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888 thermostat housing octopus

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dbraymer

New member
so I am zooming along just fine in my 1974 srv200. The ole 302 has a new cam, a four barrel, a 4 inch center rise exhaust system. So I don't think that I am an idiot, (unless you ask my wife), but the only thing I could figure to do with the multiple hoses at the thermostat housing was route the hoses which previously went to the dry joint lower manifolds in a little circle back into the housing, where the water gos to the new wet joint manifold system.

Since all water in must go out somewhere, I am at a bit of a loss as to why and wether I really need a thermostat at all. We run here in Michigan mainly above 70 degrees water and below 90 degrees air temperature. water a bit cooler up north, but you get my drift.

I am thinking that I should put on a closed system thermostat housing cap, and just ditch the thermostat itself. Anyone been down this road before? the octopus eating two of its own legs is looking pretty stupid when you remove the engine cover... but then you want to force engine block circulation before you cool the manifolds and exhaust the water....
 
The purpose of a thermostat in any internal combustion engine is to insure that the engine gets WARM enough. If you are running in fresh water, you should have a 160 Degree t'stat. Better fuel consumption and engine life vs 140 degree.
 
sandkicker said:
The purpose of a thermostat in any internal combustion engine is to insure that the engine gets WARM enough. If you are running in fresh water, you should have a 160 Degree t'stat. Better fuel consumption and engine life vs 140 degree.
Click to expand...

OK, agreed. I must have stated the question poorly. I am getting warm plenty fast, but I am using a contraption that looks hideous, that I invented myself, with no help from Ford or Mercruiser. I have rerouted the hoses that used to warm the lower manifolds into a short circuit, back into the octopus center. The newer in place center riser lower and upper manifolds are wet joint connected, and they get water from the top of the old octopus.

It seems to me that if I change to a "closed circuit" thermostat housing system, the manifolds would get very little initial cooling water.

I have heard several stories "just drill a hole in the closed circuit thermostat valve plate". This seems a little bit "too Tennessee" for me, my apologies to those mountain boys who used to out run the feds in their back roads hot rods...

I need advice on what to replace the old octopus with. maybe a picture will help, tomorrow!
 
dbraymer said:
OK, agreed. I must have stated the question poorly. I am getting warm plenty fast, but I am using a contraption that looks hideous, that I invented myself, with no help from Ford or Mercruiser. I have rerouted the hoses that used to warm the lower manifolds into a short circuit, back into the octopus center. The newer in place center riser lower and upper manifolds are wet joint connected, and they get water from the top of the old octopus.

It seems to me that if I change to a "closed circuit" thermostat housing system, the manifolds would get very little initial cooling water.

I have heard several stories "just drill a hole in the closed circuit thermostat valve plate". This seems a little bit "too Tennessee" for me, my apologies to those mountain boys who used to out run the feds in their back roads hot rods...

I need advice on what to replace the old octopus with. maybe a picture will help, tomorrow!
Click to expand...


Read post #7 in this thread that you just visited.

Look closely at the example of a raw water cooling system T-stat housing and my explanation as to how most of the seawater is sent to the exhaust system.

http://www.marineengine.com/boat-fo...de-when-water-is-too-cold&p=695931#post695931

Bob said:
The purpose of a thermostat in any internal combustion engine is to insure that the engine gets WARM enough. If you are running in fresh water, you should have a 160 Degree t'stat. Better fuel consumption and engine life vs 140 degree.
Click to expand...

Ditto!

The only time that you'd want to run at/near 140*, would be in ocean water with a Raw Water Cooled engine.
Salt begins to undergo salt crystallization at/near 143*.


.
 
RE: "I have heard several stories "just drill a hole in the closed circuit thermostat valve plate". This seems a little bit "too Tennessee" for me, my apologies to those mountain boys who used to out run the feds in their back roads hot rods..."

Many marine T'stats have this hole to prevent air locks.... If you buy the OEM version of the T'stat you will get one with that hole if its needed in that particular application. Aftermarket ones sometime are missing this hole... It's NOT a "Tennessee" thing.

Was this engine a FWC, i.e. w/ a heat exchanger at one time? Why did you go from dry joint to wet joint ??? Price??? The reason for dry joint elbows was to eliminate a common failure point in wet joint systems.... the thin wall between the exhaust passage and the cooling passage in the manifold/elbow connection.
 
sandkicker said:
RE: "I have heard several stories "just drill a hole in the closed circuit thermostat valve plate". This seems a little bit "too Tennessee" for me, my apologies to those mountain boys who used to out run the feds in their back roads hot rods..."

Many marine T'stats have this hole to prevent air locks.... If you buy the OEM version of the T'stat you will get one with that hole if its needed in that particular application. Aftermarket ones sometime are missing this hole... It's NOT a "Tennessee" thing.

