Exhaust Manifold

[ElizabethG]

Hi Gang,

This past week, I noticed that the coolant level, in my expansion tank, never seemed to move when the engine was hot, or cold. So, I removed the hose and it was clear. Then, I removed the brass elbow that the hose connects to on the exhaust manifold. It was completely clogged with what looks like calcium deposits. I cleared that out and screwed it back in to the manifold.

The paint had been flaking in that area for awhile, so I took a wire brush and started to clean it up. This is what I found.

image6-3.jpeg (138.66 KiB) Viewed 3028 times

Obviously, that hole on top should not be there as the elbow screws into the side, not the top. When the elbow is installed, I can actually see the threads from the hole at the top.

In addition, I could not locate the the hole that allows the coolant to flow into the manifold. It must be blocked with calcium deposits as well. I did, however, see a small hole on the throat of the filler neck. I'm not sure what that is for. Is that where the coolant goes on the way to the expansion tank?

When the engine is running, it's steady at 160 degrees with no leaks.

Shame on me, but this engine has been running fine for years. She has about 1,700 hours.

So, a few options...

1) Can I just run it as is and just leave the manifold about 1/2 pint low to allow for coolant expansion?

2) Can I just patch up the hole with JB Weld, screw the elbow back in and go with it? I would need to clear out the calcium blockage that blocks the coolant from moving from the manifold to the expansion tank.

3) Replace the entire manifold for roughly $800 (Includes manifold for $689 and assorted gaskets and clamps)?

BTW, the rest of the manifold looks fine, it's just this filler neck section that looks bad. I replaced the riser a few months ago. I was expecting it to be somewhat pitted with heavy deposits, but it looked fine.

I have literally spent a day trying to source the manifold at a better price, but no luck.

Thoughts?

Bill
C350 2004
#193
Atlanta, GA
Boat in Charleston, SC

[scott.monroe]

Morning Bill,

I've chased a few coolant issues over the years with my C350. Must say your manifold in the coolant cap area looks heavily corroded and replacement may be in order. You can get it from Westerbeke (looks like part # is 201026, https://www.westerbeke.com/Product/MANIFOLD/201026).

But before you lay out the $686 + gaskets etc, you may not have a problem with what you think. The way the expansion tank works is that as the engine heats up coolant is allowed to leak out through the cap on the manifold to help balance off the pressure that builds up. Then as the engine cools it forms a vacuum and pulls coolant back into the manifold from the expansion tank. This is controlled by the cap on the manifold (which can fail) and often is not tested. If there is a leak anywhere else in the closed cooling system this process doesn't work as air is allowed to leak in and out, e.g. gasket or hose failure. In my case I had a failing coolant hose on the heat exchanger. I found it because I was always loosing coolant (had low coolant in the manifold during recommissioning in the spring) in the winter months as the metal shrank and coolant was seeping out around the hose.

Lastly that little hole looks like a weep hole, don't think filling it is a good idea. If you see coolant drip lines from it you might have a cap failure.

Also don't forget to flush the coolant every couple of years and use proper coolant as it does keep internal corrosion down.

Hope this helps a little,
Scott

[KenKrawford]

Bill, I echo Scott's suggestion about NOT filling that weep hole. I seem to remember reading somewhere that it's there to bleed off pressure in case the hose becomes blocked.
I'm not sure if the exhaust manifold on our marinized engines are the same as Kubota put on Westerbeke tractor engines. I know that many parts on the block are identical to their Kubota counterparts and can be had for a fraction of the price. Might be worth looking into. Maybe Brett Wolfe will weigh in on this.

[wolfe10]

Sorry, been too long since I worked on the the cooling/exhaust system.

But, the amount of corrosion on the exterior of the of the manifold suggests other issues.

If you have 120 VAC where you store your boat, use a small (30 pint) dehumidifier draining into the galley sink. Set it at 50%.

[ElizabethG]

Ken, Scott & Brett...

Thanks for your responses!

I think for my piece of mind and especially my wife's, I think I'm going to bite the bullet and go with a new manifold.

I have a couple of emails out to see if I can get a better price than Westerbeke's list of $689 for p/n 201026. If anyone has any sources for new or used, please let me know.

Ken...On the Kubota angle, the M35B engine block is a Kubota model V1305-E which they use in their "bobcats". The only exhaust manifold I can find from them is what I would call a "straight pipe" manifold that you would typically see on a car engine. However, the manifold gasket looks the same and is about half the price of Westerbeke's list of $35.60 (p/n 200912).

Lastly, if anyone knows what the torque setting should be on on attaching the manifold to the engine head, that would be helpful...the engine head is cast iron and the manifold is cast aluminum. The service manual does not list that spec.

