944 Racecar - Head Repair August 2006
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Head Repair August 2006
Or how I became an involuntary Porsche Technician
So, Round 6 of the 44Cup Series at Summit Point didn't go quite as I hoped....
I was on my 2nd lap of the first practice session on Saturday. Approaching turn 1 I glance at my gauges and notice my coolant temps are high. I added a mental Post-It note to keep an eye on it as I started braking for the turn. As I transition into the corner I glance at the rear mirror and notice a large cloud of smoke behind me. Funny, I didn't lock up my brakes .... Holy shit, my dash danger light is flashing and my coolant temps are in the stratosphere. I coast the car into the cutoff section between the front straight and turn 3. I wave to the corner worker that I'm ok, and get out of the car. Steam and smoke are rising from under the hood.
Back in the paddock, the diagnosis is commonly agreed upon: Blown head gasket and probably warped the head for good measure. With the help of some 44cuppers I get the dead car into the trailer. I hang around for the always great 44Cup Paddock lunch and then head for home. "Should be only a 4 hour job" sez the paddock mechanics. Ha! I'm a software developer and this was most definitely a "hardware" problem...
Part 1: Removal
Time to learn. Oh an important note: This is a relatively rare 2.7L 944 engine, not the more usual 2.5L. With the help of the excellent Clark's Garage site (www.clarks-garage.com) and Winner Porsche's master mechanic Gregg Wilson a quick cell phone call away I was ready to venture into the unknown.
First, put the engine at TDC (top dead center). Sounds easy right? Just rotate the crankshaft clockwise until the timing mark shows up in the little window on top of the flywheel which is buried under a bunch of wiring and sensors at the rear of the engine. Just a few small things between me and TDC tranquility. Like the fact that Maggie always finds something more interesting than helping me wrench on my car, things like taking out the garbage, viewing the Home shopping Networks, etc. so I was soloing here. Like the fact that my sockets were either too short or too long with extensions to turn the crank. Which meant pulling the fans and shrounds just to get a tool in there. Like the fact that I had no clue what the timing mark looked like. So here I'm stretched out on top of my engine with my nose buried, left arm stretched as far as I can go to rotate the crank at the front. A red dot! is that it? Did somebody mark it for me? Look, a "P" stamped into the flywheel. Is that it? I'm looking for the letters "OT" stamped. And every two revolutions, my socket falls out of crankshaft nut since the only combo I have that works is a flex head racket, which means I have to wriggle off the top of the engine, go to the front reset it and wriggle back into position while holding it steady. After 15 mins of this, and being no wiser it was time to call the support line.
And Gregg has the secret mechanic's tip: Pop off that rubber cover in the right corner of the distributor cover (top left photo). Rotate the engine until the bright red mark (top right photo) shows up in the window. That will put you in the ballpark. Now go look at your reference mark on the top flywheel. And there she was, right in the middle of a rusty patch. Gregg also mentioned taking a look at the bottom of the flywheel. When at TDC, there is a dimple in my flywheel - looks like a little mushroom - centered in the groove ( right photo - not the best)
Next step: pull the fuel lines and fuel rail and injectors. Hey that went pretty smooth other than traveling to the Team ECI shop to go find a 22mm wrench to hold the fuel line. Unhook the fuel lines and pull 4 bolts. Into the parts box. I'm feeling like a mechanic now. Pulling crap off is right in my domain expertise.
Onto the intake manifold. Once again, a bunch of bolts, pull the cruise control out of the way - note to self: remove the cruise control, it's not getting a lotta use when racing - and whack the intake with my big rubber mallet. And into the box with other crap. Hope I remember where all these hoses and vacuum lines go.
Getting closer. Things are starting to get more complex now. Up next is the removal of the cam tower (right). Back to the Team ECI garage for a extremely long 6mm allen socket. It became the #1 tool in this process.
But before I can use this handy tool, I have to pull off the timing belt.
I pulled the distributor and belt covers and exposed the guts. The tricky part here is to lock the timing belt in position while the camtower is off the car so I don't have to reset it. The 944 motor is what's called an "interference" design - which means when you boil it down, if the timing belt breaks or is off on the timing wheel, all the little valves and pistons will merrily mash themselves into very expensive junk. Quite happily mind you, these are very selfish values and pistons and give no thought to the poor Porsche owner who has to pay for their salsa party.
