Exhaust Manifold / Riser Issue

[300sflyer]

I just removed both sets of Barr exhaust manifolds and risers to inspect them, off of two 98 TBI merc 5.7 engines in our 32' Monterey. I found a small amount of water laying in the bottom of the exhaust ports, on all 4 manifolds. There was also some water in exhaust ports in some of the cylinder heads on both engines, which I blew out with compressed air.

Obviously there should not be any water there at all, and I am puzzed by where its coming from! I removed the risers from the manifolds, and the joints there were all in excellent condition. [genuine Merc gaskets] In fact, the manifolds and risers are in very good shape, and it looks like they were new not that long ago. I have only owned the boat since April, so I am unsure of their exact age.

Other than a bad gasket, or cracked manifolds, [not the case here] how else could water get in there? The last time the engines were running, [1 week ago] was to change the oil. They ran for about a half hour, both before and after the oil change, then the boat was hauled out of the water for storage till spring. I have never had any issues starting the engines, and they run just fine. I just wonder how this water is getting in there, and how to fix it so it does not happen again!

Are there any known issues with Barr manifolds and risers like there are with GLM?

Thanks for your help!

 

[TilliamWe]

Re: Exhaust Manifold / Riser Issue

Other than a bad gasket, or cracked manifolds, [not the case here] how else could water get in there?...

Reversion.

 

[Capt Ken]

Re: Exhaust Manifold / Riser Issue

I hope you did drain the manifolds before removing the risers. If there is no rust inside the manifolds then they have not been leaking. If only a small amount of water straight down from the riser then probably came from water trapped inside the riser that flowed out when you broke the seal.

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

I hope you did drain the manifolds before removing the risers. If there is no rust inside the manifolds then they have not been leaking. If only a small amount of water straight down from the riser then probably came from water trapped inside the riser that flowed out when you broke the seal.

Yes, I did drain the manifolds first before they were removed from the engines, as part of the winterization process. There is some rust inside the manifolds in the exhaust passages.

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

Reversion.

Can you please elaborate?

 

[Bt Doctur]

Re: Exhaust Manifold / Riser Issue

the manifolds could be porous, dry them completely, fill with water from the bottom untill 1/4 inch from the top where the riser goes, and just wait to see droplets between thye 2 middle ports.

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

the manifolds could be porous, dry them completely, fill with water from the bottom untill 1/4 inch from the top where the riser goes, and just wait to see droplets between thye 2 middle ports.

I suppose that is possible, however I doubt all 4 of them would be porous. I'll test one or teo of then and see what happens.

 

[Bondo]

Re: Exhaust Manifold / Riser Issue

I suppose that is possible, however I doubt all 4 of them would be porous. I'll test one or teo of then and see what happens.

Ayuh,... Study them closely,... water leaves rust trails,...

Search to the highest point ya see rust, 'n that's where it's leakin'....

Is yer boat stern heavy,..?? ya got 13" from outside water level, to the tippin' point of the risers,..??

 

[tpenfield]

Re: Exhaust Manifold / Riser Issue

If you are not seeing any rust . . . and the amount of water is small . . . then I vote for condensation. That is why we fog engines for the winter layup.

 

[TilliamWe]

Re: Exhaust Manifold / Riser Issue

Can you please elaborate?

Sure.
Water rushes back up the exhaust, and over the "tippin' point" of the risers. Or, the engines "rock backwards" enough when you shut them off that they suck a little water from the riser back into the manifold.

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

If you are not seeing any rust . . . and the amount of water is small . . . then I vote for condensation. That is why we fog engines for the winter layup.

Can't go along with this one... There was too much water there for that.

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

Sure.
Water rushes back up the exhaust, and over the "tippin' point" of the risers. Or, the engines "rock backwards" enough when you shut them off that they suck a little water from the riser back into the manifold.

So it looks like I have two possible causes... reversion, or 4 porous exhaust manifolds. I will be checking the 4 manifolds out very closely in the next few days.

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

Ayuh,... Study them closely,... water leaves rust trails,...

Search to the highest point ya see rust, 'n that's where it's leakin'....

