Perkins 4108 exhaust manifold part

[Cap Morgan]

Hello everyone,

After 6 weeks on the hard doing bottom work and other tasks I finally launched my recently acquired 1980 Cal 39 this morning. Immediately there was more smoke coming from the engine compartment than I’d expect from burning off solvents etc.

Turns out that I need an entirely new exhaust riser assembly. I have a mechanic here in Cape Canaveral that will be building one. Where this riser connects to the header tank ( for lack of the correct name) there is what looks like an exhaust manifold. Along with the riser it is extremely rusted and I need to find a new one in a hurry.

I’ve attached a photo in which I point to the part. Can anyone identify the part for me and let me know where I can order it.

Your help in this endeavor would be truly appreciated!

[mvweebles]

Try TAD diesel (tadiesels.com) . Or Marine Exhaust of Alabama (MesaMarine.com). Pickup the copper gasket (and a spare) too.

Peter

[Cap Morgan]

Thanks a lot Peter! I’ll give em a call now.

[DougR]

So here’s the situation with your system...( based on the exact same system that was in my 1979 Cal39).

The blue exhaust manifold as seen in your photo is fresh water cooled, and capped on the aft end with a threaded flange. This threaded flange has a 90degree street elbow threaded into it, and then the exhaust riser(as you call it) is nothing but threaded pipe pieced together and wrapped with insulation.

What you need to do is remove the threaded flange on the aft end of the manifold ( 5 bolts as I recall), go to a hardware store and replace all of the pieces of threaded pipe with new and put the whole mess back together.

In my case I was unable to remove the street elbow from the threaded flange (even with an acetylene torch) and so I kept the street elbow and just replaced the system downstream from the street elbow.

Worked for an additional 10 years until I repowered the boat.

Don’t overthink this.....

[Argyle38]

What DougR said sounds right. Only thing I would add is that if you are planing on keeping the engine for a while, you might consider replacing the pipes with stainless. It's more expensive but not as expensive as it used to be. Check Grainger for the parts. I found the pipe parts needed for a riser there.


Edit: I ended up using item #EE18-410803 from TAD, shown on this page: http://www.tadiesels.com/exhaust-elbows.html#GREEN and built a riser from stainless pipe pieces from Grainger. Different manifold than you have so give them a call.

[Cap Morgan]

Originally Posted by DougR

So here’s the situation with your system...( based on the exact same system that was in my 1979 Cal39).

The blue exhaust manifold as seen in your photo is fresh water cooled, and capped on the aft end with a threaded flange. This threaded flange has a 90degree street elbow threaded into it, and then the exhaust riser(as you call it) is nothing but threaded pipe pieced together and wrapped with insulation.

What you need to do is remove the threaded flange on the aft end of the manifold ( 5 bolts as I recall), go to a hardware store and replace all of the pieces of threaded pipe with new and put the whole mess back together.

In my case I was unable to remove the street elbow from the threaded flange (even with an acetylene torch) and so I kept the street elbow and just replaced the system downstream from the street elbow.

Worked for an additional 10 years until I repowered the boat.

Don’t overthink this.....

Hello Doug, thanks for the detailed write up. How badly was your street elbow rusted when you decided to keep it for 10 more years? Mine is so rusted that the bolt heads are just stubs. I doubt that it has much life left. I do understand what you’ve related regarding putting together the downstream parts. This would be simple if I weren’t stuck on my boat at a Marina 200 miles from my tools. Anyway, I sure wish I could keep the street elbow. This would make things a lot simpler.

Thanks for the details.

[mvweebles]

McMaster Carr has a decent selection of 316 SS NPT thick wall pipe in 2-inch. If you have welding capabilities, you can also get SS exhaust pipe and mandrel bends (including U-bend= from Summit Racing.

I agree that getting it threaded into the flange is a PITA. Tough to get it right enough that it won't leak exhaust.

Good luck.

Peter

[Cap Morgan]

Originally Posted by mvweebles

McMaster Carr has a decent selection of 316 SS NPT thick wall pipe in 2-inch. If you have welding capabilities, you can also get SS exhaust pipe and mandrel bends (including U-bend= from Summit Racing.

I agree that getting it threaded into the flange is a PITA. Tough to get it right enough that it won't leak exhaust.

Good luck.

Peter

Thanks Peter!

[Lepke]

Available at TAD:

[DougR]

THIs all happened to me about 22 or 23 years ago, but for sure the flange and street elbow were definitely reusable. However they were so corroded together that I couldn’t separate them even having the street elbow red hot with an acetylene torch.

If your parts are shot, order the new flange/ pipe stub from TAD as Lepke shows in his post. Pretty sure you will need the flange/pipe as shown on the upper line in his post.....the part with the five holes in the flange.

As you probably know the exhaust manifold (painted blue) is cast aluminum and is cooled with freshwater (Antifreeze) so when you remove the exhaust flange you will get some antifreeze running out the aft end of the manifold. While you have the flange off, check the threads in the flange mounting holes in the manifold. Over the years I had to helicoil one or two of them, and if yours are marginal you might as well do it now.

[Stu Jackson]

Originally Posted by Lepke

Available at TAD:

Good advice and parts.
When you reinstall the gasket between the flange and the manifold, do NOT slather anything on the side facing the manifold. Indeed, you MUST clean the manifold side thoroughly, or else you WILL get a leak. Clean, clean, clean, flat, flat, flat. The reason to do so, beyond the potential leak, is to avoid having to clean it next time!

You should find a way to remove some of the coolant before you disconnect the manifold/flange, perhaps at the coolant pump, unless you want to replace all of the coolant, not a bad idea on a new to you engine anyway.
I recommend buying at least two gaskets. Why? The gasket material around the holes for the bolts/screws/studs is very, very slim. If/when they get wet they could/might disintegrate. Not good, but having another one right there will save you lotsa grief. BTDT.
Put just a tad of gasket sealer on the face of the gasket facing the flange, pat the gasket onto the flange, then slide onto the studs. Easier to do that way and keeps the manifold side completely clean. Do NOT put any sealant on the manifold side.

Originally Posted by DougR

THIs all happened to me about 22 or 23 years ago, but for sure the flange and street elbow were definitely reusable. However they were so corroded together that I couldn’t separate them even having the street elbow red hot with an acetylene torch.

If your parts are shot, order the new flange/ pipe stub from TAD as Lepke shows in his post. Pretty sure you will need the flange/pipe as shown on the upper line in his post.....the part with the five holes in the flange.

As you probably know the exhaust manifold (painted blue) is cast aluminum and is cooled with freshwater (Antifreeze) so when you remove the exhaust flange you will get some antifreeze running out the aft end of the manifold. While you have the flange off, check the threads in the flange mounting holes in the manifold. Over the years I had to helicoil one or two of them, and if yours are marginal you might as well do it now.

Some high temperature pipe thread sealant helps, too.


You also have, somewhere, the place to introduce the raw water from the HX into the exhaust gas before the muffler. Is that part still usable? Lepke's source might have that, too. Sometimes called a nipple, with a 5/8" or so pipe from the HX for that hose leading into the 1 5/8" to 2" metal riser. Some have used a pipe T instead of a welded nipple.

Between the end of the metal riser and the inlet port of the muffler is a good place to use "hump hose" a blue soft(er) hose to minimize vibration from the pipe to the muffler port. Catalina Direct sells it. Since I have a Catalina, that's where I got mine. Don't know who else has it but someone will.


I've replaced mine 3 times in 25 years, so I've had some 'speriences...


Good luck, all the best,


Stu