Matt Romanowski

If your this far, definatly go all the way. Pull the crank, polish it if needed. Replace all the bearings and gaskets. If you need to, get the block and head resurfaced.

Matt

Geo

This is what I did when building an engine for my Sentra SE-R. Best choice I made. Considering the cost of the build, the spare engine was a small cost and it allowed me to take my time and do it right - a labor of love.

However, a lesson learned from my experience is take nothing for granted.

cruise98

Adrial:

Good decision. I was reluctant to even comment on the dirty rebuild approach before.

To save a step, measure the bores before you loosen the crank girdle nuts. All bore measurements need to be taken with the gridle studs torqued properly. In the three 951 engines I have taken apart, the mains showed more wear than the rod bearings. Nothing dramatic in either one, but it was noticeable.

adrial

I have the tool to check the bores for roundness and will do that shortly.

Quote:

I believe its the forward most main bearing you need to take with you to the machine shop, so lower cradle can be bolted to block properly, so a measurement of bearing holes can be done. It might cost about $60.00 to $100.00 to have shop mic out everything, but info I believe is much needed prior to even starting the "complete rebuild" !

I dont follow this statement...please rephrase it.



My intent was not to resurface the upper-block mating surface, I didnt think there was a need. I would need to check to see if it is warped and then act appropriately, correct? I am replacing the head studs with racewares.


Thats interesting, the opposite from what I would have expected based on reading other people's experiences (in reference to main bearings vs. rod bearings).

Also, I have the oil pickup removed already, should I reinstall this before taking the bore measurements? I haven't taken it all apart yet, so exactly what the "crank girdle" is isn't clear to me. I didnt see any torque sequence in the factory manuals, but I imagine there is one. Thus removing the 3 bolts holding the oil pickup on and then retightening them would probably throw off the tightening sequence. Is this an issue?

All, back to taking the crank out...from where I am now (oil pump, water pump, balance shafts) still installed...which of these need to come out?

Sorry for the basic questions, but this is my first time this deep into an engine and I dont want to screw anything up!

Thanks all! Happy new year!

Mike S

Check out my "Bay Area Engine Pull" pictures and threads on this board. I pulled mine out last weekend and I've used a combination of engine cleaner, brake cleaner, WD-40 and castrol super clean. Castrol Super clean seems to work really well, its cheap and it doesn't hurt the aluminum. The engine cleaner was pretty caustic and if you don't rinse it, you can get some etching of the aluminum. I always hosed it off on mine though so I never had any issues.

Also, I have 130k on my motor and I will also be leaving the main bearings in place. I have seen enough people with over 250k and stock main bearings to make me feel that it is not necessary.

Kevin Baker

Mike, I HAVE to disagree. I mean if you are THAT far into the engine, its too easy to just do the bearings. Plus you are running the risk of something getting stuck in an oil galley.

Sure there is the issue of additional machine work and all, but...

I've got the head off the Mitsu, and was just gonna "slap it back on"., but the car is down, half apart and with 200K on the bottom end, I'd be silly not to go ahead and pull it.

adrial

Kevin, what additional machine work are you talking about?

Kevin Baker

Checking the main journals for roundness, if they are worn, having the crank machined so the crank rides round in the new round bearings. Its not likely unless the bearings themselves have been excessively worn.

AlexE

- do the crank bearings.... take a good look at the center thrust bearing. More than likely it will be worn to the copper on the front side. If you plan on pushing this car in the future this is good prevention for an extra $100
- also do a dry fit with the girdle. You will probably find that it does not torque up flush (oil pump side). If you throw it in a freezer it will shring 1-2thousands allowing you to torque it up flush again on the oil pump side.

...and there are a few other things as you will surely come across them.

Geo

OK, this is going to be long, so please bear with me. I built my first engine 5 years ago and learned a lot in the process. It's really easy to keep adding things to your "to do" list. My build started out with a budget of $1,500 and ended up at $6,000 by the time I was done. But, it eventually became an all out build project - something I wanted to do once. I learned a lot of lessons - some the easy way and some the hard way.

1. You've done most of the work already. Be careful of shortcuts. You don't have to spend $6k on your engine build. But choose wisely.

2. Have all bores and crank journals and pins mic'd. That means cylinder bores and crank journal bores. You want to make sure all bores are in spec. Any decent engine machine shop should be able to mic your bores and crank for $100 give or take. Find a good shop you trust however and trust your instincts. I had one shop recommended to me and they charged me $100 to measure my brank new crank (a long story) and it turned out they lied and never even measured. I know they didn't from the story I got (I learned something along the way that told me what I needed to know without measuring the crank - long story about Nissan engines). That said, the tolerances in teh 944 engine are pretty generous from what I'm used to working with (the Nissan engine I built has clearance specs literally 10x tighter than the 944 engine). Still, it would be a waste of money to build an engine with bores out of spec. Think about that for a bit.

The cylinder bores and crankshaft bores must BOTH be checked with the crank girdle (that has the main bearing caps integral to it) in place and torqued to spec. You see, torquing the girdle will distort the bock. The best way to do this is to bolt on a torque plate to the top of the bock and torque it to spec. This torque plate simulates the cylinder head on the block. You want round bores with the cylinder head and crank girdle in place. I have yet to hear of anyone with a torque plate for the 944, but then again, I haven't a clue who can even bore and properly prepare the 944 cylinders (these are the folks who would usually have a torque plate).

3. Have both ends of the rods mic'd. Have them checked for straightness and straightened if necessary. If you budget allows (you've done this much work already so consider your budget carefully), have all rotating and reciprocating parts balanced. This means pistons, rods, crank, flywheel, pressure plate, and main pulley.

