overheating

[alldodge]

Re: overheating

Manifolds? Do you mean the elbows?

Correct, but I meant to call them risers. Always called elbows the bend after the riser if there was one.

 

[achris]

Re: overheating

Correct, but I meant to call them risers. Always called elbows the bend after the riser if there was one.

A few of us have had this 'discussion' a few times... :facepalm:

This is how the manufacturers name the various parts. What you call them is up to you, but to make is clearer when communicating on a forum such as this, is that we all call the parts by what the manufacturer does, and that should avoid too much confusion...

Exhaust manifold (pretty universal that one)
Exhaust elbow. Bolts on the top or at the end of the manifold and mixes the exhaust gases with the 'spent' cooling water.
Exhaust riser. Section of extension (usually available in 1.5", 3" and 6") that elevates the elbow to reduce the possibility of water going into the exhaust manifold in boats where the engine sits very low.

Chris ....

 

[alldodge]

Re: overheating

A few of us have had this 'discussion' a few times... :facepalm:

This is how the manufacturers name the various parts. What you call them is up to you, but to make is clearer when communicating on a forum such as this, is that we all call the parts by what the manufacturer does, and that should avoid too much confusion...

Exhaust manifold (pretty universal that one)
Exhaust elbow. Bolts on the top or at the end of the manifold and mixes the exhaust gases with the 'spent' cooling water.
Exhaust riser. Section of extension (usually available in 1.5", 3" and 6") that elevates the elbow to reduce the possibility of water going into the exhaust manifold in boats where the engine sits very low.

Chris ....

Thanks and I will do my best to remember, old guy here.

Question please: What do you call the metal or iron sections between the elbow and y=pipe which is connected but boots on both ends?

 

[84EdH]

Re: overheating

Chris, I have been trying to comprehend the hose hook ups in the system you described above.
Do you have a diagram of the system you suggested? Is this a warm or cold system? I saw a thread you worked on with steves86ta in May 2013 with some diagrams. One was of a ford standard and another of a ford center rise, the lower thermostat housing had 4 hose connections. the one I linked above looks like it has only three.

 

[achris]

Re: overheating

Thanks and I will do my best to remember, old guy here.

Question please: What do you call the metal or iron sections between the elbow and y=pipe which is connected but boots on both ends?

You had to ask didn't you.. Yes, it's called an elbow. Usually when questions relating to exhaust parts come up I included diagrams, and number the parts...

Chris ..........
Also an old guy...

 

[achris]

Re: overheating

Chris, I have been trying to comprehend the hose hook ups in the system you described above.
Do you have a diagram of the system you suggested? Is this a warm or cold system? I saw a thread you worked on with steves86ta in May 2013 with some diagrams. One was of a ford standard and another of a ford center rise, the lower thermostat housing had 4 hose connections. the one I linked above looks like it has only three.

If you mean http://forums.iboats.com/mercruiser...center-riser-question-602778.html#post4204080 that was a GM (305)...

And the lower thermostat housing you linked to does have 4 connections. The 4th is directly below, and hidden by, the larger one for the water pump hose. If you search the number you get a slightly different view and can make it out.

Chris.....

 

[84EdH]

Re: overheating

Chris, go back to that link you posted above and look at the two drawings on post #19, by mistake, he drew Ford diagrams, with the exception of looping the the top hose to manifold to bottom return from manifold, does this look correct? if so, which diagram is what you suggest?

 

[achris]

Re: overheating

Chris, go back to that link you posted above and look at the two drawings on post #19, by mistake, he drew Ford diagrams, do they look correct? If so, which is the way you suggest?

Yes he did, but he's drawn the manifolds with 2 connection points, not one as we have in this thread.

BTW, how on earth did you remember that thread???

 

[84EdH]

Re: overheating

psycho, errr...psychic!

just posted over you:facepalm:

 

[84EdH]

Re: overheating

sorry for the confusion, what I am trying to figure out is this: will there be flow to those manifolds when the thermostat is closed?

 

[achris]

Re: overheating

sorry for the confusion, what I am trying to figure out is this: will there be flow to those manifolds when the thermostat is closed?

Yes.

I'm in the process of doing some drawings for this thread too, similar to steves86ta... :facepalm:

 

[84EdH]

Re: overheating

That would be great. Thanks

 

[achris]

Re: overheating

3 drawings, one for each option..

Chris.........

 

[84EdH]

Re: overheating

Nice job Chris. It makes sense to me now. That Bar thermostat must have a small bypass to get water to manifold when closed?
Thanks for taking the time to draw all those diagrams up!

 

[Bondo]

Re: overheating

A few of us have had this 'discussion' a few times... :facepalm:

This is how the manufacturers name the various parts. What you call them is up to you, but to make is clearer when communicating on a forum such as this, is that we all call the parts by what the manufacturer does, and that should avoid too much confusion...

Exhaust manifold (pretty universal that one)
Exhaust elbow. Bolts on the top or at the end of the manifold and mixes the exhaust gases with the 'spent' cooling water.
Exhaust riser. Section of extension (usually available in 1.5", 3" and 6") that elevates the elbow to reduce the possibility of water going into the exhaust manifold in boats where the engine sits very low.

Chris ....

Ayuh,.... True enough,... We've argued 'bout this before,....

Chris is Right, the manufacturers do list risers as elbows, 'n it's their common name in places other than North America,...

