amateur experience with head rebuild

[johnk]

Earlier this year I decided to tackle the rebuilding of my head on my own. Below is a recap of my experience for any other amateurs that are considering the same.

Over all the experience was very enjoyable and was a great learning experience. The help from Joe Alexander and this web site made it possible. I had the pleasure of stopping by Blacklick this spring after being in Columbus on business. I just wanted to introduce myself and say hello to Joe, not to take us his valuable time. Joe would not let me go until he told me everything he thought I should know. What a guy!

It probably took me three times as long as a professional, but that time was well spent gaining an understanding of how things worked. Below is a list of points that really helped, along with what I still screwed up:

Advice that really helped:
 - Jacking the engine up slightly under the transmission housing to obtain clearance for removing the valve cover
 - Removing the hood and radiator
 - Positioned the notch on the cam at top dead center before I removed the head
 - After removing the head, I covered the top of the engine block with tape and plastic and degreased and pressure washed the entire engine bay
 - Leaving the exhaust manifold attached to the exhaust when removing the head
 - Stuffing a rag around the timing chain when I removed the bolts in the chain galley so I did not drop them into the black abyss
 - Finding and experienced machine shop to do the machining. Telling them not to shave the head unless necessary
 - Replacing the water pump and all related seals while everything was apart
 - Replacing the water pump housing gasket by following the tech manual advice. The Haynes manual says that you have to remove the harmonic balancer. SL113 explained how that was not necessary saving me a lot of time.
 - I could not remove one of the water pump bolts without fear of rounding off the bold head. Being a bean-counter for so many years I forgot simple mechanical logic. Joe Alexander told me to heat it with a household propane torch which worked like a charm. Daa…
 - Replacing the timing chain while the head was off was cheap and much easier than I expected following the advice on this site. I kept the timing chain suspended through the whole process on a bungee cord strung to my ceiling
 - I purchased the correct valve spring compressor on EBay for about $60. Much quicker than rigging up a tool for me.
 - Parts were ordered from Buds Benz and Arizona AutoHouz. The latter being much quicker to ship and stay on track of orders.
 - Removing and resealing all bolts that screw into the oil or water chambers to stop unnecessary engine leaks
 - Spraying the head gasket with Permatex Copper before install
 - Checking the play on the speedometer driver housing while it is out. Installing a small washer/shim if there is any play in the gear travel.
 - The technician at the machine shop suggested I replace the thrust caps, that is until we found out they were $42 each. It runs just fine without them.

Things I still screwed up:
 - Well let’s just say I can now remove and reinstall the head with great speed! When the head is off the housing for the speedometer cable looks like it can be installed after the head. After installing and torqueing the permatex-coated head gasket, I found that there is a slight overlap of the head over the housing. I had to pull off the head, reinstall the housing and put the head back on.
The next day when I went to connect the exhaust manifold to the installed head, I realized that I should have slipped the manifold onto the head bolts when I was first setting the head on the block. I tried for two hours and could not get enough clearance to slip the exhaust manifold onto the head bolts. Another week waiting for a new head gasket. Third time is a charm, right?
 - Ordered extra gaskets I did not need, not realizing that the head gasket kit came with the exhaust manifold gasket and the miscellaneous rubber gaskets I needed.
 - Underestimated how long it takes to get the right parts. I ordered the tune up parts while the head was off, but did not check to make sure they were correct until I needed them. Had to waist another week or two waiting for the correct tune up parts after the head was on and ready to go. Even the Mercedes dealer gave me the wrong points.
 - Found a machine shop with a great reputation, but they were not as familiar with this car. The ball studs looked good to me. After waiting two months to get to my head, (they get a lot of work but don’t want to hire inexperienced technicians) they said that the heads on the ball-studs were worn into an oblong shape, and showed me a few that were. I spent $500 on new ball studs. When I examined the old ones closely upon return I found that most were fine or just needed the crown filed down. Probably only needed to replace two or three.
 - Didn’t check my parts before I gave them to machine shop. When they Shop started to rebuild the head we found out Buds sent me the wrong valve springs. Growing impatient, I had the Shop complete the job with the old springs. I will replace them myself later.
 - Got the car running, but after readjusting the valves three times I still had excessive tappet noise. Found out later that I had to make the “feel” a lot tighter than I remembered from when I last did it thirty years ago
 
So over all I would do it again. It just won’t take me so long next time. Thanks to Joe Alexander and everyone on SL113 that provided me advice throughout the project!

