Exhaust Elbow

One item that had been lurking on 'The List' for over a year was replacement of the engine exhaust and water injection elbow. It was an issue during the original survey, due to corrosion, but we never managed to find time for it with all our other more pressing projects. Well, it finally elevated itself to the top of the list when it started to leak! It still wasn't in the project schedule but, no problem, a few bucks worth of pipe fittings and a free day should get things back on track........pause here for hysterical laughter from all experienced good old boaters!

In preparation for starting the job we spent a few minutes each day for a week coating PB Blaster on the rusted bolts that held the flange of the injection elbow onto the heat exchanger. 

We've always had good luck with PBB so we were confident we could easily break loose four rusted 3/8 - 24 bolts .......pause for additional guffaws!

 

In fact, albeit with a little more effort than we expected, three of the four bolts did come out fairly easily. Clearly, no anti-seize compound had been used on the bolts at the previous installation, but three out of four is good, right? 

Located in the most inaccessible spot, the last bolt was longer than the others. Its threads extended right through the heat exchanger flange and 1/4" beyond, and were rusted badly. Using a wire wheel on the Dremel we cleaned up the exposed threads and tried everything we could think of to encourage the bolt to move; vise grips, heat, impact, more PBB with no success. So, at the end of Day1 of the 'The Battle of The Bolt' the bolt held a commanding lead!

To get better access we removed the heat exchanger hoses and core. We sent it off to be boiled out and pressure tested.

We continued the assault on day 2 and the exhaust flange gasket finally disintegrated, allowing us to rotate the elbow and get better access. But the bolt still wouldn't shift! By this time the head was completely rounded off and we were having a problem holding it with the vise grip.

The final desperate move was to use the Dremel with a cutting wheel and chop the corner off the injection elbow flange. This allowed us to completely remove the elbow and gave us much more of the bolt to grip.

Here is the flange after surgery.

With better access, and after more PBB and more heat backed up with a generous helping of profanity, we finally got the bolt to surrender.

 

What a difference 1/2" makes. We delivered 'the bolt' back to the company of it's pals. We were surprised to see fine thread black oxide bolts being used in an alloy casting. Plated bolts and coarse threads would have been much better and less likely to strip, particularly if anti-seize compound is used!

We carefully ran a 3/8"-24 tap through all the holes and were not surprised to discover that the threads in the 'problem hole' were now trashed. Helicoil anyone? 

Also, having destroyed the exhaust flange, we needed to find a new one. After a bit of internet surfing we found TAD in Hayes VA. They supplied overnight a new exhaust flange, gasket and grade 8 cadmium plated bolts.

So, on day 3 we were finally where we planned to be a couple of hours after we started! Having burned up so much time and effort we decided to go the extra mile and replace all the hoses and clamps on the engine while it was torn apart and do an oil and filter change. We got all the parts from British Marine in Alameda.

We started the hose replacements with the elbow that connects the thermostat to the heat exchanger and found it was too short.  Nothing is easy is it?

Here is the new Perkins elbow as received.

And here it is next to the old one! After a call to check with British Marine we found that there was no other part number or part available so we had to get creative. Off to O'Reilly's we go!

After searching their hose rack for 15 minutes we found something that we could modify. No clue what it was originally designed for. 

Here you can see the almost perfect match  with the old elbow.

And here it is in place on the engine. We also changed all the hose clamps to AWB brand. They are more resistant to corrosion and don't have slots in the band that can cut the hose. All the other hoses fitted with no problem.

After repairing the bad threads in the  manifold we were finally able to get the new elbow painted, lagged and installed. We even went with a new piece of  hose to the water lift can. Looks good huh! Another item off the list.