

 

[jnthn]

i did that and there is an airlock in that pipe. i removed the excess air, yet still the manifold is still hot. i don t know why there s no proper flow inside the manifold. it s new and it s volvo penta original item

 

[jnthn]

No Title

 

[jnthn]

anybody has the drawing of how the thermostat should be assembled? in which direction pls??

 

[Fun Times]

anybody has the drawing of how the thermostat should be assembled? in which direction pls??

What year and full engine model is your engine?

Though the impeller housing shown is of different design than yours, Here's a (the only) engine cooling drawing available free online for a 3.0 GL and you can turn one page back for the "stern drive" in and outlet water flows to help get you some ideas, http://www.boatinfo.no/lib/volvo/man...l_gs.html#/144

 

[jnthn]

My model is a 3.0gs PLKD

 

[jnthn]

And the impeller housing is the same as mine.

 

[dypcdiver]

Have you had the hoses off the raw water pump? If so please check you have them back in the correct order.

 

[jnthn]

They are different diameter. U cant misplace them

 

[griffin21]

Hello All, I’m new to the forums.
I have the same issue with a Penta 3.0 GS. Manifold vey hot, high pressure in the hose between the stat and the circulation pump, riser always warm to the touch.
What was the fix to this posted issue? Any help is very much appreciated. Thank you