Once I figured out how the spring tensioner device worked - another tech support call was required - the timing belt was removed and the removal of the camtower began in earnest.
This didn't go quite as smoothly. I got all but two of the allen head bolt which are buried deep in the camtower (thus the need for the long allen). Due to heat or overtorquing - they only are set with 15 ft/lbs - they were a bitch to remove. I'd crank & crank and then Snap! they would break free, scaring the bejesus out of me
But the 2 final ones wouldn't go. Another call to tech support. And the answer is? Put a larger breaker bar on them, and if that won't do it, add some pipe and go to town on those puppies. Ah, ok Gregg, if you say so... Never doubt, that did the trick. And the mysteries of the Head are revealed!
And oh yeah, I dropped two of the bolts while removing them. They're rattling around in the camtower somewhere. Guess it's another trip to the Team ECI garage looking for a magnet on a stick and then time to go fishing.
Ooooh, getting close now. I dropped the exhaust manifolds. They were held on by a mismatched collection of rusted studs. Some I removed easily, some the nut came off, others I had to double-nut to remove. 10 more big nuts and the head popped off and into a box for the machine shop. I was done. Not bad, only 8 hours to remove the head. Now all I had to do was reverse time by 4 hours when installing, and I'll be right in time with my mate's time estimate.
Part 2: Installation
Okay, I'm back and more importantly, the head is back from the machine shop. Just in time for the long Labor Day weekend. Guess what I'll be doing.
The whole machine shop thing was a good news bad news story. First the good news. The head was warped. Ok, not quite the news you were expecting. But the really good news, is it wasn't warped as much as they thought! Which means they could do their machine shop thing and shave the head down, make it square & flat again. And when it was finished it was still in spec so I didn't have to get another thicker head gasket. Which is only made for the 1989 2.7 motor and I think the S2.
The bad news, is I had bent 3 exhaust values. Most likely when the head gasket went, some coolant got into the head and momentarily hydro-locked the cylinder - remember that old "interference" thing? - bending the valves.
But the really, really bad news was that 2.7 exhaust valves were only made under a full moon in small batches by Bavarian elves using incantations provided by Harry Potter and manufactured with special plutonium inserts from North Korean spent fuel rods. Which is why a normal 2.5L valve can be purchased for 35 bucks, while for my values, the dealer list was a tidy $161.00. Each. Ouch.
Thankfully I didn't need any intake valves. A 2.5 goes for 14 bucks a pop, while a 2.7 intake lists at a stratospheric $186!
Take the nice new head gasket from my gasket kit, making sure to not to block off the oil hole that feeds the camtower in the lower left corner, and place it on the block. Gregg told me they are marked "Oben" which is "top" in German, but told me not to rely on that. Porsche had a batch of head or camtower gaskets where the person stamped "oben" on the wrong side. I take my nice shiney new head, slide it down the head studs and snug down the nuts on the studs. The 2.7 motor had a unique method of torquing the head. First you snug the bolts to a nominal value like 14 ft/lbs in a particular pattern. Wait 15-20 minutes to allow the bolts to stretch and settle. Next, using a breaker bar, tighten the bolts 60 degrees from the original start angle using the same pattern. Wait 15-20 minutes again. Finally tighten again using a 60 degree angle and you're done. Easy. Sweet!
This is going pretty good. Next, it's time for the camtower. Slid my new camtower gasket on the head, add a dab of grease to hold it. Add some bearing grease to each of the lifters (round cylinders on the right) to keep them from falling out when I turn the camtower over. Set the camtower to TDC, using that red mark remember? And gently flip the assembly over and place it on the head. Only to realize I forgot to put in the centering pins which align the tower and the block. Pull assembly off and back on workbench. Go find bag with part. Insert pins. Back with camtower. Rotate and watch as 2 lifters immediately fall out and disappear into the engine bay. Return tower to bench. Retrieve lifters. Clean, re-goop lifters and insert back into tower. Place tower in place and watch as 2 different lifters fall out. Rinse and repeat.
