My 1978 3.0 L head stud replacement thread
08-22-2011, 03:24 PM
#16
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My (cheap) camera does have a macro setting, and that is what I was using. The trouble was, the light was bad (it was night) and I could not pick up enough light on the valve for the autofocus. I will try again, using a worklight and then things should be better.
That picture on the other thread is after an intial quick clean up. I did have some of the typical oil breather gunge, but not too bad relative to what I've seen in other pics. I think the engine is still fairly well sealed, but I will re-fresh all of those items.
I am not taking the engine itself apart. I do not have any valve guide wear symptoms, the mileage is not that high (just over 100K) and very good leakdown and compression. So, I will do a thorough freshening of the external systems and plug it back in. There was a part of me that wanted to go all the way, but I also have a 75% finished way over-restored 944S (where I did a full rebuild on the motor) project languishing! I need to get at least one car on the road in this decade!!
That picture on the other thread is after an intial quick clean up. I did have some of the typical oil breather gunge, but not too bad relative to what I've seen in other pics. I think the engine is still fairly well sealed, but I will re-fresh all of those items.
I am not taking the engine itself apart. I do not have any valve guide wear symptoms, the mileage is not that high (just over 100K) and very good leakdown and compression. So, I will do a thorough freshening of the external systems and plug it back in. There was a part of me that wanted to go all the way, but I also have a 75% finished way over-restored 944S (where I did a full rebuild on the motor) project languishing! I need to get at least one car on the road in this decade!!
08-23-2011, 01:04 AM
#17
Removed the front engine mount, fan/alternator, engine harness, and shroud. There's nothing worth saying about the process. It's well-documented elsewhere. Just a few pics to show. I was pretty pleased with the general cleanliness of the top side with the exception of the reach of the breather leak.
One pic of the whole of the breather cover oil leak. Lots of caked gunk, but the borders are well defined. It looks chunky where I started to scrape at the gunk with a screwdriver as I debated just when and how to do the cleaning in a manner that would avoid crap dropping into the case. I don't intend to split the case, so I want it to stay clean in there. My thinking is to clean it while inverted on the engine stand. The gunk can drip straight off into a drip pan.
Next, a couple areas where there is caked material on the cylinder head fins of the middle cylinders of either side (#'s 2 and 4). The symmetry struck me. I doubt it means anything.
And, finally the engine shroud color. It's green resin fiberglass which I believe is characteristic of the 2.7 cars but painted red. The red has rubbed off in a few places showing the green through. I don't know the history of engine shroud colors, but I assume the red is original for the SC model. It's all probably laid out in the 911 books that I've had good intention to read for several years now.
One pic of the whole of the breather cover oil leak. Lots of caked gunk, but the borders are well defined. It looks chunky where I started to scrape at the gunk with a screwdriver as I debated just when and how to do the cleaning in a manner that would avoid crap dropping into the case. I don't intend to split the case, so I want it to stay clean in there. My thinking is to clean it while inverted on the engine stand. The gunk can drip straight off into a drip pan.
Next, a couple areas where there is caked material on the cylinder head fins of the middle cylinders of either side (#'s 2 and 4). The symmetry struck me. I doubt it means anything.
And, finally the engine shroud color. It's green resin fiberglass which I believe is characteristic of the 2.7 cars but painted red. The red has rubbed off in a few places showing the green through. I don't know the history of engine shroud colors, but I assume the red is original for the SC model. It's all probably laid out in the 911 books that I've had good intention to read for several years now.
Last edited by Brett San Diego; 08-23-2011 at 03:19 AM.
08-23-2011, 09:51 PM
#18
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Looks like no big surprises, which is good.
The only comment I'll make, as i left too early to help much, is that you should always lower the motor only an inche or two at a time-put eyes all around it to make sure nothing is pulling, caught, pinched, etc- repeat. Invariably, a wire can be forgotten or something caught on a 1/2 shaft-whatever. This applies to installation as well.
If you need any special tools, give me a holler.
The only comment I'll make, as i left too early to help much, is that you should always lower the motor only an inche or two at a time-put eyes all around it to make sure nothing is pulling, caught, pinched, etc- repeat. Invariably, a wire can be forgotten or something caught on a 1/2 shaft-whatever. This applies to installation as well.
If you need any special tools, give me a holler.
08-24-2011, 01:25 PM
#19
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If you do not send the heads out to have the valves done, you can check for leakage by pouring low viscous fluid into the port and look for weeping around the valve contact area. I use gasoline but I read that it is not a good idea. If it stays dry, you have a good seal. If the seal leaks, lightly tap (brass hammer) the stem top of the valve to bounce the head in the seat. That should release any debris or compress a small carbon partial. If there is a light weeping, you can do a light compound lapping and also have the guide clearance checked while the valve is out. If fluid pours out that is a different matter. If you do lap a valve, there is a tool that has an adjustable ball that measures the ID of guide hole size. The difference between that and your valve stem size will tell you if you are within spec.
The 2 tools are not that costly and are good to have around.
Harbor Freight and I think Pep Boys sell huge jack stands that are high enough to drop the engine to the ground. I have used the PepBoys on the P car and the Harbor with the tractor but not on the 911.
The 2 tools are not that costly and are good to have around.
Harbor Freight and I think Pep Boys sell huge jack stands that are high enough to drop the engine to the ground. I have used the PepBoys on the P car and the Harbor with the tractor but not on the 911.
