Dry Joint 4.3 Manifolds on old "cold manifold" system

[Howard Sterndrive]

I have 2008 4.3 Dry Joint manifolds on my 1985 MR185 (229 V6 Chevrolet)

I had to use the old cold manifold style thermostat housing (has to do with alternator mounting) so I a plugged the riser feed port and have just 1 hose to each manifold feeding the bottom.

I see my temp gauge climbing gradually at WOT... past 170..sneaking past 180..so I back off and it cools down again.
The risers are about 160F when I drop off plane and run back and check... after a minute or five at idle they are cool to the touch.

I see a 27-864547A02 gasket for "FULL FLOW" that has 2 wide open holes at the riser joint for water flow. The current ones have 1 wide open and 1 restricted.

I guess it is worth a try to use the full flow style.... thoughts?

 

[Howard Sterndrive]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

2 weeks to get the gaskets out of the USA... typical.
I might try to just open the restriction in the ones there- if I wreck it, I have new ones coming.

 

[Don S]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

Did they work ok with the restrictor gasket before and just now started overheating, or has this been going on since installation?

Can you post a pictuer of your engine and how the hoses are plumbed from the Tstat housing?

 

[Howard Sterndrive]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

This is all new. I have only put about 5 hours on the engine and new SEI drive, so today was the first WOT running.
It's an OMC Tstat housing because it's an OMC alternator bracket and belts and the Merc Tstat housing won't fit in there. But I do have the octupus style Merc one with the check balls- if I have to, I will get the Merc alt bracket to hang the alt. low.

To keep the moisture down in the manifolds, OMC uses a warmer thermostat (160 instead of Merc's 143) so there is a 160 stat in it - a new one. I thought about putting a 140 in or clipping a coil off the spring of the 160 and kettle testing it to get it to 150 or so.
best pics I have at the moment
-the two manifold hoses run to the bottom of the manifolds (old school style)

I removed the barb fitting you can see in this pic of the manifold and plugged it

 

[Howard Sterndrive]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

gasket I have in there:

gasket I ordered:

 

[Don S]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

That picture doesn't really help much, can't see where any of the hoses hook up.
You also have to understand the thermostat housing is an integral part of the dry joint cooling system and the type riser gaskets used. The dry joint Tstat housing has 6 outlets and feeds the risers and manifolds seperately. You can't do that with the type Tstat housing you have.
You are obviously trying to do something Merc never did with the dry joint manifolds.

 

[JustJason]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

you really can't mix and match cooling system parts. It sort of works on paper, but seldom works in the real world. Your best bet is to set up the cooling system the correct way, even if that means having get a bracket to move the alternator to get it plumbed correctly.

 

[Don S]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

I got to thinking about this project more and more just because it could make it a lot safer for engines to have those little narrow passages eliminated between the water and the exhaust passages.
I have been looking at Service Manual #37 for the Dry Joint system, along with manuals 31 and 32 just to see how things are done on the newer engines.
What I have found out, is that the Dry Joint system is NOT used without seperate hoses going to the risers or elbows themselves. Never is all the water run into the bottom of the manifold and out the exhaust like the older style manifolds and elbows.
With the new riser/elbow made as one, the gasket with 2 open holes is NEVER used.
The restrictor gasket is used and and the restrictor side of the gasket MUST be put on the side the water goes into.
The thermostat housings that DO NOT have outlets to the risers/elbows also have a water distribution housing in the system that puts water to the risers.
One other point is the size of raw water pump used. There are only a few Alpha diagrams, and they are all Gen II drives with higher flow pumps than the Gen I drive pumps.

Anyway, have a look at those manual links above and see what conclusions you come up with.

 

[Howard Sterndrive]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

Thanks Don.

I actually have a GenII drive as this is a 1992 boat, so if I relocate the alternator and just use the 2008 style water manifold, I would have the 2008 cooling system stem to stern.

I'm going to take a run or two down the lake with the open gaskets (I ordered them anyways) and feel up the manifolds. If not kosher, I will make it all 2008 with a low mount alt bracket.

I can see why Mercruiser wants the lower manifold hotter... they don't want condensation building in the manifold. When you shut the engine off cold, it probably wets the spark plugs and makes for hard starts.
That trail of water you see pouring out the muffler of a car on a cold morning...would be running right back into the cylinders with a risered manifold.
These new dry joint riser gaskets even have a little "tray" built in probably to catch that condensation. You can see it in the first pic - that funnel shape makes a moisture pan. They warn not to put the gasket in upside down. (suppose it would restrict that way too)

 

[Don S]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

These new dry joint riser gaskets even have a little "tray" built in probably to catch that condensation.

According to the Merc rep we had when I was in AK, that "tray" is for the slight amount of water sucked back into the exhaust due to reversion, not condensation. At idle there is always a small amount of reversion, especially on V6 engines.
I doubt condensation would ever be enough to harm the engine.

Upside down gaskets could sure set up a lot of turbulance and probably cause a running problems at higher rpms.

 

[Howard Sterndrive]

Re: Dry Joint 4.3 Manifolds on old "cold manifold" system

I drilled out the riser gasket water passages to 1/2"
no change.

Tried my modded 150F thermostat
no change

Tried with thermostat removed
engine ran about 130F, but manifolds still quite warm to the touch

and with that last run, I'm actually thinking my impeller is the problem.

I undid the feed line to the tstat hsg. and ran the engine in the lake - good flow at idle
revved to 1200 rpm - good gusher, but I'm thinking the flow at high rpm is not good for some reason

with the 19P prop, at wot of 4600 it seems to overheat way faster than with the 20P four blade revving out at 4300....definitely rpm related
-could still be a flow vs. restriction thing due to my playing engineer, but
impeller kit ordered- full one with housing...what the heck- might as well eliminate it from the list of possible problems

I'm wondering if when I was doing all my distributor timing nonsense, I rolled the engine backwards enough to cause vanes to flip over. eager to look.
Also when I first mounted the drive, it seemed reluctant on muffs to let water through.... even at full hose pressure....