Thanks!

Bill
Atlanta
#193

[hperros]

I had the same issue with the brass elbow. It was always blocked and the level in the expansion tank would not change. A mechanic told me that the accumulation of calcium that blocks the hole is due to the dissimilar metals and he advised me to use indian head. So far it has been clean of calcium. If you remove the elbow to clean it, you also need to clean the hole in the manifold which surprisingly is very small. -- my two cents!

[KenKrawford]

Ok Harry I'm going to assume that using the terms "indian head" and "two cents" in the same post is just a coincidence ! Are you referring to Permatex's Indian Head Gasket Shellac?

[JohnNorton]

I had an issue with coolant leak for some time. Finally found the problem was a small hole just above the expansion fitting on the manifold (exactly as seen in the photo). JB weld fixed the problem. To my thinking the system does not need a "bleed hole", which would defeat the entire purpose of an expansion tank. Plug the small hole, clean the tank, re-connect the expansion line. I did this over a year ago- no problems.

[ElizabethG]

Hey John,

When you plugged the weep hole in the coolant filler neck, of the exhaust manifold, did the expansion tank work correctly? In other words, did the coolant level rise and fall?

The reason why I'm asking, is that I though that weep hole was the outlet for the coolant to flow back and forth from the expansion tank to the exhaust manifold.

If I take out the brass elbow that screws into the manifold, I don't see where the coolant enters the manifold unless that orifice is clogged with calcium deposits. If it is clogged, I want to know where that clog is so that I can clear it.

Does anyone know if the coolant orifice is a straight shot across from where the brass elbow enters the manifold? That would be a big help before I go poking new holes in the cast aluminum.

Bill
Atlanta
#193

[JohnNorton]

Bill: I certainly would not go poking any holes ! As to coolant levels rising and falling- can’t say I have looked, but I will this weekend and report back to you. I do know the line to it always has, when cold, an air bubble in it. Does this mean nothing is going through- perhaps but not sure. My engine temp stays at just above 160 deg., no coolant loss, no coolant on or around the engine. Perhaps I can learn something here- if the hole I filled with JB is in fact supposed to be there-- ?? Or if it was weeping coolant before I JB welded it was because my overflow tank line not working; again--- ??. I do know the fitting at the neck is not plugged. If I am not getting any overflow movement, well that is a concern. I’ll observe the overflow tank level changes of lack thereof, let you know.

Thank You: John Norton

[ElizabethG]

Hi John,

I look forward to seeing what you find this w/e.

Regarding the air bubble that you have when the engine is cold...the expansion tank is higher than your engine. You should be able to manipulate the hose to force the bubble to rise into the expansion tank. Kind of like watching the carbonation bubbles rising in your favorite pint of beer

Bill
Atlanta
#193

[hperros]

Ok Harry I'm going to assume that using the terms "indian head" and "two cents" in the same post is just a coincidence ! Are you referring to Permatex's Indian Head Gasket Shellac?

Hi Ken
Yes, it's the Permatex product. I have good success with it, but it is extremely messy. It goes everywhere within seconds and then it is impossible to remove it. I use a glove and apply the stuff with my finger and not with the ball-shaped brush they provide. I also used it successfully on one of the machine screws that holds down the fuel gauge in the fuel tank that was leaking.

Good pun about the cents !! Haha...

[hperros]

If I take out the brass elbow that screws into the manifold, I don't see where the coolant enters the manifold unless that orifice is clogged with calcium deposits. If it is clogged, I want to know where that clog is so that I can clear it.

Does anyone know if the coolant orifice is a straight shot across from where the brass elbow enters the manifold? That would be a big help before I go poking new holes in the cast aluminum.

Bill
Atlanta
#193

The brass fitting connects to a small hole on the manifold that it is impossible to see. However, it is there. You remove the elbow and then get a paper clip (or something very thin) and poke around inside where the elbow screws in. You can also try from inside of the neck, near where you see something that looks like a hole. Just keep poking in there and you will find it!! The hole is extremely small compared to the brass elbow. Yes, it is a straight shot through the metal.

[JohnNorton]

Bill: I can confirm that after running the engine for a couple hours this past weekend the overflow line works as intended.
Please note: THE HOLE WAS ON THE OUTSIDE, ABOVE THE 90 degree OVERFLOW FITTING and was leaking coolant every time I shut down a fully warm engine. I expect this was working as an expansion release. The hole was filled with the JB WELD FROM THE OUTSIDE of the manifold, not from inside the neck. - John

[ElizabethG]

Hi John,

Thanks for the update!

Glad to hear your expansion tank is working correctly.

Bill
Atlanta
#193