Gurgling coming from exhaust

[Galvez83]

Hi all, i noticed on my manifolds water entry port once the hose is removed that a small amount of bubbles are present. Engine is a 5.7gs and the manifolds and risers are a month old. I replaced them due to new to me boat and i had no history on it. I wanted to be safe. Long story short. On the 2nd sea trial the boat overheated and i had to return to the marina. New impeller was toast. I hunted down the impeller parts in the block. Now i have a concern, once i removed the hoses the feed each manifold i saw what looks like gurgling. Is a small amount fine or is this a bad sign?

 

[cyclops222]

Garden hose hook up ? or floating in the water ?

 

[Galvez83]

Garden hose

 

[ESGWheel]

Need some help understanding the conditions and what you are observing. If I were to guess it’s this:
You have the motor running (at idle) on muffs and pull of (one at a time) the Raw Water hose to the manifold. Between the time you pull it off and shove it back on you are hearing (seeing?) gurgling coming from the manifold hose inlet. Something akin to water burping out of that manifold hose inlet. All the while there is a stream of water pouring out of the removed hose. Further, you were compelled to do this (remove the hoses) in order to check you have good flow (no impeller parts blocking these hoses) post the impeller disintegration and overheat.

• Is this a correct assessment?

If yes, as you are aware that water inlet on the manifold eventually connect to the exhaust side of the riser, so without the pressure of the raw water system the exhaust gases are making their way back down the water passages in the manifold and causing what you are seeing would be my evaluation > ie its ok.

That said, there may still be an issue (overheat cause). So, if I may, let’s step thru it.

• The new impeller had one good outing on it, no issues of overheat or any other issues whatsoever. Correct?
• When it overheated what were your indications? And how hot (if you noticed) on the helm gauge did it get? Concern is may have warped heads or other issues due to overheating.
• Towed back or motored back to dock? I assume motored based on description > how long did it take?
• What do you think caused this impeller to fail?
• With the new manifolds did you do a pressure or leak test?
• Was the manifold and impeller replacement done by you or a shop?

Here is my point: either you had a freak failure of a new impeller or something is wrong. And if wrong, it will rear its ugly head again. What could be wrong? Something like a cracked hose that feeds the Raw Water Pump (RWP) causing it to suck air and thus run dry and ruining the impeller. Remember when on muffs it provides pressurized water to the RWP but in the water the RWP is sucking water in thru a series of hoses and connections. If there is a break somewhere above the waterline, it will suck air.

Interested in your thoughts on all this.

 

[Galvez83]

Need some help understanding the conditions and what you are observing. If I were to guess it’s this:
You have the motor running (at idle) on muffs and pull of (one at a time) the Raw Water hose to the manifold. Between the time you pull it off and shove it back on you are hearing (seeing?) gurgling coming from the manifold hose inlet. Something akin to water burping out of that manifold hose inlet. All the while there is a stream of water pouring out of the removed hose. Further, you were compelled to do this (remove the hoses) in order to check you have good flow (no impeller parts blocking these hoses) post the impeller disintegration and overheat.

• Is this a correct assessment?

If yes, as you are aware that water inlet on the manifold eventually connect to the exhaust side of the riser, so without the pressure of the raw water system the exhaust gases are making their way back down the water passages in the manifold and causing what you are seeing would be my evaluation > ie its ok.

That said, there may still be an issue (overheat cause). So, if I may, let’s step thru it.

• The new impeller had one good outing on it, no issues of overheat or any other issues whatsoever. Correct?
• When it overheated what were your indications? And how hot (if you noticed) on the helm gauge did it get? Concern is may have warped heads or other issues due to overheating.
• Towed back or motored back to dock? I assume motored based on description > how long did it take?
• What do you think caused this impeller to fail?
• With the new manifolds did you do a pressure or leak test?
• Was the manifold and impeller replacement done by you or a shop?