Was this engine a FWC, i.e. w/ a heat exchanger at one time? Why did you go from dry joint to wet joint ??? Price??? The reason for dry joint elbows was to eliminate a common failure point in wet joint systems.... the thin wall between the exhaust passage and the cooling passage in the manifold/elbow connection.
Click to expand...
I went to a center riser system for performance. I swapped out the old log 3 inch 95% dry joint system for a center riser 4 inch system. I got some rpms and of course more mph. Everything working fine, but I would like to clean up the goofy home made plumbing on the octopus. I am looking at the OMC thermostat housing with just a pair of final output barbs to the exhaust manifolds. This would also take an elbow from the intake manifold to position the housing, so it totals out quite a few bucks, so I am wondering if there is a simpler one piece "fits and solves" the problem.
We are just trailering in and out of fresh water, corrosion problems not expected on any systems up here in the soon to be white north. We do have to make darn sure to get all the water out of the wet exhaust systems before the almighty hulk shows up.
 
allow me to restate the question:
I converted an old 888 mercuiser from the original water cooling where there were two inputs and one output of water per each side, manifold and riser TO a system where there is only a single water input preside.
I reasoned that I could short circuit the water flows that originally went to and from the manifolds. every works, the engine warms up, stays cool, and I go faster.
But this does not look good, and it is not elegant. Does anyone have experience with this modification
 
A picture of this thing would be really helpful.
If I am understanding the situation, you have too many hoses going to the exhaust manifolds. You just need one per side. The hose coming from the top of the thermostat housing should go to a low point on the manifold. Usually this is an elbow fitting under the manifold that incorporates a drainage fitting (blue knob). The water flows up through the manifold, into the elbow where it mixes with exhaust gas and then over the side back to the lake.
The original manufacturing used shaped hoses but these are sometimes NLA in which case you will have to resort to using Shields exhaust hose if you need to fit new ones.
If you have 4 outlets on top of the thermostat housing then you can cap off the unused ones.
As others have mentioned you must have a thermostat to operate the engine. If it doesn't meet minimum warm up temperature, then the rings don't expand enough. In fact nothing fits properly as the engine is designed and engineered to run with heat expansion taken into account. Running it cold es no bueno.

I'll add that going from a 3 inch to a 4 inch exhaust system on such a small engine probably makes no gain in horsepower.
 
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1. You should not use OMC thermostat housing with Mercruiser components. I am sure it can be done but would not recommend.

There are basically three versions of the cooling system you are using.

See link below and look at STANDARD COOLING SYSTEM designs I II III

http://www.marineengine.com/parts/m...0-4-bbl-gm-305-v8-1987/0b525982-thru-0b773739

I and II use a different thermostat housing but use 4 hoses (2 to elbows, 2 to exhaust manifolds)

III uses a different thermostat housing but only uses 2 hoses to exhaust manifolds. (correct gaskets would be needed at elbows to manifold junction)

So I would suspect that if you were to purchase/find the III design thermostat housing (all needed parts as described in parts breakdown) then you would be down to 4 hoses.
 
o2batsea said:
A picture of this thing would be really helpful.
If I am understanding the situation, you have too many hoses going to the exhaust manifolds. You just need one per side. The hose coming from the top of the thermostat housing should go to a low point on the manifold. Usually this is an elbow fitting under the manifold that incorporates a drainage fitting (blue knob). The water flows up through the manifold, into the elbow where it mixes with exhaust gas and then over the side back to the lake.
The original manufacturing used shaped hoses but these are sometimes NLA in which case you will have to resort to using Shields exhaust hose if you need to fit new ones.
If you have 4 outlets on top of the thermostat housing then you can cap off the unused ones.
As others have mentioned you must have a thermostat to operate the engine. If it doesn't meet minimum warm up temperature, then the rings don't expand enough. In fact nothing fits properly as the engine is designed and engineered to run with heat expansion taken into account. Running it cold es no bueno.

I'll add that going from a 3 inch to a 4 inch exhaust system on such a small engine probably makes no gain in horsepower.
Click to expand...

Yep, you have gotten it. Except instead of capping the extra hoses, I routed them into a short circuit, one per side. In my minds eye, this allowed all flows the same as previously, although one flow was unrestricted and pretty darn short. As I said, I have an octopus that is eating two of its own legs. One small thing I can add to the forum, if you have a 302 that is wide open throttle capped off below 4000 RPM, (torque limited?) and you cam it and carb it, AND go to center rise exhaust 4 inch instead of 3 inch, you will go a bit faster with each of these previous steps.
However, as some thoughtful members of this group might suspect, the engine running temperature (at this point of my experiment) appears to be above center on the gauge at wot and 4200 rpm (and temperature rising, so I throttled back). I am using a 14 3/4 x 17 stainless propeller.

Hence my search for getting the right parts to assure maximum cooling after warm up.

