Uneven exhaust flow

[805HD]

I pulled the water pump off the block. Thinking maybe the starboard side inlet had some kind of blockage... nothing. Wide open. I then removed the hoses running from the thermostat housing to the manifolds and ran the boat. The starboard side hose is returning less water then the port side. Which makes sense since the starboard side exhaust is the one with less water return.

So I’ve narrowed the restriction down to being BEFORE the manifolds and elbows. Question now is what’s causing the restriction?!

 

[RicardoMarine]

I pulled the water pump off the block. Thinking maybe the starboard side inlet had some kind of blockage... nothing. Wide open.
I then removed the hoses running from the thermostat housing to the manifolds and ran the boat. The starboard side hose is returning less water then the port side. Which makes sense since the starboard side exhaust is the one with less water return.

**So I’ve narrowed the restriction down to being BEFORE the manifolds and elbows.
Question now is what’s causing the restriction?!

Your best friend will be using the P of E..... process of elimination.
Test/change one item ONLY at a time.
When used systematically and methodically, the P of E won't let you down! There is no disputing this!



**Understand that nothing up-stream from the T-stat housing will be causing an un-equal seawater flow to the exhaust system.
In other words, any seawater being introduced into the engine alone has not yet been split or divided in order to equally supply the exhaust system. That split or division occurs at and within the T-stat housing.
With exception to some jet pump systems, this will apply to any Raw Water Cooled Merc, OMC, Volvo Penta, Indmar, PCM, etc.
In other words, you do not need to be a Merc Tech in order to make a suggestion re; this particular issue!


In post #1, you mentioned; "Obviously there is a restriction somewhere".
In your most recent post #31, you have made that assessment again.
I would say, yes, that is very likely what is going on!



I have occasionally read whereby someone has added restriction to the better flowing side in hopes of increasing flow to the problematic side. I would not suggest doing that.
Find the restriction, and you will have found the problem.


Chamfer any sharp edges that may be restricting flow.
Look at the interior of the hoses for any signs of delamination.
Look at the ID of any 90* fittings that may be causing a restriction.
During the process, you may find an object that is causing the restriction (i.e., impeller pieces, for example).
Occasionally Starboard parts can be swapped to the Port side (or visa-versa) as part of the P of E.




.

 

[kghost]

Oh how I wish we were neighbors lol

still having troubles. So I put brand new elbows on and have the right gaskets in the right order between the risers. And I’m still getting a restriction on the starboard side exhaust. Running at idle, the temp seems to hover around 160 give or take. Port side is returning plenty of water but starboard side is no where near enough. This is running with the drive lowered into a tub. Both pipes steaming. Nothings leaking. Water pump on the block is brand new. And the boat didn’t have this issue before the engine was pulled.

I dont think it would be the impeller because because the problem, whatever the hell it is is isolated to the starboard side only.

Ive eliminated a lot of variables now.. Any ideas?
Thank you

Ii very well could be the impeller and anything below it or after it restricting/lessening water flow to thermostat housing.

The lack of full water pressure inward could be causing a lack outward............Mercruisers typically show less to one side under normal conditions. (one elbow warmer than the other).

So start at the impeller and work your way back to thermo housing

 

[805HD]

In other words, any seawater being introduced into the engine alone has not yet been split or divided in order to equally supply the exhaust system. That split or division occurs at and within the T-stat housing.


Chamfer any sharp edges that may be restricting flow.
Look at the interior of the hoses for any signs of delamination.
Look at the ID of any 90* fittings that may be causing a restriction.

Understood. Thank you for the reply..

I took the thermostat housing off and inspected it. Found one fingernail sized piece of scale, aside from that all passages are open. I don’t know where the piece of scale came from because it just fell out when I removed it. I suppose that could be related to the issue or be the issue but something tells me it’s not going to change anything if I put it back together and run it.

Really beginning to lose hope on this one.

Although I have minimal experience working with boats and unleaded engines for that matter. I do have a pretty extensive background working on diesels and for being only 30 years old I have been around the block a few times. I don’t think I’m over looking anything obvious here but I’m starting to second guess myself.

Could there be something within the block or intake manifold restricting water flow?

 

[805HD]

start at the impeller and work your way back to thermo housing

Okay. Yea if you look at the reply I just wrote to your best friend lol you will see I didn’t find much in the thermostat housing other then a small piece of scale and although I can’t tell you exactly why, I don’t believe that’s the problem.

Ill start art at the impeller and work my way up. Your statement makes sense.

Im not shooting for 50/50 return. But 90/10 just can’t be right. The port side GUSHES water while the starboard looks like more of a spray.

Ill inspect the impeller the PS cooler and the water inlet from the stern.

Thanks a million

 

[805HD]

So today I pulled the drive, impeller was in perfect shape.

