Top End and Reseal
 

I am planning a top end and reseal to my '86 3.2 / 90k. It runs well, but is consuming significant oil - 350-400m/qt. Compression and leakdown good on all (185/less than 10%), but #4 (150/50%). I intend to split the case to make sure the bottom end is Ok and to replace the intermediates.

I'll share my work, but I am really slow, so bear with me. I need to do double duty photographing, bagging, and documenting my disassembly, so it will slow me down. This is a winter project and if it takes me five or six months, I don't care. Here is the motor out of the car, plus intake and exhaust ports.

My goal is to address my oil consumption problem and fix #4. If parts are in spec, they are going back in. I am documenting this to give back to the board. The experienced guys won't learn anything, but maybe some new folks will find some value. There is someone on the board that I have in mind that I am hoping will coach me if I need it, since sometimes the varying opinions can be a little overwhelming.

Motor on stand.

Edit: I sometimes feel a little silly posting my rebuild because this probably seems so completely elementary to many people that post routinely and do stuff that completely blows me away. However, I found a lot of inspiration from the people that, like me, are novices. Totally need the help and guidance of those more experienced, but to the 'greenies" out there that went before me - I salute you. http://forums.pelicanparts.com/suppo...leys/wavey.gif

http://forums.pelicanparts.com/uploa...1258942292.jpg

Intakes look pretty clean - techron works.

http://forums.pelicanparts.com/uploa...1258942361.jpg

http://forums.pelicanparts.com/uploa...1258942405.jpg

Exhaust not so hot. Barrel nuts were a bear. Cut a slot in them with my dremel, got them cherry red, then used a big screw driver with a vice grip attached for torque. It was a lot of work.

http://forums.pelicanparts.com/uploa...1258942486.jpg

This is my problem cylinder. The only thing unique is that there seems to be something flaking off the back of the valve. I am hoping the compression and leak down issues are related to the head and not the p&c. I'll know more in a week or so once I get the head off.

http://forums.pelicanparts.com/uploa...1258942575.jpg

Good luck with the rebuild Greg.

I'll be watching this one.

Make sure you have Waynes book. Go slow. Don't skip steps.

Clean your work bench. You are going to need 2 1/2 times the flat space of the work bench for storage and cleaning . Pick a machine shop that has Porsche knowledge and experience. I had to have all my head work re-done to the tune of another $800.

Old Tee - Thanks, all good suggestions. I have owned Wayne's book for about five years (longer than the car, lol) and have carried it to work every day for the past six months. I have a storage shelves not in view of the pictures, but wish I had a bigger bench area. Also, there is one shop not too far that has Porsche jigs, but I plan to ship them to one of the supporters of this board.

Let me know if you need any help....I'm learning too.

Good luck!

I just took out a 930 motor to reseal some leaks, adjust the valves, etc. Probably will spend time polishing/powdercoating, etc... Seems like a fun winter project :).

I am tempted to just take the motor completely apart, and like you, just fix stuff falling out of spec.

But it seems that its tough to "just" replace what needs to be done. If you crack open the bottom end, you pretty much have to replace all of the gaskets. If you want to see what the main bearings look like, you pretty much have to get new rod bolts/etc as they aren't reused... etc, etc. Pandora's box comes to mind.

Is there any "economical" way to disassemble the bottom end? I look forward to your pics :). Good luck!

Subscribing...

Who did the valve adjustments in the past? Was it a shop? Just wondering.

The bottom end gasket set is only about $75. If all the mains and rod bearings are in spec, I will just button it back up. If I check all of the rod bearings, I would need to replace all of the bolts, but I might just open one or two and replace only those bolts. However, I am also tempted to buy a set of ARP's, haven't decided, but at $225 it's a reasonable investment. Sealants for the full motor are probably another $100.

Keep in mind, my goal is NOT a rebuild, it's a top-end and reseal. The only thing I am doing for sure on the bottom is on the intermediates.

signing-up. Thanks Greg.