Eventually I'm able to invert the camtower assembly and place it on the head. Now since the cam is set to TDC, some of the lifters aren't flush, so the whole assembly doesn't sit flush. You have to carefully push as you insert the bolts - using that long allen - and draw down the tower until it's flush on the head. This time, in keeping with my earlier practice, I manage to drop 2 bolts into the camtower. But, using my budding mechanic skills, I kept the magnet on a stick from last week, so was able to shave the 5 minute round time to fetch it from the ECI garage. See? Already saving time.
Well, maybe not. As I have to go to the garage anyway to fetch a torque wrench that can do 14 ft/lbs. Since that's all the camtower bolts want. A call to Gregg to verify my bolt tightening methodology elicited the advice to let the bolts settle after the first round. And then go back and recheck them. Good advice if you're a pro. Me, on the re-check, I managed to snap one of the bolts. And of course, it wasn't one of the exposed ones. Oh no, it broke off deep down in camtower hole. By now, tech support is answering my calls with: "What is it now?" instead of "Hi Cris!". Ah he says, that sounds like a classic case of the bolt stretching and then snapping instead of tightening. "What now Gregg?" "Why you have to remove the camtower of course." Of course. Luckily the snapped bolt was sticking above the head's surface so it was easily removed with some pliers. Being more skilled with the recent practice, I only managed to drop 2 lifters this time instead of the 4 previously. I used one of the allen bolts from the bottom side, replacing it for now with a 8mm bolt.
With that, I was done for the day. Off in search of the TiVo and beer.
Back to work, I'm starting to smell the barn here. Put the timing belt back on, unlock the spring tensioner. Replace the distributor and belt covers. Install the intake manifold. Trace and reconnect all the vacuum lines. Off to Pep Boys for one spark plug. Plug in the fuel injectors. Replace the fuel rail. Hook up the fue lines. Install the distributor cap and plug wires. Remove the fuel rail and reroute the spark plug wires. Re-install the fuel rail and fuel lines. Unhook the fuel lines so I can put the stupid fuel rail plastic cover on. Rehook up the fuel lines. Add coolant by pouring it directly into the block and then reattaching the coolant pipe on the cam tower. Reinstall the fans and shroud. Add 6 quarts of Mobil 1 - at $43 a case - replacing the 6 quarts of Mobil 1 that had 3 laps on it before the head gasket blew.
By now, the day is waning. Unlike yesterday where it poured all day, today and the rest of the Labor Day weekend was beautiful. The car is ready to fire. I'll do that first thing Monday morning. Now its time to go bar-b-que. And of course, drink beer.
Mid Monday morning. If all goes well, I've got an hour or so buttoning up the car. Maybe I can get a nice motorcycle ride in this afternoon.
Ok, moment of truth. I turn on the kill switch and crawl into the car. Turn the key and let the fuel pump work for a minute and turn the key. The motor cranks, fires and starts running. Yay! I watch the oil pressure, its at 1.5 bars and starts creeping up and then all of a sudden drops and the warning lights flash on the dash. What the hell? I kill the motor and get out of the car and this is what I find:
Well, not precisely this. This is after I dumped 25 lbs of nearby cat litter on the mess. My well developed grasp of the obvious told me we had a problem here. Time to call in the Pros. I called Gregg and begged him to pay a visit to the scene of the disaster. Meanwhile, while waiting for him to show up, he suggest grabbing a buddy to see if they can tell where the leak was. I found Tom Holmes over at the garage and dragged him back. After dumping in another quart of oil, I cranked the engine and immediately Tom called me to stop. "It's shooting out like a garden hose on the side of the block." There goes my afternoon motorcycle ride.
Gregg soon showed up and after looking where the oil was coming out with the use of a mirror, exhibited his own fine grasp of the obvious: "You got a hole in the side of your block ". But after looking at it with the mirror, I noticed it was nicely machined with threads. I rummaged through the bag of discarded parts the machine shop gave back to me. "Is this the screw that goes in there?".
"Well yes, but what's even more important is that part next to it. That's your problem. That's an oil restrictor and it needs to be inside your head not in your hands."
It turns out the 2.7L motor, like the 3.0L, had a oil restrictor in the feed from the block to the camtowers. The 2.5 motors don't have this part. It seems that the machine shop removed the part from the head while working on it, but neglected to put it back. And didn't tell me when I picked up the head. Figuring I guess, that I would know enough to 1) miss it and 2) put it back. Wrong on both counts.
