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Sun Jul 22, 2018 8:22 am

As I was trying to pull loose my cylinder heads to replace pushrod tubes, the cylinder head and both cylinders all began to separate from the case as a whole. From what I have gathered in the Muir book, it is not good when the cylinders come off in this manner. I pulled the whole unit as one to clean all surfaces and reseat the cylinders (with aviation sealant perhaps). Upon removal, I noticed my piston rings seem to be very, very loose. I am trying to make sense of the Haynes manual on end gaps, but I have a feeling I need to order all new piston rings. Any thoughts?

(Also, how in the heck can i separate the head from both cylinders? Rocker arm and tubes along with pushrods are removed but this is not budging...

Sun Jul 22, 2018 8:30 am

You have to have rings in cylinder by them selfs to check ring gap. What you see of the rings out of the cylinder is normal. It seems as there pretty carboned up. I would at least clean up everything and check ring gap. If its a high milage motor you could buy a new cylinder kit. The heads will come off, theres nothing but carbon and corrosion holding them on. Be carful prying and pulling, they will come off.

Sun Jul 22, 2018 9:29 am

Something looks wrong /broken in that pic of the case. Might even be a crack there.

Sun Jul 22, 2018 10:17 am

Deebs756 wrote:

The second compression ring looks normal but the top compression ring in this pic (the one nearest the combustion chamber) appears to either have lost its tension or is stuck in the piston groove. Measuring piston ring end gap is done by removing the ring from the piston then inserting it squarely into the cylinder down about an inch, the other measurement you're interested in is the gap between the top or bottom face of the ring and the ring groove in the piston. The opening in the case where the cylinder spigot would seat looks a bit odd here as well, possibly just a metallic shim or piece of shim at the top of the hole, but further investigation or a clearer picture would be in order.

You should be able to get the cylinders to come loose from the head using some heat and judicious use of a rubber mallet, being sure to hit the cylinders straight on and not at an angle on the fins. A healthy soaking of the cylinder to head joint with penetrating oil may also be called for.

Sun Jul 22, 2018 10:48 am

calvinater wrote: Something looks wrong /broken in that pic of the case. Might even be a crack there.

If you are referring the piece hanging above the piston against the case, it's the paper gasket I haven't removed yet. If there's something else you notice, would you be able to point it out to me? Thank you

Sun Jul 22, 2018 11:13 am

Centered over the piston Is that a crack or a casting mark?

Sun Jul 22, 2018 12:59 pm

calvinater wrote: Centered over the piston Is that a crack or a casting mark?

Turns out it's a casting mark, goes straight up to the split in the case... Had me worried.

On a positive note my top ring is broken in half so time for some new rings all around.

Sun Jul 22, 2018 4:37 pm

Thanks for the help today everyone. I will not be pulling the pistons, but can I please get some feedback if these are correct? The measurement stamped on the piston reads 85.45 mm. I also verified the 2x2x5 with a set of vernier calipers.

https://www.jbugs.com/product/311198169A.html

If there is a better resource for these, I don't mind paying a little extra for good quality.

Thanks again!

Sun Jul 22, 2018 6:07 pm

Usually broken rings are caused by wore out ring grooves unless you broke it . Pistons and Cylinders are cheap .

Sun Jul 22, 2018 6:25 pm

Exactly.
Check the ring groove where that broken one sits: could you tell us what the clearance is? (The largest feeler gauge that will slip in there). Any more than .002" & they are toast.
vwoldbug wrote: Usually broken rings are caused by wore out ring grooves unless you broke it. Pistons and Cylinders are cheap.

Sun Jul 22, 2018 6:40 pm

i second checking ring clearance in piston, looks to me just from glance you have very high milage or aircleaner not doing its job. need pistons and liners. when there look at 1 rod bearing, or at least wigle rods and see if it lose, also inspect cam lobes with flashlight. if you put new rings on wore out pistons soon you will be back.

Sun Jul 22, 2018 6:53 pm

I'm with vwoldbug. $200 or less and as long as the heads are good you've got like new compression. I'd probably drop the heads off to be cleaned and the valves lapped (or do it yourself).

