1987 AQ131A (120 hp), clanging/banging noise, and pressure release noise

[`teh1]

Hi Guys,

1987 AQ131A (120 hp), I can try to provide more information as asked but all I really know about it is that the boat was created with it in 1987.

I am currently faced with 2 concerns as follows:

When the throttle is half to full, random clashing sounds can be heard. Sounds like metal against metal. My thoughts from looking online are either the starter getting smacked by the fly wheel or the U joints. Any suggestions on tests I can do to find that out would be great.

Also sometimes it makes sounds like it's releasing some kind of air pressure. Only at lower speeds, when coming down from higher throttle. I'm not sure that it always happens, either, but most of the time.

Any ideas?

Editing this in, Here are a couple of links that seem to relate...

This sounds almost exactly like what is happening - I even had the same reaction of thinking it was water. No drop in RPMs, but definitely happens randomly a couple times a minute.

http://forums.iboats.com/volvo-pent...ives/banging-noise-while-high-rpm-579208.html

And this, seems to be a similar sound as well:

http://forums.iboats.com/volvo-pent...-chain-clanking-against-flag-pole-450270.html

 

[Leedanger]

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

It's unlikely to be flywheel housing bearings or starter if it's only happening at half throttle...same goes to U-joints, you'd hear it right away most likely. We would have to know the engine serial number to give you any more information...impossible to diag without it.

 

[`teh1]

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Volvo Penta: 729063 (Made in Sweden!!!!) heh

 

[`teh1]

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

See below attachment...

PN | 867981 | 8629 |
SN | 729063 |



I was thinking, when enough air pressure is released fast enough, the sound is that of a BANG. There is a chance that the sound I was hearing at half-to-full throttle is the same air pressure release sound that I was hearing after letting the throttle down, just lower pressure and slower release. Don't quote me on it, because I can't say for certain. Just a thought that maybe they are related.

 

[Don S]

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Pull the upper gear box and check for water in the bellows, also check the ujoints, and pull the seal out of the back of the flywheel cover and see what the bearings look like.

 

[`teh1]

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Hi, Don,

Thanks for your input. I have removed the upper gearbox and here is what it looks like, looking at the bearing, into the intermediate housing, through the bellow and at the U Joint.

As you can see, the oil appears to have some whiteness to it (it shouldnt be that light of gray, should it?) and it is pretty thick. That means that water has gotten into it, right? So I should replace it and some seals?

The previous owner said he had the bellows newly replaced - Perhaps water was getting in through them.

That said, the fact that the U-Joint has rust on it also indicates potential exposure to water, yes? other than that though it seems solid. I don't feel more than a fraction of a millimeter of play and it moves freely.

ALL THAT SAID, I'm not the expert so please correct me if I'm wrong!



The next step is for me to remove the flywheel cover. Do you have any instruction sets on doing that?

 

[Don S]

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

Re: 1987 Volvo Penta (151 hp), clanging/banging noise, and pressure release noise

I can't tell in your first picture if it's water or not. Photo is overexposed and impossible to be sure. You were there, was there water in the bellows? From the looks of the ujoints there was, they are rusty.
The gear lube is gray, sure sign of water. It should look like engine oil, or dirty engine oil, not gray.

 

[`teh1]

Re: 1987 AQ131A (120 hp), clanging/banging noise, and pressure release noise

Then for sure water got in. As I mentioned the bellows were replaced before I got the boat, so there is no-longer water in them. It seems that there used to be, and it made its way into the gear box.

What do I have to do to prevent that, exactly? I read something about getting new seals.

Now that I have eyes on the Flywheel Housing, how can I remove it? Do I have to actually take out the engine, or can I remove it via the bolts I see through the back of the boat? If the latter, should I fully remove the stern drive then in order to remove the bolts on the housing?

I do have the workshop manual handy, but it doesn't talk about what to do when the engine is on the boat.

 

[dypcdiver]

Re: 1987 AQ131A (120 hp), clanging/banging noise, and pressure release noise

Something is not running true as the paint in No.1 photo is scoured away between 7 and 9 o'clock.

 

[`teh1]

Re: 1987 AQ131A (120 hp), clanging/banging noise, and pressure release noise

Ah, yes, that is a good point. I don't remember seeing any corresponding marks of any kind on the U Joint though. I'll have to check again. Meanwhile I am still figuring out how to take off the flywheel cover... I'll have to get to it tomorrow, as I have to work today.

 

[Mullin]

Re: 1987 AQ131A (120 hp), clanging/banging noise, and pressure release noise

^ It's just from running the motor with the drive raised up in the transport position.

That first pic looks like there is wet crud in the flywheel housing. What is that?

Yeah definitely water in oil there. And just too so it's been there for a while. The PO may have replaced the bellows and not changed the oil (seems unlikely) or he may have replaced the bellows but not fixed the actual problem (seems more likely).

 

[`teh1]

Re: 1987 AQ131A (120 hp), clanging/banging noise, and pressure release noise

The stuff up against the bearing there looks like dirty bearing grease to me. Looks just like the automotive grease I use on my bicycle bottom bracket bearings...

Since the gnarly grease in the tranny isn't leaking into the bellows, does that mean the seals are fine?

The "PO" only told me he replaced the engine oil. He made no mention of the tranny. But I see what you are saying. It makes way more sense that the problem is not solved. I will ask and confirm.

 

[`teh1]

Re: 1987 AQ131A (120 hp), clanging/banging noise, and pressure release noise

This sounds a lot like what im hearing but not just at full rpms.

Engine back fires at high RPM - Engines Forum - Boating World Magazine

Also I got this from the previous owner...

I did not here a clank at any rpm . I had a mechanic friend of mine do a lot of preventive maintaince prior to last summer. I dont remember if he did tranny oil. I can ask him. He seen an oil seepage so pulled motor to do oil pan ... Ended up also doing front and rear main seal and timing gear and chain. We used it for the summer months a few hours a week.

I just talked with him. We didn't do anything with the tranny oil. We changed the impeller and bellows and large fuel line and cleaned electrical connectors under dash during the winter before last to get it ready for last summer.... Did the engine pull and gaskets / timing chain and gear at same time.