08-24-2011, 02:13 PM
#20
If you do not send the heads out to have the valves done, you can check for leakage by pouring low viscous fluid into the port and look for weeping around the valve contact area. I use gasoline but I read that it is not a good idea. If it stays dry, you have a good seal. If the seal leaks, lightly tap (brass hammer) the stem top of the valve to bounce the head in the seat. That should release any debris or compress a small carbon partial. If there is a light weeping, you can do a light compound lapping and also have the guide clearance checked while the valve is out. If fluid pours out that is a different matter. If you do lap a valve, there is a tool that has an adjustable ball that measures the ID of guide hole size. The difference between that and your valve stem size will tell you if you are within spec.
The 2 tools are not that costly and are good to have around.
Harbor Freight and I think Pep Boys sell huge jack stands that are high enough to drop the engine to the ground. I have used the PepBoys on the P car and the Harbor with the tractor but not on the 911.
The 2 tools are not that costly and are good to have around.
Harbor Freight and I think Pep Boys sell huge jack stands that are high enough to drop the engine to the ground. I have used the PepBoys on the P car and the Harbor with the tractor but not on the 911.
Brett
08-24-2011, 06:36 PM
#23
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08-24-2011, 07:08 PM
#24
08-25-2011, 02:03 PM
#25
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ED------------- “Let's keep race, religion and sexual bias out of the conversation here.”
But, but, but, Ed, although:
1. P cars are only a cult and not a religion; many find religion when strange sounds rumble from the engine bay.
2. Race/racing is definitely a valid subject.
3. If a Porsche aint sexy, then we are all lost. OH, uh, missed the word BIAS. I am not sure we can go there, automatics are a touchy subject.
But, but, but, Ed, although:
1. P cars are only a cult and not a religion; many find religion when strange sounds rumble from the engine bay.
2. Race/racing is definitely a valid subject.
3. If a Porsche aint sexy, then we are all lost. OH, uh, missed the word BIAS. I am not sure we can go there, automatics are a touchy subject.
08-31-2011, 03:48 AM
#26
exhaust off
The exhaust is now off. I don't know what you guys are talking about. A little penetrant, and my exhaust nuts came off like butter (well, one backed out the stud, but no matter). Maybe it's that this 911 has been in Las Vegas or San Diego all its life. 
I had the MAPP gas at the ready and swear words on the tip of my tongue, but neither was needed.
5 of the exhaust ports looked similar, but the residue coating #4 was much whiter. I thought that was interesting, but I don't know what it means, if anything. I know I said all the intake ports looked similar, but one of them had a little oil pooled against the intake valve when I looked closer. It may have been #4.
Exhaust port of #5 (The rods projecting into the exhaust ports are the air injection ports, a feature of 1978 and 1979.)
Exhaust port of #4
I also realized this evening that one cylinder head, #5, is different than the others. The intake side of #5 has more "missing" fins.
And what I assume is a production date stamp is different.
Date stamp of #5
Date stamp of other heads
Things that make you go hmmm... When I bought the 911, it had harness eye bolts in the rear bulk head and rear floors. And, the second owner had the very old harnesses among his pile of stuff. It's pretty clear it saw some track work back in the day with the original owner. A few years ago when I took off the sump plate to change it, I found a broken valve "elephant foot" up against the sump screen, and now it's evident a cylinder head has been replaced. Clearly, there has been a major failure in the past, possibly on the track. I wonder if it was a broken valve spring, which is a known problem with 78's.
Brett
I had the MAPP gas at the ready and swear words on the tip of my tongue, but neither was needed.5 of the exhaust ports looked similar, but the residue coating #4 was much whiter. I thought that was interesting, but I don't know what it means, if anything. I know I said all the intake ports looked similar, but one of them had a little oil pooled against the intake valve when I looked closer. It may have been #4.
Exhaust port of #5 (The rods projecting into the exhaust ports are the air injection ports, a feature of 1978 and 1979.)
Exhaust port of #4
I also realized this evening that one cylinder head, #5, is different than the others. The intake side of #5 has more "missing" fins.
And what I assume is a production date stamp is different.
Date stamp of #5
Date stamp of other heads
Things that make you go hmmm... When I bought the 911, it had harness eye bolts in the rear bulk head and rear floors. And, the second owner had the very old harnesses among his pile of stuff. It's pretty clear it saw some track work back in the day with the original owner. A few years ago when I took off the sump plate to change it, I found a broken valve "elephant foot" up against the sump screen, and now it's evident a cylinder head has been replaced. Clearly, there has been a major failure in the past, possibly on the track. I wonder if it was a broken valve spring, which is a known problem with 78's.
Brett
08-31-2011, 04:19 AM
#27
I got part way through cleaning the case before running out of solvent. I went through about 3 liters of mixtures of hexanes with dichloromethane and acetone (just used everything I had on hand). As a chemist I have access to solvents. I borrow some from time to time. I turned the side to be cleaned on the bottom, so the grime would drip off rather than run down the engine, then just squirted the cleaning solvent from a squirt bottle in one hand and used a wire brush and toothbrush with the other. I placed a plastic trough to catch the dirty solvent. This is the suckiest task of this job, but also one of the more rewarding. This quantity of volatile solvent should only be used with plenty of ventilation, and an activated carbon filter mask would also be a good idea.
Oil breather leak area before
oil breather leak area after
One side of the bottom almost done before running out of solvent.
The other side of the bottom.
Oil breather leak area before
oil breather leak area after
One side of the bottom almost done before running out of solvent.
The other side of the bottom.
Last edited by Brett San Diego; 08-31-2011 at 01:22 PM.
08-31-2011, 06:52 PM
#29
Team Owner
wow those are pretty amazing pics. Some good detectove work too.. i cant remember which cylinder head studs broke now .. and you are right definitely 5 was replaced. Anybody know why that cylider would have less fins ?
I pulled out my air injectors a while back and put in plugs with copper sealing washers. really cleaned up underneath the engine.
I pulled out my air injectors a while back and put in plugs with copper sealing washers. really cleaned up underneath the engine.
