2006 Mercruiser 350 BIII Hot Manifold?

[WhyKnott]

Hello iBoats!

First post, be gentle! Boater from Albany, NY here! Waiting for the SNOW to stop!

I am a new owner to a 2006 Bayliner 325 SB and twin 350 Merc MAG MPIs w/Bravo 3s. The Bravoitis bulletin was completed on it, not only were the hoses replaced, they also installed thru-hull raw water intakes (Although, without a strainer, a bit nervous about that).

On the sea trial, my surveyor with his infrared gun saw manifold temps get up to about 208 - Service has stated that this is considered normal operating but due to my concern, they pulled the risers and manifolds off to check the gaskets and for any obstructions only to find nothing. This is the side (starboard) that has new manifolds and risers. He also hooked it up to ECM diagnostics and was able to see proper flow numbers for the raw intake system.

Looking for ideas or am I worrying too much? Vessel is set to be delivered in a few weeks so I can get my hands on it if I need to check something.

 

[Scott Danforth]

welcome aboard.

was the picture taken at or close to 1800 RPM and just getting on plane? if so, its normal as the water flow is low and the heat output is high, throttle up, get it out of the hole and go boating.

 

[alldodge]

twin 350 Merc MAG MPIs w/Bravo 3s .... Bravoitis bulletin was completed
also installed thru-hull raw water intakes (Although, without a strainer
starboard) that has new manifolds and risers

Correct if I'm wrong, but assume the Bravoits bulletin was completed before the thru hulls were installed in an attempt to fix the heat issue.

Has new mans and risers but only one on the starboard side is reaching this amount of heat, Not both motors, correct?

If this is the case then I have same concern

What is one of the motors serial number, and are they closed or open cooled?

 

[WhyKnott]

welcome aboard.

was the picture taken at or close to 1800 RPM and just getting on plane? if so, its normal as the water flow is low and the heat output is high, throttle up, get it out of the hole and go boating.

So, if memory serves correctly, this was while we are on plane and at WOT, which was around 4200 RPM, I think we hit about 42 MPH. I know he took some other imaging after coming down from WOT to Idle, I can't remember if that is this image. I should have kept track of the timing.

 

[WhyKnott]

Correct if I'm wrong, but assume the Bravoits bulletin was completed before the thru hulls were installed in an attempt to fix the heat issue.

Has new mans and risers but only one on the starboard side is reaching this amount of heat, Not both motors, correct?

If this is the case then I have same concern

What is one of the motors serial number, and are they closed or open cooled?

That is 100% correct - the bulletin was completed with all of the hoses replaced. On one of the service orders, they mention the steering column had to be removed to access.

After that, they still saw some high temps, however the raw water intake thru hull on the port motor resolved all issues and ran cool, which has OEM Man/Risers, never been replaced.

The Starboard motor though is the one with new Mans/Risers and that is the one that was running hot. I pushed to have the thru-hull replaced prior to purchasing the boat, which they did, but we did not re sea trial.

The Engine Serial numbers are as follows:
0W624177
0W624191

EDIT: They are open cooled motors

 

[WhyKnott]

I do have a sneaking suspicion that possibly the water intake passageway in the lower unit of the B3 could be clogged up with Zebra Mussels - they mention the drives have never been separated. That's just a hunch though - not sure if it could actually cause the issue.

 

[alldodge]

Thanks for the serial number.
Your not getting sufficient water coming into the bottom of the manifold to keep it cool. This can happen with either to much restriction or to little. Water being feed to the risers comes from the manifold and also a hose with a built in restriction. The restriction makes sure the block and manifolds get filled before the risers. Once filled any excess water not used by block/manifold passes out the riser hose.

Don't know if you have the 3 or 7 point drain system.

I the 3 point drain this restriction is created by a Tee. This tee depending on the year can either be a all in one piece or on which has bushings installed inside the Tee.



The 7 point drain uses check balls in a Tee which is attached on top the thermostat housing



If the port side has less restriction then the starboard more water will go in that direction. Look at those locations for more or less restrictions. The spring loaded check balls can get stuck open as well as closed

 

[WhyKnott]

Thanks for the serial number.
Your not getting sufficient water coming into the bottom of the manifold to keep it cool. This can happen with either to much restriction or to little. Water being feed to the risers comes from the manifold and also a hose with a built in restriction. The restriction makes sure the block and manifolds get filled before the risers. Once filled any excess water not used by block/manifold passes out the riser hose.

