Head Gasket Repair

After I got the car home I parked it in the garage and there it sat. After some time had passed, I could bear to look at it again, so it was time for repairs. My preferred method would have been to tow the car to Lynmor Auto repair, have Chris Manfredi fix it, then pick it up a short time later. However, a careful examination of my checkbook meant that course of action would not be possible. So, fellow Metro NY PCA member Ed Scholl arrived at my house around 9:00 AM on Sunday. At 1:00PM, the cylinder head was in my dirty sweaty hands.

If you are still interested, here is the entire story. I'm not going to provide a step by step guide, there are other places that do that already (one place is the 944 garage, located at http://porsche-944-garage.tripod.com/). Instead  I will provide some hints and some pictures.

One 1989 944 turbo engine, all parts attached.
 

The removal went fine with only two minor difficulties (well, to be perfectly honest, the entire job is a pain in the butt, but that's life). The timing and balance belt covers are held with a number of small bolts. The bolts pass through the front cover and screw into nuts held captive in the rear cover. Two of the bolts decided that they liked being attached to the nuts, so much so that the plastic rear cover broke, meaning that the nuts in the cover spun along with the bolt. A few whacks with a chisel, and the offending pieces were gone.

In this shot, the airbox is gone, the belt covers are removed, and the distributor cap is off.

The only other difficult parts were removing the bolts that hold the exhaust manifold to the collector. I learned from Doug Donsbach that you don't need to remove the header from the head, all you need to do is unbolt the header from the collector. No problem, just remove the 6 bolts, and you're done. However, this car, being a Porsche, requires you have small wrenches, 3 wrists, and about 50 different combinations of socket extensions, wobble extensions, and flex adapters to remove the bolts. Eventually, they were gone. The other difficult part is removing the water connection at the back of the motor. There are two bolts, but you can't see them, or get a socket on them. Instead, you use a small wrench and curse a lot. Finally, those bolts were removed. After the cam box was unbolted and removed (being careful to catch the lifters) it was time to remove the head bolts.

This is always the fun time. Will the bolts come off? Will the studs stay in the block? Will a stud break? Will a nut round? Luckily, there were no problems, and after sweating it out, all ten nuts came off. With a little lifting, the head came right off.

This is looking down into the block. You can see the tops of the pistons (they have a lot of carbon on them).

I have now cleaned the block and the pistons, and we are ready to start putting it back together.

This is the head (with exhaust) removed.

Here are the two gaskets, new at the top, old at the bottom.
 

Here is a close up of the old head gasket. The area in red is where the gasket failed, allowing combustion gas to enter the water jacket.

The head was sent to machine shop for examination, cleaning, and surfacing. The shop found all my valve guides were worn, so new ones were installed. The head was slightly warped, so it was milled flat, thorougly cleaned, then read for installation.

I bought a cylinder head gasket kit from the local Porsche dealer, Sportique, along with new head nuts and bolts. I bought a wide fire head gasket from Jason at Paragon. Now all I need is some time, and the car will be as good as new.

Fast forward the entire summer. Between having a new baby, family obligations (vacation, wedding to attend in Colorado, baby christening, birthday parties), and work, I did not spend much time working on the Porsche. Holy cow, summer is over, and the track season is quickly passing. Time to get back to business.

Here is the head, fresh from the shop, with new wide fire ring gasket layed on top.

Well, there are lots of parts, can I figure out how they go back on?
 

I started by making sure all the gasket surfaces were clean, then I put the head on. Before I started torquing it, I cheated and attached the coolant fitting at the rear of the block. Next I placed the exhaust headers on. Wait a minute, there is no room to fit the headers! Uh oh, time to take the head off, install the headers, then put the head back on. Oh no, that would require removing the coolant fitting again, NO WAY. With some help from my brother, I was able to lift the head high enough to get the exhaust manifold back on.