Here is my point: either you had a freak failure of a new impeller or something is wrong. And if wrong, it will rear its ugly head again. What could be wrong? Something like a cracked hose that feeds the Raw Water Pump (RWP) causing it to suck air and thus run dry and ruining the impeller. Remember when on muffs it provides pressurized water to the RWP but in the water the RWP is sucking water in thru a series of hoses and connections. If there is a break somewhere above the waterline, it will suck air.

Interested in your thoughts on all this.

That is the issue..boat is not pulling water on muffs. I have put 3 types of muffs and minimal water makes to the lower hose on the impeller housing. I even taped the last set of muffs and that is the only way to get a steady stream out of the impeller. When engine overheated i was about 200 to 300 feet from the marina. The engine alarm went off and that prompted me to look at my temp gauge. Once i saw it i turned off the engine and proceeded to open the hatch to investigate. Luckily, i had another impeller on the boat at the time. The impeller that was shredded to granules was an OEM Volvo part.

I have gone from outdrive to engine looking for loose hoses or other indications of cracked hoses and found nothing. I looked at the engine flush mount and it was tight, similar to the issue with VP blue cap not tight. I even took the thermostat housing off to inspect and nothing other than bits and pieces of the impeller. At this point the boat is at my usual repair shop for troubleshooting. I will report back on findings.

While i was hesitant to drop it off, i really had no choise as i was coming up empty. Regarding the warped heads, so far no water in the oil....i hope it stays that way. I am able to run full water pressure via a garden hose hook up to the engine. While doing so i kept checking for the all too familiar milkshake in the oil, but nothing. I left it running for 30 minutes at different RPMs and the oil is coming up fine.

 

[ESGWheel]

Ah, ok so understand better now. And no longer an issue about the gurgling sound > case closed.

And sounds like there will be no issues with the overheat since you caught it in time and did not need to run that way. Given you have checked from the outdrive to the pump, this is a mystery. So will be highly interested in what they find. Please post a follow up.

Also, and you may be aware already, but I was not: there are 2 different flush connection types on these motors (1) those that can be only used for flushing and (2) those that can be used in lieu of muffs, ie can run the motor on it (at idle + a little bit). See this post (link) and look at post numbers 87 thru 89. If you have the 2nd type (blue cap), you can go muff free in the future

 

[Galvez83]

Update, still no indication and it has gotten worse. The riser and manifolds are new both sides. When the manifold inlet hose is removed after the engine is warm you get a lot of pressure coming out of the hose into the thermostat housing. So far tests have been done at the marina in the water. Engine pumps water but by the looks of it its getting a lot of backpressure.

1. Maybe the manifold gasket is bad?
2. Block somewhere in the new manifolds and risers on both sides?

Being that both sides are at play this has everyone scratching their heads. Both manifolds and risers are Barr. What could cause both manifolds and risers to build up such pressure allowing the engine to overheat? The impelled has been changed 3 times already. 1st one was shredded and replaced after hunting down the remaining parts. 2nd and 3rd impeller are moving water. Boat has a thru hull so the drive water inlet is out of the equation. No thermostat, still overheats. Maybe someone could chime in and explain and advise on how to proceed.

 

[ESGWheel]

Clearly, it’s much harder to do this via back-and-forth postings vs. being there and I am not sure I can help further but I will give it a try.

The symptoms you are having is overheating. With the boat in the water, it overheats at the dock at idle or perhaps at a slightly elevated RPM. Even without the t-stat installed.

The presumed root cause is excessive backpressure from the exhaust not allowing proper water flow in the manifolds and perhaps even overcoming the entire cooling system (not pulling water on muffs) causing overheating. This backpressure theory is derived from pulling off the manifold hoses and getting a lot of pressure (exh gas not water) out of the manifold hose end.

I am stating it this way as it helps me and perhaps others separate out the two. In other words, the issue is overheating. The ‘why’ has yet to be truly determined.

More: this is a new to you boat (a 2001 Wellcraft with 5.7gspefs) where, based on your recent posting, there have been a lot of questions ranging from low oil pressure (was a false reading) to not getting above 10MPH to distributor questions. I am only trying to get the entire picture.