Here on this side of the planet, Risers are the thingies on top of the manifolds, that direct the flows aft,...
Riser Blocks are the thingies that raise the risers for low mounted motors, to get the 13" minimum from the outside waterline,...
Elbows are the cast thingies that direct the aft flows, downward to the y-pipe,...

I concede that Chris is correct on all counts in his argument,....

But searchin' websites of American retailers will show that the American twist on the english language is at play in this discussion,...
Kinda like Windshields, 'n Windscreens, or a hood, vs; a bonnet,...

 

[john hennessy]

Re: overheating

Chris,
in the upper drawing, you can see that mercruiser cool the manifolds as though they were an extention of the block water jacket, i would think this is to promote water temp rise in the cooling system, especially in cold climate operation, it would use the exhaust heat to raise the overall temp of water behind the thermostat.

there are sufficient threaded openings in the osco manifolds to feed water into the rear of the manifold, allow water out of the front/top of the manifold just below the riser/elbow and back to the thermostat housing as mercruiser have in the log style, then as you can see from my pictures, i could run the "hot" water from the themostat housing directly to my risers.

however, this would require isolating the water in the manifolds from the risers with a separator plate with no holes in it.

it would also require removing plugs in the manifold that have been there for years, and believe me that 'aint easy

and the price of the MC housing plus the stat and additional hose and fittings soon mounts up.

i have already installed the Barr housing, yes there is a bypass across the thermostat, i purchased a mercruiser hose to go from the t/stat housing to the circulating pump but i will have to modify it with a piece of copper tube as it's too short and relocate the altenator adjuster bracket to clear the hose but no big deal.

if i find that the rear of the osco manifolds are getting too hot, i will feed the water to both ends instead of just the front.

as far as the pipe in the picture between the risers, with the old t/stat housing and a themostat installed, there was no flow of water on initial start up and the exhausts were getting very hot, so i had a feed at the starboard end of this hose from the raw water pump to cool the exhaust, i intend to remove this unless the by pass in the t/stat housing is not large enough to supply enough water to the exhaust on initial start up prior to the t/stat opening, restricted to about a 1/4" hole.

i now believe that the root of my problem was running the raw water feed directly into the circulating pump because at all times i had no over heating at idle when the efficiency of the raw water pump was better than the circulating pump, however, when the throttle was opened up the engine speed increased and the circulating pump became more efficent and at an undetermined point would out strip the raw water pump and suck the feed hose flat stopping the supply like a tap thus up would go the temp, when i throttled back, it would cool down almost instantly because the hose would expand again.

i did some rough calculations for water flow through the feed pipe, but did this with the asumption that the pipe work was rigid not soft and that the raw water pump would not restrict the flow in any way but i now think at above 3000 rpm the raw water pump hits a wall and becomes a restiction to the demand of the circulating pump, best layed plans of mice and men etc.

 

[achris]

Re: overheating

....i did some rough calculations for water flow through the feed pipe, but did this with the assumption that the pipe work was rigid not soft and that the raw water pump would not restrict the flow in any way but I now think at above 3000 rpm the raw water pump hits a wall and becomes a restriction to the demand of the circulating pump, best laid plans of mice and men etc.

You are calculating the gross flow of the circ pump, without taking account that it also has a source other than the raw water pump, the water already in the engine block. (The clue is in the name, 'circulating' pump).

If you want to go with the manifolds as extensions of the block water jacket (first drawing) then you need to put a t-stat housing/cover with the 8 ports, the ones EdH posted the link to. If you want to use the Barrs FM 29-0083 (that you already own), then you need to use the last drawing. We have given you the information requested, which T-stat housing you use and which drawing you follow is now up to you. All of the drawings I made will work.... I have no practical knowledge of how either the second or third drawing will perform. In Australia it is very rare to see any of these engines still in a boat. It's now more than 35 years since one was new... We tend to change our engines a little more frequently than that. The last '888' I saw was in 1996, and even then the owner was seriously contemplating re-powering.

Chris.........

 

[achris]

Re: overheating

Ayuh,.... True enough,... We've argued 'bout this before,....

Chris is Right, the manufacturers do list risers as elbows, 'n it's their common name in places other than North America,...

Here on this side of the planet, Risers are the thingies on top of the manifolds, that direct the flows aft,...
Riser Blocks are the thingies that raise the risers for low mounted motors, to get the 13" minimum from the outside waterline,...
Elbows are the cast thingies that direct the aft flows, downward to the y-pipe,...

I concede that Chris is correct on all counts in his argument,....

But searchin' websites of American retailers will show that the American twist on the english language is at play in this discussion,...
Kinda like Windshields, 'n Windscreens, or a hood, vs; a bonnet,...

Just because a shop uses the wrong name doesn't make it the right name.... Would you really like all drives before 1986 to be officially known as 'pre-alpha'? :frusty: :frusty: :mad2:

 

[alldodge]

Re: overheating

Just because a shop uses the wrong name doesn't make it the right name.... Would you really like all drives before 1986 to be officially known as 'pre-alpha'? :frusty: :mad2:

I might if I could get some cute smile faces in response, could be fun.... ok it wouldn't be

 

[achris]

Re: overheating

I might if I could get some cute smile faces in response, could be fun.... ok it wouldn't be

"He who stirs the chit-pot should be forced to lick the spoon."
-Anon.