I did the last two adjustments. The second was a "re-do" as I felt the valves were still pretty noisy after the first. They really didn't quiet down much, so that and the high oil consumption confirmed my decision that the motor needed some love.

11 of 12 exhaust studs are out and the 12th is about 60% drilled. I purchased the stud drilling guide from the guy on the board that makes them. I probably could have made it 12 for 12 with only heat and a pair of vice-grips, but didn't perfect my technique until exhaust stud #2.

Why are you removing the exhaust studs? I didnt see anything on your posting for that job.
Bruce

I soaked them in PB Blaster for more than a week, but even with heat the nuts were too badly corroded to be griped by a wrench or socket and the interiors of the barrel nuts were too badly corroded for a long allen to bite. The combination of a lot of corrosion on the stud, screwing up the top of the studs with my dremel and the four studs came out instead of the nut coming off, I figured I would just remove the others. I know there was some risk in that approach, but no price to pay on this one.

Hope all goes well. Much like you, I'm doing my first engine drop in the upcoming weeks, and then top end and reseal as well. I have high oil consumption like you and will likely inspect all pistons and rings also, seeing as it's a turbo. Keep the pictures coming.

Subscribed.

Here's my hosed up studs and the exhaust stud drilling fixture. The drilling fixture works well, but I was still paranoid and kept taking it off to verify that I wasn't destroying my head. It's far better not to drill if you can avoid it.

http://forums.pelicanparts.com/uploa...1259982975.jpg

Greg:

You were right about taking those awful studs out. They look bad; like you said earlier.

Now, just so I am clear on this point, when you said you "drilled them" out, did you drill the stud to get them out? Or, did you drill out the hole for the stud and now will re-tap the head?

Thanks.

Thanks for taking the time to document your work. I'm sure there are far more beginners/intermediates (like me) on the board than "experts" who will benefit from your posts. As you said too, your posts will help inspire others who are on the fence confidence-wise, to give it a go themselves.

Thanks for taking the time.

Tom

I used a 1/4 inch cobalt bit and drilled through the center of the stud. It's a very tight fit and wouldn't recommend it unless you have the drill guide. It's even challenging with the drill guide. I must have stopped and removed the guide more than twenty times to check my work and vacuum the metal shavings out. I still need to run a tap down the hole to clean up the threads, but am going to wait until I have the heads off and have easier access.

Progress was slow this weekend with holiday activities and schlepping a xmas tree back to the house, plus all the lights. I did manage to complete the drilling, removed the fan shroud and took one of the chain covers off, but that's it. I am doing a lot of cleaning as I go, which is also slowing me down.


http://forums.pelicanparts.com/uploa...1260194695.jpg

My administrative skills are generally pretty weak, like my desk at work typically reveals. However, I have been pretty disciplined photographing and documenting. Wayne says in his book to take lots of photographs, and I can tell you that even though I have taken a lot, I go back to check on a few things and realize I don't have good photos - going forward I will take even more.

One thing I hope will help is making notes on the bag as I bag items. I am listing what is in the bag and if there are any special notes about the stuff. Here is an example.

PS - Good documentation, photos, and everything to stay super organized helps ease any anxiety and thoughts like "I must be an idiot to think I can actually do this".

http://forums.pelicanparts.com/uploa...1260198584.jpg

Greg, You ll have bags of directions but that piece in the bag is suposed to have 3 8mm nuts and wavey washers....looks like youre having a great time.
Bruce

Greg,

Actually I think it's really cool every time someone starts a rebuild for the first time. I remember mine like it was yesterday, and I've done around 30 since then. (Not all mine!)

The feeling you get when you first start the engine that you rebuilt is priceless. Enjoy the process, take your time, and do it right. It's especially temptng to start hurrying when you get close to the end.

My biggest tip besides extensive bagging which you're doing? Before you start assembly, lay everything out. Count the parts and be sure of the ones you're going to need. There's no feeling worse than finding an oil-pump seal laying on the floor after you've sealed the case and wondering if it's an extra, or if you forgot to put it in.

I know that I have read about laying stuff out, but understanding why it was so important escaped me....until now. Great tip, thank you.