Going with the exhaust backpressure theory: I cannot imagine that it’s the risers, not just b/c they are new, but even if had some casting deviation that did not allow proper sealing between manifold and riser (even with the gasket) the path of least resistance should be out the exhaust bellows, Y pipe, etc.

Thus, explore what is downstream of the risers > any possible blockage with that? There used to be ‘flapper’ valves in the exhaust system, not sure if the age of your boat would include them. Check. A restricted exhaust system will also preclude the engine from delivering its full performance and this may be the reason cannot get up to speed (link). Was that ever resolved?

If all good, pull off the risers (not manifolds) and inspect. Have a scope? Use it to look down the exh bellows, into the Y pipe and beyond as much as possible.

If all good, go back to the Raw Water Pump (RWP). Even though a new impeller it does not mean getting the full action out of it. You said you had flow; I assume this was observed when pulling off those hoses without the t-stat installed, but is it to spec? If the housing is oversized or scored the pumping action is decreased. Recall you initially had an unexplained shredded impeller. Did whatever do that score up the RWP housing? My suggestion is to completely remove that from the equation by getting another RWP. Here is a good source for them at less cost than new (link).

While this must be incredibly frustrating, keep pushing and posting, as this is 100% fixable.

 

[cyclops222]

Something to keep in mind about any water cooled engine during a FIRST COLD start. ...........I have seen thermostats sold with ...NO NO cold engie ......Bleeder Circulation hole in the thermostat plate. Car ? Not so critical. Boats ? Can be deadly with drain out of cooling system overnight. Then a test run of motor OUT of floating in a lake. A fast idle at startup will cause the pump to MOVE a LOT of water instantly.
I never .......test any engine out of river / lake floating condition. Why cook a failing coolant system ?

 

[Galvez83]

Clearly, it’s much harder to do this via back-and-forth postings vs. being there and I am not sure I can help further but I will give it a try.

The symptoms you are having is overheating. With the boat in the water, it overheats at the dock at idle or perhaps at a slightly elevated RPM. Even without the t-stat installed.

The presumed root cause is excessive backpressure from the exhaust not allowing proper water flow in the manifolds and perhaps even overcoming the entire cooling system (not pulling water on muffs) causing overheating. This backpressure theory is derived from pulling off the manifold hoses and getting a lot of pressure (exh gas not water) out of the manifold hose end.

I am stating it this way as it helps me and perhaps others separate out the two. In other words, the issue is overheating. The ‘why’ has yet to be truly determined.

More: this is a new to you boat (a 2001 Wellcraft with 5.7gspefs) where, based on your recent posting, there have been a lot of questions ranging from low oil pressure (was a false reading) to not getting above 10MPH to distributor questions. I am only trying to get the entire picture.

Going with the exhaust backpressure theory: I cannot imagine that it’s the risers, not just b/c they are new, but even if had some casting deviation that did not allow proper sealing between manifold and riser (even with the gasket) the path of least resistance should be out the exhaust bellows, Y pipe, etc.

Thus, explore what is downstream of the risers > any possible blockage with that? There used to be ‘flapper’ valves in the exhaust system, not sure if the age of your boat would include them. Check. A restricted exhaust system will also preclude the engine from delivering its full performance and this may be the reason cannot get up to speed (link). Was that ever resolved?

If all good, pull off the risers (not manifolds) and inspect. Have a scope? Use it to look down the exh bellows, into the Y pipe and beyond as much as possible.

If all good, go back to the Raw Water Pump (RWP). Even though a new impeller it does not mean getting the full action out of it. You said you had flow; I assume this was observed when pulling off those hoses without the t-stat installed, but is it to spec? If the housing is oversized or scored the pumping action is decreased. Recall you initially had an unexplained shredded impeller. Did whatever do that score up the RWP housing? My suggestion is to completely remove that from the equation by getting another RWP. Here is a good source for them at less cost than new (link).

While this must be incredibly frustrating, keep pushing and posting, as this is 100% fixable.

New pump housing has been ordered this morning to test that theory. The overheating is at idle and on and off at high rpms while static. No clear indication why the new impeller was shredded to beggin with. Another VP impeller was installed as i am not a fan of the cheap very flexible ones Amazon sells. All hoses where inspected and clear. The engine was flushed via a hose to remove all the impeller parts that had broken off.

