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  #1   IP: 73.83.157.183
Old 05-12-2019, 02:52 AM
infy infy is offline
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Looking for advice on an Atomic 4 repair / replacement

I'm on another forum asking some questions and I'm getting some great help there. They also pointed me to this community which is focused on the Atomic 4 and I figured this would be a great resource to help me make some decisions too.

The backstory.. I purchased a 78' Catalina 30 at rock bottom price mainly due to the condition of the gas A4 raw water cooled engine. The previous owner had a mechanic take a look at it and after diagnostics the mechanic basically pointed them to Moyer Marine with quotes for a new engine. So, pretty bad news. Sounds like they determined the block is a write-off.

By the looks of it.. They did *not* take the head off and I don't believe they inspected cylinder walls, gaskets, or valves. I've attached the inspection report... but the short story is:

Cylinder #1 has 0 compression
Cylinder #2 has 30%
Cylinder #3 has 50%
Cylinder #4 has 50%



At worst case, this is a ~$10,000 repower project. Unless I can save the current engine.. or find a replacement used engine.

Plan A:
My current conclusion is that there's still a chance this is only a top-end problem and the block, rings, and etc is OK. But I won't know until I disassemble it.

Photos:



Plan B:
Meanwhile, I've began looking for a replacement engine and I've found a potential candidate. I'm told it ran a month ago, has about 550 hours on it, fresh water cooled, and came out of a Catalina 27. But it looks like it belongs in a dust pan. I don't see any deep corrosion, but everything is covered in surface rust. I'm going to check it out on Sunday and if it looks promising, I'll buy it. It's not on a test stand... but I plan to try and convince the owner to allow me to hotwire the starter with some jump leads to a battery to crank and do a compression test. At minimum I could turn it over by hand and make sure it's not seized.

Photos:



Right now I'm trying to figure out the best way to hotwire or evaluate an A4 on the back of a truck bed.

Any thoughts/suggestions on the overall strategy? Or insights to the pattern on the original A4?
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Old 05-12-2019, 08:37 AM
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I would do some more testing before shopping for a new motor. It is much more likely that you have a stuck valve than a cracked block. Take the valve cover off and look for broken valve stem or broken valve spring and turn the motor by hand or starter and see is all the valves are moving.
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Old 05-12-2019, 09:33 AM
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A two stage cooling system pressure test will tell you if an engine is viable or scrap metal.
  • Stage 1 - Test the entire system excluding the water pump. If it holds pressure, you're good. If not, proceed to . . . .
  • Stage 2 - Test the manifold separately. If it doesn't hold pressure, good. The manifold is easily replaceable. If it holds pressure, the block must be considered junk.
This testing protocol is not 100% conclusive but close enough for a quick assessment.
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I purchased a 78' Catalina 30 at rock bottom price mainly due to the condition of the gas A4 raw water cooled engine
That means there should be some budget left for engine work and whatever else is needed. Where did that $10K repower figure come from? Are you including a professional Rolls Royce mechanic to do the work?

I would go ahead and look at the engine for sale today and make the sale contingent on the aforementioned pressure test as well as the tests you mentioned. For the right price it could be a great source of spare parts at the least.
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Last edited by ndutton; 05-12-2019 at 11:24 AM.
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Old 05-12-2019, 10:01 AM
Dave Neptune Dave Neptune is offline
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Check the above and note that the compression figures could be a simple valve adjustment or just sticky valves. This is especially so if it has set for a long time.

I have often seen low compression numbers go away after the engine is started and ran for a bit. This will often shake the valves and rings loose.

My ole A-4 had far worse numbers and it ran for 34 more years for me and it is running now for the new owner, keep the faith.

I'd try a bit of "spray" oil into the cylinders and let them soak for a day or two and give the engine a spin on the starter once in a while. Then try starting and it may take some "motor crack" (starting fluid). Also add some MMO or my favorite some 2-stroke oil to the gas at about 100:1 for some oil to get delivered to the valve stems. I have seen and experienced this working far more often than not.

Can it be confirmed that the compression check was done with the throttle and choke wide open?