Don't know if you have the 3 or 7 point drain system.

I the 3 point drain this restriction is created by a Tee. This tee depending on the year can either be a all in one piece or on which has bushings installed inside the Tee.



The 7 point drain uses check balls in a Tee which is attached on top the thermostat housing



If the port side has less restriction then the starboard more water will go in that direction. Look at those locations for more or less restrictions. The spring loaded check balls can get stuck open as well as closed

Thank you!! So it's safe to assume the temps we are seeing are not considered 'normal', right? Also, quick question - where do you pull these diagrams from?! I just ordered the Merc Manuals and B3 manuals.

Also, is there a place where I can look for these parts if I wanted to order them? Such as the restrictors, the motors are 2006 year. I assume I'll have to pull a part some of the hoses and check for blockage and check the ball valves. I'll also have to see if I have a 3 point or 7 point system.

 

[alldodge]

IMO, while you may not be able to leave your hand on the exhaust, you should always be able to touch any part of the exhaust without getting burned. A 200+ reading is way to hot in a engine room.

There are two sites I use to look up parts
Mercury, then select parts, then enter your serial number
https://www.mercurymarine.com/en/us/.../parts-catalog

Mostly BAM, select motor/drive type, find motor and serial number range
http://www.mercruiserparts.com/parts...ndrive-inboard

Here is the link for your motor serial number range
http://www.mercruiserparts.com/350-m...-0w310000-thru

 

[alldodge]

I do have a sneaking suspicion that possibly the water intake passageway in the lower unit of the B3 could be clogged up with Zebra Mussels - they mention the drives have never been separated. That's just a hunch though - not sure if it could actually cause the issue.

Unless the zebra mussels are in the starboard side thermostat housing or hose, I don't see them as the issue. The rest of the motor(s) are cool enough. Also you now have thru hulls so the drives are no longer in the picture.

If the drives or have not been removed I would remove them to check engine alignment, U-joints and gimbal bearing. Then change drive lube and reinstall. Just part of regular maintenance starting point

 

[rickasbury]

What about the simple question like the raw water pump? I sure went thorugh a learning experience with my boat when I first got it..impeller was fine but the top/bottom had a "slight" score and would not pump enough water and ran hot- not over heat but run close to it.

 

[alldodge]

What about the simple question like the raw water pump?

The pump and impeller can cause over heating issues, but in all cases I've seen/heard it will be in more then one area. I'm assuming the surveyor checked all over the motor for heat issues and only found the one manifold. This would not be the pump or impeller. Would always be a good thing to check if it was not. Also assuming they were checked and/or replaced when heat issues were first found, cheap compared to manifolds and risers

Woops my bad, thought I was responding to the OP

 

[alldodge]

Just realized something, your first post comment of the "starboard" was meaning that this is happening on the starboard motor, NOT the starboard manifold. Thie pic posted looks like this is the port manifold of the starboard motor, correct?



So water should be moving from the bottom of the manifold up thru the riser and out (red arrow). This pic shows the manifold is not getting much water.

Wonder if the correct gasket was used between the manifold and the riser?

The item on the left, is that the power steering cooler?

 

[WhyKnott]

IMO, while you may not be able to leave your hand on the exhaust, you should always be able to touch any part of the exhaust without getting burned. A 200+ reading is way to hot in a engine room.

There are two sites I use to look up parts
Mercury, then select parts, then enter your serial number
https://www.mercurymarine.com/en/us/.../parts-catalog

Mostly BAM, select motor/drive type, find motor and serial number range
http://www.mercruiserparts.com/parts...ndrive-inboard

Here is the link for your motor serial number range
http://www.mercruiserparts.com/350-m...-0w310000-thru

This is excellent! Thank you for all of those links! They are super useful - just found the fuel filters for the Gen 3 Fuel Cooler module and I see the ball valves required on the T Housing.

My gut feeling was it's too hot - the mechanic that looked at swerved me the other way in saving it's fully within spec, but when asked for documentation, he said he couldn't provide it. The surveyor though said it was an issue at that temp.

So, I guess I'll start with my infrared gun - get updated temp reading when it gets up here. I'm also going to replace those ball valves as pre-emptive maintenance since they seem easy to replace.

