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!!!!

I did some more testing.
1.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. This leads me to the engine side again.
2.The circulating pump looks fine including the bypass opening.
3. Running the engine without the thermostat, the pressure is a little lower but still builds pressure.
4. The water from the hose between the raw water pump and the thermostat housing goes up to 4 inches at idle. Seems high.
Now I took the boat to my marina today 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 we have to remove the head and replace a blown headgasket. Note that the clear hose does not show bubbles and the hose that sent water out of the boat had no bubbles either. Air from the leak down test was not noticable on the valve cover or the thermostat housing. Do you think 20% leakage is enough to take the head off?

 

[jeffnick]

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

Pulling the head is about all that's left? With all the other stuff you've done it should be a piece of cake.

 

[Glastron3.0GLP-C]

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

I haven't done a head gasket change but reading the manual it looks straight forward. However, I am thinking to let the marina do the work. They quoted 10 hours X $100 plus $300 for the machine shop to mill, pressure and vaccum test the head (no valve job) and $200 for gaskets. They have more experience and I really do not have the space to work for so many hours. I usually bring the boat to my driveway for 3-4 hours and the neighbors are starting to lose their patience. What do you think about the marina labor and prices? Normal?

 

[dypcdiver]

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

I'd double check the thermostat housing again before pulling the head. When I had problems it was only cured by cleaning the corrosion out of the ports (V8) and the bits of impeller rubber from the bypass port with a bendy bit of wire (rubber not visible).

But the 15% and 20% leakage on ADJACENT cylinders is quite compelling.

 

[Glastron3.0GLP-C]

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

The thermostat housing has minimal corrosion and all openings are clear and not reduced by rust. So the only thing left is an exhaust gas leak from the engine to the cooling system. The 15% and 20% leakage might be an indication. I hope the head gasket will cure the problem. If I am lucky it is only the head gasket and not a crack in the head or block.
Now I am trying to figure out why the head gasket blew. AFTER the blown hose the engine run for 1-2 minutes without water and propably overheated (the gauge sensor without water was reading 0). The other posibility for a blown head gasket might be that the cylinder 3 and 4 that show 15% and 20% leakage are the ones that had wrong spark plugs RV15YC4 while the other two cylinder had the correct RS12YC. The wrong spark plugs are slightly hotter and I do not know if this can damage the head gasket.

 

[jeffnick]

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

Have you looked into a reman long block?

 

[Glastron3.0GLP-C]

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

I think it would be more expensive. $1500 for long block, $200 shipping, 200 gaskets and maybe $800 installation, it is more than $2700. My engine was a long block replacement in 2012 by the previous owner and has only 30 hours. So if the head tests good the engine is almost new. If not maybe a long block is the answer. I hope spending $1500 on the head gasket will fix the cooling pressure problem.

 

[jeffnick]

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

Who did the reman on the motor? Some have a 7 year warranty.

 

[Jammer864]

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

The different spark plugs arent going to cause that problem.
On a related note, when I was working as a car mechanic I received several sets of spark plugs that had different, used, or damaged individual plugs in the set. ALWAYS open the boxes and check your supposedly new parts when you receive them.

 

[Glastron3.0GLP-C]

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

Who did the reman on the motor? Some have a 7 year warranty.

7 years warranty? Which company? Do you mean 1 year? Anyway, I do not know who did the engine in 2012 since the previous owner bought it but I am sure they would not cover a head gasket claiming overheating.

 

[jeffnick]

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

7 years warranty? Which company? Do you mean 1 year? Anyway, I do not know who did the engine in 2012 since the previous owner bought it but I am sure they would not cover a head gasket claiming overheating.

This is where I'd get a replacement motor if/when I need one.
Marine Engines | Mercruiser Engine | Rebuilt Marine Engines | Boat Engine

 

[Glastron3.0GLP-C]

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

Thank you for the link. I may use them. The warranty is the best I have seen for marine engines.

"7 years or 500 hours against defects in material and workmanship. After 1 year there is no coverage for labor costs or shipping. We do not cover. Repairs that were not pre authorized. Damages caused from overheating, freeze cracking, operating with low or with old oil, piston damages, diagnosing time, damages caused in shipping, customers or installers."

 

[Glastron3.0GLP-C]

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

The other posibility for a blown head gasket might be that the cylinder 3 and 4 that show 15% and 20% leakage are the ones that had wrong spark plugs RV15YC4 while the other two cylinder had the correct RS12YC. The wrong spark plugs are slightly hotter and I do not know if this can damage the head gasket.