Dave Neptune
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Old 05-12-2019, 11:38 AM
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Quote:
Originally Posted by Tim View Post
I would do some more testing before shopping for a new motor. It is much more likely that you have a stuck valve than a cracked block. Take the valve cover off and look for broken valve stem or broken valve spring and turn the motor by hand or starter and see is all the valves are moving.
Agreed - I'd want to wait and see what a disassembly reveals. But it's not very expensive and could be a good investment for parts or a spare. The trick will be properly evaluating the condition without having the ability to start it.
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Old 05-12-2019, 11:49 AM
infy infy is offline
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Quote:
Originally Posted by ndutton View Post
A two stage cooling system pressure test will tell you if an engine is viable or scrap metal.
  • Stage 1 - Test the entire system excluding the water pump. If it holds pressure, you're good. If not, proceed to . . . .
  • Stage 2 - Test the manifold separately. If it doesn't hold pressure, good. The manifold is easily replaceable. If it holds pressure, the block must be considered junk.
This testing protocol is not 100% conclusive but close enough for a quick assessment.
I'll read up on this. I've done many compression tests but never a cooling pressure test.
Quote:
Originally Posted by ndutton View Post
That means there should be some budget left for engine work and whatever else is needed. Where did that $10K repower figure come from? Are you including a professional Rolls Royce mechanic to do the work?
Got 3 mechanics to quote the project. They used Moyer Marine to price replacement engines. Roughly $6,000 for a new engine and $3,000 for old A4 removal, shipping, and complete installation.

A perfectly good Catalina 30 with a running motor can be found for roughly $10k in this area so there's only so much I can justify before I'm in too deep.
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Old 05-12-2019, 12:06 PM
infy infy is offline
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Quote:
Originally Posted by Dave Neptune View Post
Check the above and note that the compression figures could be a simple valve adjustment or just sticky valves. This is especially so if it has set for a long time.

I have often seen low compression numbers go away after the engine is started and ran for a bit. This will often shake the valves and rings loose.

My ole A-4 had far worse numbers and it ran for 34 more years for me and it is running now for the new owner, keep the faith.

I'd try a bit of "spray" oil into the cylinders and let them soak for a day or two and give the engine a spin on the starter once in a while. Then try starting and it may take some "motor crack" (starting fluid). Also add some MMO or my favorite some 2-stroke oil to the gas at about 100:1 for some oil to get delivered to the valve stems. I have seen and experienced this working far more often than not.

Can it be confirmed that the compression check was done with the throttle and choke wide open?

Dave Neptune
I'm not in touch with the mechanic who completed the original inspection. So I'm not sure what procedures they followed for the compression test.

But I do know that they were unable to start the engine at all. It would turn over, but that was it.

Great tips on the valves! I'll remove the valve cover and take some photos... Looks like a few things need to come off first... carb.. and fuel pump.
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Old 05-12-2019, 01:25 PM
Dave Neptune Dave Neptune is offline
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With the cover plate off you will be able to "see" if the valves are sticking and also be able to work any loose if need be.

Dave Neptune
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Old 05-12-2019, 03:27 PM
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Take it slow!

Infy, First off, welcome to the group, you have found the best place for "all things A4". Dave and Neil have given you sound advice on the "road back" on getting your engine back in service. As Neil suggested, a pressure test of the block and manifold are an imperative place to start. Once you have established that they are sound, getting it running is just a matter of making sure that you have spark and clean fuel. There are several of us who have Catalina 30s, so any of the oddities of this combination have been dealt with before. Once the galley of a C-30 is removed, working on all of the engine accessories is quite easy. By the way, your engine looks far cleaner than what mine did when I purchased it about 10 years ago. It now runs "like a watch" and is extremely dependable.
Tom
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Old 05-12-2019, 04:57 PM
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Quote:
Originally Posted by infy View Post
Got 3 mechanics to quote the project. They used Moyer Marine to price replacement engines. Roughly $6,000 for a new engine and $3,000 for old A4 removal, shipping, and complete installation.
Sounds to me like these three mechanics each expect $2500 for one day's work.
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Old 05-12-2019, 06:41 PM
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No kidding. I don't see what the big deal is. It's 8 bolts, prop shaft, exhaust, water intake, and wiring harness. Lego kits are more complicated. But I don't know. Maybe there are gotchas.

I just spent the day at the marina. Confirmed compression us abysmal. 10 psi, 30 psi... this block may be a lost cause after all.