If I cannot run wot for several minutes without over heating, I will have to "Tennessee engineer" some king of scoop and electric pump to put more cool water into the system.

But first, I should tear apart the existing housing, clean up the passages and maybe even buy a proper new theromstat housing, clean and appropriate hosing.

Do you know what parts I should seek to replace the old octopus eating its legs?
 
OK you got it, but those are Chevrolets. I gots me a Ford.

But you are understanding/right on the problem. I guess that Volvo brought or relabeled OMC stuff somewhere along the line, and then the Fords kinda dissappeared. So when I bolted that Cobra exhaust manifold onto the motor, I went into the "never before contraption" land... The only things I can find are a fairly valuable elbow that goes from the intake manifold to a horizontal fit, and then you bolt the more or less universal thermostat housing on top of that.

If there is a better method than the several hundred dollars involved here, please speak up now.

as it is, I will run as the boat is for this season.
 
You should never run WOT unless you wanna kill the poor thing.
post a pic
There are just way too many variations of thermostat housing. If you give is a picture then it will be far easier to recommend the proper thing. Generally speaking there are plenty that will work, are easily found on Ebay and cost less than $50. BUT, don't cheap out on engine related stuff. Buy the best you can.
 
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You cannot make an intelligent decision about the temperature of the system unless and until you can determine the temperature of the engine in degrees... not just "above center".
 
dbraymer said:
OK you got it, but those are Chevrolets. I gots me a Ford.

But you are understanding/right on the problem. I guess that Volvo brought or relabeled OMC stuff somewhere along the line, and then the Fords kinda dissappeared. So when I bolted that Cobra exhaust manifold onto the motor, I went into the "never before contraption" land... The only things I can find are a fairly valuable elbow that goes from the intake manifold to a horizontal fit, and then you bolt the more or less universal thermostat housing on top of that.

If there is a better method than the several hundred dollars involved here, please speak up now.

as it is, I will run as the boat is for this season.
Click to expand...



As I am not going to reread your original posts so I am going to ask here.

Did you state you had a Ford engine before your last post?

Did you state you used a OMC/VOLVO center riser exhaust manifolds and elbows before your last post?


That aside, Your engine temp should hold steady around 160 degrees with a 140 degree thermostat.


Ford left because they could not compete with GM Marine. Well into 90's all OEM marine ford engine users OMC maybe Volvo were using point ignitions........Almost all GM based engines or at least Mercruiser were using electronic and EFI/TBI...


If you secured OMC/Volvo exhaust manifolds and risers, Why did you not also get the thermostat housing to match that design?
 
""However, as some thoughtful members of this group might suspect, the engine running temperature (at this point of my experiment) appears to be above center on the gauge at wot and 4200 rpm (and temperature rising, so I throttled back).""


If I remember correctly, The OMC if thats what you are using are single hose connections at bottom of manifolds. This would/could explain your temp increase. Reduced water flow based on design when matched to Merc thermostat housing.

With the correct thermostat housing delivering the right amount of water flow to the manifolds the temps may be lower or more normal based on your prior gauge readings.

using a Merc thermostat housing designed for 4 outputs to manifold and elbows that may be giving you reduced flow especially depending on how you spaghettied the not used hoses.............could be of concern.


Best to use all matched components so what ever manifolds/elbows came from. Find the matching thermostat housing
 
The 888 was one of the few times Mercruiser used ford engines. The thing about Ford intakes is the thermostat is vertical on the plenum so Mercruiser, OMC, Volvo Penta, Waukesha (Marine Power), and a few others had to use this elbow doo dad to orient the marine thermostat housing correctly.
When I was dealing with Ford 302s in my old Carver (what a POS that was) They had this insane (waukesha) closed cooling system that had these aluminum Y castings, and a big copper surge tank and this bonkers thermostat housing thing. I ripped all that out and put OMC Cobra Center dump manifolds and thermostat housings on there to run it open cooling. As I recall the manifolds had a 3/4 NPT tapped hole on the front (and rear, which was plugged)corner that took a 1" barb fitting and open gaskets between the mani and the elbow. I used a Cobra thermostat housing which worked fine when the boat was actually running which was not that often due to a lot of other issues, but that's a different story...
Anyway, the thing is that the OP seems to have the 888 thermostat housing which was made for log style manifolds (ew) and may have been closed cooling.
So now that you've read this far, yes you can use the OMC thermostat housing with your Cobra center dump manifolds. It points to the right, has a big hose attachment for the circulation hose, a smaller 1" inlet for the seawater supply, and two 3/4 outs for the manifolds. These are all over Ebay for twenty bucks. The thermostat will be your standard issue 160 degree.
Swap the 1" barb fittings for 3/4 and use new Shields-Flex wet exhaust hose in the 3/4 inch size.
 
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