Mystery to be solved - reward to whoever gets it!

[The Hammer]

Re: Mystery to be solved - reward to whoever gets it!

Okay I've been following this thread and trying to imagine whats going on but I have absolutly no expierence with inboards, so this is going to lead to the stupidist question ever. Does it matter which way the boat is leaning? :redface:

 

[sharkmtn1]

Re: Mystery to be solved - reward to whoever gets it!

Don't be fooled by those restrictor gaskets. Their claim to create water back pressure thus keeping the riser full is a bunch of nonsense. You don't want the water to hangout and create back pressure, you want water to flow and absorb heat and keep moving.

 

[Simoniz]

Re: Mystery to be solved - reward to whoever gets it!

Don't be fooled by those restrictor gaskets. Their claim to create water back pressure thus keeping the riser full is a bunch of nonsense. You don't want the water to hangout and create back pressure, you want water to flow and absorb heat and keep moving.

I doubt they create much back pressure, probably just enough to keep the riser and manifold full of water.

sure you want the water to flow and absorb heat but you want the entire water jacket of the manifold and riser to be filled with water.

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

John,

You said:
"Lets go back to your experiment where you close off the port side, then release it, and the flow stays good on both sides."

No, what I said was:
"I proved this to myself by removing the supply hose to the port side and blocking the outlet at the tsat....the port outlet hole on the transom completely stopped and it went full flow out the starboard side...that proves they are seperate."

Also I explained that I have tried the restriction of the port hose in an earlier thread ... yes it does force more water out the starboard ...but why should I have to "rig" something? There has to be something that has happened (and can be corrected) that caused it to start getting hotter.
This is what the mystery is.

So far the only thing that -may- be the answer is to switch back to the restrictor gasket above the riser... I will let everybody know how that turns out.
I don't know why Mercruiser changed things with Service Bulletin 99-10,
If anybody else does ... please chime in.
It may have been due to corrosion issues or something ... I know when I changed my manifolds the first time there were restrictor gaskets between the risers and elbows and full flow 4 slot gaskets between the risers and manifold.
When I removed the restrictor gasket there was considerable scaling buildup beneath the 2 sides that just had the little holes ... to the point that I wondered how any water at all was going through those small holes.
That is when I saw 99-10 and went to full flow 4 slots above and below the risers and thats when I -think- this heat thing may have begun.

I know it doesn't make any sense ...you would think with less restriction that it would cool better but as I think about it ...as has been said ... the flow will follow the path of least resistance. If port side has least resistance then it will get the majority of the flow ... so maybe (and I am just theroizing here) the restrictor gaskets allow for a little "equalizing resistance" between the two sides and will let them run closer to the same temps. (with starboard being -slightly- higher) Which is what it was like when I bought it new.

Then it makes me wonder why Mercruiser changed things with 99-10??

I will let eveybody know what happens.

Kirk

 

[John_S]

Re: Mystery to be solved - reward to whoever gets it!

I was refering to this comment:

I can take a C-clamp and clamp off the port supply hose at the Tstat housing and the water will then pour out the starboard side and spit at the port. The starboard manifolds, risers and elbows then run cooler than the port! All the while the engine temp. stays rock solid at 165! AND when I then remove the C-clamp (with the engine still running) the heavy stream REMAINS on the starboard side!!?! (you would think it would go back to the other side like it was before the test began)
If I shut the engine off and let it sit a while then restart it then again starts with full flow out of port.

When I read that comment originally, I thought it said both side were running cool.
BTW, I agree with how the water comes out the relief ports. That is exactly what I encountered this spring.

I can only speculate on why Mercuiser changed them, but companies don't spend money on a service bulletin if it wasn't needed. My speculation is that when they originally changed from 4 hose to 2 hose, they left the gaskets the way they were. They worked OK, and in most cases didn't cause any issues. After additional testing, generated the service bulletin recommended change. From personnel experience, using the same manifolds, they run slightly cooler (by hand touch) with the open vs restricted. I have run 3 seasons with the open.

BTW, I also agree you do have a problem. I have never had risers so hot at idle that I had to remove my hand. Obvously, if you ran it hard, you have to let it idle for a while.

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

Yep, there is a problem here somewhere (not perceived) and I hope to find it.
Some don't think so and thats ok for them.

I just recall what Richard Dreyfuss said to the mayor of the town in Jaws:

"I know you won't admit theres a problem until this shark comes right up and bites you on the *****"

Well I don't want to get bit on the ***** by the sharks off of Cape Fear (which is where I boat a lot in the summer) so I am making sure this gets straightened out.

Thanks John

Kirk

 

[CheapboatKev]

Re: Mystery to be solved - reward to whoever gets it!