I may take it apart to satisfy my curiosity as to what happened to this tired donkey. At least the weight off will make it lighter for removal.
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Old 05-12-2019, 06:50 PM
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Quote:
Originally Posted by infy View Post
I just spent the day at the marina. Confirmed compression us abysmal. 10 psi, 30 psi... this block may be a lost cause after all.
Please read back through the replies in this thread. Dave Neptune, Tim and Thatch have tried to explain that poor compression is not a death sentence by itself. Those three guys are among the best this forum has to offer so please, please heed their advice.
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Old 05-12-2019, 06:51 PM
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I can have my engine out of the boat in an hour. Another hour had the new one in and it was running that day.
Funny thing was towing the old rusty one to the crane through the marina and then passing the same people going the other way with nice shiny one soon after. They were mighty impressed with the quick rebuild!
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Old 05-13-2019, 12:41 AM
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Quote:
Originally Posted by ndutton View Post
Please read back through the replies in this thread. Dave Neptune, Tim and Thatch have tried to explain that poor compression is not a death sentence by itself. Those three guys are among the best this forum has to offer so please, please heed their advice.
Certainly didn't miss that I'm reading up on how exactly to do that test and what equipment I need.

But if I need to have the block machined... for oversized pistons... I wouldn't bother. I've received quotes for the A4 machine labor and rebuild and the cost came out to be nearly $4,500 at two shops. At that price, I'd rather purchase a turn key rebuilt engine from Moyer Marine.

The day turned around with some great news. I inspected the replacement A4 engine and completed a compression test. 120 all around! Went ahead and bought it for $450. It came with everything for the fresh water cooling system too.

I'm about to order some gaskets to replace while I have it out. Possibly do the oil pump too since I'll drop the oil pan?



By the way.. there's a oil drain plug on the bottom front, right? Leaked a bit as soon as I got it home.

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Old 05-13-2019, 12:53 AM
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Quote:
Originally Posted by infy View Post
I'm reading up on how exactly to do that test and what equipment I need.
Might be too late but here's the reading material for that procedure...
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File Type: pdf Pressure testing a block.pdf (9.6 KB, 49 views)
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Old 05-13-2019, 01:12 AM
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By the way.. there's a oil drain plug on the bottom front, right? Leaked a bit as soon as I got it home.
Distro/Alternator SIDE of the engine down low under the starter.

It probably leaked when it got laid over because there isn't a seal to stop oil from leaking out from the flywheel end
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Old 05-13-2019, 10:30 AM
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New oil change method?

I think we may be on to something here, just tip the engine up on it's flywheel end and let the oil run out. As Jerry said, there is no oil seal on that end of the crankshaft.
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Old 05-13-2019, 11:58 AM
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There's still a chance the current engine could still be saved. Haven't given up on it. But I can't do much on it on weekdays at the marina.

So I plan to spend a few evenings working on the replacement A4. In case I do end up having to use it.

I've got some basics in mind.. but what necessary seals, gaskets, and hard-to-get-to parts should I be sure to add to my list?
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Old 05-13-2019, 11:59 AM
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Quote:
Originally Posted by roadnsky View Post
Might be too late but here's the reading material for that procedure...
Perfect. Thanks for posting that.
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Old 05-15-2019, 01:10 PM
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Okay - I drained the water out of the block and did a cooling system pressure test using the PDF guide posted by roadnsky. It looks like I got it setup correctly.

The block held pressure and I don't think it dropped at all over the hour.

But what exactly does that tell me?

I've got practically 0 compression in the cylinders. If the block holds cooling pressure what would the next step be?
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Old 05-15-2019, 01:51 PM
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good news!

good pressure test tells you that the lack of compression is not due to a cracked head or cylinder block. It also tells you that the exhaust manifold is ok.

I think I would be looking, as has already been suggested, at sticky valves.

Pull the plugs and turn it over to see if the valves are moving. More conclusively, pull the valve cover plate and see what you can see there.

Hope that helps,

Peter
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Old 05-15-2019, 08:09 PM
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That helps!

I removed the valve cover to check on the valves. It's tricky to turn the engine over and record a video of it. I just have some photos for now. The valves look... ok. I'll try turning the engine over and record a video.

Keep in mind that all 4 cylinders have no compression. So if it's something wrong with the valves, it must be wrong on all of them. Which seems.... unusual. But I suppose it's possible.

I'm going to remove the exhaust manifold and also see if I can manage to get the cylinder head off.
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Old 05-15-2019, 08:25 PM
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Are you confident in your Compression Gauge and procedure?
Also, did you do a "dry" AND "wet" test?
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Old 05-15-2019, 08:36 PM
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Yeah. The compression gauge is new. I used the same gauge to test the rusty A4 I purchased on Sunday. That engine read 120 on all 4 cylinders.

Dry test.

Also did the "thumb over the spark plug" test. Felt no air pressure at all.
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Old 05-15-2019, 08:43 PM
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it's pretty clear you have a good engine with stuck valves. Stuck open, when they stick it's always open.
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