Good luck to you, I started my tear down on my 86' 3.2 like last week, I'm about to split the case today

Thanks marcsalleras - good luck to you too. You're a head of me.

More progress today, but need to stop after just a few hours - 13 days before Christmas with lots of non-Porsche stuff to do. Like I said, I am slow, but this is really a fascinating project.

Left timing chain cover is off along with 1,2,3 cam tower and head bank.

Sprockets look pretty uniform to me, so I will plan to reinstall along with the chain.

http://forums.pelicanparts.com/uploa...1260641722.jpg

http://forums.pelicanparts.com/uploa...1260641855.jpg

Cross-hatching visible on all three, but cylinder walls most exposed on #2. I don't know what to make of the carbon patterns on my pistons, but #1 has coast to coast coverage. #3 carbon appears thicker.

http://forums.pelicanparts.com/uploa...1260642023.jpg

Close up of #2, but the photo doesn't do a good job of showing the cross-hatch marks.

http://forums.pelicanparts.com/uploa...1260642089.jpg

Heads look OK to me based on my vast experience with Porsche engines. ;) Seriously, I was afraid the valve faces would look worse. Is there any way that I can examine the guides, I am just curious about the oil consumption?

http://forums.pelicanparts.com/uploa...1260642460.jpg

The guides are measured as side movement of the valve and the seals on the guide also wear. I leave the decision of the guide wear to the machinist.
The last set of heads, I told the machinist to replace the 12 and he called and said they were already changed and in very good condition, he honed them slightly so he was happy with them and put them back together.
another at 90K needed all guides replaced so its a crap shoot when you take it apart.
Bruce

A small hole guage and a mic will let you gather the info you want.

Ok, a little more work this weekend, but with just a few days to Christmas, there hasn't been much time at all for the engine. I did get the chain and heads off 4,5 & 6. #4 was my low compression, high leak-down cylinder, but there is no visible evidence of any possible cause. I can only see an inch or so of the cylinder wall, but it looks perfect - cross hatching clearly visible top, sides and bottom. I have to assume one or both of the valves weren't fully seated. I'll never know if it was my valve adjustment or some carbon.

http://forums.pelicanparts.com/uploa...1261313506.jpg

http://forums.pelicanparts.com/uploa...1261313525.jpg

close up of #4, can't see much in photo

http://forums.pelicanparts.com/uploa...1261313579.jpg

If my piston ring end gaps are in spec, I intend to reuse. Once I clean the cylinders, my plan is to coat the walls then just a light coat of oil, essentially replacing what is currently on them. No deglazing or any other prep. Does that sound correct for reusing rings?

Also, what is the best way (safe) to remove that carbon ring at the top of the cylinders? Thanks.

Having great fun.

Thats a carbon deposit not a ring groove in the cylinder so you really dont have to do anything with it. Are the cylinders nikisil or alucil? Looks like youre really moving along on the engine.
Bruce

Bruce - The cylinders are nikasil - 11 ribs and slightly magnetic. The ring of carbon deposit seems like oily tar with some carbon mixed in for good measure, it tells the story of my high oil consumption. Actually, it seems to be cleaning up with a plain paper towel and some rubbing alcohol.

You want to pull a cylinder, especially the one that was the worse, then one to see for comparison. Then you will see the blowby down the different rings and down the skirt. The last post I did on the restud you can see the rings and blowby which was negligible .

Bruce

Ok, a little more progress this weekend. Cylinders off and and dilvar exhaust studs are out. I discovered it's all about technique when it comes to removing the studs. Wayne's book is clear, but the written word is always subject to interpretation. In the end, I heated only inside the cylinder spigot and they came out pretty easily, heating any other part is a waste of time.

The cylinders look good and my bore gauge indicates about .005" out of round on #4, which was the cylinder I was concerned about. I will measure the others, but looks well within spec. I still need to measure the piston ring side clearance. It appears like very little blow-by on the pistons.

