1994 Volvo Penta 3.0 GL overheating (long read)

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Not sure where your numbers came from. How can you measure 8 ohms at 175??

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Sent you a PM

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Okay new test meter worked great! Here are the reading I took using the pot.
100? - 578ohms (Faria gauges says 450ohms)
175? - 98ohms (Faria gauges says 99ohms)
250? - 34ohms (Faria gauges says 30ohms)

So it looks like my gauge is showing a lil hotter off the bat but the later temps should be correct. I owe alot of thanks to bruceb58 for taking the time to help me work through all of this.

So I think I can say I have eliminated that as a potential problem and the boat is actually overheating. I ran a clear tube from the raw water pump to the hose that connects to the thermostat and I did see some small air bubbles. I was running it on muffs with the water hose on full blast. Here's a video sorry it's a lil dark since it was getting late.

So next I''m going to try taping the outdrive inlets and just filling the hose with water from the water pump inlet no pressure and just seeing if I can detect where there may be a leak. Bruce also suggested I try the clear hose on the inlet side of the raw water pump to make sure its not the pump that is sucking air.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

update...
The clear hose I had would not fit on the inlet side of the water pump.

I went ahead taped up the inlets on the outdrive and put disconnected muffs over the tape to help plug them. I then disconnected the outlet hose that goes from the water pump to the thermostat and filled it with water and I did not detect a leak at the pump, hose or outdrive. I then disconnected the inlet hose from the water pump and filled the hose with water that connects to the outdrive. I still could not detect a leak.

When I return from vacation next week I'll pull the risers and check the flapper and see if I can find a restriction on that end. Unfortunately I may have to take it to a shop after that.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

So I just got back from vacation and I dug in a little this morning but I hit a road block in search of a flapper.

I unbolted the riser and found a lot of rust but it seems like there is still good flow there.


I then removed the hose that goes from the riser to the exhaust pipe and that was a lil dry on one end so I think that needs to be replaced.

I then looked down the exhaust pipe and this is what I saw.


Just a pin and no flapper. Hmm, Why would a previous owner remove the flapper and not the pin?

That's as far as I got because didn't know how to remove the exhaust pipe. I tried to feel around where the exhaust pipe exits and I felt a couple bolts that may or may not be the right ones. It's tight behind the engine and I don't want to accidently unbolt the outdrive, haha.

Any tips on how I can check to make sure there is not a burnt flapper restricting flow down that pipe? I turned the water hose with a spray nozzle on in that pipe and it didn't fill up or overflow, all the water when down and out the outdrive. I had on a previous attempt removed the rubber hose from the outdrive to the engine exhaust and I couldn't see any restrictions from that view.

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

I am not super familiar with 3.0 risers but it looks like 3 out of the 4 channels are completely blocked off. Is it supposed to be that way?

To see if your flapper is blocking anything down there, you would have to remove your exhaust bellows where it connects to the transom housing.

Edit: I see you did that already. Also conceivable it made it through the hose to the other side as well.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Yeah I left the plate on for that photo. The plate restricts the water to one hole on purpose. Here's another pic with it removed.


Maybe there is no restriction because when I looked into that pipe I saw nothing but a hole. I'm going to play with running some water and looking in there. I wonder if I can use a towel stuff a hose and run water up the exhaust pipe, disconnected from the engine with no riser of course.

Where does the exhaust water end? I saw the hose has like mini holes in it that dribble the water out.

Thanks,
Jesse

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Probably most is going to come out the idle relief ports which is in the transom assembly. A little may make it to the exhaust bellows.

 

[dypcdiver]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

If you are looking for the " idle relief ports" it is hidden above the transom shield anode.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Ahh I see that now after I put it all back together for a test start. I don't know if i can get behind that but the water was flowing well. I went ahead and ordered a new bellow since the one going between the riser and exhaust pipe was hard and flaking. It also was kinda squashed and I thought that could restrict the flow if it blocks the water coming from the riser. After I put that in i may just take it for a test run near a mechanic shop and if it still overheats ill leave it at a shop.

Thanks for everyone's help on this one ill post an update when I get it out in a few weeks.

 

[Lou C]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Your riser temp is very high (160) it should be closer to 100 or so. Its possible that the flapper that was there, fell down the pipe because it melted and it may be in the bottom of the exhaust pipe. You'd have to pull the drive off and look in the exhaust bellow to see if its blocking the exhaust exit.
I might want to do some more testing of that exhaust system. Take off the manifold and install the riser onto it with a new gasket. Then hook up a garden hose to the water inlet on the manifold and turn it on. Look and see how much flow you get. If you get good flow, then it is possible there is a blockage in that manifold or the riser that is contributing to the high temp.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Your riser temp is very high (160) it should be closer to 100 or so. Its possible that the flapper that was there, fell down the pipe because it melted and it may be in the bottom of the exhaust pipe. You'd have to pull the drive off and look in the exhaust bellow to see if its blocking the exhaust exit.
I might want to do some more testing of that exhaust system. Take off the manifold and install the riser onto it with a new gasket. Then hook up a garden hose to the water inlet on the manifold and turn it on. Look and see how much flow you get. If you get good flow, then it is possible there is a blockage in that manifold or the riser that is contributing to the high temp.

