Replacing FL 120 Exhaust Elbows

[DCParks23]

We are about three months into our 1980 CHB 45. Twin FL 120’s 1800 hours. All previous owners did a great job maintaining the engines. Now it’s my turn. Been on boats all my life 45+ years. First experience with Diesel engines.

Exhaust elbows showing some serious signs of corrosion. Purchased new elbows from ADC. Got all the bolts loose, which I feel like that was lucky. Noticed coolant dripping from the bottom of the elbow. Didn’t expect that. Hit pause on the project. I wasn’t equipped to handle a coolant dump. Do I need to drain the coolant before pulling the elbows off? Or is this just a little residual.

 

[psneeld]

I think you do have to drain coolant to the bottom level of the manifold.


I also remember that I did like you and didn't realize and worried about how much coolant may have leaked into the rear cylinder...so unless someone here knows better...you may want to bar over the engine a couple of times to make sure little or no coolant mae it to the rear cylinder(s).

 

[catalinajack]

You are wise to replace the elbows. They were at the end of their useful life.

We are about three months into our 1980 CHB 45. Twin FL 120’s 1800 hours. All previous owners did a great job maintaining the engines. Now it’s my turn. Been on boats all my life 45+ years. First experience with Diesel engines.

Exhaust elbows showing some serious signs of corrosion. Purchased new elbows from ADC. Got all the bolts loose, which I feel like that was lucky. Noticed coolant dripping from the bottom of the elbow. Didn’t expect that. Hit pause on the project. I wasn’t equipped to handle a coolant dump. Do I need to drain the coolant before pulling the elbows off? Or is this just a little residual.

 

[catalinajack]

Next you should consider re-torquing the heads and then adjusting the valves, something that should be done at least at 1,000 hour intervals.

We are about three months into our 1980 CHB 45. Twin FL 120’s 1800 hours. All previous owners did a great job maintaining the engines. Now it’s my turn. Been on boats all my life 45+ years. First experience with Diesel engines.

Exhaust elbows showing some serious signs of corrosion. Purchased new elbows from ADC. Got all the bolts loose, which I feel like that was lucky. Noticed coolant dripping from the bottom of the elbow. Didn’t expect that. Hit pause on the project. I wasn’t equipped to handle a coolant dump. Do I need to drain the coolant before pulling the elbows off? Or is this just a little residual.

 

[Xsbank]

Why is there coolant in the elbows? Raw water, yes.

 

[psneeld]

The elbow seals the end of the fresh water cooled manifold I believe.

 

[hobbystuff]

Yes. Drain the coolant down below the exhaust manifold. The elbow seals off the aft end of the water jacket.

Get everything off, clean and dress the surfaces. Use a new gasket, and some sealant - I can't remember what kind I used, but it was at the recommendation of ADC.

Fill the coolant back up, make sure all the air is clear from the cooling system and go boating.

 

[catalinajack]

ADC recommends Permanente #2 but on the engine side only. Don't know why not on both sides but I replaced mine recently and no leaks.

 

[jleonard]

When I replaced mine the lower section of the exhaust manifold was corroded about 1/16 inch deep in the center. Not quite all the way thru that’s why it didn’t leak. I pulled the manifold off and had that end milled off until the surface was solid cast iron again. Took off approximately 1/8 of an inch total.
Machining that end doesn’t hurt anything

 

[TJM]

I will be doing the same swap out in a month or so. Is that Permatex sealant ? Maybe a Typo ? I have never heard of Permanente.

 

[BigTime]

following

 

[rgano]

When I got my elbows from ADC, they sent me two gaskets, one for the front end which has coolant passages cut and the aft end, which has no passages cut. Be sure you put the correct one on the aft end.

 

[catalinajack]

Yes, typo. Permatex #2.

I will be doing the same swap out in a month or so. Is that Permatex sealant ? Maybe a Typo ? I have never heard of Permanente.

 

[DCParks23]

Came across engine manual and figured out where I need to drain coolant from. Also saw a diagram of the fresh water flow so it all is starting to make sense. Appreciate the help.

I think you do have to drain coolant to the bottom level of the manifold.


I also remember that I did like you and didn't realize and worried about how much coolant may have leaked into the rear cylinder...so unless someone here knows better...you may want to bar over the engine a couple of times to make sure little or no coolant mae it to the rear cylinder(s).

 

[catalinajack]

If you are going to bar the engine over, remember to retract the shut-off solenoid to stop all fuel supply to the injector pump. It's a safety issue in that turning the engine over by hand may cause the engine to start, not a good thing. A remote possibility but easy enough to prevent an accident. Just retract the plunger and hold it in place with a wire tie.

As for having ingested water into a cylinder, that will not happen if you drain the coolant first, easy enough to do. I attach tubing to the petcock and drain the coolant into a five gallon bucket. I drain it all to ensure I get it below the manifold. Then, I later put it back in. But, now would be your opportunity to refresh your antifreeze which should be done occasionally. In my case, when I changed elbows, the coolant was less than a year old. Have fun.