And Gregg, never having seen a 2.7 apart, didn't know to tell me to make sure it was in place. But he did know exactly what it was once it appeared in my hand. A comedy of errors to be sure. What to do? Why you guessed it. I have to pull it all apart again and reinsert the missing piece. Luckily since the head didn't have to be pulled, I just need access to the oil hole (above), I could leave the intake and exhaust manifolds on.
For the rest of this tale, go back up to Part 2 and read along until you get to the part where I turn the key. Then come back, I'll wait .... Meanwhile, another trip to PepBoys for another $43 worth of Mobil 1.This time, I fire it up and, Whoohoo! Oil gauge to 5 bars and no mysterious fluids squirting out of the engine. I'm patting myself on the back when I notice the garage filling up with smoke. Not all of that oil ended up on the floor, a fair amount remained on the exhaust headers where it's cooking off. A box fan pointed out of the garage door solved that. I let the car run for 20 minutes while I bleed the coolant. I turn off the motor and head for the beer. A nice fine Outmeal stout, methinks.
So with one week to go, I'm ready for the NASA National championship for the 44Cup at Mid Ohio. So will the car work through the weekend? Will I come back covered with glory, oil or mud? I'm sure there will be a tale of two. But for now, in the words of my bud GW,
Head Repair August 2006
Or how I became an involuntary Porsche Technician
So, Round 6 of the 44Cup Series at Summit Point didn't go quite as I hoped....
I was on my 2nd lap of the first practice session on Saturday. Approaching turn 1 I glance at my gauges and notice my coolant temps are high. I added a mental Post-It note to keep an eye on it as I started braking for the turn. As I transition into the corner I glance at the rear mirror and notice a large cloud of smoke behind me. Funny, I didn't lock up my brakes .... Holy shit, my dash danger light is flashing and my coolant temps are in the stratosphere. I coast the car into the cutoff section between the front straight and turn 3. I wave to the corner worker that I'm ok, and get out of the car. Steam and smoke are rising from under the hood.
Back in the paddock, the diagnosis is commonly agreed upon: Blown head gasket and probably warped the head for good measure. With the help of some 44cuppers I get the dead car into the trailer. I hang around for the always great 44Cup Paddock lunch and then head for home. "Should be only a 4 hour job" sez the paddock mechanics. Ha! I'm a software developer and this was most definitely a "hardware" problem...
Part 1: Removal
Time to learn. Oh an important note: This is a relatively rare 2.7L 944 engine, not the more usual 2.5L. With the help of the excellent Clark's Garage site (www.clarks-garage.com) and Winner Porsche's master mechanic Gregg Wilson a quick cell phone call away I was ready to venture into the unknown.
First, put the engine at TDC (top dead center). Sounds easy right? Just rotate the crankshaft clockwise until the timing mark shows up in the little window on top of the flywheel which is buried under a bunch of wiring and sensors at the rear of the engine. Just a few small things between me and TDC tranquility. Like the fact that Maggie always finds something more interesting than helping me wrench on my car, things like taking out the garbage, viewing the Home shopping Networks, etc. so I was soloing here. Like the fact that my sockets were either too short or too long with extensions to turn the crank. Which meant pulling the fans and shrounds just to get a tool in there. Like the fact that I had no clue what the timing mark looked like. So here I'm stretched out on top of my engine with my nose buried, left arm stretched as far as I can go to rotate the crank at the front. A red dot! is that it? Did somebody mark it for me? Look, a "P" stamped into the flywheel. Is that it? I'm looking for the letters "OT" stamped. And every two revolutions, my socket falls out of crankshaft nut since the only combo I have that works is a flex head racket, which means I have to wriggle off the top of the engine, go to the front reset it and wriggle back into position while holding it steady. After 15 mins of this, and being no wiser it was time to call the support line.