Okay I've been following this thread and trying to imagine whats going on but I have absolutly no expierence with inboards, so this is going to lead to the stupidist question ever. Does it matter which way the boat is leaning? :redface:

You are 100% correct..That is the silliest question ever

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

Hammer,

Hey buddy,
At this point I am willing to listen to ANY questions or answers that may put me on the path to the solution to this problem.

The boat is level here on the trailer and for the most part sits level while in the water ... the times the boat rocks and is not level I don't feel would play a part in this, but thanks for taking time to think about helping me solve this.

If you think of anything else please ask.

Thanks
Kirk

 

[HT32BSX115]

Re: Mystery to be solved - reward to whoever gets it!

Okay I've been following this thread and trying to imagine whats going on but I have absolutly no expierence with inboards, so this is going to lead to the stupidist question ever. Does it matter which way the boat is leaning? :redface:

Um, no. it doesn't really matter at all.....


And no, there's really no "stupidist" question or questions! (although there have been some real DOOZIES here in recent times.....and just about everybody here has asked 1 or 2 good ones !! me included!!)




Kirk,


I went back and reread some of the posts but I didn't see if you ever ENSURED that you have no debris blocking either side of the y-pipe......like a water shutter, gasket fragments, dead critters, tennis ball, F-napkin etc......

If you did, I missed it! (I do that frequently!!!)



Cheers,


Rick

 

[bruceb58]

Re: Mystery to be solved - reward to whoever gets it!

I think I would try this.

1) remove the rubber exhaust hoses off of the risers.
2) connect a garden hose to the thermostat housing where the input from the raw water pump would normally go and then observe the water flow.
3) Disconnect the manifild hoses from the thermostst housing and connect a "Y" fitting and have the garden hose supply water that way.

May tell you a lot.

 

[JustJason]

Re: Mystery to be solved - reward to whoever gets it!

At this point i'd start compeletely over. Manifolds are getting hot, so you have a cooling system problem. With any cooling system problem you start at the impellar and work your way forwards(or backwards, dependind on how you see it).

Have you taken the drive off and inspected the water cavity in the drive and gimbal housing? Have you removed the main cooling line that plumbs into the tstat housing (the line that carries all the water) and done a water volume output test yet?

 

[Fun Times]

Re: Mystery to be solved - reward to whoever gets it!

I think I would try this.

1) remove the rubber exhaust hoses off of the risers.
2) connect a garden hose to the thermostat housing where the input from the raw water pump would normally go and then observe the water flow.
3) Disconnect the manifild hoses from the thermostst housing and connect a "Y" fitting and have the garden hose supply water that way.

May tell you a lot.

That's a good idea, I would also start the engine getting it up to temperature, then pull each hose going to each exhaust manifold one at a time and measure the water flow into a bucket within a certain amount of time frame.

This test should help tell you if the problem is in the exhaust system or in the thermostat housing area.

And jason's test of pulling the main cooling line, should help tell you if the problem is further back down the line.

Does the water flow come out more even when the engine is cold versus hot?

 

[The Hammer]

Re: Mystery to be solved - reward to whoever gets it!

Okay, It was mentioned this has been progressly getting worse for two years, If the motor mounts wore on one side causing the engine to lean to one side therefore the Y pipe wouldn't be level, is that plausable? Would only need a jack to check.

 

[wire2]

Re: Mystery to be solved - reward to whoever gets it!

Given the info in the preceding posts, I think it may be a case of a siphon being established on 1 side or the other.
The side with the higher flow at a given time will also have slightly more volume in the riser after the highest point. That will cause a slight difference in static pressure, thereby perpetuating the flow imbalance.
If you mechanically force it to the other side, the same situation exists and will continue to flow more there.

It would take a couple of low pressure gauges at the risers to verify. Possibly 0-30" w.c.

 

[JerryIrons]

Re: Mystery to be solved - reward to whoever gets it!

It almost sounds like you have less water coming through the whole system now. Especially if you can pinch off the one side, and then the other side works correctly. Is there any way to test by increasing the volume of water going through it, ie with a hose etc at certain points?

 

[SuperNova]

Re: Mystery to be solved - reward to whoever gets it!

"No there isn't. The y- pipe horns come together at the bottom of the "y" into a common plenum which then bolts onto the transom plate just ahead of those exhaust ports......"


The exhaust gas goes out the upper portion through the big outlet.
The water is held (mostly) to the lower portion of the pipe by gravity and mostly exits through the two ports at the transom.
Therefore there is a direct connection as to how much water is comming down each leg versus how much is comming out of each of the two exit ports on the side of the transome plate. See pic.

