A puzzle, finishing someone else's rebuild

[ronstory]

All--

I bought a old A4 build-in-process from a guy that ended up going diesel. So it basically came as a partially assembled short block and a bin of parts. Basically, I got an A4-in-box and now trying to figure out what been done and what needs redoing.

As a bit of foreshadowing, the bores were not cross-hone, the numbered pistons are all in the right holes, but the arrows are all pointing towards the flywheel. (sigh) And half of numbers on the connecting rod/caps are on the side with the cam.

The block has been stripped of paint, but water jacket cover looked like it had never been removed... and that was true. I broke 4 of the bolts removing the cover and it was full of scale.

So I just pulled the piston/rod assemblies and found a bit of good news. The crank was ground and rod bearings are new. Also, the piston rings are new as well.

Since I don't have any docs on the what he bought and some of the assembly has been incorrect, how do I determine if the rings are installed correctly?

[ronstory]

Ok, got the crank out and main bearings are new as well.

Now i'm starting to second guess whether the rings are new. They seem sharp and I can't seem to find any vertical wear but after removing them, the inside of the rings seem dirty, and it also looks like the piston ring groove was not cleaned out.

These piston rings have very small square 'step' taken out of the inside end of the ring, and both the top and bottom rings look identical. I could not find any markings to denote an up side the ring.

Also, if there a trick to removing the camshaft gear? Mine is on really tight, even after I bent back the retaining tab.

Can I just leave the gear on the camshaft when I remove it? I know I will need to reuse the retention plate/seal.

[Al Schober]

If you don't have one, get yourself a copy of the Moyer Manual. Covers all the neat stuff like numbering & orientation of the pistons, rods & caps, etc. As I recall, 'front' of an engine is defined by the location of the timing gears.
Rings can easily be checked for fit by removing them from the pistons and putting them into the bore. Use a piston (upside down) to push them to the bottom of the bore. Then measure the end gap of the ring. A good ring will have an end gap of less than .010". I did one engine where the old lower rings had a gap of over .100" - they were just along for the ride! PO did mention that the engine was smoking a bit..
Yes, the upper rings are the same.
Checking piston clearance is a bit trickier. Don't know your 'shop' capabilities. I think I satisfied myself that piston fit was OK using feeler gauges, but don't recall the details.

[ronstory]

Al--

Thank-you. I have the MM manual... two actually. One for the boat and one at home.

The trouble is the moyer manual is well organized, the box of parts I bought is not.

After looking at the pics posted on the forum, I've come to the conclusion that I don't have have hastings rings. So one more thing to order from Ken.

My shop capabilities are pretty good, but waiting on a friend who is a machinist since he has all the cool Mitutoyo toys. ;^)

I also want to send the oil pump to MM for testing. It would be my luck that I would spend all the time get all the specs right only to find out that the very inconveniently located oil pump was marginal.

[lat 64]

Ron,
I used to be an auto machinist sort-of. But I had a learning curve on specifics to this motor.
Awesome that you can get help from a machinist, but a cautionary note: some things on th A-4 are particular to that engine, ie. Piston orientation.
Sounds like it was put together wrong, so take it apart and reasemble as per the manual.
Re-reading different sections of it again, more stuff becomes clearer as you dig in.

Good luck, keep calm, and carry on,

Russ

[ronstory]

Thank Lat! I read it cover to cover on a week-long biz tip a couple weeks back. I just wish they had a electronic copy so you could search by keyword, but still... it's all in there.

Now just waiting on the spring compressor to arrive from Amazon today to get the lifters and valves and cam out.

I also dug into the giant bin of parts got to bottom and emptied it. We now have now confirmed that piston rings are original. Included at the bottom was the piston ring installer tool that was used and setup for the 2 9/16" bore size... plus a pristine and up-opened piston ring installer tool. ;^)

This is going to be a detective-based rebuild. lol

[ronstory]

A good bit of progress. With the trusty Wilde 600 (Thank-you Amazon), the short block is now free of valves, lifters and camshaft(with gear attached).

The springs are not all the same height, regardless of whether intake or exhaust. So is there spec or should I just buy new ones from MM? I'm creating a list and will be checking it at least twice. ;^)

The only things remaining are the three troublesome manifold stud that my stud puller did not grab, an testy 1/8 pipe barb fitting on an oil line and those three pesky small brass stoppers that looked to be glued in on this block. Plus removing the idler gear... but all are soaking in PB blaster so I have hope.

Should be able to get my friend to look at it this weekend and drop it off at the machine shop next week.

[thatch]

At $50 for a set of valve springs, the investment is almost a must. When you compare the old ones to a new one, you'll see what I mean.
Tom

[ronstory]

Thatch--

Thank-you. That was what I figured... and it's great to have confirmation.

More parts to order from Ken. ;^)

I got the internal 1/8" oil plugs removed last night courtesy of an impact screwdriver. The 3 exhaust studs are still a no-go... as well as the idler gear hold-down bolt. Look like I'll let that be handled by the machine shop.

[ronstory]

Ok, got some of the engine measured this afternoon with the help of a friend with really cool tools. Yes, I have tool envy.

Cylinder bores – Min was 2.5650 – Max was 2.567 on #4 - over MM 2.565 max
Valve Guides All were 0.3150 to 0.3153 - in the ball park
Valves stem 0.3105, 0.3110, 0.3115, 0.3115 - have some wear but smooth
Crank main journals 1.9870 - lost about 0.001" from new factory spec - looked good
Crank Rod Journals 1.5600 – 1.5607 - Lost about 0.002 to 0.0025 material - looked good but there was 7-8 thousands of gap with the bearings
Cam bearing 0.0018 – 0.0020 clearance to camshaft - looks fine
Piston Wrist pins had a fair amount wear that you could feel with your finger

Oil pump looked really good – 0.002-0.003” between gears and wall, gasket was 0.005” and everything looked smooth

[ronstory]

Apologies for the radio silence. Got distracted by work and life in general, but I'm baaaack.

The oil pump is at the Amish machine shop in PA to get tested, just waiting on word from Ken. Plus Ken and I have been reviewing the parts list and I'm pretty much a +10 thousands engine. Everything is about 1 thousand over the max for the mains, rods and cylinders.

I do have some questions on the valve guides and tolerances and could use some Afourian wisdom. After reading the rebuild bible a couple of times, the new accepted amount of clearance for valve stems to guides is 0.003-4.

I just measured the guides again and i'm getting pretty much 0.3153-58 for a tight friction fit. If I buy new valves, any idea the nominal size of a new valve? Right now I'm at 0.004 clearance, which is the max with the old valve. I'm trying to figure out I can just replace the valves and keep the original guides.

All feedback appreciated.

[ronstory]

Ok, just talked with Ken and while he was pretty sure the existing guides tolerance would fine the new valves, he mentioned the with their warranteed motors... they typically replaced them.

So new valve guides it is. ;^)

[sastanley]

Yup..if you are that deep in it, might as well replace.

[ronstory]

Just dropped off the crank this morning at the local machine shop to have the mains and journals ground down for +0.010 bearing. I asked them to check the balance it as well.

Now the waiting game continues with health check of the oil pump. I need that back before I can drop off the block to be machined and cleaned up.

... this is becoming a game of inches. But at least it's not metric.

[ronstory]

While I'm waiting for the verdict from Ken and the Amish Ones, I mock assembled the new stainless exhaust.

Feedback welcome.