And Gregg has the secret mechanic's tip: Pop off that rubber cover in the right corner of the distributor cover (top left photo). Rotate the engine until the bright red mark (top right photo) shows up in the window. That will put you in the ballpark. Now go look at your reference mark on the top flywheel. And there she was, right in the middle of a rusty patch. Gregg also mentioned taking a look at the bottom of the flywheel. When at TDC, there is a dimple in my flywheel - looks like a little mushroom - centered in the groove ( right photo - not the best)
So step 1, a five minute job has taken about an hour... The guys in the paddock were using software engineering estimates when they said 4 hours. I figure at this rate I'll be heating the garage before I'm done.
Next step: pull the fuel lines and fuel rail and injectors. Hey that went pretty smooth other than traveling to the Team ECI shop to go find a 22mm wrench to hold the fuel line. Unhook the fuel lines and pull 4 bolts. Into the parts box. I'm feeling like a mechanic now. Pulling crap off is right in my domain expertise.
Onto the intake manifold. Once again, a bunch of bolts, pull the cruise control out of the way - note to self: remove the cruise control, it's not getting a lotta use when racing - and whack the intake with my big rubber mallet. And into the box with other crap. Hope I remember where all these hoses and vacuum lines go.
Getting closer. Things are starting to get more complex now. Up next is the removal of the cam tower (right). Back to the Team ECI garage for a extremely long 6mm allen socket. It became the #1 tool in this process.
But before I can use this handy tool, I have to pull off the timing belt.
I pulled the distributor and belt covers and exposed the guts. The tricky part here is to lock the timing belt in position while the camtower is off the car so I don't have to reset it. The 944 motor is what's called an "interference" design - which means when you boil it down, if the timing belt breaks or is off on the timing wheel, all the little valves and pistons will merrily mash themselves into very expensive junk. Quite happily mind you, these are very selfish values and pistons and give no thought to the poor Porsche owner who has to pay for their salsa party.
Once I figured out how the spring tensioner device worked - another tech support call was required - the timing belt was removed and the removal of the camtower began in earnest.
This didn't go quite as smoothly. I got all but two of the allen head bolt which are buried deep in the camtower (thus the need for the long allen). Due to heat or overtorquing - they only are set with 15 ft/lbs - they were a bitch to remove. I'd crank & crank and then Snap! they would break free, scaring the bejesus out of me
But the 2 final ones wouldn't go. Another call to tech support. And the answer is? Put a larger breaker bar on them, and if that won't do it, add some pipe and go to town on those puppies. Ah, ok Gregg, if you say so... Never doubt, that did the trick. And the mysteries of the Head are revealed!
And oh yeah, I dropped two of the bolts while removing them. They're rattling around in the camtower somewhere. Guess it's another trip to the Team ECI garage looking for a magnet on a stick and then time to go fishing.
Ooooh, getting close now. I dropped the exhaust manifolds. They were held on by a mismatched collection of rusted studs. Some I removed easily, some the nut came off, others I had to double-nut to remove. 10 more big nuts and the head popped off and into a box for the machine shop. I was done. Not bad, only 8 hours to remove the head. Now all I had to do was reverse time by 4 hours when installing, and I'll be right in time with my mate's time estimate.
A Naked 2.7 Engine Block - rated PT (Porsche Technician) only
That was a lotta work. It's time for a beer. Or two.
Part 2: Installation
Okay, I'm back and more importantly, the head is back from the machine shop. Just in time for the long Labor Day weekend. Guess what I'll be doing.
The bad news, is I had bent 3 exhaust values. Most likely when the head gasket went, some coolant got into the head and momentarily hydro-locked the cylinder - remember that old "interference" thing? - bending the valves.
But the really, really bad news was that 2.7 exhaust valves were only made under a full moon in small batches by Bavarian elves using incantations provided by Harry Potter and manufactured with special plutonium inserts from North Korean spent fuel rods. Which is why a normal 2.5L valve can be purchased for 35 bucks, while for my values, the dealer list was a tidy $161.00. Each. Ouch.
Thankfully I didn't need any intake valves. A 2.5 goes for 14 bucks a pop, while a 2.7 intake lists at a stratospheric $186!
Installation is the reverse of removal right? So what was the last thing I did? Oh right, time for a beer. Be right back.
