Diving into my 1st A4 rebuild!

[wristwister]

Is this bad?



Yes, that's a chunk of connecting rod hanging out a hole blasted through the block! It's my daughter's Tartan 30.

So please stay tuned as I dive into my first A4 rebuild, barrage you all with stupid questions, and become Don Moyer's favorite customer. This engine's obviously unrebuildable, so I've already located another A4 to rebuild, picking it up this weekend.

First purchase: the service and overhaul manual.

Wish me luck!

[Hawkeye54]

Wrist, my only advice is to study the Moyer manual, take your time, and keep Ken's phone number close at hand.

Good luck going forward - I look forward to reading about your progress.


Rick

[Crazer]

I'll be watching with interest. I have a lot of affection for Tartan 30s...very handsome boats.

[wristwister]

Yup, I was thrilled when my daughter found a very sweet Tartan 30 for a very good price (priced low because we knew the engine was on it's last legs). I also own a Tartan 30, also A4 powered, and over the years I've really come to appreciate the design and build of that old tub. Definitely a boat worthy of putting some money and elbow grease into.

[sastanley]

Good thing Moyer is casting blocks! Hopefully you can break the motor down, not find any other issues, and just buy a new block and put it all back together (of course I'd recommend rebuilding anything like rings, valves, etc. that needs it while it is apart.)

[wristwister]

Shawn, I've located another A4 to rebuild, picking it up this weekend. My plan is to rebuild that, then take it down to my daughter's boat, swap it in, then bring her engine home and have a look at it. If there's a way to rebuild her engine, maybe I'll do that. Or maybe I'll just remove the good parts, hang onto them (or sell them), and send the holed block to the recycler.

[Al Schober]

My son had a rod failure in his Volvo. Punched a hole in the oil pan. On the plus side, failure diagnosis was easy - didn't need any fancy computer hookup!

[wristwister]

OK, I picked up the engine and I've started plowing into it. Here's the story; the guy I bought it from didn't know much of the history of the engine. His A4 went out, so he bought this one from someone who had supposedly started taking it apart with the intent to rebuild it. Turns out the guy I bought it from went with a diesel repower, so he sold this one.

Here's what the cylinders look like:



Now doesn't that look pretty? Heck, it even looks like fresh hone marks to me. The rest looks pretty good too. It makes me wonder whether I really want to to a complete tear down on this engine or not. What would you folks do?

[Launchpad McQ]

Was that the red one in a garage on Seattle Craigslist last week? If so, you lucky dog! Fresh honing in the cylinders?! That looks like it might work out way better than my recent sight-unseen Craigslist engine purchase.

[wristwister]

Yup, it's the only A4 to have been on the Seattle CL over the last few weeks. $125, I'm happy with it so far. Missing a few parts, but another trip down to Vallejo to grab those parts off my daughter's A4 will fix that.

[sastanley]

Nice find...fill us in on the details when you have a chance. I've only rebuilt a few motors in my day, but the "lip" you can feel at the top of the piston travel can often tell the story on how old the motor is, plus a good measurement of cylinder bore with a micrometer.

[wristwister]

No lip whatsoever at the top of the bores. Yes, a micrometer measurement is in order.

Cracking the case open to check out the crank, cam, bearings, rods etc. is a big deal at this stage. I need to decide whether I want to go there, or whether I clean everything up, put it back together, and see how she runs.

What would you all do?

[sastanley]

So, I bought a used Japanese spec motor for my '91 Civic in about 2000. Most motors that get imported are advertised at 40K miles or less, and someone else in the US already installed and ran this motor for a bit before I bought it, so I bought it at least 3rd hand.

I decided (since the motor in my car was still running at the time, and I was in between marriages and trying to stay out of trouble) that I would tear it all down...the cross-hash marks were still visible on the cylinders, and there was no measurable lip either, but I decided to do a light hone, new crank bearings and new rings since I was that far into it and in no rush. My SAE mechanic step-father advised me that if I am doing new piston rings, that I should hone the cylinder to allow everything to seat properly.

I still have that motor installed in that Civic, but haven't run it in a few years. The boat shifted my priorities, but I plan to get the now classic Civic back on the road this spring.

[wristwister]

OK boys and girls, the engine is completely apart. It all came apart easily, very few sticky bolts and just a couple applications of the stud remover needed.

I've closely inspected the parts, and I've got questions, but I may not like the answers! The crank journals have a bit of scarring. The main bearings look decent, but here's what the worse of the two journals looks like:



The rod journals on the crank look pretty decent, but a couple of the rod bearings show a little pitting. Here's the worse of them:



So what do you say, am I looking at having my crank turned and buying new oversize main and rod bearings? That's going to be about a $400 bill! How bad would it be to put the engine back together as is? Does this scarring/pitting mean MUCH reduced engine life for sure? Remember, these two pics are by far the worse. Any other scarring/pitting is not nearly as noticeable.

Thanks.

[tenders]

Ignorance speaking here - what makes that happen, old/low oil?

I guess we all have our specific reasons, and I haven’t done what you’re doing right now, but if I were, the whole point of taking the engine down to this level would be to put it back together again having resolved, not ignored, any conditions like that whatsoever. I would absolutely do that work and cough up the $400 (assuming the rest of the block is solid) rather than wonder every time there was the slightest hiccup using the engine that a shortcut might have contributed to it.