However, here is my big issue. I did shove the top compression ring in cylinder #4, made certain it was level at approximately where the cylinder and case meet. End gap was .65 mm. The wear limit is .8mm. Assuming that the end gap started at .3 (mid point of new according to book), then the ring is 70% of the way from new to wear limit. This translates to another 30k miles before it would hit the wear limit.

Does any of this make sense? Should I re-ring at the risk of new rings seating properly or keep the old rings and not worry too much about the end gap? Decisions, decisions....

Back to work tomorrow, but will steal some time next weekend.

#4 piston
http://forums.pelicanparts.com/uploa...1262021568.jpg

No mas dilvar

http://forums.pelicanparts.com/uploa...1262021626.jpg

Better shot of cylinder
http://forums.pelicanparts.com/uploa...1262021792.jpg

Greg, As I was saying about blowby, you have no tarnishment below #1 ring so I can believe the rings are still doing their job. There will be nearly no wear on the nikisil and doing the rings now along with the valve job you will be putting too much stress on the bottom end. Recommend you open the bottom, reseal, inspect, change out the intermediates, new chain rails, close it up for the next few years.
Bruce

Bruce - thanks for the quick feedback. I only put 3 - 4k miles a year so even if I only get another 30k to 40k miles from the existing rings, that is ten years of driving. Plus, I won't need to worry about the rings seating or causing undue stress on the bottom end as you suggest.

I will do as you suggest regarding the crank. I'll check the mains and if they look good, I won't touch any of the rod bolts. I do have the intermediates.

One more question. I was thinking about replacing the valve springs just because it seems like the get fatigued, but you thought the existing ones would be Ok for street driving. Does that still seem reasonable? I don't mind replacing them if you think they are at risk for breaking. Thanks again.

All you do is drive the car, just build to spec, the springs will support your driving. If you want them replaced, theyre not terribly expensive but you ll never feel the difference just Sunday driving.
Bruce

Bruce - Thanks. I am going to stay with the existing springs. I continued to search the forums and while I know there are failures, it mostly seems to be from stress.

I removed the heads and rockers from the cam towers. The only mark I saw on one of the camshaft lobes was on #1 intake, but there was no marks on #1 intake rocker.

Does the lobe need repaired? I can feel it with my fingernail. Can it be polished or does it need reqround? Also, are the radial marks on the camshaft bearings normal?

I also found pitting on one rocker - #1 exhaust. Does this need repaired?

Hopefully, this doesn't translate into regrind and polish of both cams and rockers, but if it does, it does.

#1 intake lobe
http://forums.pelicanparts.com/uploa...1262369680.jpg

#1 exhaust rocker

http://forums.pelicanparts.com/uploa...1262369733.jpg

A little more progress today. I split the case. One point worth noting, the case is far easier to separate once all the bolts are removed. :rolleyes:

My bearings and crank appear Ok when I compare them to the photographs others have posted. The intermediates are showing copper as expected. For me, the benefit of splitting the case is 1) to know the condition of my bottom end, 2) to replace the intermediates, and 3) to make sure that no crap got in the bottom when I was doing the top.

I will probably spend the next few weekends cleaning - sloppy job, then begin the process of reassembly.

Here are my photos - comments welcomed.


http://forums.pelicanparts.com/uploa...1262453917.jpg

http://forums.pelicanparts.com/uploa...1262453961.jpg

http://forums.pelicanparts.com/uploa...1262454004.jpg

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Greg, it is looking good. If you pull the beariings off the case, bag them with the exact location such as 4 L or 6R so they go back exactly where they camr from. The back of the bearing should have a 930 part number on it.
Bruce

Greg,
Have you identified the cause of your oil consumption?

Bruce - Thank you once again. I plan to do exactly as you say 1L, 1R, 2L, etc. I will check the part number on the back bearing - not sure if " back" translates to #1 or #8, but I am sure one of the bearings will have the part number.

Bob - I have not as yet. I am guessing it is the guides, but the heads are no disassembled yet, so can't confirm. I will post as soon as I know.

#8 wouldnt count but #1 use left and right as it shows the most wear of the mains
Bruce