Reading the Mercruiser Service bulletin No. 98-14http://www.boatfix.com/merc/bullet/98/98_14.PDFsays that the use of short reach or wrong heat range spark plugs can cause detonation (resulting in head gasket failure). I believe this is my case with the short reach and wrong heat range RV15YC4 spark plugs. What do you think?

 

[gator fan josh]

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

That seems high for a head gasket change. I did one myself on Friday and I am no mechanic, took me 5 hours. The gaskets cost 50 bucks and the machine shop milled the head and replaced a valve seat for 60 dollars. I think you could change the gasket, these are about the most simple engines ive ever seen. I did have to cut about three threads off the rear stud on the manifold with a hacksaw so i could get it off. the design on the exhaust pipe being so close to the engine so that you cannot remove the manifold bolts is very poor.

 

[Glastron3.0GLP-C]

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

Maybe my high pressure is from a wrong part raw water pump. (I doupt impellers can create such a high pressure though). Anyway, there are two pumps one for 3.0l 21214595 and one for the larger engines 21214599. They look identical. I hope I do not have the wrong one. I read somewhere that for the 3.0l at 1500rpms for 10 sec you get about 2 gallons in a bucket. Does anyone know what is the normal output in gallons for any of these pumps?

 

[Don S]

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

The pump housing and impeller are the same on the two pump. Just a slightly different mounting holes or pins are the difference. Nothing changes on the pump itself.

I don't remember seeing any volume specs, but I can't imagine that changing from pump to pump. I will do some checking though.

 

[Don S]

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

Here is the only thing I can find on checking the water flow, from any of Volvo's service manuals. It's for checking for insufficient water flow, not excessive, but it looks like about 1" at idle is normal.
The test must be done in the water, not on the muffs and a hose.

a. Procedure - Disconnect water supply hose from transom
bracket at thermostat housing. Operate engine at specified
idle RPM. Hold end of hose level with the top of the flame
arrestor.
b. Results and Conclusions - A 1 inch (2,5 cm) head of water
discharge, water supply is good. If less than 1/2 inch (1.2 cm),
look for source of water loss.

It's also the same test on any of the SBC V8's and the 8,1's

 

[Glastron3.0GLP-C]

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

Thank you for the research Don. It is a little bit strange that the Volvo engineers are using the same water pump output in a 3.0l to 8.1l. I would suspect the demand for raw water might be higher on large engines. Anyway if it is working fine all these years why question it?

The test with the drive in the water showed about 4 inch head of water but the end of the hose level was maybe at mid engine. I guess water sypply at the top of the flame arrestor level could be a little lower maybe 1-2 inches. So adequate water supply and likely not even close to create the extreme pressures.

I still can not think of where the problem is.
The manifold/elbow side looks like is not affecting the pressure. (see test earlier) Focusing on the engine side we have the thermostat housing and thermostat (ckecked good), block, head and any exhaust gases entering the system.
Last item I can think is the circulating pump which looks good. I assume it is supposed to circulate maybe 50 gallons per minute at WOT and the raw water pump sending 18 gpm at WOT. When the engine is cold 18gpm are bypassed to exhaust but when warm thermostat controls how much of the 50 gpm are replaced with cold water. I assume about 8 gpm cold water goes to warm engine and 10 gpm cold water is bypassed for a total of 18 gpm raw water pump output. All these in a normal operating system.

Circulating pump is pushing water thru the block and exiting from the thermostat housing. If the pump was sending water backwards that would explain the high pressure at the hose and the housing. I believe all circulating pumps are bidirectional. However, I can not see how it can suck water from the block instead of pushing water to the block. It looks impossible. Any thoughts?

 

[Don S]

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

The circulation pump is not a pressure pump of any kind, all it does is stir the coolant. That's why an air bubble will cause overheat. The pump can't push the air out.

Circulating pump is pushing water thru the block and exiting from the thermostat housing. If the pump was sending water backwards that would explain the high pressure at the hose and the housing. I believe all circulating pumps are bidirectional. However, I can not see how it can suck water from the block instead of pushing water to the block. It looks impossible. Any thoughts?

I know on the V8's the pumps can run backwards since the reverse rotation engine used the same pumps as the standard rotation engine. So running backwards shouldn't be an issue. But your's runs the same direction every other 3.0Ls circ pump runs, so that's not an issue.

I think if it was my motor, I would pull the set screw out of the top of the thermostat housing and drill out that bypass hole to just clean up the rust. It may be open to a point, but closing down and possibly causing the higher pressure.

Have you removed the riser and tried flushing from the outlet side of the elbow and seeing if anything comes out than might only show up when running. Does your C model have a temp switch on the top of the exhaust elbow?

 

[Don S]

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

Which one of these pictures is like your exhaust system?

Early

Late