But that’s just one line of thinking.

[edwardc]

You need to get some plastigauge and measure the actual bearing clearance.

Good oil flow and pressure is the lifeblood of the engine. Worn or scarred mains will reduce the max available oil pressure and negatively impact engine lifetime.

I agree with Tenders. Seems a shame to go this far and then not fix it.

In for a penny, in for a pound. After all, its a B.O.A.T (Break Out Another Thousand)!

PS - Found this nice little "How-to" on Plastigauge: http://www.plastigaugeusa.com/how.html

[wristwister]

Thanks Tenders, that's certainly the way I'm leaning.

Regarding the crankshaft, the rod journals all look fairly pristine. The fwd main journal is as shown in my pic above. The actual bearing surfaces look good, it's the center of the journal where the bearing oil groove is that appears rough. The rear main bearing shows a similar situation, but not as much. The main bearings themselves look very good. I'm wondering whether the roughness in the oil groove area is a problem, or a normal type of wear that's no problem.

Regarding those pitted rod bearings, yes they need to be replaced. But again, the rod journals on the crank look pristine. So a question here is; provided all the clearances measure out within tolerance can I just replace the couple pitted bearings, or do rod bearings always get replaced as a full set?

I think a call to the Moyer tech line might be in order here!

All this sounds like a fine reason to call the Moyer tech line. I'll be doing that this week.

[wristwister]

OK boys and girls, journal/bearing measurements are mostly in, and most of my clearances are beyond Moyer recommended numbers, so regardless of my questions above on bearing and journal scarring it looks like I'm going to bite the bullet and go for a crankshaft grind and oversize bearings.

So that brings up a question: do I have the crankshaft grind done first, then see where the main and rod journals measure at, then order the correct oversize bearings? Or do I go with, say, .010" oversize bearings and tell the machine shop what size to grind to?

[Ram41662]

When having engine parts turned, I've always told the machinist the target spec range and we will discuss which set he thinks he will achieve. Once we are in agreement, I have the turning done before ordering the components that have to interact with the turned piece. That way if anything more is found out of whack or something goes wrong during the process I don't have a set of wrong-sized parts, i.e. 0.010" bearing when I need 0.015".

To be honest, 95% of the time I could have ordered the parts since the outcome was right on the money, but I'm a unlucky SOB, so I expect the worst.

[wristwister]

Thanks Ram, I also just had a nice chat with Ken at Moyer. The crank is now in the hands of the machinist. When I get it back, I'll call Ken again and get the appropriate bearings.

While I'm waiting for that, I've got plenty to keep me busy. I'm going to clean and strip all the castings and prime and paint them. My daughter has an interesting color scheme in mind for this engine, I'll surprise you all with that later ...

[wristwister]

So here I sit at the airport waiting for a much delayed flight, why not post an update on my A4 build!

Why am I at the airport you ask? I came down to my daughter's boat to pull all the goodies I'll need off her blown A4 to install on the A4 I'm rebuilding. Head, manifold, carb, distributor, etc. etc. etc. All together about 88 pounds of stuff. I know this because my suitcase containing all this stuff wasn't even close to the 50 lb baggage limit. So ... I transferred several of the heavy parts over to my carry on! Checked baggage now weighs 49.6 pounds, carry-on is ridiculous! Much fun trying to explain what these chunks of iron are to the TSA agent! Now my challenge will be to nonchalantly put my carry on into the overhead bin when I can barely lift the sucker off the ground!

Anyway, crank is back from the machinist, block comes back this week after being tanked, magnafluxed, honed, decked and measured. More stuff will be ordered from Moyer when I get those block measurements back. I'll clean up and paint all the goodies I'm bringing home, then hopefully next week it all goes back together.

[Hawkeye54]

Wrist, great tale of what you have to do in these TSA days -- I am eagerly awaiting the chapter in this story on how you get the assembled engine BACK to your daughter's boat.
( Somehow, I can't see a Flight Attendant assisting you to load it into the overhead bin )


Rick

[lat 64]

A fully dressed A-4 needs to be gate checked. Don't you know anything?

I was at SeaTac just yesterday! I missed you I guess. I had an ameter, terminal block, winch parts kit and gobs of small parts stashed in my checked pack. I supposed it looked quite suspicious in the x-ray.

r

[wristwister]

I got in real late last night. All my bits and pieces made it home, but the wifeypoo is a bit pissed because her nice luggage reeks of grease and gas, and the frame is a bit twisted. I might owe her a new one. Chock it up to the overall rebuild cost.

[tenders]

TSA PSA: no drill bits allowed in carryon luggage.

https://www.tsa.gov/travel/security-...and-drill-bits

I had a few extra hours on a business trip last year before my flight took off. I had a rental car, so I doubled back to a Home Depot I’d driven past and picked up some pretty nice cobalt bits. Well, they turned out to be one checked bag more expensive than I’d expected.

Couple of weeks ago I expected a hassle over my old A4 propeller in a suitcase I checked to London. Nope. Could have carried it on too.