Bayliner 175 engine knocks at full throttle

[pappabarz]

I have a 2007 bayliner 175 with the 3.0L mercruiser engine. A couple of weaks ago we were out boating and I noticed a knocking sound coming from the engine. We had 7 people in the boat and we were pulling 2 seventy pound kids on a tube. The sound was not constant and it went away when I pulled back on the throttle. I went back out later by myself and noticed the knocking/popping sound when I went to full throttle, again it was not constant and it went away when I back off the throttle. I know this is a small engine and I should not push it too hard. Has anyone experienced this? Is this something I should look into or is this normal for the 3.0L?

PLease reply !!
Thankyou !

 

[JustJason]

Re: Bayliner 175 engine knocks at full throttle

im not surprised.... your asking alot out of that poor 3 liter.....

Try high octane fuel
Try propping the boat for towing/max load if you plan on having that many people one the boat alot.

 

[achris]

Re: Bayliner 175 engine knocks at full throttle

What year is the engine?

What are your Wide Open Throttle revs?

Chris...........

 

[chiefalen]

Re: Bayliner 175 engine knocks at full throttle

He was way over loaded and pulling skiers. All alone on the boat what is wot?

Rpm should be 4600 max.

Now a word about wot. I always run about 500-1000 rpm under wot.

You run wot all day every day and over load your gonna blow that motor.

And that noise you heard could be the out drive. Check the fluids all around.

Motor oil, and out drive oil.

Grease up the gimbal if you have the zerk inside the transom.

I would also check the compression, and pull the spark plugs to see what they look like.

 

[pappabarz]

Re: Bayliner 175 engine knocks at full throttle

Today I ran up the boat and I noticed the noise at 4500 RPM. It is not constant and goes away as soon as I pull back the throttle. Is this normal ? The engine does not miss or lagg when it makes this noise. This engine may have done this since new but I didn't notice because I rarely rev over 4000 RPM. Does anyone know if this common ? Does anyone have one of these boats that makes the same noise ? I would appreciate any feedback on this issue.
The engine is a 2007 model.
WOT RPMs are 4800-5000

 

[180shabah]

Re: Bayliner 175 engine knocks at full throttle

We seem to be overlooking the obvious here. It is a 3.0, and thus doesn't come with a water seperator. He is describing a classic lean condition. Time to replace fuel filters and add a water seperator(get an extra canister for it, so you can change it after your first tank of fuel).

 

[chiefalen]

Re: Bayliner 175 engine knocks at full throttle

That boat still under warranty? If yes i wouldn't touch anything and bring it to the dealer.

Brand new boat.

But i know you were way overloaded and pulling 2 tubes.

What does the plate say about poundage? 750? You were 1000 pounds over.

You got up on plane? And was running at 4500 rpm's?

Don't tell the dealer.

 

[pappabarz]

Re: Bayliner 175 engine knocks at full throttle

Where Do I Get A Water Seperator ? How Often Should The Fuel Filter Be Changed ?

 

[180shabah]

Re: Bayliner 175 engine knocks at full throttle

Where Do I Get A Water Seperator ? How Often Should The Fuel Filter Be Changed ?

Parts are available at the top of this page.....

Or walmart(or local equivilent). Cost for a water seperating filter is $25-40USD and the replacement canisters are $8-15USD

Fuel filters should be changed at least once per season.

 

[Bondo]

Re: Bayliner 175 engine knocks at full throttle

Is this normal ?

Nope,... It's Not Normal,... At All.....

You're detonating the motor when you hear that Noise,+ Probably are when you Don't hear it....
That Motor will be an Anchor in No time if you don't Fix it...

Alot of things can bring on Detonation,....
Overloading is 1,... Running a Lean condition is another....

It sounds like you might be doing Both.....

 

[JustJason]

Re: Bayliner 175 engine knocks at full throttle

its an 07 boat.... can ya take it back to the dealer?

 

[Robj]

Re: Bayliner 175 engine knocks at full throttle

Take it back to the dealer and let the warranty deal with it. Don't touch anything.

Have a great day,

Rob.

 

[pappabarz]

Re: Bayliner 175 engine knocks at full throttle

Today I took the boat back to the dealer, we filled up with premium fuel (91 octane) and went out on the water. Again, at approx 4500 rpm the eng started to make the ticking/popping noise. After running at the boat a while the mechanic noticed a leak in the head gasket on the # 2 cyl. which they are now gonna replace. Would this be the cause of the ticking/popping sound I get at 4500 - 4800 rpm ?

 

[chiefalen]

Re: Bayliner 175 engine knocks at full throttle

Did it over heat at all?

 

[pappabarz]

Re: Bayliner 175 engine knocks at full throttle

No this boat has never overheated

 

[pappabarz]

Re: Bayliner 175 engine knocks at full throttle

Today I heard back from the dealer. They replaced the head gasket and the thermostat and took it out on the water and it still made the noise at 4500rpm. They are going to try some other adjustments but are not to sure why this is happening........ The mechanic told me he has a friend that has the same boat with the same problem. Any suggestions?

 

[chiefalen]

Re: Bayliner 175 engine knocks at full throttle

Tell you dealer you want a new engine. Pretty soon they will have all winter to put a new one in.

If you ever get it back right please follow the weight limit of the boat. Each person is thought to be 200 pounds.

Your boat im guessing would be 3 people if your pulling tubes or skiers.

 

[Don S]

Re: Bayliner 175 engine knocks at full throttle

Tell you dealer you want a new engine.

Merc or the dealer isn't going to "Give" him a new engine just because he asks for one.

The mechanic told me he has a friend that has the same boat with the same problem. Any suggestions?

I sure hope your "dealer" and mechanic are Mercruiser certified dealers and mechanics. They should get Merc Tech service involved. They may already be familiar with the problem and have a fix for it.

 

[180shabah]

Re: Bayliner 175 engine knocks at full throttle

........The mechanic told me he has a friend that has the same boat with the same problem....

OH, well if that boat does the same thing, yours must be fine.....BS!!! Don't let him convince you all is well. I agree with Don, it is time to get Mercruiser involved, if they aren't already.

 

[chiefalen]

Re: Bayliner 175 engine knocks at full throttle

Tell the mechanic that you have a friend jumped off a bridge, maybe he should to.