I reringed my 2.0 Type IV and it was fine, but the ring lands were still perfect and tight (I forget the actual number now, it's been a while. But well within spec.) Yours looks pretty munged up, and if you had a broken ring you've probably got damaged lands.

$200 is cheap insurance and saves you having to pull the engine again soon.

Sun Jul 22, 2018 10:01 pm

FeelthySanchez wrote: Exactly.
Check the ring groove where that broken one sits: could you tell us what the clearance is? (The largest feeler gauge that will slip in there). Any more than .002" & they are toast.
vwoldbug wrote: Usually broken rings are caused by wore out ring grooves unless you broke it. Pistons and Cylinders are cheap.

yeah the pistons are probably NG.
.004 with a new ring, is a good wear limit, put the second ring in the top and measure with that to get an idea.
If the side clearance is too high the rings tend to break.

Mon Jul 23, 2018 3:15 am

FeelthySanchez wrote: Exactly.
Check the ring groove where that broken one sits: could you tell us what the clearance is? (The largest feeler gauge that will slip in there). Any more than .002" & they are toast.
vwoldbug wrote: Usually broken rings are caused by wore out ring grooves unless you broke it. Pistons and Cylinders are cheap.

Alright, I'll check when I get off work today, thanks for the tip. Any recommendations on maker of piston? I see Mahle is popular, but cip1 wants $369 for them... Dang

Mon Jul 23, 2018 6:57 am

You don't need mahle. AA ones are fine, but if you check out CB performance they have Moresa for not a lot of money.

-Frank

Mon Jul 23, 2018 7:00 am

Frank Bassman wrote: You don't need mahle. AA ones are fine, but if you check out CB performance they have Moresa for not a lot of money.
-Frank

I also would not pay the $$$ to go Mahle pistons in an engine in this condition.

By the way: I did use the CB Performance Moresa pistons/cylinders in my 1600cc rebuild 1.5 years ago, and those came with made-in-USA Hastings rings.

Mon Jul 23, 2018 7:12 am

The AA pistons I bought for the 1835 were a surprise to me. Haven't run them yet, but out of the box I was able to balance them to half a gram across all 4 by shuffling pins. No idea who made the rings (didn't think to look when I took them off to clean) but I doubt they're Grants. ;)

Mon Jul 23, 2018 8:25 am

If the top end is worn out this much, the bottom end is probably in similar condition. You really ought to bite the bullet and split the case. Rebuilding just the top end, on a worn bottom end, leads to a bad ending. Seen it many times.

Mon Jul 23, 2018 9:23 am

VW_Jimbo wrote: If the top end is worn out this much, the bottom end is probably in similar condition. You really ought to bite the bullet and split the case. Rebuilding just the top end, on a worn bottom end, leads to a bad ending. Seen it many times.

Jimbo, This is overwhelming to a beginner as myself, but I am willing to try it. I have a little experience in machining, but if I purchase a STOCK rebuild kit, will there be any additional maching I will need to do to something such as a new crankshaft? If it's a follow procedure type deal where I just essentially "plug and play", I feel as though I can handle that taking my time. Anymore and I would consider taking it to a shop...

And thanks everyone for the help on the pistons, I found the moresa ones you guys suggested.

Mon Jul 23, 2018 9:46 am

VW_Jimbo wrote: If the top end is worn out this much, the bottom end is probably in similar condition. You really ought to bite the bullet and split the case. Rebuilding just the top end, on a worn bottom end, leads to a bad ending. Seen it many times.

100% right.

You asked about machining, but you don't really know until you take it apart and check/measure the components. Mr. Duncan helped me with my rebuild and it took time to measure and evaluate what was needed. There were also several trial assemblies before final assembly. I think it's been almost a couple of years now, engine runs flawlessly. Incidentally, we also used the Moresa pistons/cylinders and they perform very well.

My experience is in paint and V8/V6 engines, but in all cases I have found that it's the prep (or lack of) that will make or break you. Every time I cut a corner it comes back later like a bad relative.