Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

The bypass hole at the housing is clean and perfectly round. I understand that if everything else fail I could either enlarge this hole or add a bypass hose using two T-fittings before and after the housing. But the system was not designed this way and this would be a temp fix that might set the system off balance with overheating at different conditions. I might try a brand new thermostat housing first because after all these years I see some rust. Not much but maybe it is affecting operation.

My C-model has a temp switch at top of the elbow which screws on a dead end hole. (no connection to exhaust or water). There is another plug that connects to the exhaust opening. I guess it is there to easily inspect if water is leaking into the exhaust passage. I have removed the elbow and run water through it. It is not easy to run ti backwards. However, one of the tests was to connect a hose at the housing thermostat housing and send the water outside the boat bypassing completely the manifold/elbow section. The pressure was still there. Note that the water was flowing free of visible bubbles.



The second diagram (later Glp-C)

 

[Don S]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

Both of those pictures are for a GLP-C model. One is the early model, (top) and the lower picture is the later model. You have the later model.

Pull the plug (#13 in the lower picture) and hook up your pressure gauge to that connection.

I am wondering if that temp switch on the riser may be telling us something if the engine is not overheating but the alarm is going off.

Is the inside of the exhaust hose that clamps to the elbow smooth inside? Not all bubbly from an overheat and maybe blocking the water passages a bit?

 

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

The alarm was coming from the temp switch at the thermostat housing. I disconnected it and the alarm stopped. When connected again the alarm started. The block and head was at 170 degrees when I checked with my infrared gun. The temp gauge was also 170. Riser and manifold only 90. So is it possible to overheat in some area without knowing?

The rubber exhaust hose is smooth inside and the water passages are centered at the wider part of the hose. This is where I found an impeller piece. The pressure is still excessive after taking the impeller piece out.

Unfortunately my elbow does not have plug 13. (If I remember correct).Part number on casting 3588683 Even if it was there I can not connect my pressure gauge since the valve cover is in the way.


I do not believe it is a restriction in the manifold/riser side because when I bypassed the whole section using a hose allowing the water to flow free from the thermostat housing directly outside the boat the pressure was still high. Test without water on the manifold/elbow was only for 15 seconds. The riser is reasonably clean and the manifold was new last year.

 

[Don S]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

I do not believe it is a restriction in the manifold/riser side because when I bypassed the whole section using a hose allowing the water to flow free from the thermostat housing directly outside the boat the pressure was still high.

I think it's time to say that what you "Believe" is going on is not good enough. You have to start testing things. If you don't have pressure at the elbow, then the question would be WHY NOT. Back up and find another place to test. Like that plugged hole in the top of the thermostat housing. Where is the last place in the system that has high pressure?

 

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

I will try to pressure test at the riser if I have the plug 13 and I can fit a gauge. Maybe I will try to remove the manifold drain and fit the pressure gauge there.

The plugged hole in the top of the thermostat housing is where I have already fit my pressure gauge and did my pressure testing. The last place in the system that has high pressure is the thermostat housing. The hose that has high pressure is from the housing to the circulation pump. The hose from the housing to the manifold feels soft. Why I do not have high pressure at the elbow/manifold and only at the thermostat housing side is a good question and I wish I could find the answer.

Here is the testing I have done:
1. I took out the thermostat housing and checked the bypass hole,
2. I put a new tested thermostat, the old one tested good too.
3. I took out the riser and I found an impeller piece the only one missing from last year between the riser and the rubber exhaust but still excessive pressures.
4. I checked one more time the impeller and it is perfect since I changed it at the start of the season.
5. I checked also the entry point at the manifold which is 90 a degrees fitting 982728 and I put a wire to make sure nothing is there.
6. I put a clear hose between the thermostat housing and the manifold inlet and another clear hose between the raw water pump and the thermostat housing. No bubbles before or after the engine up to 3500 rpms where the pressure was 35 psi!
7. I got water out of the exhaust when I connected a garden hose at the manifold inlet hose. I actually opened also the manifold drain and I stopped/started the water flow several times to remove any minor rust or sand. For the block I forced water thru the thermostat housing opening against the normal flow and water was coming from the circulating pump. I opened also the block drain.
8. When a hose is connected to the thermostat housing (outlet to manifold) and sending the water out of the boat bypassing the manifold/riser the pressure is still excessive. So manifold/elbow are not contributing to the pressure problem.
9.The circulating pump looks fine including the bypass opening.
10.Running the engine without the thermostat, the pressure is lower but still builds pressure.
11. Disconnecting the raw water pump outlet hose to the thermostat housing the water goes up to 4 inches at idle.
12. The cylinder compression results were Cyl 1=168 cyl 2= 175 cyl 3=180, cyl 4= 170.
13. I took the boat to my marina and they did a leakdown test. The test results are Cyl 1=5%, Cyl 2=5%, cyl 3=15% and Cyl 4=20%. They say it is a head gasket.

