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$6,600 to rebuild Atomic 4? replace/rebuild

54K views 73 replies 37 participants last post by  travlin-easy 
#1 ·
I just received a quote to rebuild the Atomic 4 motor on my 1979 C&C 34. I was shocked at the $6,640 price tag for this job and I asked them to hold off on the repairs while I consider alternative options.

During haul-out this season, it was noticed by the yard crew that the motor was creating knocking sound and I ordered the engine be pulled from the boat for inspection. A few weeks later I received a diagnosis of the problem...here is what they said:

"There was a bad connecting rod that was causing the banging. Also the cylinders are worn out and need to be bored out and larger pistons & rings installed. Along with a bad exhaust valves, bearings and valve guides."

They are suggesting a total engine rebuild. I am concerned that the value of the boat does not warrant such an investment and was hoping to get some feedback from the SailNet community.

The engine needs some work, I understand that, but is a rebuild my best option? I plan on selling the boat in about 3 years for an upgrade, but I can't use/sell the boat with a compromised engine.

Questions:
-Do I ask them to repair the connecting rods and handle the minor repairs myself?
-Do a full rebuild?
-Go all in and do a diesel swap? (hoping that I can extract 50% value when I sell)
-Look online for rebuild motor and have yard install?

Any insight, thoughts, words of wisdom, etc... would be appreciated. Thanks for reading!

-Chris
 
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#29 ·
Can I ask what do we mean when we say rebuild. ? Does it mean taking parts to the machine shop? Does it mean running a hand drill hone run up an down the cly walls and lapping the valve seats, new gaskets, bearings and done? How much has to be done to get to get x amount of trouble free hours. Each engine will have its on needs. What I am asking is how much is enough on average? Regards, Lou
 
#30 ·
Lou, it's all about the spec. For instance, if the valve seats and guides are worn beyond spec, if the cylinders are beyond spec, if the crank bearings are out of spec, it is going to cost more to rebuild than an engine that hasn't got scored and ovaled cylinders, spun bearings, sloppy valves, etc. A well maintained and babied 2000 hour engine will be a cheaper rebuild than a beat to hell, never maintained 500 hour engine.
 
#31 · (Edited)
We would most likely agree in person but over the Internet so many parts of somebodys thought process is missing :)

On my boat just getting the motor out

I had to design a tool to reach the bolt heads under the fiberglass engine bed and the time just went UP from there
 
#34 ·
A big consideration for me would be, what's the condition of the rest of the boat?

I wouldn't sink $6k into a boat that is falling apart. I'd get the engine running and sell as is. On the other hand, a new $10-12k diesel in a beautifully restored and maintained boat may well be an investment that can be (at least partially) recouped in three years time. I'm guessing you're somewhere in the middle, but depending on which end of the spectrum I was leaning toward, would partially guide my decision as to how much I'm willing to spend.
 
#36 ·
There is some great feedback here, thanks to everyone for the input! After reading these threads I've decided to explore the rebuild option myself. I'm good with a wrench, having tackled many auto engine jobs myself, and I think this option is at least worth exploring before I pull out the checkbook. I love the personal pride/knowledge that comes with a DIY project. Grasping the importance of a reliable motor out on the water, I anticipate many hours of research and labor in my future. I plan on meeting with the mechanic at the yard to get a better understanding of the problems...I used the motor all season, and while it occasionally had a rough start, I found it to run like a champ!

The Moyer website seems like a good place to start, and I know I can always rely on the forums to help clear up any questions.

Thanks again for all the input, I never expected such thorough feedback.

Wish me luck!

Chris
 
#37 ·
Good decision. You are going to get a lot of fun & satisfaction out of the project - a new engine will be a bonus. :D

If you haven't already, I strongly suggest you check out Porfin's thread about his ongoing rebuild of a Perkins 4108. Obviously the specific mechanical info will differ but there are lots of tips & tricks he is doing that will transfer to your Atomic Bomb.

Have fun, take lots of pictures and keep us posted.
 
#39 · (Edited)
Well, its been a few weeks and I thought I'd give an update along with some pics...

