Intake Manifold Cracks

[nateo]

Hi there,

Today I noticed some surface cracks on the starboard side of intake manifold (see pics), however it doesn't appear to be venting any gases.

Gauge on boat reads about 190-195, analog gauge hard to tell for sure. I don't have smartcraft gauge yet just read about those recently.
Received the following readings with IR gun:

210 - starboard exhaust manifold
200 - port exhaust manifold
175 - thermostat housing

Water does appear to be flowing out of both sides of exhaust vents on exterior of boat. Is there likely something clogged? Also should I be looking to replace intake for the cracks?

 

[Bt Doctur]

your running too hot, fix that first

 

[alldodge]

That looks like paint cracks, can it be chipped away with a screw driver?
Your motor is running to hot, has the impeller been changed?

 

[nateo]

your running too hot, fix that first

Good point and thanks for the reply. Any idea why it's running too hot, exhaust manifolds clogged?

 

[Bt Doctur]

Always start with the impeller

 

[nateo]

That looks like paint cracks, can it be chipped away with a screw driver?
Your motor is running to hot, has the impeller been changed?

I was hoping it was that as well but confirmed with a pick, actual cracks. I put in a new impeller for this issue hoping it would clear up but the one I pulled out looked new and got same result after replacing.

 

[nateo]

I also tested the thermostat (in a pot on stove) for this issue and it opened up at 160.

 

[alldodge]

Need to start removing hoses and other things trying to find out where the restriction is. Look at the power steering cooler

 

[nateo]

Not sure if this info helps but the elbows were only about a 100 degrees where as the risers and manifolds were around 200.

 

[nateo]

your running too hot, fix that first

any idea what the surface temps should be such as the manifolds, etc?

 

[alldodge]

If those are old, I would pull and inspect after doing the easy stuff.

 

[alldodge]

any idea what the surface temps should be such as the manifolds, etc?

With an open cooled motor, they should no more then the 140, water is constantly going thru them.

 

[nateo]

Here's some things I checked. I pulled off the two bottom hoses (one at a time) from the starboard manifold. Water drained from the manifold so I'm assuming that it's not clogged up there. I checked the hoses at the t-stat housing for any obstructions. I pulled the drive off and then back flushed the powersteering cooler (water came out of bell housing, no other debris). I then stuck hose in water inlet hole in bell housing and ran it that way. I also check the starboard shutter and it is still in tact. Still observing the same temperate issue. hum..

 

[Scott Danforth]

cant assume anything

pull the elbows and look into the passages. if this is a salt-water boat, i would simply buy new manifolds and elbows.

 

[nateo]

couldn't find option to delete a reply

 

[alldodge]

I'm going to need the engine serial number and if you have the 3 or 7 point drain system? Also assuming you have an open cooling system and not closed

There use to be check balls in the thermostat housing but that hasn't been used in many years

 

[nateo]

cant assume anything

pull the elbows and look into the passages. if this is a salt-water boat, i would simply buy new manifolds and elbows.

I gave this a shot tonight. The big hole in exhaust manifold was completely clean. The little holes were clean. It all looked surprisingly clean. I've noticed that the hose going to elbows is not hot, however the hoses going to bottom of manifolds is very hot. I pulled one of those hoses while engine was running and it was pumping water fine (more then I expected even). I'm leaning toward maicoman's suggestion and switching out this single point drain system to 7 point drain. (going to set me back about $700 in parts though).

 

[nateo]

If I have a 160 degree thermostat, can anyone tell me about what the outside temperature of the thermostat housing should be when using a IR thermometer?

 

[alldodge]

If I have a 160 degree thermostat, can anyone tell me about what the outside temperature of the thermostat housing should be when using a IR thermometer?

should be 160 or very close to that

 

[Scott Danforth]

. I'm leaning toward maicoman's suggestion and switching out this single point drain system to 7 point drain. (going to set me back about $700 in parts though).

they are brass pipe plugs available at your local ace hardware for $0.53 each. my math says its under $4