Hot Stbd Riser

Both manifolds are new, riser elbows will be here next week.

It the manifold that the t-stat, carb and distributor bolt onto that needs replacing now...

How did yours make out??? Did they pull the risers yet?
 
Yeah. . .I posted in the other thread.

The risers/manifolds on the engine were pulled. The mechanic put in "full flow" gaskets. Helped. . .but a problem remains. I have not driven the boat since the work was done (on Tuesday).

I suspect the Raw water pump the mechanic put in over the winter is bad. He (naturally) suspects a problem somewhere else in the outdrive (riser tube?). Either way. . .next step is to pull the boat. Pulling the boat is a few hundred clams, so I am electing to defer the work until either I do mid season bottom cleaning, or something else breaks.

In the meantime, the engines are authorized to run marathons at higher than normal cruise speed. . . short (1/2 mile) high speed sprints are also ok. Medium distance sprints (W.O.T for more than a very short time) are out.

When I was out with the mechanic, we went over both engines with the IR gun. . . . . and he spend a good amount of listening to the engines while under high load. They sound good. They look good. The only problem is that one seems to have restricted water flow. :smt021

But the mechanic says I shouldn't run at W.O.T. for very long anyway, even if everything is perfect, as it is very hard on the engines. I can buy that. I want these things to last *forever*

Regardless, I am a bit bummed by the state of affairs. But honestly the way I run the boat normally, the heat problem won't limit what I do. This is allowing me to be a bit pragmatic about HOW I fix this stupid problem!!
 
H2ONUT said:
Yeah, if I remember the camera... the intake manifold has rust, and it looks like there are a few pin holes with air escaping.

I'll also try to take a pic of the exhaust manifold inlet also..
Click to expand...


The new problem I believe you are talking about is the intake manifold which usually has negative pressure in it where by it sucks things into it rather than blowing air out. I would start a new thread on this topic. Good news on the manifolds...I know it was frustrating but a worthy problem to resolve.

-John
 
H2O.

I'm about to replace manifolds/elbows on my 5.0 twins (I believe they have the three inch spacer/riser). Raw water cooled AJ. Did you buy Mercruiser OEM parts, Osco, GLM, etc, and from where? I've done some price research and the OEM = $$$$$$.

Do the "kits" include everything, or is there some "a la carte"?

Thanks for your help!

Reel
 
I used GLM and got them from a guy on E-Bay out of New Jersey.

spots1994 is his E-bay name. Just do a search on "Mercruiser Exhaust"

Everything bolted right up!
 
"OK, now I have a new problem... The intake manifold had water lying on it from the various hoses... I have bubbling from the the right hand side on the manifold below the carb..."


I think the area you are talking about is where the choke coil is. There is a small exhaust crossover there to heat up the choke spring. It will blow bubbles if water fills up the cavity. Is that the area you saw the bubbles in?

-John
 
John, it's in that same area but on the right hand side. There are small pin holes in the casting. I just verified it leaking at lunchtime.

I figured a little dremel action and JBWeld should hold me thru the summer... No??
 
H2ONUT said:
John, it's in that same area but on the right hand side. There are small pin holes in the casting. I just verified it leaking at lunchtime.

I figured a little dremel action and JBWeld should hold me thru the summer... No??
Click to expand...

That will work fine. Eastwood Company makes a number of rust incapulation products (paint) that will seal it up and make it look nice. Intake manifolds, like exhaust manifolds eventually need to be replaced on raw water cooled engines.


I'm sure you are glad that you are back to boating...have a good weekend.

-John
 
Haven't left the dock yet, I'll find out in the am :smt038
 
starboard exhaust

I posted earlier about the same topic and I still haven't resolved the issue. My mechanic is MIA. What temp should an MPI 7.4 Bravo III run at. I am crusing at around 175 or so and at idle the gauge reads 170. My problem like the first poster is the starboard exhust is runnig hot and the port is cool. Water flow seems good to the mainifold and I changed the t-stat. I am considering pulling apart the risers/elbow. But I find it hard to believe the mechanic screwed it up. New exhaust was just installed.

Any thoughts?
 
I got out a little while ago, all temps now are the same after a hard run for about 5 minutes. Elbows were about 120*.

My gauge is still running on the warm side. After the hard run, the temp spiked to about 180* then settled back to the 150* mark. Lots of steam also and then it goes away.

After looking at the page with the layout of the t-stat on Merc's website, mine is not the same. My t-stat sits right on top, on the site it shows the stat going in first, the cork gasket and then a brass sleeve. Mine is just the opposite. (This is how I found it and put the new stat in just like I found it).
 
H2ONUT said:
I got out a little while ago, all temps now are the same after a hard run for about 5 minutes. Elbows were about 120*.

My gauge is still running on the warm side. After the hard run, the temp spiked to about 180* then settled back to the 150* mark. Lots of steam also and then it goes away.

After looking at the page with the layout of the t-stat on Merc's website, mine is not the same. My t-stat sits right on top, on the site it shows the stat going in first, the cork gasket and then a brass sleeve. Mine is just the opposite. (This is how I found it and put the new stat in just like I found it).
Click to expand...

Those temps are within spec. Congratulations on getting that problem fixed. Don't worry about the tstat layout....as I said they had multiple configurations. The bottom line is consistent temps on both sides.

gmcleer, let me take another look at your thread and see if I can help.

-John
 
Re: starboard exhaust

gmcleer said:
I posted earlier about the same topic and I still haven't resolved the issue. My mechanic is MIA. What temp should an MPI 7.4 Bravo III run at. I am crusing at around 175 or so and at idle the gauge reads 170. My problem like the first poster is the starboard exhust is runnig hot and the port is cool. Water flow seems good to the mainifold and I changed the t-stat. I am considering pulling apart the risers/elbow. But I find it hard to believe the mechanic screwed it up. New exhaust was just installed.

Any thoughts?
Click to expand...

Where did you post it? I did a search on your id and nothing about an overheating riser turned up.

-John
 
Getting ready to bolt it back together. How much torque should be used when tightening exhaust manifold Bolts?

I bet someone knows the answer!

Thanks!
 
25 ft lbs... :wink:

20 ft lbs for the riser/elbow bolts
 
Where did you get everything from? What brand did you use?
 
John and company,

I posted a few weeks ago. I had a mechanic replace the exhuast mainfolds, 6" extentions and risers plus the impeller (raw water) and the circulator pump. The boat runs at about 175 with 50 psi + of oil pressure. I replaced the t-stat and removed the riser and extention, all was clear. From the t-stat housing water appears to be flowing equally. WOT is about 4300 on the tach. I can cruise at 3400 and not overheat but the starboard riser is too hot to leave your hand on for more than a second or so. The port riser is warm but not hot. any thoughts?

Thanks,
 
What happens when you run without the t-stat?

Can you take it back to the person who fixed it, any warranty?
 
H2O,

Everything apart right now.....GLM parts in box.....I have an afterthought question.

The starboard manifolds have a pipe attached that goes up to the intake manifold area.....the port manifolds do not have this pipe. Did your engine have this setup? Do the manifolds have a correct threaded opening for this pipe fitting and if so (hopefully!) did the port manifold have a plug for the same hole?

When looking at OEM parts, there is a separate part number for the port and starboard manifolds....I'm guessing because of the fitting/pipe.

Please let me know what you found when doing yours.

Thanks,

Reel
 
I do not have the pipe to the manifold. Both manifolds are reversible. And yes, they supply the plugs for the holes in the manifold.

You should be OK!
 
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