Eventually I'm able to invert the camtower assembly and place it on the head. Now since the cam is set to TDC, some of the lifters aren't flush, so the whole assembly doesn't sit flush. You have to carefully push as you insert the bolts - using that long allen - and draw down the tower until it's flush on the head. This time, in keeping with my earlier practice, I manage to drop 2 bolts into the camtower. But, using my budding mechanic skills, I kept the magnet on a stick from last week, so was able to shave the 5 minute round time to fetch it from the ECI garage. See? Already saving time.
Well, maybe not. As I have to go to the garage anyway to fetch a torque wrench that can do 14 ft/lbs. Since that's all the camtower bolts want. A call to Gregg to verify my bolt tightening methodology elicited the advice to let the bolts settle after the first round. And then go back and recheck them. Good advice if you're a pro. Me, on the re-check, I managed to snap one of the bolts. And of course, it wasn't one of the exposed ones. Oh no, it broke off deep down in camtower hole. By now, tech support is answering my calls with: "What is it now?" instead of "Hi Cris!". Ah he says, that sounds like a classic case of the bolt stretching and then snapping instead of tightening. "What now Gregg?" "Why you have to remove the camtower of course." Of course. Luckily the snapped bolt was sticking above the head's surface so it was easily removed with some pliers. Being more skilled with the recent practice, I only managed to drop 2 lifters this time instead of the 4 previously. I used one of the allen bolts from the bottom side, replacing it for now with a 8mm bolt.
With that, I was done for the day. Off in search of the TiVo and beer.
By now, the day is waning. Unlike yesterday where it poured all day, today and the rest of the Labor Day weekend was beautiful. The car is ready to fire. I'll do that first thing Monday morning. Now its time to go bar-b-que. And of course, drink beer.
Mid Monday morning. If all goes well, I've got an hour or so buttoning up the car. Maybe I can get a nice motorcycle ride in this afternoon.
Ok, moment of truth. I turn on the kill switch and crawl into the car. Turn the key and let the fuel pump work for a minute and turn the key. The motor cranks, fires and starts running. Yay! I watch the oil pressure, its at 1.5 bars and starts creeping up and then all of a sudden drops and the warning lights flash on the dash. What the hell? I kill the motor and get out of the car and this is what I find:
 |
| I thought the Exxon Valdez was in Alaska |
Well, not precisely this. This is after I dumped 25 lbs of nearby cat litter on the mess. My well developed grasp of the obvious told me we had a problem here. Time to call in the Pros. I called Gregg and begged him to pay a visit to the scene of the disaster. Meanwhile, while waiting for him to show up, he suggest grabbing a buddy to see if they can tell where the leak was. I found Tom Holmes over at the garage and dragged him back. After dumping in another quart of oil, I cranked the engine and immediately Tom called me to stop. "It's shooting out like a garden hose on the side of the block." There goes my afternoon motorcycle ride.
"Well yes, but what's even more important is that part next to it. That's your problem. That's an oil restrictor and it needs to be inside your head not in your hands."
And Gregg, never having seen a 2.7 apart, didn't know to tell me to make sure it was in place. But he did know exactly what it was once it appeared in my hand. A comedy of errors to be sure. What to do? Why you guessed it. I have to pull it all apart again and reinsert the missing piece. Luckily since the head didn't have to be pulled, I just need access to the oil hole (above), I could leave the intake and exhaust manifolds on.
 |
| Oil Channel with Restricter in Place |
 |
| Putting the screw to hold the oil restrictor in the hole where all the oil streamed out |
For the rest of this tale, go back up to Part 2 and read along until you get to the part where I turn the key. Then come back, I'll wait .... Meanwhile, another trip to PepBoys for another $43 worth of Mobil 1.This time, I fire it up and, Whoohoo! Oil gauge to 5 bars and no mysterious fluids squirting out of the engine. I'm patting myself on the back when I notice the garage filling up with smoke. Not all of that oil ended up on the floor, a fair amount remained on the exhaust headers where it's cooking off. A box fan pointed out of the garage door solved that. I let the car run for 20 minutes while I bleed the coolant. I turn off the motor and head for the beer. A nice fine Outmeal stout, methinks.
So with one week to go, I'm ready for the NASA National championship for the 44Cup at Mid Ohio. So will the car work through the weekend? Will I come back covered with glory, oil or mud? I'm sure there will be a tale of two. But for now, in the words of my bud GW,
"Mission Accomplished!"
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