Is yer boat stern heavy,..?? ya got 13" from outside water level, to the tippin' point of the risers,..??

The boat sits pretty normal in the water compared to other boats of this same size. The water line is about 4 inches above the u-joint bellows. Without geting out a tape measure, I would think that gives it at least 13" if not more.

 

[Bondo]

Re: Exhaust Manifold / Riser Issue

The boat sits pretty normal in the water compared to other boats of this same size. The water line is about 4 inches above the u-joint bellows. Without geting out a tape measure, I would think that gives it at least 13" if not more.

Ayuh,.... Guessin' ain't gonna cut it,... Measure it, as it's a know problem...

That's why they make those 3", 'n 6" riser blocks..

'n 13" is the Minimum...

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

Ayuh,.... Guessin' ain't gonna cut it,... Measure it, as it's a know problem...

That's why they make those 3", 'n 6" riser blocks..

'n 13" is the Minimum...

I have 14.5" from the waterline to the top of the elbow. [Not the tipping point inside the riser]

Merc says "SELECT THE APPROPRIATE EXHAUST RISE–HEIGHT TO MAINTAIN A MINIMUM OF 13 in. (330mm)
BETWEEN THE TOP OF THE EXHAUST ELBOW AND THE WATERLINE OF THE BOAT AT MAXIMUM
RATED LOAD."

According to that info, I should be ok, however I'm not sure. To complicate matters, the underside of my engine hatches, are already close to the top of the engines. I don't believe I would have room to add a 3" block let alone a 6" one.

 

[Bondo]

Re: Exhaust Manifold / Riser Issue

I have 14.5" from the waterline to the top of the elbow. [Not the tipping point inside the riser]

Merc says "SELECT THE APPROPRIATE EXHAUST RISE–HEIGHT TO MAINTAIN A MINIMUM OF 13 in. (330mm)
BETWEEN THE TOP OF THE EXHAUST ELBOW AND THE WATERLINE OF THE BOAT AT MAXIMUM
RATED LOAD."

According to that info, I should be ok, however I'm not sure. To complicate matters, the underside of my engine hatches, are already close to the top of the engines. I don't believe I would have room to add a 3" block let alone a 6" one.

Ayuh,.... Did ya have a party on the back deck, last time out,..??

Was the stern, drug in low when retrievin' on the trailer,..??

Donno.....

Any rust trails inside the exhaust passages,..?? Sometimes ya gotta look Real hard, with extra lightin'....

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

Ayuh,.... Did ya have a party on the back deck, last time out,..??

Was the stern, drug in low when retrievin' on the trailer,..??

Donno.....

Any rust trails inside the exhaust passages,..?? Sometimes ya gotta look Real hard, with extra lightin'....

Had a few nights of entertaining in the back of the boat during the summer... perhaps an extra case of beer too... LOL!

The boat was lifted straight out with a travel lift on to my trailer, so the back end was not any deeper in the water. I drained the blocks and the manifolds before towing it. There is rust inside the manifolds where the water was laying in there. Im going to block off the manifolds and pressure test them with 15-20 PSI of air. I'll spray a bit of soapy water in the exhaust ports, and see if I get any bubbles.

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

Just finished pressure testing the 4 manifolds with 25 PSI of air, and a bit of soapy water. No air bubbles anywhere, so I can only conclude there are no issues with them or the risers.

Not sure where to go from here...

 

[HT32BSX115]

Re: Exhaust Manifold / Riser Issue

Just finished pressure testing the 4 manifolds with 25 PSI of air, and a bit of soapy water. No air bubbles anywhere, so I can only conclude there are no issues with them or the risers.

Not sure where to go from here...

Howdy,

how did you pressurize the manifolds and risers?

 

[300sflyer]

Re: Exhaust Manifold / Riser Issue

Howdy,

how did you pressurize the manifolds and risers?

I only pressure tested the manifolds. I bolted a 1/2" thick steel plate with a gasket to the top of the manifold using the 4 bolt holes. I then connected my regulated air line to the bottom of the manifolds, with a rubber hose and hose clamps.