Time to torque the head. As per the factory book, I coated the studs with oil, installed new washers and nuts, then started the procedure. First, each nut gets torqued to 15 ft lb. You have to torque each nut in a specific order. After each has been set to 15, you tighten 90 degrees for each, then another 90. That's it, the head is back on, the studs have held. Next time to torque the exhaust fasteners. These are special lock nuts, they don't spin on, you have to turn each one. Done. A few days later I put the cam assembly back on. This required that all the lifters be cleaned, placed in the cam assy, then gently put on the head, being careful that none fall out. Now you set the cam mark to the mark on the housing, then tighten each fastener. This isn't as easy as it sounds, since some the bolts are inside the cam housing. You take a long 6mm allen, fit the bolt on the allen, then play the old 'operation' game, where you carefully thread the bolt though the access hole, then into the threads, then gently turn it, praying that the bolt won't fall off and get lost in the housing. Once the internal bolts are done you can do the external. At least you can see those, but you need a good assortment of various length extensions, wobbles, and universal drive sockets to install each one.

So lets see, the head is back on, the exhaust is back on, the cam is back on. Next I re-installed the cam belt, being careful to make sure the timing was set. Now it's time to put the intake manifold back on. Hey, it's starting to look like a motor again, and not just a collection of parts. The intake doesn't require that much skill, but you do have to be careful be careful because there are 4 individual gaskets, each one must be perfectly aligned, the bolts installed, then torqued. Of course, this being a Porsche, you can't really get at all the bolts, so you must struggle and curse. I rounded off one of the bolts as I torqued it, but I think it has enough torque. Next time the intake comes off, those bolts go in the trash. Oh yeah, one more thing, the dipstick mounts to the other side of the intake. It uses a small bolt, but you can't insert it because there is no room. After some muttering, but no real cursing, and the use a 1/4" Dakota J Wrench (courtesy of Steve Timmins) the bolt was installed. Note - if you want to remove the intake manifold, leave the dipstick attached to the INTAKE. It just plugs into the oil pan. That will save you 30 minutes, easy. With the intake back on I installed the fuel lines, then connected the fuel injector wiring. Oh yeah, I installed new spark plugs.

Next up, connect all hoses and vacuum lines. Of course, not all the bolts are the same, and it's been a few months since I took it apart. Eventually I figured out how it went back together. Before I put the belt covers on I wanted to rotate the engine to make sure it turned freely, and to ensure the cam was timed properly. There is a small inspection hole in the bellhousing, at the rear of the engine. There is a small OT mark stamped on the edge of the flywheel. When the engine is at Top Dead Center (TDC) you can see the OT mark through the hole. To see the mark you have to lay on top of the engine. Close your left eye, position your right eye so that you look between the fire wall and a brake line, then squint. When someone turns the flywheel you can see it turn, and if they go slow, you will eventually see the OT mark. So at about 11:00 PM I got my wife up off the couch and had her lay on the motor, close one eye, and squint. I did get her a clean soft mat to lay on. I crawled under the car and turned the motor over. As the cam pulley got close to the mark, I told my wife to look for the mark. No dice. I went around again. No dice, no OT mark. What's going on. I had my wife turn the engine over. I did not see the mark. Hmmm, this is strange. I had her turn the motor some more, and there it was, the timing mark. It was about 3 teeth off on the cam pulley. I retimed the engine, then verified that it was good. Then I installed the timing belt covers.

It was almost time to fire the beast up. I put the rest of the intake plumbing on, then filled the engine with coolant. Will it run? Will the lifters pump up? Will the valves go up and down? I put the key in, turned it, waited some time for the fuel pump to pressurize the fuel rail, then cranked it. After a cough or two it started up!! It was running very poorly, only on three cylinders, but it was running. I let it idle a bit, while I looked for leaks, etc. Nothing obviously wrong. I got in and stepped on the gas. It died and would not restart. I got depressed and went to bed.

