5.0 Volvo Penta SX-M Overheat

[Mr Rumblur]

After receiving some input about using Marine Tex to fix the cracked block, we decided to give it a try. Now we're addressing the overheat issue. It gets up to at least 210 and acts like it could keep going up while on muffs (all times it's ran have been on muffs).

We've replaced the impeller and the thermostat. While replacing the thermostat, we discovered RV antifreeze even though it's ran several times prior. I assume this means poor circulation so decided to check manifolds/elbows. There was very minimal visible corrosion. Is it common for there to be "hidden" corrosion deeper?

We also disconnected the hoses going from thermostat housing to the manifolds. A bunch of water came out of the manifolds. It appeared to have a little pink in it. Then we ran it briefly while still disconnected. At first, some water came out of thermostat housing, only under decel. When we ran it again, nothing came out. Isn't water supposed to come out of there? If so, is it only when it reaches thermostat temp? We didn't run it up to temp. Have we narrowed it down to the circulation pump? Thanks!

5.0gl pefs 4012048045 3869056

 

[Don S]

Re: 5.0 Volvo Penta SX-M Overheat

Do you have the full model number or serial number of your engine. At this point no one has a clue to year, or even if it's a Ford or Chevy so really hard to give specifics.
Here is a link to Volvos overheat diagnostic file.
http://www.4shared.com/file/50572185/e88f1d89/Volvo_Penta_Overheat_Diagnosis.html

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

5.0gl pefs 4012048045 3869056

 

[Don S]

Re: 5.0 Volvo Penta SX-M Overheat

Chevy 305, Year 2000, carbed, with power steering, with an SX-M outdrive.

Do you have plenty of water volume and pressure? If there is low flow volume or pressure, to much air will be sucked in and the pump will not prime.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

Thanks for the link! I've read on here to not use too much pressure with muffs so have been doing what I'd consider medium pressure/volume, based on the full scale of my particular garden hose/muffs setup anyway. Maybe best to drop it in the water since I don't have a test tank?

Is it possible for it to be "airlocked"? I had accidentally ran it before reconnecting one of the hoses connected to the impeller housing (aka raw water pump??). I believe it's the one taken off for winterizing. Between that and possible low pressure/volume like you mentioned, is that what you'd focus on first?

 

[Don S]

Re: 5.0 Volvo Penta SX-M Overheat

I've read on here to not use too much pressure with muffs so have been doing what I'd consider medium pressure/volume,

Turn the pressure on full and try it. You can read all sorts of things on forums that aren't true.
Just make sure the muffs don't float/fall off. I tie them on with a light rope.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

Will do. Thanks for the forum tip. I need to stop assuming that someone who knows better will catch all and correct all ;-) When I try this again, am I correct in looking for flow out of the thermostat housing (where I disconnected the hoses that go to manifolds)? Is there a better place? Thanks for your help!

 

[Don S]

Re: 5.0 Volvo Penta SX-M Overheat

Check where the water goes into the manifolds.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

And it should flow there all of the time, no matter the temp, correct? It doesn't rely on thermostat function?

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

So the raw water pump does house the impeller, correct? I've now turned the hose on full with no change. So, I'm ready to either put it in the lake for testing or try Bubba's modified method. When hooking garden hose directly to inlet side of raw water pump, I assume that water flows everywhere it needs to. Can I run it just like on muffs unless it still gets hot?

 

[Don S]

Re: 5.0 Volvo Penta SX-M Overheat

You might want to look at the impeller again, if you ran it dry long enough without water, it's burned up.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

If you're referring to when the hose was disconnected, that was before the impelller change. Wouldn't hurt to check it's condition and the way the veins lay/angle. They are supposed to lay the way they naturally angle with engine rotation, correct?

 

[Silverbullet555]

Re: 5.0 Volvo Penta SX-M Overheat

If you go to marinepartsexpress they have a document and write up on adding the hose attachment to the 2003 and older volvo's. In 2002 and before, the raw water flush was not designed to run the motor on. In 2003, Volvo changed the design so you could run the boat using the hose attachment. I have not done the mod to my boat, but I bought the parts to do it and I might get around to it as it would make it much easier to run the boat. Though, I have never had problems running on the muffs.

For your muffs, do you use the type that have water in on both sides or just one side. I know that both sides of the intake are connected in the lower unit, but I always felt better with muffs that bring the water in on both sides instead of just one.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

If you go to marinepartsexpress they have a document and write up on adding the hose attachment to the 2003 and older volvo's.
Thanks! I'll check it out.
For your muffs, do you use the type that have water in on both sides or just one side. I know that both sides of the intake are connected in the lower unit, but I always felt better with muffs that bring the water in on both sides instead of just one.

I feel the same way so am using the dual.

 

[Tail_Gunner]

Re: 5.0 Volvo Penta SX-M Overheat

If you go to marinepartsexpress they have a document and write up on adding the hose attachment to the 2003 and older volvo's. In 2002 and before, the raw water flush was not designed to run the motor on. In 2003, Volvo changed the design so you could run the boat using the hose attachment. I have not done the mod to my boat, but I bought the parts to do it and I might get around to it as it would make it much easier to run the boat. Though, I have never had problems running on the muffs.

For your muffs, do you use the type that have water in on both sides or just one side. I know that both sides of the intake are connected in the lower unit, but I always felt better with muffs that bring the water in on both sides instead of just one.

http://www.marinepartsexpress.com/engine_flush.html


View attachment 89204

View attachment 89204

That plumbing allows bypass of the drive pickups???

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

Thanks for the info and links. I will pursue this later today and update on here.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

I wanted to remove all doubt about there being enough volume/pressure. So, we put it in the lake. Still got hot. Still nothing coming out of hoses that go to exhaust manifolds.

I pulled the outlet hose off of raw water pump. A decent amount of water was coming out under acceleration. To make super sure, I did pull the impeller and it looks good. I'm not certain that the veins were angled correctly. How do I check this, even if just for my install? I've not done one before. When I said "we've replaced the impeller and the thermostat" in first post, I was referring to the mechanic while he had it to fix the crack.

Have I narrowed it down to the circulation pump? Thanks in advance!

 

[Don S]

Re: 5.0 Volvo Penta SX-M Overheat

I did pull the impeller and it looks good. I'm not certain that the veins were angled correctly.

Do you know what a good impeller is supposed to look like?
When you took it apart, the vanes should have straightened out. They should NOT remain curved for more than 10 minutes. If they do, the impeller needs replaced.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

I assumed it was good since the vanes were all present, pliable and yes, they did straighten out quickly.

 

[Mr Rumblur]

Re: 5.0 Volvo Penta SX-M Overheat

I've narrowed down the area of the circulation problem. I put the garden hose directly into the supply pump inlet while a helper started the boat. I already had the hoses disconnected from the manifolds. Within a few seconds, water started coming out of them. Is there another impeller or something in the outdrive that helps lift the water?