3.0 GS PNCA blew waterhose between t-stat and circulating pump

[aerobat]

hey gents !

today i went out for a quick ride and after half an hour i blew the big waterhose between the tstat and the engine mounted circulating pump.

i never had this issue in 4 years having this boat - last year i replaced the intake/exhaust manifold and this year i replaced the exhaust riser and the impeller - to see this hose blew after maybe 2 engine hours this season.

so the riser and manifold are brand new and any blockage can be excluded.

how the heck can this hose blow on an open cooling system where there should be no significant pressure ???


thanks for any hints

 

[Bt Doctur]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

The exaust riser is clogged from scale or the wrong gasket was used .

 

[Maclin]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

Do not automatically rule out new parts. They may be incorrect or installed incorrectly. Keep in mind this is a new problem after instralling new part. With new risers I would suspect that gasketing is not correct, maybe needs a block off plate or one was installed and does not need one. Did you compare the new parts to the old parts to see if passages were the same and also for proper fitment, same nuber of hose fittings, etc.

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

With new risers I would suspect that gasketing is not correct, maybe needs a block off plate or one was installed and does not need one. Did you compare the new parts to the old parts to see if passages were the same and also for proper fitment, same nuber of hose fittings, etc.

the old riser looks the same like the new one when it comes to the water passages. it was installed with the restrictor plate in the direction like labeled on the plate and had not any issues.

but there was a lot of rumours that the label is WRONG and indeed by common sense installing it like labelled will result in blocking the waterinjection into the riser ( the hose which comes from the tstat ) by this plate.

so i installed it 180 deg reversed so it does not block off the water injection - but now i,m not sure anymore if that were not false rumours and if there is not a deeper sense in the position of the restrictorplate and the labelled position has to be followed strictly...

when i understand right late models of the 3.0 do not even have a separate waterinjection into the riser.

 

[Bondo]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

the old riser looks the same like the new one when it comes to the water passages. it was installed with the restrictor plate in the direction like labeled on the plate and had not any issues.

but there was a lot of rumours that the label is WRONG and indeed by common sense installing it like labelled will result in blocking the waterinjection into the riser ( the hose which comes from the tstat ) by this plate.

so i installed it 180 deg reversed so it does not block off the water injection - but now i,m not sure anymore if that were not false rumours and if there is not a deeper sense in the position of the restrictorplate and the labelled position has to be followed strictly...

when i understand right late models of the 3.0 do not even have a separate waterinjection into the riser.

Ayuh,... That sounds like a logical place to start,...

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

does anybody has a link to a waterflow diagram of a 3.0 ? of course in a perfect manner 3.0 GS PNCA.

unfortunetly i have to let easter holidays to wait before i can get new risergaskets and a new waterhose

 

[Bt Doctur]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

 

[Bt Doctur]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

But looking at the way the riser is set up in this pic there is no seperate hose for water like some merc applications. I guessing the restrictor plate should not
be there .Cant see the one slot having enough flow to the riser.
Can someone post a link to the manual?

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

Thanks much bt doctur ! The funny thing about the riser : look closely to the restrictor plate between the two riser gaskets. The Slot on this plate is on the right side but the waterinjection on the left side. So installing it this way like on the pic results you block off the waterflow on the riser. It was installed in my boat like on the picture but appears to make no sense - for what a waterinhection from the tstat at all when the plate blocks it ???. So Now i have put the restrictor plate opposite so the slot on it matches with the water injection from the tstat - and blew my hose of the recircpump....

 

[Bt Doctur]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

unless the parts labled 9 are 3/4 to 1 inch in diameter I would omit the restrictor plate. To blow hoses indicates that water is not leaving the engine. What size is that #9 going to the riser?

 

[Bt Doctur]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

Water always has to flow thru the exaust regardless of thermostat opening. What your calling water injection would be needed to cool the rubber exaust components until the therm opens and water flows thru the exaust manifold and then the riser.

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

Its a small , i guess 1/4 or 1/2 inch hose from the tstat to the riser. The smallest hose in the entire cooling system in any case. The manifold has nevertheless a waterinjection and when i got it right it gets water regardless of tstat opening. I,m at the boat , us there a quick way to upload pictures from the phone camera ?

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

ok, i brainstormed the waterflow principles on my engine and also looked into my old riser and i believe now i messed it up by myself with reversing the restrictor plate with the slot towards the riser water injection from the tstat . the water injection is above the restrictor plate and does not block the water entry to the riser but only the backflow into the manifold - this water is directed so directly to the exhaust.

when i understand it right the manifold is not fed with water until tstat opens . and when the tstat opened i - due to the fact the restrictor plate has only one slot - blocked off the main waterflow through the manifold to the riser and out the exhaust. the water could not leave the engine , pressure built up and the hose bursted.

i will renew the hose and change the position of the restrictor plate when i get parts and gaskets after easter and hope i did not damaged somesthing else.

if that proves to be true i will never again work intentionally against the volvo manual and go for hints from "experts"...

 

[dypcdiver]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

Some times the bellows are not located correctly and clamped over the water flow port in the riser, thus restricting the out flow of the cooling water.

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

Ok - i installed a new hose and changed the position of the restrictor plate without any success - the pressure at this hose is high as hell. I removed the entire restrictor plate without any sucess. I run the engine without the tstat and it improved the condition a little but pressure is still very high. Can it be that the brand new riser is wrong ???? I will tomorrow try to reinstall the old riser... i,m out of ideas...

 

[Bt Doctur]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

Your going to run the engines for about 15 seconds.
Test 1: Remove the hose 9 from the exaust manifold , using muffs turn on water, start engine ,go to 1500 rpm, check for hose pressure.
No pressure in hose= restriction in manifold /riser
hi pressure= suspect head gasket pushing combustion gas into cooling system
Test 2: MOTOR NOT RUNNING apply water hose pressure to exaust manifold using hose 9 , water should free flow thru the exaust manifold and riser and out the prop area with no back pressure. If water does not flow freely, suspect manifold/riser problem.

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

i did test no1 and removed the no9 hose. pressure at hose was still high , no change beyond flooding the bilge.

so i also had dark thoughts about the head gasket , but somehow i cannot believe i just blew it on a short normal ride where the boat never had issues and still starts fine, idles fine, has normal power, no water in oil, no milk in head or oilfillerpan...

i will reinstall the old riser which looks better than i believed - if this also fails i,m afraid i will have to take the pain in pulling the head.

the old riser is OEM volvo, the new barr marine, but it appears to be the correct one.

 

[Fun Times]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

There could also be a restriction in the very small hard to find bypass hole inside the Thermostat housing. Searching iboats, you should find diagrams by Don and others showing where to look. May want to check into that too. Good luck.

 

[Bt Doctur]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

what about test #2?

 

[aerobat]

Re: 3.0 GS PNCA blew waterhose between t-stat and circulating pump

i was only able to perform test 2 halfway since normally i,m permanently on the water with this boat during season . i pulled the waterhose from tstat to exhaust manifold and blew by mouth into it.

you can do it, the air seems to escape via the riser/exhaust .

@funtimes : thanks, i will in any case take a close look to the tstat , first i will now reinstall the old riser which definitvly worked on my boat to fully exclude the barr marine riser has somewhere a restriction/fault brand new out of the box.