Yeah Lou, I thought it was weird the post from the flapper was still there but not the flapper. I pulled the exhaust hose form the oudrive but I couldnt see any kind of blockage. I have to say I'm a little intimidated about pulling the outdrive. I'm going to install the new hose on the riser this weekend. I did try to run water down the exhaust pipe but it just flowed out with no blockage from the back of the boat.

I'm going to check the inlet hose running from the outdrive to the water pump for bubbles with a clear hose, since there were some bubbles going from the pump to the motor. If the air leak is coming from the outdrive and not the pump I guess it needs to be pulled, I've just never done that before. After this weekends test I'll know a little more, I'll record a little video too. Hopefully I reach a solution I can solve but i'm still considering taking it to a new mechanic if it's the outdrive.

Thanks,
Jesse

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Is this what it looks like if my outdrive is sucking air? I have it on muffs, water hose is on full blast and this is what I get while it's idling. I don't believe there should be any air in the hoses correct?

Thanks,
Jesse

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

That's a lot of air.

Make sure your muffs are in tight and even duct tape them on if you have to to make sure its not sucking air around the muffs.

There are a few places where you could be sucking air at the drive while on muffs. The one between the upper and lower shouldn't matter because that would be in the water even at speed. The other is where the water hose hooks up to the pivot housing(round o-ring and the other where the drive mates with the pivot housing(oblong o-ring).

Part numbers 20 and 35 in the following diagram. This is an OMC page but the Volvo is identical
OMC Stern Drive Transom Mount Parts for 1994 3.0 L 302DCMMDA Stern Drive

The other place could be a cut hose. I would think that would be unlikely but you never know.

You could connect your water supply hose directly to your water pump through some of your clear hose and probably see your temp problems go away. Then you could concentrate on the air. Would be interesting to run your boat in the river with that clear hose on there!

 

[dypcdiver]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

bruce58 is correct, other places to check are the hose No. 37 for cracks and make sure it is secured at both ends plastic nipple 18 one end and the bulkhead penetrator 74. also check on the inboard side of the penetrator to make sure the suction hose is secure.
Beyond that then only other source for air is the seals between the lower and upper gear housings, however this should be submerged at idle but out when on the plane. Best of luck. Let us know how you get on.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Problem solved!!!

So I decided to take my boat to a shop near the water. I lined up a new mechanic and drove the boat down to the River, but before I took it to the shop I decided it be a good idea to do one last test since I’ve done a lot to the boat and to check those clear hoses.

Boat did not overheat, I thought for a second it was going to when I was 30 mins in, I was pushing it at full throttle and the temp rose from 175 -200, then it dropped down to 175 and ran about there for a few hours without an issue, thermostat must have kicked in. I intentionally ran it pretty hard to try and cause an overheat but it ran great. I kept the clear hoses on and they stayed solid with no air bubbles on idle and on plane.

I think I fixed the issue when I took the exhaust riser off really cleaned it out and put a new bellow on. The old bellow was squashed warped and cracking. The bellow has a rib in the middle which I believe provides space for the water to shoot out of the sides of the exhaust riser. The old bellow was squashed which would restrict the flow a little. Anyhow problem solved, I’ve now removed my clear hoses and will enjoy, well after I fix my newest problem, a broken throttle release button, hahaha.

Thanks everyone for all your help!

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Awesome!!!

 

[dypcdiver]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

I am pleased for you, however the exhaust cannot cause the air in the plastic pipes clearly seen in your YouTube clip.
I suggest that for this season you enjoy your boat now you have cleared the restriction that allows it to cool properly. But be aware that air was being sucked in from somewhere and will most likely get worse until it causes a problem. Looks like you might need to schedule some time for an investigation during the off season. Have fun.

 

[bruceb58]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

Would really need to have the clear hose installed while the boat is in the water and not on muffs. If the muffs were introducing the air, he doesn't have an issue.

 

[JesseRuiz]

Re: 1994 Volvo Penta 3.0 GL overheating (long read)

The air bubbles were most likely coming from the muffs because once I put it in the water the clear hose showed no bubbles at idle, on take off, or at plane. I had someone watching them the whole time I was testing the boat in the water.

Thanks
Jesse