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]

A4 rebuild

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.