The next day I asked for help from the rennlist (www.rennlist.org) community. I got a lot of good responses, but nothing helped. It was very strange because I had spark, and you could smell gas. What is going on? I checked all the connections on the throttle area, and all other connections. Nothing! Finally, I gave up and pulled the distributor off. I checked timing, and found, to my horror, that it was way off, at least 20 degrees! How did it move so far? Again, with Lauren's help, I retimed the motor, then I found the source of the problem. I fogot to tighten the belt tensioner. It was loose, and that allowed the belt to jump teeth. I got a sick feeling in my stomach, because if it moved too far, the valves could hit the pistons, bending them and requiring the head to come off again. I could not bear that. Anway, I retimed the motor and it started first crank. However, it did not run well at all. It seemed to run on three cylinders, and idled very rough. OH NO. Time to do a compression check and / or leak down test. My friend Henry has a compression tester, and he was going to come over and check it out. He had some car problems and couldn't make it. I did some more testing, and the car started to run better and better. Soon it was running great. I suspect the hydraulic lifters were flat and needed time to pump up. Boy was I relieved!!

So, I put everything back on and went for a ride. It smoked a lot, but that was just liquid wrench and old oil burning off. I watched the temp gauge carefully as I drove around the block. It went to the first mark, then kept on going up. I went to the second mark and stopped. Hmmm, better bleed the coolant. I did that, and got a lot of air out. Time for another drive. Same thing. I bled the coolant some more, but the temp didn't do any lower. What is going on? Then I checked some more things. The engine is hot, the heater is blowing HOT air. What's that, the lower radiator hose is cool? That is not right. The heater hose is hot, the water pump is working, the thermostat must have died. OK, time to replace that.

I heard the thermostat was a bear to replace. For some strange reason, Porsche uses the world's strongest snap ring to hold the T Stat in. I think you could probably tow the car by the stupid thing. And, this being a Porsche, they researched the location very carefully, taking great care to position it in the most unreachable location imaginable. You can't see it from the top. You can see it from the bottom, but you can't reach it. So, by laying under the car and reaching up with an inspection mirror, I got to know the 944 thermostat snap ring. Again, I asked for help from Rennlist and I got some great suggestions. Next I went to Sears and bought two snap ring pliers (I owned a set of snap ring pliers, but they would not fit into the area). I tried the small set, but the angle was wrong. I tried bending them in a vise, but the tips broke off. The larger set was too long to fit, so I returned them both. George B from 944 Ecology said he uses an old KD Snap Ring plier. I went to a good tool place, found the KD plier, bought it, and a cool looking smaller plier that seemed like it would help.

That night I tried for 2 hours and I failed miserably. Pat Leber, another Rennlist helper, told me that he doesn't use pliers, he uses a pick and pulls one edge of the ring out. I tried that, but had no luck.

The next night I had my wife help. She looked from above while I struggled from below. With her help I was able to guide the tips of the snap ring pliers into position. But, as soon as I squeezed, the tips would fall out of the ring. After struggling for another hour I got mad and grabbed a large pry bar. Soon, the old thermostat was out (in pieces) but the snap ring remained. I was about ready to give up and take the car to the shop. It was now September, and I wanted to go to Pocono on 9/7. I didn't have time to take the car to a shop, and besides, I was now mad, and would not let a snap ring get the better of me! I looked at it carefully. No room to get a dremel in there. No room to reach in with large pliers. I tried about 50 different combinations of snap ring pliers, snap ring plier bits, picks, pullers, and pry bars. I seriously though about removing the water pump! Finally, finally, I was able to bend one half of the ring out. That snap ring was seriously stuck! Then it hit me, try the magic of Liquid Wrench. I sprayed. I waited. I pried. I sprayed. I waited. I pried. Hey, the snap ring moved! It is loosening! It will come out. With more prying and pulling the snap ring came out!!!!

The next day I installed a new thermostat (after testing it) and a new snap ring. I put the hoses back on, then filled with water. I drove the car. The car stayed cool. Problems solved. Next up, club race at Summit Point on September 30.

Before that event I have to:
  check car thoroughly - all nuts and bolts, all hoses, all suspension pieces
  install new front brake pads
  flush brake fluid
  remove 1 quart of water and replace with water wetter and antifreeze.