I then verified that the water inlet through the transom was not clogged. I blasted air through it off the compressor. No restrictions.

I then took another look at the t-stat housing and heard some scales bouncing around inside of it. So I slammed it a couple times on the work bench and got a good amount of rust/ scale chips out of there. Put everything back together with poppets and thermostat installed and ran it. Problems still there. Weak water return from starboard exhaust and lots of steam.

Ran the boat off the hose hose for about 5 mins, temp gauge got to 180f and hovered there. Inferred temp guns reading 140f port elbow and 150f starboard elbow.

The only thing i have not checked is the power steering cooler for restriction. I am currently at a loss and don’t really know where to go from here. Should I just go dunk the boat in the lake and run it?

 

[mcomm]

YES, you should.

 

[kghost]

"""""Ran the boat off the hose hose for about 5 mins, temp gauge got to 180f and hovered there. Inferred temp guns reading 140f port elbow and 150f starboard elbow. Ran the boat off the hose hose for about 5 mins, temp gauge got to 180f and hovered there. Inferred temp guns reading 140f port elbow and 150f starboard elbow. """"





Explain "off the hose"


Your thermostat should be ~ 140*

Your running temp should be 160*

if 180* there is something still wrong


Your impeller is perfect, what about gaskets at impeller housing? good? If torn then air/exhaust could be getting in.

If you remove outdrive...ugh I know............remove incoming water hose at thermostat housing and stuff garden hose into it and back flush and see if anything comes out at gimbal water port.

 

[kghost]

Your best friend will be using the P of E..... process of elimination.
Test/change one item ONLY at a time.
When used systematically and methodically, the P of E won't let you down! There is no disputing this!



**Understand that nothing up-stream from the T-stat housing will be causing an un-equal seawater flow to the exhaust system.
In other words, any seawater being introduced into the engine alone has not yet been split or divided in order to equally supply the exhaust system. That split or division occurs at and within the T-stat housing.
With exception to some jet pump systems, this will apply to any Raw Water Cooled Merc, OMC, Volvo Penta, Indmar, PCM, etc.
In other words, you do not need to be a Merc Tech in order to make a suggestion re; this particular issue!


In post #1, you mentioned; "Obviously there is a restriction somewhere".
In your most recent post #31, you have made that assessment again.
I would say, yes, that is very likely what is going on!



I have occasionally read whereby someone has added restriction to the better flowing side in hopes of increasing flow to the problematic side. I would not suggest doing that.
Find the restriction, and you will have found the problem.


Chamfer any sharp edges that may be restricting flow.
Look at the interior of the hoses for any signs of delamination.
Look at the ID of any 90* fittings that may be causing a restriction.
During the process, you may find an object that is causing the restriction (i.e., impeller pieces, for example).
Occasionally Starboard parts can be swapped to the Port side (or visa-versa) as part of the P of E.




.

What a crock of SH!T!

Dont know the system therefor cant speak to it directly, only in generalities................Again a waste of a post and only for number count!!

CHAMFER???? CHAMFER THIS!

Who would chamfer anything WTF?????

 

[RicardoMarine]

Rick, good suggestions, and I'm glad to see that you posted to this thread.

Thanks Jack..... I appreciate the compliment.


I predict that mcomm will be along shortly to add his contribution.


.

 

[805HD]

"""""Ran the boat off the hose hose for about 5 mins, temp gauge got to 180f and hovered there. Inferred temp guns reading 140f port elbow and 150f starboard elbow. Ran the boat off the hose hose for about 5 mins, temp gauge got to 180f and hovered there. Inferred temp guns reading 140f port elbow and 150f starboard elbow. """"





Explain "off the hose"


Your thermostat should be ~ 140*

Your running temp should be 160*

if 180* there is something still wrong


Your impeller is perfect, what about gaskets at impeller housing? good? If torn then air/exhaust could be getting in.

If you remove outdrive...ugh I know............remove incoming water hose at thermostat housing and stuff garden hose into it and back flush and see if anything comes out at gimbal water port.

off the hose meaning muffs. I inspected all the impeller housing gaskets and verified their order as well. Not a bad suggestion about the back flush minus the part about removing the outdrive again lol

as as far as the thermostat goes, 140 or 160 at this point even without it the boat still runs hot! Starting to lose hope here!

Im going to take a look at that power steering cooler today.. rod it out the best I can. Maybe some of those passages are starting to close up..

 

[805HD]

Another thing I just thought of, although the engine was aligned using the alignment tool. It leans a little to port. Could this have anything to do with it?

The drive slides right in and the alignment tool had good deep grease lines on it all the way around. But looking at the engine you can see it definitely leans to port (same side exhaust that has plenty of water return)

???

 

[kghost]

No, water is under pressure.