I picked up the motor from the harbor, and it was already completely disassembled and housed in several plastic bins. After getting the run down from the lead mechanic, I brought the parts back to the basement of my girlfriends condo (I live in a 1 BR apt in Chicago, which is already cluttered enough with boat parts and tools...thanks Katie!).

Room

(Candid camera in the dungeon.)

I spent the first weekend going through the work order prepared by the yard, assessing the condition of the various components in question. The main items in need of replacement are: 1 connecting rod, full set of bearings, full gasket set, full set of valve springs, full piston rod set, thermostat, cam shaft grinding (which was already done by the mechanic at the yard), and I decided to have the main components (block, flywheel cover, etc...properly cleaned by a local motor shop).


(The block looks in need of a new paint job!)

Auto part Metal

(Exhaust Manifold and Valve Cover Plate.)


(The oil pan also could use a new coat of paint.)

After my inspection, I ordered the parts in question from MoyerMarine.com along with the Service and Overhaul Manual and some other basic tools from Amazon.com (piston ring compressor, engine brushes, degreaser, Permatex Form-a-Gasket, etc...). I plan on dropping off the block, flywheel cover, etc... at the engine shop tomorrow to have the old paint removed and the applicable components baked, acid washed (or glass blasted if appropriate) while I tinker with cleaning and oiling the misc. components such as the carburetor, ignition system, and oil pump.

Auto part Games

(I examined the rods and pistons for damage. The bearing on one of the rods had begun to spin and was the main culprit in this rebuild...The mechanic explained that due to the spun bearing, the rod experienced compromising temperatures and needed to be replaced. I bought a used one off of him for $40 (top left).)

I've already started degreasing and cleaning the valves and lifters. Most of my today has been spent pouring over the Moyer Overhaul Manual. I've found this extremely helpful (along with some other great posts on this site).

Once I get the parts back from the engine shop, I can start to plan the reassembly.

One quick question: Before deciding on an engine shop, I called around looking form someone who can provide the correct services for the block, etc...and I received recommendations from other engine shops for the place I am ultimately going to work with. The shops owner suggested that we bake the block and perform an acid wash of some type to remove all the paint and gunk built up in the water jacket. The other components, he suggested, should be cleaned with a glass blasting (he said glass was less abrasive on the parts than sand). Do these treatments seem appropriate? I remember my father warning about the potential for pieces of the glass to get lodged in the "nooks and crannies" of the motor, ultimately causing problems down the road (he is rebuilding the motor of his 1968 Thunderbird). Is this something I should be wary of?

Well, that's all I have for now, apologies for the lengthy post. I'm always open to feedback/suggestions so don't hold back.

Happy Easter,

Chris
 
#40 · (Edited)
Glass beading works well - it won't harm machined surface. If they are going to bead the block, I'd get it hot tanked afterwards to ensure all the beads are out of it. If you are getting a set of rifle brushes, going through the oil galleys and so forth afterwards will really ensure it's all clean.

Read Porfin's thread on rebuilding his 4108 - lots of tips on painting the engine inside & out.

Get your rods resized and get the mains line honed as well - better bearing crush if you do and it doesn't cost much if you get it done along with the valve job. If you had a rod bearing spin you'll need to get the crank ground undersize as well. This is all standard engine building procedure.
 
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#41 ·
Thanks Sloop,

I already had the crank ground down, and purchased the appropriate sized bearings to accommodate the new size. I bought a set of engine brushes, so I plan on going through the motor with them and ensuring all the gunk is clear and no remnants of glass are present. As for the rod honing, I'm not familiar with this procedure...the mechanic suggested that I hone a few pieces of the motor during the rebuild, but I haven't researched the specifics on this yet.

Thanks for the feedback, as for Porfin's posts, I have already gone through them several times and will definitely use his documentation as a guide in my rebuild...he did a great job outlining his rebuild!

