924Board.org

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

Edit: they're out - amazing what a bigger socket set will do. Last on the 'do this stuff to remove the head' list is find the tabs, pry, and break free...

Sleykin · Posted: Sat Aug 14, 2004 10:30 am Post subject:

This might be of help if you have a highspeed connection.
http://www.cannell.co.uk/944%20Reference.htm
_________________
Glenn Neff
Medford, OR
87' 924S

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

Woohoo, the head is off! Things make so much more sense now. All 4 intake valves are bent, that's for sure. They're the originals and it looks like the 4 exhaust ones were swapped out earlier when the PO said the timing belt first went out (bad roller for anyone curious). They're bent about the same amount in the same way so the only thing I can figure is that he didn't have everything lined up with TDC right when he put all the parts back together.

The pistons and the head itself looks fine though they do have some carbon buildup. What's the best way to clean that out? I see no scoring on the cylinder walls or damage anywhere but to the valves. While I'm in here and since the water pump came from Napa a year and a half ago I'll probably wind up replacing that along with the belts and intake/exhaust/head/camshaft assy. gaskets. Might as well do some of the vacuum lines that are hard to reach too. Would regular parts stores carry the hard plastic kind? I've never had to find this type.

I guess the next step is to order parts, get the head to the shop when they come in, and do other things in the meantime? Thanks for the link, by the way. I'm downloading now.

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

You are going to need some valve guides, and without the machine shop disassembling the head and checking the parts, you aren't going to know how many, or even if the head is usable.

You can go ahead and order the expendable stuff that you know you need to reassemble (head gasket set, hoses, pulleys, rollers, belts, water pump, etc...), but I would hold off on the valves, and valve guides till you know how many guides, and what size to order.

I would be careful when considering removing the carbon buildup from the tops of the pistons. The deposits can be very hard, and any material that you loosen that falls down along the sides of the pistons against the cylinder walls will be hard to retrieve. This debris can damage the cylinder walls when the engine is started. If the buildup is not thick, I would leave it alone. You can always use a fuel system cleaner to remove it after the engine is reassembled and running.

The cylinder walls have a special treatment that allows the aluminum alloy to be removed and leaves the silicon proud (high). this is what the iron coated pistons are supposed to be making contact with. Do not scrub the cylinder walls with any sort of material. The cylinder wall preperation could get damaged, and require an overbore, and new pistons.

Sleykin · Posted: Sat Aug 14, 2004 3:38 pm Post subject:

Yes... like gohim said take the head to the shop first if you aren't doing the head yourself. Many times the machine shop can get even better prices for the parts than you will find.
Very interesting to read up about the boring/honing process. You hone the cylinders with felt pads and a solution that makes the aluminum harder than the rings. Many cases of these engines being re-ringed with no cylinder work needed.
_________________
Glenn Neff
Medford, OR
87' 924S

wdb · Joined: 02 Nov 2002 Posts: 2024

great link Sleykin , I should have the pet info in about 13 minutes .

wdb · Joined: 02 Nov 2002 Posts: 2024

yep it works ok how to I get it to gnucleus before P shuts down that site .

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

Ok, no cleaning up the pistons - got it! And find somewhere to take the head before getting parts. Anybody know a shop in San Antonio?

It always seems like I have another question... actually two. Are the large nuts that hold the head on reuseable, or should I go find some new ones? And the exhaust studs - Clark's Garage says something about taking them out, but I got the exhaust manifold out just fine by only taking the nuts off so the studs are still in there. Is it recommended that those get replaced?

The pipe going into the muffler also came out but it was loose anyway. Still, that's going to be fun to get back together right I'm sure.

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

Question - I found a head for sale - pretty sure it's $100

"Head.... good / V.good condition has about 112,000 to 114,000 miles on it."

Might this be a better route than taking mine in to a machine shop?

Sleykin · Posted: Sun Aug 15, 2004 5:35 am Post subject:

It sounds like it would be a better route to me. You will want to check it for warpage and replace the valve seals. When I replaced my headgasket at 165K miles I pulled the valves and checked the guides etc. I lapped the valves in mostly to verify the seat widths. It all checked out great. The head nuts are re-usable as are the washers, but the book says to either use new washers or rough up the surface that contacts the head with course sandpaper. The idea being the washers are not to rotate as you torque the heads.
_________________
Glenn Neff
Medford, OR
87' 924S

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

This might be a dumb question, but how would I go about replacing the valve seals? Machine shop?

Sleykin · Posted: Sun Aug 15, 2004 6:36 am Post subject:

Valve spring compressor. Pop the keepers pull the springs and ols seals glue on new ones put it back together.
Good idea to do some looking while you are in there and check the valve seats and guides.
A machine shop would be the easiest route and shouldn't cost more than about $60 or so.
_________________
Glenn Neff
Medford, OR
87' 924S

Sleykin · Posted: Sun Aug 15, 2004 5:11 pm Post subject:

This site has a fairly well ilustrated gude to tensioning the belts with the krikit tool in case you are interested...
http://www.arnnworx.com./
_________________
Glenn Neff
Medford, OR
87' 924S

The Fife · Joined: 17 Mar 2004 Posts: 241 Location: San Antonio, Texas

Great, thanks! Hopefully my last head-related question for awhile: the head is off an '84 944 - this is the same part as what's on my '87, right?

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

The 84 head should bolt on, but it is not exactly the same as your 87 head.

The 87 head casting is slightly different, and you will probably find that some threaded holes are either not drilled and threaded, and there are some extra threaded holes that you do not need.

Most all replacement parts: (valves, valve guides, and gaskets) should be the same though.

I have been told that the later heads are better than the earlier ones, (while selling off some used parts accumulated over the years as I build a replacement engine for my 87 924S). Those Buyers were looking for the later heads to rebuild for replacement or performance engines for their own cars.

Any used head you buy should be checked out by a competent machine shop before you install it. I would expect you to find out that it needs some sort of work/replacement parts. This would be true of virtually any used head you buy (even if it doesn't have bent valves), after all, the engines are 16-22 years old, and the engines the heads came from were disassembled for a reason. This is going to drive the cost of the replacement head up close to that of fixing your head (except fixing your particular head will always cost more, since you need to replace all of your valves) Personally, I think you would be better off having your head repaired by a competent shop since it would be virtually new by the time repairs are completed with all of the new valves and guides.

If you buy a used head and just slap it into the car, you won't know if it's any good until you turn the key. If the engine starts, you still won't have any idea of how long it will last.