If thermostat is 160 then normal running temp would be 180.

The scale issue is troubling.

I did one two seasons ago, similar issues, found big chunks of scale.
Got everything out and made sure all parts were replaced in the correct orientation and tje correct order of assembly. The thermostat should be in the correct location. It can be put in the wrong location.


I forget but what year is this engine and what is the specified thermostat temp?

 

[kghost]

Off the muffs???

Dry?
In the lake?

In a barrel?

Not sure what ur saying

 

[805HD]

Off the muffs???

Dry?
In the lake?

In a barrel?

Not sure what ur saying

ive been bouncing back and forth between running it on muffs and with the drive lowered into a tub

the boat is a 1987 it’s got the 454 with a alpha drive
S/n b558933

the thermostat is in the correct location unless there is something I’m not aware of. It sits under the top cap of the thermostat housing. And I believe it calls for a 140* but I replaced it with a 160* only reason I replaced it was to see if the old one was causing a issue. Could only get my hands on a 160*

 

[makomark]

a clear piece of tubing with a hose barb and a couple clamps can be very helpful in diagnosing water flow problems.

you need to make sure ALL the water pumped by the drive is making it to the thermostat housing....without restriction.

Visual inspection of the oil cooler and hose is usually the best method....compressed air usually doesn't arrive with enough volume to be definitive in a water flow issue...

 

[805HD]

a clear piece of tubing with a hose barb and a couple clamps can be very helpful in diagnosing water flow problems.

you need to make sure ALL the water pumped by the drive is making it to the thermostat housing....without restriction.

Visual inspection of the oil cooler and hose is usually the best method....compressed air usually doesn't arrive with enough volume to be definitive in a water flow issue...

I pulled the hoses off that feed the manifolds from the thermostat housing and ran the boat. The starboard side hose had significantly less water flow the. The port side. So the problem has to be from the thermostat housing back.

I inspected the thermostat housing, the hoses and the impeller without finding anything suspect. I’m going to tackle the cooler today. Other then that being the problem I don’t know what else to do. I’ve looked at everything multiple times now

 

[805HD]

This is the water im getting from the impeller running on muffs. Disconnected before the oil cooler at idle. Seems a little low to me?

 

[o2batsea]

friend, having the engine on "muffs" is no way to diagnose cooling issues as you cannot simulate having the drive submerged and moving through the water. go get it wet and drive it

 

[805HD]

friend, having the engine on "muffs" is no way to diagnose cooling issues as you cannot simulate having the drive submerged and moving through the water. go get it wet and drive it

True true... just stressing out and getting sloppy over here! Plus the lake is a decent drive when I’m almost 100% I will have a problem. But your right.

Today I verified water coming in from impeller good flow for being on the hose. Then I verified water flowing through the oil cooler after I rodded it out and inspected with flash light. Again good flow. I again pulled the hoses from the manifolds that feed water from the thermostat. Ones a trickle the others got good flow.

From what I can conclude, the thermostat housing is the culprit. There is nothing else to blame. Ordered a new housing and a 140* thermostat. HOPEFULLY this problem will no longer be a problem after that.

 

[805HD]

I also found this diagram, raises a eyebrow for me. Dose this look correct? The orientation in which the hoses are ran from the thermostat housing to the manifolds and elbows is reversed from what I have on my engine. Thermostat cap hoses run to elbows and thermostat tee (with poppets) run to exhaust manifolds. This diagram is showing opposite. Which routing is correct?

 

[kghost]

Well now.................that's a problem,

The Poppets got to the elbows which was expressed early on!!

The thermostat cover ports go to the bottom of the manifolds.

When theses four hoses are in reversed locations guess what? You get STEAM!!!!



Now we are getting somewhere!





Looks like an assembly mistake..............





Remember when the thermostat housing in totality has 4 hose ports, the incoming COLD water goes FIST to the elbows to keep the exhaust cool.

In your case (the design with the poppets) the incoming COLD water pressure opens the poppets to allow the COLD fresh water to the elbows.

Like I said earlier, in newer designs they went to fixed orifices and did away with the poppets.

Once the thermostat opens the the majority of water goes thru the thermostat itself and up through the manifolds.

This is why your elbows were getting so hot, NO FRESH COLD WATER.

Without the thermostat in place you were putting fresh COLD water everywhere especially to the elbows but through the wrong hose/ports.........that is why the "problem" seem to go away.........

Swap the hoses and forget about everything else..............Oh and put the 140 degree thermostat back in! Oh and a big full cooler full of BEER.....
Your head must be very hot by now and will need some cooling off also!

Your done here!

