Volvo Penta Overheating

[herring627]

Hey guys, you know how sometimes you want to just give up, well I am filling like that right now. This is when I turn to you all for help. My 2002 VP 5.0 GL-C overheated terribly a couple months ago. Impeller was shredded and thermostat ugly. Both are replaced along with manifolds yet it continues to overheat (buzzer goes off around 190 degrees).

The Volvo Penta Overheat Diagnosis (see link below) guide is informative and extensive but at some places gets a bit too technical for a newbie. So my question is - what do I do next? I read over and over that if their is air getting into the engine it will cause overheating. Would you agree? Where would I turn to next?

1. Do I do a "clear hose test" to determine whether air or water is entering or exiting the raw water pump?
2. Do I perform this same to est at the thermostat?
3. Do I perform a "cylinder leak down test"?
4. Do I perform the acetone leak test for the risers (viz. Don S. test)?

And then there are other things to check like the ECMs for DTCs? Should I go this route first? Other things to consider - there is likely water in my oil (silver in color from dipstick, but only when engine is hot, otherwise dark brown) and likely prior water intrusion in engine (see pic.) So thank you for giving this post a look at and adding your sage advice below. In the end, say I buy the parts, identify a leak, I wonder if I will proceed to fix or take it into the mechanic. Time will tell.

 

[alldodge]

Impeller was shredded and thermostat ugly. Both are replaced along with manifolds yet it continues to overheat (buzzer goes off around 190 degrees).

Since the impeller shreadded, I would ask did you find all the pieces?
If this is unknown, did you back flush the cooler and look inside to see if things were hung up?
Is this a fresh or salt water boat?

 

[Scott Danforth]

As AD stated, find the pieces of the impeller. Also, check the water inlet casting/fitting on the drive that the supply hose connects to

 

[herring627]

Since the impeller shreadded, I would ask did you find all the pieces?
If this is unknown, did you back flush the cooler and look inside to see if things were hung up?
Is this a fresh or salt water boat?

No, I haven't found the cooler to detach from. I get hooking up garden house to the outlet (#6) but where is this "cooler?"

 

[Scott Danforth]

start at the thermostat housing and work backwards to the impeller to look for pieces. Also, the exhaust ports you posted a pic of have issues. one has excessive oil blow-by, possibly valve seal, possibly rings. the other shows signs of rust.

 

[jimmbo]

When my impeller shredded in 2011, I found all the openings in the raw water pump plugged solid, I flushed the hoses and recovered almost all of the pieces. The pieces I didn't find were very small, so I figured they would either be flushed out the exhaust manifolds or end up in the block waiting to plug up one of the flush hoses. That was 7 seasons ago...

 

[alldodge]

OK then check the piece Scott mentioned in post 3, have been known to clog up

check the water inlet casting/fitting on the drive that the supply hose connects to

 

[Scott Danforth]

actually they corrode and break off.

 

[herring627]

start at the thermostat housing and work backwards to the impeller to look for pieces. Also, the exhaust ports you posted a pic of have issues. one has excessive oil blow-by, possibly valve seal, possibly rings. the other shows signs of rust.

All hoses attached to thermostat as well as raw water pump have been removed and emptied out, except for the one attached to the raw water cooler (#11 on diagram). Is this part even accessible?




And as for the exhaust ports - all are rusted with the exception of the one "oil blow-by" port. While this leads to pour performance and further damage down the road this is not the cause of my overheating, correct?

Let's get back to the OVER HEATING PROBLEM - are you suggesting that these 1/4 inch impleller pieces could be a cause to overheating? And, going back to my initial post, how does air cause over heating issues?

I know, many question marks here, thank you for your time and wisdom.

 

[Scott Danforth]

item 11 is an oil cooler. it makes an effective strainer to prevent debris from making it to the thermostat housing as it is the first thing that sees water from the drive. they get plugged often.

 

[BRICH1260]

Make sure you do not have two O rings on the water pump allowing it to suck air. Did that once and I got hot.

 

[herring627]

Since the impeller shreadded, I would ask did you find all the pieces?
If this is unknown, did you back flush the cooler and look inside to see if things were hung up?
Is this a fresh or salt water boat?

 

[alldodge]

Why would pieces back flow into the cooler?

Need clarification of your question. Water goes thru the pump, then to the cooler, and then to the thermostat housing. You would remove the hose going to the thermostat housing and the pump, then back flush the cooler back to the pump. You don't need to take the cooler off if you can see thru the cooler for pieces.

 

[bruceb58]

Water goes thru the pump, then to the cooler, and then to the thermostat housing.

I always thought it was from the drive, to the cooler and then to the pump and then to the thermostat housing.

 

[alldodge]

I always thought it was from the drive, to the cooler and then to the pump and then to the thermostat housing.

You might be right, your a VP guy I'm Merc, and Merc doesn't do it that way. Also looking at the part layout just looked the same to me, but your probably right, I've seen different stuff with VP

 

[bruceb58]

You might be right, your a VP guy I'm Merc, and Merc doesn't do it that way. Also looking at the part layout just looked the same to me, but your probably right, I've seen different stuff with VP

OMC did it that way as well and when they transitioned from OMC to Volvo, they kept it.

 

[Lou C]

Yep on most VP engines as in the OMC Cobra, the P/S cooler is right behind the stbd exhaust elbow/hose, so you would not get bits of impeller back there, these would be between the VP engine mounted impeller housing and the thermo housing. However, there is a plastic fitting in the pivot housing that can crack and suck in air when the engine is on plane. I would go back to the Volvo overheat diagnosis document, I have it and it is very good and explains how to check for air being drawn in and other less common causes of overheating. I would do all the tests they describe, not skipping anything. I did this on my Cobra modifying it for the difference in impeller location. What I found in my case was that I had marine growth inside the water intakes of the drive restricting raw water volume. Once I fixed that, no more borderline overheating (ie 185*). Back to 160-175 which is normal with a 160* stat. You really have to make sure that your impeller is putting out enough volume of raw water with the boat in the water and that no air is being sucked in. That and making sure your exhaust elbow cooling passages are not restricted by rust.
These open cooling systems depend on a high volume of cool water in and out. Any restriction to the in and out flow, will cause elevated temps. Since they are not pressurized, you can have boiling in the hotter parts of the cyl heads even with temps of only 190 on the gauge, so you really want to sort this out. Long term overheating will damage head gaskets and necessitate a top end overhaul.

 

[herring627]

At any rate, I was able to get back to the cooler when I removed the distributor cap. When I looked into the oil cooler nothing was lodge in there. But why would it have been? It isn't the normal flow of water and water has been flowing fine through the intakes via earmuffs. But now I have a bigger problem! I will start a new post with it but will also copy it here for continuity.

So I took off the distributor cap to get to my oil cooler. And of course I made a first timer's dumb mistake - I didn't have the outline for the proper order of wiring leading to distributor ... and of course I got the arrangement incorrect and now - I think I killed my boat! When I turned the ignition the engine did start but with a knocking sound and would not idle in neutral. Then it died. So I tried again, turned over a couple times but no start, tried again, turned over once stopped. Each time it sounded like it was hitting something. Since then I corrected the arrangement of wires and charged the battery to rule that out. Result - no change. Where on earth do I go from here?

Like I said, I am starting a new post with this one as I couldn't find anything in forums addressing this issue.