Exhaust leak?

[Ajax]

I think I have an exhaust leak, but I need advice on confirming it.

I'm pretty sure this is a later model A-4. It doesn't have the PCV mod. I think I read that without the PCV upgrade, the engine will smoke a bit under load, so I didn't fret the slight wisp of smoke that would come up from the cabin.

Today, at higher RPM's, I hear a ticking sound. It sounds like a tick, not a "clack" of metal and I haven't experienced any loss of performance. There is a little more smoke now. It actually doesn't start until the engine warms up, and then I have to get it near max RPM's. It's like the metal expands from and allows the leak. If I throttle back, the tick mostly subsides after a minute, as if there isn't enough back pressure to leak out much.

Does this sound like an exhaust leak to you? If so, do you think it's the exhaust flange? Where else might there be an exhaust leak?

Thanks,

Ajax

[sastanley]

Ajax,

Lots of possibilities. If it is NOT an exhaust leak, they often let some oil smoke out of the fill port on the front of the motor. The PCV kit usually helps with this. Moyer & Indigo both sell one.

If it is an exhaust leak like you think, it would be between the manifold flange and the elbow where the water is injected. That area is usually built out of black iron pipe...cheap to build/replace..I did mine the first winter I had the boat...

In the meantime (since I know you have Frostbites for the next few weeks,) do you run the blower while running??? If not, do so..it will help a little bit.

As for the ticking sound..that could be a valve out of spec. I think I have one too...but mine are in spec, so I also think it might be a failing accessory drive bearing. The valves are on the port side and the accessory drive is on the stbd side (just aft of your new thru-hull).

[jpian0923]

I hate to keep harping on this but, can you get video of what you are describing? I know for years on this forum (and others) that a well described symptom can be diagnosed and solved rather quickly but, with cheap digital cameras and youtube to post videos, I don't see why the first order of business is not to take a video and post it here. Ok, I'm done ranting.

Can you get video?

[joe_db]

Here is how I tracked down an exhaust leak. With the engine running, pour MMO into the carb slowly. You will produce an impressive smoke screen from the exhaust and any leaks will be obvious.

[Ajax]

Shawn-

Using the panoramic, can you draw a circle or an arrow to the area that you're referring to?

JP- I can easily do this, but I figured that the audio quality wouldn't be up to the task of making an audio track that would provide anything useful. I'll make something today.

Yes, I run the blower and that usually takes care of the worst of it. I observed smoke wafting out of the oil fill cap vents and it appears to be coming from other places. The engine exhaust is white and steamy with only the barest hint of any blue and no real oil smell so I don't think the rings and stuff are too badly worn. This light blue smoke down in the cabin is coming from elsewhere from the engine.

I'll get some A/V of the engine running for you.

[sastanley]

Rich, the problem is there is no exhaust system attached to the panoramic.

Below, is a pic of my engine with the hot section circled. It is simple black iron pipe under the heat wrap.

The accessory drive is the unit that drives the belt for the alternator..they are often noisy because the bearings are oil starved due to the engine's aft tilt. This is discussed here --> http://www.moyermarine.com/access_repair.htm

To further expound on the issue mentioned earlier regarding the PCV kit, the original 'slash tube' is supposed to let the carb suck in the blow by fumes thru the flame arrestor..although most seem to agree that there is not sufficient suction at the flame arrestor to do this. This is the reason the PCV kits were created.
I've also attached a pic of my PCV installed so you can see the difference between it and the stock slash tube configuration...also pictured.

[Ajax]

Awesome, that's a great help. I have a Vernalift thingy, so I have to see how the exhaust gets to that. I don't have great access to that side of the engine. I'll have to remove a lot of stuff.

That large, rectangular manifold that connects to the heat-wrapped pipe- I assume that it bolts to the block and that there is a gasket between them? Have you ever heard of that failing?

And thanks for the PCV upgrade photo also.

[sastanley]

Don't have any info on the manifold..Mine has been replaced with a Moyer unit...but yes, there is a gasket in there.
Try this part number - GASK_08_147

[Ajax]

Don't have any info on the manifold..Mine has been replaced with a Moyer unit...but yes, there is a gasket in there.
Try this part number - GASK_08_147

Ok, cool. Based on the ticking sound and the smoke, my theory is that either the manifold gasket or the flange gasket on the end (where your heat-wrapped pipe begines) is leaking.

I didn't make it down to the boat last yesterday, but I should be able to make it there today to make a video and take photos.

[Bold Rascal]

Oil Filler smoke

Nice Pics Shawn.
Not to hijack your thread Ajax but I wanted to ask Shawn if he thought adding the PVC kit was worth it.

We ran our A4 several hours this weekend (actually sunday and monday) and there was enough smoke/fumes coming from the fill tube cap (once she was warm) to cause me to leave the engine access hatch open and well ventilated.

Ajax, your ticking sound might be a stuck lifter. Hope you sourced both your exhaust leak and ticking source.

[sastanley]

Bold Rascal..yes....definitely. We acquired the boat late in August a few years back..The haze & fumes was the the first thing my wife complained about (actually, the entire boat wreaked of 'oily motor'). In my case, the PCV kit made a HUGE difference..it was the first modification I made to the engine that fall. We'd putzed around quite a bit before and after the installation the first fall season we had the boat, and there was an immediate and noticeable change in the 'cabin haze'. There was a layer of black/brown scum I could almost scrape off the inside of the boat anywhere near the engine room. Additionally, the cushions and anything that could absorb odors did so...and it was awful. The boat got a thorough cleaning/de-greasing that first winter to take advantage of the lack of oil now spewing into the cabin.

We can motor for hours and hours with no trouble, smell or oily smoke in the boat now. I do get a slight blue smoke out of the exhaust, but I also know this motor was drowned twice (at least), and the P.O. had to yank the head to break the rusted piston(s) & valves loose..I am sure this has had some detrimental effects to condition of the rings & cylinder walls in #3 & #4, so that likely accounts for some of the oil fumes & blow by floating around in various parts of the engine.

Bottom line, the PCV kit made a huge difference in my boat.

[Ajax]

Ok, I've listened again and it's either lifter noise the the accessory bearing as previously suggested. I discovered that the brass fitting for the oil pressure gauge line weeps a tiny bit when the engine is running, and my oil level had drifted to the bottom "fill" line. When I added oil, pressure and sound was much better.

Here's a video before I added oil:
Ticking sound

[Bold Rascal]

Hard to tell for sure,

But it sounds like lifters to me.

Have you thought about doing a compression test on each cylinder? Might be you have a valve(s) sticking. You might try squirting some Mystery oil onto each of the valves thru the spark plug hole, rotating the engine afew turns (not running) letting it soak for awhile and then see if there's any improvement.

[sastanley]

Ajax, don't you have one of those mechanic stethescope thingies? Even a long handled screw driver will work. The accessory drive bearing is a nice low grinding noise. In my case it drowns out all the other sounds I am trying to pinpoint...

[Ajax]

I have a compression gauge kit. I'll try everything listed above, but like I said, it got a lot better after I simply added some engine oil. It sounds like it's coming from the top, aft part of the engine.