Engine Rebuilding - Experiences

[Skitzerow]

I thought maybe I would try a discussion group on engine rebuilds.  

I felt there were issues with my engine because of misfires and etc.  So for the past 6 months I have been slowly, when I got time, taking my engine out and tear it down.  This is what I have discovered so far:

1)  The engine has been re-built once to first oversize pistons.
2)  The head has one of the water leaks that dropped water into #3 cylinder and caused some surface rust on the bore.
3)  Found it had a newer transmission converter from Midwest Converters in Rockford, IL.
4)  Found the tachometer bushing everyone is talking about is worn almost 1/16 inch.
5)  Today found that timing chain guide from the tach sprocket was put in backwards and broke in half. Just about all chewed up. The tongue according to book should have pointed toward the tachometer gear sprocket.
6)  My #5 camshaft had a scored lobe on it.
7)  The head is below the low thickness spec without shimming camshaft
This was interesting, because a head I got from another place was the exact same thickness but the #8 camshaft shaft towers were shimmed considerably.

I am sure there is more to come.  But quite satisfied I started to redue this before major, major problems. Maybe what I have is major to some, but rebuildable. Itis actually fun.

Have not looked at the crank yet.  

But how small this block looks without all the hardware hanging on it?

SDK

[lurtch]

Hello SDK,

The discription of your engine dilemma is almost a carbon copy of the issues I have just recently worked through on my engine.  I had  1) water-in-the-cylinder (#5)   2) severely scuffed cam lobes  3)  way out of tolerance camchain sprocket shafts  4) three head bolts that had below spec torque  5)  severe corrosion in the water passages which rendered the head not-rebuildable.

The cam lobe scoring was the result of  a loss of  holding torque on the ball stud adjusters.  They gradually backed themselves out  - - which then eliminated the clearances in the valve train.

Water entered my #5 cylinder as a result of massive corrosion of the thin wall between the head bolt holes and the adjacent water passages.  The head proceeded to waste away, thereby  diminishing the head bolt torque.

The surface rust in your cylinders may not  really be a show-stopper. I was able to dress mine down satisfactorily with emory paper.  I can email photos of  my cylinder walls if that would be helpful.

Regards,  Larry in Calif.   ( lstla@pacbell.net )

[Skitzerow]

Well about 1-1/2 years on my engine rebuild.  Got to start it up the other day.  Four or five times using some starter fluid on the intake and it started up.

The good side is mechanically it purred like a kitten.  I felt really good on that part.  I was sitting in the car as it ran a little and notice some gas shooting up in the air a little bit.  Kind of looked like Joe Alexanders fuel injection test apparatus.

Anyway tightened those down and all was good.

Then I thought I would look under the engine and see if there were any leaks. Yup, a doosey.  The side plates for a couple of the water jacket gaskets were leaking like crazy.  I tried to tighten a little more and the last one would not stop leaking.  The gaskets I bought were kind of stiff.  Not very pliable.  I had put them on with some gasket sealant in the dead of winter.  The cold probably didn't make it any easier to seat them.  And when I tightened a little bit some of the gaskets cracked around the screw holes.

This was not nice.  There were only two options to get back at those side plates.  One to remove the starter.  The second to take off the intake and exhaust manifolds.  I opted for the manifolds because it looked like I would of had to lower the whole transmission in order to get the start out of the way to get at the plates.

I guess I am going to go back to good ole faithful cork gaskets with Indian sealer.  I was not in favor of the original gaskets being so stiff anyway.  I don't see how those gaskets would be much good.  There hardly no give at all when screwing down the covers over the gasket.

I hope I get it the second time around.

If any of you engine rebuilders have had good luck with using a gasket and sealant on the block side plates that don't leak let me know.

Thanks
Scott

SDK

[TheEngineer]

I like to use 5200 Marine sealant on everything, even hoses.

[Raymond]

I used MB sealant from the dealer and nothing leaks.  It was expensive, but I planned to do the overhaul only once.  I was very careful about cleaning the mating surfaces first, and I used new hex socket head screws evenly torgued.

I needed a new block.  So I bought a donor short block from Star Quality in Maryland.  The engine was seriously misrepresented.  It was supposedly an SL engine that had never been overhauled.  It turned out to be an SE engine and the crankshaft was burned from improper installation of oversized bearings and one of the pistons was broken.  I was only able to salvage the block.  I had the cylinders bored and the crank journals line-bored.  Everything else in the engine was junk.  I paid $1700 for the "never rebuilt", "SL" short block and in the dispute wth Star Quality, they refunded me $250.  So beware when buying used parts.  Anyone want a crankshaft with a couple of overheated journals and some piston rods?

I'm considering having my original SL block re-sleeved and stored for future use.  Anyone ever do that successfully?

Ray
'68 280SL 4-spd Coupe