 

[WhyKnott]

What about the simple question like the raw water pump? I sure went thorugh a learning experience with my boat when I first got it..impeller was fine but the top/bottom had a "slight" score and would not pump enough water and ran hot- not over heat but run close to it.

Impellers were replaced in 2017 per the Service history - I am planning to replace these anyways when it's up here in a week. I'll check for score - Is the best way to remove to simply run light sandpaper across to remove any lines seen within the housing.

 

[WhyKnott]

Just realized something, your first post comment of the "starboard" was meaning that this is happening on the starboard motor, NOT the starboard manifold. Thie pic posted looks like this is the port manifold of the starboard motor, correct?



So water should be moving from the bottom of the manifold up thru the riser and out (red arrow). This pic shows the manifold is not getting much water.

Wonder if the correct gasket was used between the manifold and the riser?

The item on the left, is that the power steering cooler?

That's correct - this is the Starboard Motor, port side manifold. Sorry I may not have used the correct terms in that first post!

The mechanic did go through and replace the gaskets as part of the survey work.
Exact wording from the invoice was "Manifold gaskets may be improperly installed on stbd motor, causing hot water to be partially clogged. Opened up and checked gaskets on both sides, replaced 2 gaskets, the other 2 were fine. Close back up and tested, manifold is still running hot. Parts: Elbow Gasket, OS Exh Elb Gasket, Merc, OS"

After that, the thru hull was installed too, but not retested.

Let me grab the engine pics and see what I can see in relation to the thermal imaging pic.

 

[Lou C]

That does seem hot to me. I know that some Mercruiser manifolds were plumbed different than the unrestricted design used by OMC/Volvo to keep the manifolds hotter, the idea being that at idle and trolling speeds condensation in the manifolds would get burned off and not then collect and run down the center exhaust port. But this may be hotter than normal even if that is the case here. On my OMC/Volvo style system, at idle the manifolds are usually at about 100-->115. After coming off plane the highest I have seen them, when the cooling system is all good, is about 135-140, they cool back down to about 100-115 after a brief period of idling.

In that thermal image what makes me think there is something wrong with the water flow is the dramatic difference between the manifold and the riser temp. Normally, the risers are about the same temp or slightly hotter depending on where you take your measurements. In this case the manifolds are more than 2x as hot as the risers and that does not seem normal to me.

 

[WhyKnott]

Just realized something, your first post comment of the "starboard" was meaning that this is happening on the starboard motor, NOT the starboard manifold. Thie pic posted looks like this is the port manifold of the starboard motor, correct?



So water should be moving from the bottom of the manifold up thru the riser and out (red arrow). This pic shows the manifold is not getting much water.

Wonder if the correct gasket was used between the manifold and the riser?

The item on the left, is that the power steering cooler?

So that item on the left is the Oil Filter... LOL Sorry I should have known that..... :laugh:

 

[WhyKnott]

That does seem hot to me. I know that some Mercruiser manifolds were plumbed different than the unrestricted design used by OMC/Volvo to keep the manifolds hotter, the idea being that at idle and trolling speeds condensation in the manifolds would get burned off and not then collect and run down the center exhaust port. But this may be hotter than normal even if that is the case here. On my OMC/Volvo style system, at idle the manifolds are usually at about 100-->115. After coming off plane the highest I have seen them, when the cooling system is all good, is about 135-140, they cool back down to about 100-115 after a brief period of idling.

In that thermal image what makes me think there is something wrong with the water flow is the dramatic difference between the manifold and the riser temp. Normally, the risers are about the same temp or slightly hotter depending on where you take your measurements. In this case the manifolds are more than 2x as hot as the risers and that does not seem normal to me.

I had no clue that they were even restricted, that was news to me when AllDodge responded. Learn something new everyday! I can also see how it could cause issues though if not working properly.

I do agree, the temp is VERY different which is the worrisome piece. On Sea trial, it hit all of it's spec'd numbers with RPM, WOT, etc.

 

[alldodge]

Opened up and checked gaskets on both sides, replaced 2 gaskets, the other 2 were fine. Close back up and tested, manifold is still running hot. Parts: Elbow Gasket, OS Exh Elb Gasket, Merc, OS

The replaced 2 gaskets comment leads me to believe they were the wrong ones, otherwise why were they replaced :noidea:

Here is what the gasket should have looked like


This is for closed cooling