It all doesn't just merge at the Y point. I don't think it is a cyclone
effect.
Y pipe 4 pic is, of course, upside down.

This is how I know there isn't enough water comming through the starboard side... it just spit/sputters out that port.
Port side full flow.
Had just about equal flow out both holes when new.

This is how I know something is/is going wrong.

Kirk

Alright, I stand corrected.
I went out and looked at the Y-pipes in the shed and they all have the three holes, so my statement about the common plenum is incorrect.
However, your assumptions of how the system works and where and how water should flow are also possibly incorrect.
I have a 28 foot boat with twin engines and I just went out and fired both engines on the hose to see how the water flowed. Both engines acted the exact same way. The upper exhaust hole BOTH spit and sputtered a little water until the t-stat opened....at which point A LOT more water started coming out of the PROP. AT NO TIME did I get any kind of serious water flow out of the little ports up at the transome. SO the real issue may not be the side thats running hot, rather the side that's running cold. All four of my risers were warm enough at IDLE to not allow me to set my hand on them for more than a second or two.
Maybe someone else on here can check their boat and see how it works...maybe mine isn't working correctly.

Yep, there is a problem here somewhere (not perceived) and I hope to find it.
Some don't think so and thats ok for them.

I just recall what Richard Dreyfuss said to the mayor of the town in Jaws:

"I know you won't admit theres a problem until this shark comes right up and bites you on the *****"

Well I don't want to get bit on the ***** by the sharks off of Cape Fear (which is where I boat a lot in the summer) so I am making sure this gets straightened out
Kirk

Here is what I have:
1999 Bayliner 2655 with 5.0L V8 (carb) , Alpha 1 gen. 2 drive

I can definitely understand you wanting to make absolutely sure your boat is running perfectly before you head out.......sorry for making light of your concerns previously.....You definitely have a problem and should get it fixed before you head that far out in the ocean again.......I'll try to help best I can......I now understand your fear....

 

[Quadruplecccc]

Re: Mystery to be solved - reward to whoever gets it!

Been following along here and am wondering if you also changed the base plate and all the gaskets to the impellar housing ? If I remember your model has a base plate, correct?

I too had trouble finding an overheat problem . I hadn't changed the base plate which somehow produced low water volumn throughout engine. Started back at the beginning, replaced all and trouble was gone.

Hope this helps!

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

Thanks guys,
I am still working on this thing ...haven't had much time in the last few days.

Most I have talked to so far have said their risers got hot but not to the point to the point that you couldn't place your hand on them ... and then they proceed to tell me it's normal for the starboard side to run a "little" hotter than port (more than one have said no more than 20 degrees is normal)
but who knows?
I wish I knew what the real "normal" is.
All I know is it wasn't like this when new and I want to find out what to do to put it back that way ...plain and simple.
I have tried just about everything I and many others can think of.

As for the base plate ...yes that was changed earlier along with the impeller.
I saw the You Tube where somebody put a clear hose on the input from the leg and saw bubbles and discovered their base plate was the culprit. Tha's what prompted me to change mine. My old one wasn't worn though and the new plate made no difference. But that's OK it eliminated that as being the problem.

I won't quit ...my next experiment is to change back to restrictor gaskets and see what happens.

I'll let you guys know.

Kirk

 

[NHGuy]

Re: Mystery to be solved - reward to whoever gets it!

Kirk, I have just read through your thread and I didn't see whether you changed out the thermostat housing/water distribution block. There is a chance there has been some erosion in there causing the effect you are getting. That's all I can see except your idea to go to the old style restrictor gaskets. But why do that if Mercruiser says don't?
If you do that and the problem is still there I have no ideas.

Good luck, I am following your thread with great interest.

Pete

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

Thanks for the idea Pete,

I actually mentioned that in one of my threads I think (it may have been on another forum) thats why I was looking for a cutaway diagram of this thermostat housing. If something in there has eroded away, well, it did it in a manner that really smoothed out and by appearance now looks normal.
I cannot find any diagram of it which shows the flow paths though...even in the Mercruiser stuff. So unless somebody has one that is good and can shoot me a picture I guess I am going to have to take this one back off and take it to a dealer and compare.
This housing looks real clear ... so if there is nothing eroded away I would hate to shell out those kind of uneccessary bucks if you know what I mean!
But if I find there is something missing and the water flow has just smoothed things out I will be overcome with joy and will gladly spend big bucks to get one.

If anybody out there knows where I can find a flow diagram of the thermostat housing (not the engine flow diagram in the Merc manual...I have that) or can send me a pic of what the inside of a known good housing looks like I would be extremely grateful.
I am attaching a pic of the type housing I have (stolen from a parts site)

Thanks for any help guys

Kirk