-Chris
 
#42 · (Edited)
Thanks Sloop,

I already had the crank ground down, and purchased the appropriate sized bearings to accommodate the new size. I bought a set of engine brushes, so I plan on going through the motor with them and ensuring all the gunk is clear and no remnants of glass are present. As for the rod honing, I'm not familiar with this procedure...the mechanic suggested that I hone a few pieces of the motor during the rebuild, but I haven't researched the specifics on this yet.

Thanks for the feedback, as for Porfin's posts, I have already gone through them several times and will definitely use his documentation as a guide in my rebuild...he did a great job outlining his rebuild!

-Chris
Resizing the rods involves having the cap mating surfaces ground down slightly to make the big end slightly "football" shaped, then they hone it to perfectly round again at the original factory diameter. To do the wrist pin end (small end) they ream the hole and press in bushings that also bring the hole to original factory specs.

We're talking thousandths of an inch here.

The reason for doing it is because the strains on those components are largely "linear" along the rod so the holes tend to get slightly elongated along the long axis of the rod - again, thousandths of an inch but that's what you're dealing with in an engine - precision really counts towards power and longevity. That's why they call it "blueprinting".
 
#44 ·
Well, I thought I would just close the loop on this thread and give a quick update...

I am very happy with my decision to take on the project. The money I saved is not even close to the enjoyment/education I gained from the job. It was not without it's fair share of bumps and curve balls, but I am happy to say that the motor is back in the boat and has been running better than ever. I happened to run into the mechanic during my (delayed) launch and he complimented me on the reassembly...I told him Moyer did it.

Thanks for all the feedback and insight, couldn't have done it without ya!

Chris
 
#47 ·
You should talk to Don Moyer at Moyer Marine. If you call him up and speak to him directly you are likely to get a fair answer and price. He has given me excellent free and unbiased advice in the past and his company is the reason why I am keeping my A4 and am not repowering. I somehow never trust boat yards.
 
#51 ·
Well, it's almost the start of the 2014 boating season here in Chicago and I can't tell you how much I'm looking forward to some warm weather and precipitation that's not in the form of snow. I was down at the boat yard today taking my first assessment of the Spring To-Do-List and I got to thinking about where I was this time last year...with my A4, dissembled, sitting on a work bench in the basement...I thought it might be worth updating this post on my experience with the newly rebuilt A4 during the 2013 season.

First off, I have to sincerely thank everyone who helped me long the way: the wise contributors from Sailnet.com, everyone at Moyer Marine (who truly are amazing...the advice/consultation are second to none!), and my fiance for reminding me that "you can teach yourself anything".

Ok, enough with the mushy intro...

The A4 on my 1979 C&C 34 has never run better, really. She starts right up at the first hint of spark and runs so smooth. Doing the rebuild myself allowed me to really understand the mechanics of this motor, so trouble shooting shouldn't be difficult if anything arises in the future. During the rebuild, I made sure to follow the instructions outlined in the Moyer Marine Handbook, reading…and re-reading, each section before proceeding. I sheared a few bolts and made a couple trips to the machine shop but finally got the motor together in time for the season. I had the crew at the boat yard install/connect the motor for me…in fact, when I launched for the season, the guy who helped me push off commented on the motor (he was one of the guys who actually installed it in the boat), saying he was impressed that it was a DIY job.

During the season the motor ran great, no issues at all. The experience or rebuilding it on my own was one I would encourage others to undertake. What one man can do, another can do…just manage your expectations for the job and get the right tools/instructional materials.

I've attached a video of the first time I fired up the A4 after the rebuild (if it doesn't embed in this post, try the link). I did a little fine tuning after this, but it's hard to express the accomplishment I felt when I heard this beast roar...even if it was puttering a llittle.

Total Expense: Aprox. $800.00.
Total Quote to Rebuild: $6,600.00

Thanks again for everyone's contribution, happy sailing!

Chris

 
#53 ·
#56 ·
Good job ! keep posting :) it is a lot of help when a thread is updated by the OP. Because of your success we have learned a little. Thanks once more for sharing . It may save some old boat from the bone yard. Even if a thread turns out to be less then joyful it is a helpful learning tool.
Kind Regards, Lou
 
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