Volvo Penta D6-350 can't go above 3,100 RPMs???


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Okay, so I had a temperature spike recently and could use your help diagnosing the problem. I got this spike when going at idle speed. I immediately turned off the engine and notice a loss of coolant. Maybe about 1/2 to 3/4 gallons. I figured it must be an impeller since it I got the spike at idle speeds.


So, I check the sea strainer and nothing there. I removed the impeller and it looks like new. I topped off the coolant and tried again. The temp came back down and stayed at normal operating temperature of 185 degrees. The problem is now that I can't get that engine above 3,100 RPMs or so.


I have since run the boat a week and two later and the temp stays right where it should with no further loss of coolant. Would there be a fault stored in the EVC keeping the RPMs lower than WOT? I would assume if there was it would keep the RPMs much lower like 2,000. So, what are your thoughts?


I would hate to think I have a head gasket issue and, if so, what sort of symptoms would I see? Thanks for your help as I am really at a loss here.
 
Mmmm, well first thing I would want to know is where did the coolant go ?

Then....what computers do you have, on mine, I can go into system diagnostics and see if there were any faults.

I would do a quick oil analysis and even faster check your dipstick to see if the oil level is up or looks any different than the other engine.
 
Yeah, I hear you. Trying to diagnose this stuff myself is near impossible. The coolant was sitting in the bilge of the boat. The oil looks good just like the other engine. No milky color and no rise in oil levels. Same as the other engine.

Okay, I did a hard reset by turning off all the power to the engines overnight. I went back in the early AM to see if perhaps an error or fault code was stored in the EVC and thus limited RPMs. I believe the hard reset should have erased any fault codes. I don't think that's my problem anyways. The issue of loss of power and lower RPMs has not gone away. Also of note is that the boat idles smooth just as before.

Something went to crap when I had that short temperature spike to 203 degrees. The boat has a heck of time getting on plane with the port motor suffering from a loss of power and much lower RPMs. Everything seems fine up to about 1,800-2,000 RPMs and then the port engine seems to fall on itself just when I believe the turbo is starting to make some boost. It feels like I may be getting little to no boost or perhaps even supercharger output. Thoughts? What else to try?

Could it be an issue of high exhaust gas temps that caused a spike? Now an exhaust leak with minimal back pressure with little to no turbo boost? Or, worse, low compression in a cylinder or two? FML. I am lining up a VP service tech to come help me diagnose the problem on Wednesday, 24th. I am out of town all week for business so hoping for the best.

And I have no idea why they call these "pleasure" crafts. I have another name for it.
 
Ok, so I am certainly not a pro diesel mechanic...however pretty good at the basics.

So....coolant in bilge, means (I think) it boiled over somehow....so great news vs. you know where it is.

Oil on both sides the same, more great news.

No codes, well who knows.....Volvo's don't appear to tell us much...unless you have the FACTORY tools to read them.

At 1,800 - 2,000 is about when he super charger clutch starts to disengage and the turbo spool up of course. What Formula do you have, you MIGHT have a boost gauge, although I think most of us don't...but if you did, I would check that.

For sure I would check the turbo boost, low boost would for sure mean no power and thus MIGHT be what you are experiencing. Why you overheating...could be you picked up a bag, caused water restriction, then the bag fell off the pod when you slowed. (assume you have pods, but outdrive could have same issue)

Anyways....not much more I can think of this second.
 
Thanks for your help toofast. Yeah, I am thinking the same thing. I hope the VP service tech can get to the bottom of it on Wednesday. I will keep you posted.
 
Okay, the VP technician called me with his diagnosis. Hooked up his computer to the port engine and it showed no codes. After a sea trial, he said the port-side supercharger clutch is shot. No material left on the clutch and it´s basically metal on metal. That explains the loss of power as it was trying to engage the supercharger but couldn´t with no clutch. Would this explain my temp spike?

For your information, there was a group of jet ski´s following our boat before the temp spike. I decided to plow water at 2,400 RPMs for about 2-3 miles to create a large wake. My kids and their friends insisted we do that to watch them get serious air. Could this have killed what was remaining of my clutch? And could this have caused the temp spike when I came back off the throttles and then idled for a few minutes?

Does that make sense to you guys?

He also checked the starboard-side supercharger clutch. He said it looked much better with some signs of wear. It´s a 2007 after all. I wonder if I should replace both of them or wait until the other one fails?
 
I'm generally a fan of replacing parts in pairs figuring both have the same hours and usage.

Not sure of the cost of the blower clutch replacement but maybe you can negoiate a little discount on the second clutch labor since the tech will be there and already have the necessary tools out.
 
Yeah, good point. It doesn't look like an overly complicated job but it comes down to having time to do it myself. I will keep you posted as I am waiting to hear back on repair costs. I know the clutch itself is about $825.
 
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