4. Have the top of the block (deck) checked for straightness. If it's in spec, great. If not, have it decked to true it.

5. If you were doing a truly **** build, you would have the crank bores and cylinder bores align bored (keeps all holes perfectly lined up). You would also have the block decked exactly perpendicular to the cylinder bores. (consider this optional - show for perspective if you will)

6. Have the cylinder head checked for flatness and machined if necessary.

7. At minimum have the valves lapped (ensures a good seal for the valves). Better to have the recut. Optional would be blending the valve seats into the runners and gasket matching the intake and exhaust manifolds.

These are the things that come to mind from my build. If you'd like to read more about it, you can here: http://home.earthlink.net/~geo3/beast-toc.htm

It's not a 944, but much applies. If you have any machining done to any bores, be sure to deburr the holes. Clean everything. I don't know if the 944 block has oil galley plugs that are easily removed, but if it does, remove them and thoroughly clean the galleys. Use a rifle cleaning kit. You can get an attachment that looks kind of like a tampon to screw onto the end. This works great. Get a lot of them. Keep cleaning until the swab comes out clean. Don't forget to reinstall the plugs and seal with whatever is called for. Same for the head. Very long story, but a sloppy head builder sent me a head they didn't clean out after one of their processes and I assumed they had. Caused a total write-off of my $6k engine. Yes. Heartbreaking.

It's too late for you, but for anyone else building an engine, I would recommend taking a buttload of reference photos of the engine before tearing anything down and at certain intervals of the teardown. While reviewing my reference photos during the assembly process I realized I missed the head registration pins. Lost an afternoon and a $65 head gasket, but it could have been much worse.

Have patience. Make it a labor of love rather than hard labor.

Good luck.

Granite 944

"All, back to taking the crank out...from where I am now (oil pump, water pump, balance shafts) still installed...which of these need to come out?"

Short answer is....everything!
A "complete" rebuild will envolve some machining, and more so a total cleaning of the block. This is best done by the machine shop, using their equiptment, however, everything must be off. The "girdle" is the removable section of the block that sandwiches the crank into the main block (known as the lower crankcase section in the FSM). Checking the cyl. bores is supposed to be checked with the girdle installed and torqued (also if block is bored). This is also done when checking ID bore of mains to see if they’ve been pounded eggshaped. (unlikely). When I mentioned the forward main bearing being installed in order to check things, I was thinking of this in the event the crank was already removed. I did this myself, so crank was out and ready to be mic’d at the machine shop when I took everything in. It’s the only way to get girdle re-aligned, without anything else in there. (you’ll see when you get it apart. Cruise98 brought up a good point in doing the bore check first, before removal of crank. Do remember, all parts that are to be checked, should be at a "normalized" temp. Preferably about room temp. (68 degrees),especially if your going to check against FSM spec. and not just the clearances between parts. Expansion coeffecient of alluminum is high. Yes there is a sequence for tightening girdle in the FSM (section 13-20), and note there is a torque value change per a TSB that makes it a 3 step torque value now for the large bolts (12mm). It was not in my FSM. If not in yours, I suggest you get access to the TSB’s through Alldata.com. You can leave the oil pickup off,(just put the bolt back in). The machine shop can check all neccessay stuff. Get an itemized report of it, or fact simily. (Really suggest a machine shop familiar with these Porsche engines). I’ve already stripped my engine to nothing but the head and water pump studs. Its been to the shop (I dropped it off), they checked everything against specs. I now know what the total condition of this engine is, and what is going to be required to rebuild. You are into this engine “rebuild” pretty deep right now. You will most definitely end up doing and spending a lot more on this engine than you originally thought. NOW YOU MUST ASK YOURSELF…….DO I DO IT RIGHT, OR HALFASSED? IS IT GOING TO BE A REAL REBUILD? OR JUST A KINDA OVERHAUL? (BIG DIFFERENCE IMHO). I am expecting to pay a minimum of $2800.00 to do my engine. (and I’ll do most all of the assembly work). I am by no means an expert, especially with these cars. This is my first also. But I have had a little experience in rebuilding and assembly of other engines. Take your time, research before you get to far into something, find yourself an apropriate machine shop, and above all, have fun doing it (money helps too!). TIFWIT.

pete944

Great thread going here. Lots of excellent advice. I'll be doing my S2 motor in a year or two and will be following alot of the advice here. I haven't built a 944 engine but have rebuilt various others. I had a VW bug that took 3 engines before I got it right. The aircooled VW is a lot simpler than a 944 engine but all the same principles apply. The first 2 I built weren't reliable and had a few problems but I did the last one right and man did that thing make power (it was great fun to destroy 5 liter Mustangs and WS6 Firebirds with a lowly VW bug). I can't stress enough how important it is to have a good machine shop check every spec and do any needed machine work. Get the block clean enough that you wouldn't mind it being on the table with you during open heart surgery.

I think I'll get a complete used motor to rebuild when I do mine so I can take my time with it. There's no better way to do a bad job than rush through it.

Granite 944

"I think I'll get a complete used motor to rebuild when I do mine so I can take my time with it. There's no better way to do a bad job than rush through it."

I agree of course, I'm doing the same. One thought, though it is more work, is to install used motor in your car, and rebuild the original. Only worth it if you believe in the total originality of the car, and of course, it truly is the original engine (purist). Matching component numbers can mean a lot in the long run? By the way, I do love that Blue color on your car!

pete944

I'm not that concerned with originality. The 'new ' motor will be turboed. Maybe I'll rebuild the original engine after the 'new' one is in and keep it if I ever want to return the car to original condition.

Thanks for the compliment on the color, it's not in great shape so it's going to get a repaint in the spring. I like the color of yours, too. I don't think I've ever seen that one in person.

Geo

Do Porsches even have "matching numbers?"

I wonder. My Nissan didn't come with them. I suspect it's a domestic thing.