 

[RicardoMarine]

I also found this diagram, raises a eyebrow for me. Dose this look correct? The orientation in which the hoses are ran from the thermostat housing to the manifolds and elbows is reversed from what I have on my engine. Thermostat cap hoses run to elbows and thermostat tee (with poppets) run to exhaust manifolds. This diagram is showing opposite. Which routing is correct?

805HD, that is the same schematic that I posted for you in post #25. Jack's successive post #26 (quoting me) also shows it.

805HD, look at these two images.
Is there a way that you could show us how your system is plumbed to the manifolds, spacers/risers and elbows (shown by Jack), and with the T-stat housing shown in the image to the right?
If you have a PC with MS Paint, you can manipulate the schematic to show what you have.... or print it and mark it up with a pencil.

Minus showing Spacers/Risers (shown to the left in the schematic), it should depict the correct hose routing for your scenario.
I agree.... swap the hoses and give it a try.



And by the way..... you may want to charge your cell phone battery..... according to the picture, you're down to only 11%!




.

 

[kghost]

805HD, that is the same schematic that I posted for you in post #25. Jack's successive post #26 (quoting me) also shows it.


Minus showing Spacers/Risers (shown to the left in the schematic), it should depict the correct hose routing for your scenario.
I agree.... swap the hoses and give it a try.



And by the way..... you may want to charge your cell phone battery..... according to the picture, you're down to only 11%!




.

Another useless post for post numbers.


Zero value add..... what a Douche bag!!

I answered him.
That was all that was needed.

You would need the drawing as you have no first hand experience with Mercruiser.

Many of us DO.
We know these things already from actually working on the product.

What a Douche Bag!

 

[805HD]

ahaha! Oh wow gentlemen I don’t know how I missed that one.

Today i reversed the hoses and the water return was perfect. 140* thermostat and poppets installed. About 10 mins on the muffs and the elbows were almost identical temperatures warm to the touch, I could rest my hands on them without pulling away. The temperature gauge was still around 180*(which is concerning) but under higher RPMs it would drop. Going to dip her in the lake next weekend and see how she runs. I’m going to attribute the higher temps to low water pressure off the hose for now.

Still had had some steam

I can not stress how much I appreciate you fellas going above and beyond to help me. And I will pass that knowledge along to each and every boater that I can help on the water and land. This forum because of guys like you is invaluable!

Thank you a thousand time over. If any of you ever decide to make the mistake of visiting the great state of commifornia the drinks are on me.

Thanks again!

 

[mcomm]

You are very welcome!

 

[kghost]

Take a picture of the thermo housing and hose routing.


My first thought is the "poppet balls" are stuck shut or not opening properly.

The two hoses going from the T to the elbows, Remove from the T and check the balls. If stuck that would be a problem.

If they are no longer round where they seat in the T the pull apart and reverse them. Note the specific thread count on the LONG screw they are mounted on.

Report back

If you reread this thread POST # 7....................I stated the fact that the poppet ports go to the elbows.


FYI
I have a 1987 Cobalt also...........Had it since 1995............Same cooling system, Exactly the same and worked on hundreds if not more of exactly the same...........


just sayin..............Something Dicardo cant say...................But he sure will upload someone else's information and pictures he copied.

Another FYI, The "manual" pics he uploads are NOT from his personal collection of manuals. He "borrows" then from other sources.

Mine are from my own soft copies, which I also have the hard copies in my possession.

 

[805HD]

Sweet, I really like the boat and got it for a decent price off a buddy. I’m still concerned because of the steam and the 180* on the temp gauge but I think it will be worth putting it in the lake and seeing how she does before I completely lose my freaking mind.

Feeling hopeful but still very concerned. I got a big trip coming up to the river in TWO WEEKS

 

[805HD]

FYI
I have a 1987 Cobalt also...........Had it since 1995............Same cooling system, Exactly the same and worked on hundreds if not more of exactly the same

hey jack! Question for you!

I bought a new thermostat housing, but I’m confused on the order of the cork gasket, the thermostat and the thermostat sleeve.. according to the diagram I’m seeing the thermostat goes in first followed by the cork gasket and then the sleeve ?

So the actual thermostat sits down inside the housing? My current set up the thermostat sits on top of the sleeve flush with the housing under the top cap..

Does this sound right?

 

[kghost]

These are the two images from my manuals.

left image is for 454

right one is from a V6 manual. The sleeve does not show the cut outs but I added it for comparison of the over all assembly.

It is obvious by the photo that the sleeve is ON TOP. Note the orientation of the cut outs in the sleeve. They point towards the engine block at ~ 10:00 and 2:00 o'clock
The only issue is the circular gasket. One image shows it below and the other above.

I am not sure it matters as the height of the sleeve will be the same.

I would say go by the image on the left!

Been a while since i have physically been inside one.

Also the image of the thermostat itself is the original OEM type. Mine lasted almost 30 years and finally failed.