John K

 


   

[garymand]

Very nice overview, thank you.  I'm confused about the speedo thing: 'When the head is off the housing for the speedometer cable looks like it can be installed after the head."  Do you meen the Tach?  How did the shop put in new guides?

And yes, on the balls.  Its amazing how long these balls last.  I had a euopean 280SE with well worn cloth seats.  the balls were as worn as the seats, but they were pretty round under the 1/8 to 3/16" tower left from the hole in the rocker.  You could see where the tower was wearing the hole oblong!  Since the whole car was very well used to the point where I didn't want to keep it and couldn't ask much for it, I chose to file down the towers and any sharpe ridges on the balls.  With a few valves and new guides, the motor ran fine and the valves adjusted and din't whear in as  I feared the would.

[stickandrudderman]

I think you'll find that if you search this forum you will find ways to reduce your errors. EG: The tach drive CAN be removed/installed without taking the head off.

[jameshoward]

The exhaust manifold is also doable, at least on a left hand drive car, without taking off the head or much else.

[johnk]

I saw where the forum said you can slip the exhaust manifold back onto the head after the head is installed. That is why I first installed the head without the exhaust manifold attached the first time. The problem is on my car there just wasn't enough clearance to push the manifold out away from the head enough to slip it over the manifold boats. I tried everything I could including loosening the engine mount, dropping the exhaust hangers and disconnecting the exhaust pipes from the manifold. I used tire irons, the jack, everything I had. I was able to disconnect the the back manifold from the pipe, but I could not free up the front manifold from the exhaust. The bolts were easy, but even heat and a chisel wedge would not separate them. After two hours I was concerned about breaking the exhaust manifold and so I went ahead and reordered a new gasket. It was less than an hours work to pull the head off again and do it right.

[ja17]

Hello John,

You should have called or emailed, I could have saved you some trouble. Sounds like you are on track now. 

Happy motoring
Joe Alexander
Blacklick,Ohio

[garymand]

You have to disconnect the muffler pipes.  A lot easier than taking the head back off.  And I've replaced the tack drive with the head on.  I had a broken oil pump drive, so everything came out the hole.  Not sure what the problem might be at the tach drive. 

[johnk]

Thanks gents. You are right in that I should have asked for help, and I really appreciate your offers to help more. In retrospect it sounds like I could have taken the tach drive housing apart in peices as a whole unit I could not drop it staight down into the whole. Part of my issue is that I discovered the tach issue right after I torqued down the head, so immediately removed the head, reinstalled the tach drive and re-torqued the head and the same head gasket before the permatex had a chance to dry. I really wanted to drive the car to a family party on the fourth of July so I was willing to take the chance. The next day after spending two days trying to deal with the exhaust manifold my conscious got to me and I started to start over with a fresh head gasket.

Sooo my learning take-aways were: a) do dry runs in un-familiar areas, b) don't let a lack of planning or time cause you to do more stupid things, c) head gaskets should not be used twice even if an hour apart because the issue is crushing the steel ring, not the dry time of permatex and most importantly, d) when all else fails take the time to ask Joe and all of my friends on sl113!

[garymand]

Hey, we've all learned lessons that way.  Some of us are willing to admit it.

[Shvegel]

If you over tighten the valve cover bolts it can cause the brackets under the valve cover to pull in and contact the cam. Drove me nuts. You will see wear on the brackets if you pull the valve cover.  I have the in-car valve spring compressor if you need it. I am in CLE.

[johnk]

Thanks for the offer Shvegel.  I have one too now. A very handy tool.

Over tightening the valve cover was not the problem for me and the noise is much quieter now.

[Novamonte]

When I replaced my cylinder head I also replaced the studs for the manifolds. As it was difficult to get the head off with the exhaust manifold still attached to the downpipe I figuerd that I should wait to install the new studs until the head was in position. It worked perfectly - just put two nuts on each stud and tightened them against each other to keep them in place, and then installed the studs with a socket wrench on the top nut. Then took the two nuts off and replaced with a proper cupper plated exhaust nut.