Even while on the hose (not muffs) the engine temp gets to 170 degrees. I find that interesting. I base that on another similar engine i built that while on the hose it would not raise the temp at all. That clearly tells me there is a clog or poor water flow somewhere.

I have a boroscope and i will inspect the riser and manifolda along with the downpipe to determine if any obstructions are present before installing the new impeller housing.

 

[ESGWheel]

Sounds good. And you never defiantly said but since you are running on a hose (not muffs), your flushing hose connection is the blue cap style (see post 6) and picture below. Is this correct? (not trying to be rude, just double checking....)

And for reference, my 2005 5.0 GXi-E running on the blue cap flush connection at idle will hit 170F, takes a bit but its one of my preseason tests to make sure all is good.

 

[cyclops222]

Guys Are the garden hoses. Capable of providing the same or MORE GPM as the submerged drive pump ?
Why I did do the testing in lake water.

 

[Galvez83]

It has a similar connection with a transom hook up. Both have been disabled to rule out air. https://www.westmarine.com/seafit-w...B9BHz_Hd-ZlnjsisOML27CRtT1RWS3WUaApfyEALw_wcB

Sites-WestMarine-Site

West Marine

www.westmarine.com

 

[Galvez83]

Guys Are the garden hoses. Capable of providing the same or MORE GPM as the submerged drive pump ?
Why I did do the testing in lake water.

The test was at sea

 

[cyclops222]

Would like to help if I could. But my brain is being eaten alive all the time now. I can not remember long or short time events or people.
Good luckwith a odd ball problem.

 

[ESGWheel]

Guys Are the garden hoses. Capable of providing the same or MORE GPM as the submerged drive pump ?

If your engine has the blue cap, its designed to be used to flush the engine with the motor running. The VP manual says “Turn water on full and start the engine. Let the engine idle until engine temperature stabilized at its normal operating range.” So yes, its capable but obviously only so much as you are highlighting. I never run the motor up to full RPM but will bump it to 2000 and back with no issues. Been doing it for years and more than once during preseason (any time I do work on the motor, I run it on the flush port to temp).

It has a similar connection with a transom hook up. Both have been disabled to rule out air.

I am not familiar with your aftermarket setup but now I suspect possible improper hose routing may be causing the overheating (even if disabled). I am back to new to you boat and that perhaps you did not install this flush connection (yes, no?). If so, suggest go back to original OEM set up. Also, and need to ask, so do not take offence, are the RWP hoses on correctly? Its easy to get them switched.

 

[Galvez83]

If your engine has the blue cap, its designed to be used to flush the engine with the motor running. The VP manual says “Turn water on full and start the engine. Let the engine idle until engine temperature stabilized at its normal operating range.” So yes, its capable but obviously only so much as you are highlighting. I never run the motor up to full RPM but will bump it to 2000 and back with no issues. Been doing it for years and more than once during preseason (any time I do work on the motor, I run it on the flush port to temp).


I am not familiar with your aftermarket setup but now I suspect possible improper hose routing may be causing the overheating (even if disabled). I am back to new to you boat and that perhaps you did not install this flush connection (yes, no?). If so, suggest go back to original OEM set up. Also, and need to ask, so do not take offence, are the RWP hoses on correctly? Its easy to get them switched.

Yes, hose connections are accurate

 

[Galvez83]

I am slightly concerned by a possible blown head gasket or warped heads after the overheating event. Everything else is clear. No obstruction to the new risers and manifolds. Impeller and pump are clear and it seems i have gotten all the broken impeller parts out. I checked and flushed all the hoses and block for several minutes. I am starting to think of those 2 items. I even removed the circulation pump and removed the plate at the back to check the metal impeller and nothing. I do not have water in the oil l, i checked twice. Once running and after 20 minutes. Anyone has any idea where else to look?

 

[ESGWheel]

Start with a compression test but if ok, then need to do a leak down test (link).