Any other test besides the manifold water pressure? Any ideas on what is happening based on the above tests?

 

[Don S]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

13. I took the boat to my marina and they did a leakdown test. The test results are Cyl 1=5%, Cyl 2=5%, cyl 3=15% and Cyl 4=20%. They say it is a head gasket.

Did "They" check to see if that head gasket leak was also leaking into the cooling system?

Are you going to replace the head gasket?

 

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

You did hit the nail on the head! I would expect after the leak down test the marina to check where the air leaks. Crankcase, intake and exhaust valves are irrelevant, only cooling system leak matters for the pressure issue. Air could not be heard but the marina did not fill an open hose and at the same time to pressurize the cylinders to see if the water level is changing. Anyway, I am still debating to trust the pros and to put a work order to change the head gasket. 10 hours of labor at $100 plus gaskets and machine shop about $1500 total. I hope the marina is right on their diagnosis.
Why should I agree if am not sure? First there is not much left to check. Also the cooling system is pretty simple: Water volume in equals water volume out. If there is more volume in than volume out the system builds pressure. Volume out is reduced by a restriction. Volume in is increased by exhaust gas leaking in the cooling system. I did not find a restriction so very likely the volume in is increasing by exhaust gas coming from a blown head gasket or a cracked head. Am I missing something? Is my thinking over-simplified?

 

[Don S]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

Have you ran the boat since the head gasket change?

 

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

The boat is still at the mechanic. The head will be sent to the machine shop for checking and milling if I agree to do it. I will give you an update if the head gasket is changed later this week. At this point I am thinking to just sell the boat half price and do not do the head gasket.

 

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

Have you ran the boat since the head gasket change?

I have not decided yet to change the head gasket. If I do the machine shop will check the head for any cracks and mill it if it is warped. Then the marina will put the head back but I do not know if the excessive pressure will still be there. They also put about 15 psi air pressure to the block and left it overnight. It holds pressure fine so no cracks on the block either.
The marina is an official Volvo Penta dealer and also holds a MerCruiser "Premier" Status but they can not figure out what is wrong. The marina owner told me he is baffled and needs more time to check it. It looks like I underestimated a very difficult problem.
I really need some ideas on this site from experienced mechanics or highly skilled DIYs.

 

[Grub54891]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

Been following this thread,hope they figure it out as I would like to know what the issue is also,in case I run into the same thing.
Grub

 

[Don S]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

I really need some ideas on this site from experienced mechanics or highly skilled DIYs.

Since they are a Volvo dealer, they should contact a Tech Rep from Volvo.

You have to start testing things. If you don't have pressure at the elbow, then the question would be WHY NOT. Back up and find another place to test. Like that plugged hole in the top of the thermostat housing. Where is the last place in the system that has high pressure?

 

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

Don the shop is still trying to find out what the problem is so I can not do any tests now. Meanwhile I try to research the symptoms a little more.

1. While I had the high water pressure issue my riser and manifold temperature was only 90 degrees. What are possible reasons for low temperature on manifold and elbow?

2. The clear hose tests showed no bubbles and the block while pressurized with 15 psi air was holding fine all night. Is it still possible to have an exhaust gas leak into the cooling system?

3. The overheat temperature switch set the alarm but at the same time the temperature sender was sending signal for only 170 degress. My infrared gun was also showing 170. Is the temp switch showing a local overheat or it is just defective?

 

[Glastron3.0GLP-C]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

Still I have no idea what creates the high cooling pressure. Is it too much water coming in at high rpms? I was reading Service Bulletin Group Number Version 20-0 11 03 for older 3.0L engines and mentions kit 3858253 which contains part 3857875-restrictor. Has anyone ever used this Volvo Penta water restrictor? How does it look and where is it installed?

 

[Colliemcc]

Re: Blown cooling hose between thermostat housing and circulation pump at 45 psi!!!!

Any update on this.

 

[Troybleth]

Any update???