Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

[badger42]

Hi all-
I've read through just about all the post i could find on the subject but haven't seen anything similar.

Specs: 1999 Volvo Penta 5.0 Gi PWTR with a SX-M/1.60 outdrive.

Problem:
Loud rhythmic rattle from back of engine when under load (in water) above 1800rpms; noise increases from a little at 1800rpms to very loud at >3000rpms and sounds like somethings going to break apart at >3800rpms.

In neutral or without load (out of water) the engine/drive spins and sounds fine, all the way up to 4500rpms; however; when the trim is tilted up even a small amount (5 degrees) a ?whirring? sound and slight vibration can be heard, and it gets louder with greater tilt (about 10 degrees).

Fluid levels in the motor and outdrive are ok and oil appears to be fairly clean. This noise began after stopping to fish for a few hours; on the way out it seemed to run fine, but had to idle home.

I bought this boat used a week ago and it ran fine for the "test drive" and the first day (this happened on the second day)! The place that sold it said they checked the coupler, gimble, and alignment during an inspection... but they also Painted over the Zinc Anode and stuffed the blower exhaust hose end behind the engine so i sure wouldn't consider them experts.

Since the noise is definately heard in the engine box, would this be related to the engine coupler? Would you "hear" the u-joints through the engine compartment?


Any suggestions? Thanks!

 

[sean16921]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

my engine/drive was making the same noise and it was a semi seized up u-joint because of water in the bellows

 

[Don S]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

Pull the drive, check for water in the bellows. Also check the gimbal bearing and the ujoints. Of course the ujoints may feel good, but could still be the problem.

 

[badger42]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

Finally got the drive pulled- no water, gimbal is clean and rotates smoothly and the u-joints appear in good condition (though i understand that doesn't neccessarily mean they are ok).

The boat is headed to the Volvo shop tomorrow, possible culprits being:

Engine mounts- though they appear tight
Alignment- not sure if it can come out of alignment in a few minutes
U-joints- not quite ready yet to spend the $500 for new ones
Engine coupler- though no "burnt rubber" smell
Lower Unit- there were some shaving on the magnet but no "chunks", sounds smooth out of the water, noise seemed to be coming from engine compartment, but might have traveled up the drive train.

One question- in the Penta SX, does the oil dipstick go into a reservoir? I'm curious if there could be clean oil in the top/reservoir while dirty oil circulates throught the rest of the drive??

Any thoughts? Thanks.

 

[badger42]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine- Blown Heads!?!

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine- Blown Heads!?!

The dealer now says the heads are blown and water is getting into the cylinders!

This is going to be a costly repair, does anyone have experience with this?

Just wondering how i could blow heads/gasket when everything else seemed fine- no overheating, ran at regular rpms, turned off to fish for an hour and started back up making the "noise".

Also, if things were bad enough in the engine to blow a head, is it worth spending the money to fix it or will more problems keep popping up?

Seems like there were probably existing engine problems- am i getting hosed here?

 

[badger42]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

It's a 1999 with 290 hours on the engine, as indicated by the jerry-rigged hour meter zip-tied to the engine. I believe it was repositioned there to accommodate a water-depth gauge.

Does the fact that it only rattles under load (not in neutral) seem likely for a blown head gasket?

 

[xltier]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

Yes, in one case its working, in the other its just spinning.

a motor that is running with water in it is gonna make noise weather its in gear,nuetral what ever.there is more to this story.plus if there is water burning thru seems thou there would be losts of steam out the exhaust when run on land.what about a loose coupler or flywheel bolts.?a bad head gasket that leaks doesnt usually happen that quick.get another opionion.

 

[badger42]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

Thanks for all the information!

It turned out to be a blown head gasket, and when the heads were taken off, they were found to be cracked too. Not a cheap fix, but the mechanics said the block was still in good shape.

The guys i bought the boat from came through and helped pay for alot of the repairs, so in that aspect, i guess it wasn't too big of a dissapointment.

 

[KJSmitty]

Re: Volvo-Penta 5.0Gi/SX Loud Rattle behind Engine

Good friend of mine has the same engine/drive combo. Same thing happened to him. Purchased use boat - ran great yet with a minor starter problem. Went from replacing starter to the Volvo shop pulling the engine to change the flywheel ring. No more than got the engine out and it was evident it had been semi submerged. The starter/ring issues ended up being from water in the cylinders - heads pulled and found cracks.

Nothing like that to ruin your fun/boat purchase.

Long story short however - and the reason I mentioned it, that was back in 2002 and after the repairs, he still owns it today and it has been running great ever since.

Very nice to hear that the previous owners are helping you out with the tab!!

Best of luck!