Falcondrivr

I replaced my cam tower gaskets 1 year ago, along with the grommets. My oil drip didn't go away entirely. A reasonably good local wrench told me that now it's leaking between the head and the chain housings. So, I'm probably going to tackle the job soon. I haven't decided weather to drop the engine again, or go in from the rear. Labor seems to be about the same to me.
Here's the question; since I'm going to be accessing the chains and cams, what else should I replace while I'm in there? Motor has 159,000 miles and has never been apart. Runs perfectly, doesn't burn oil, outruns 996s at Sebring...
Do the chains wear? how about the "guide rail, "supporting bow," or "tensioner blade?" All of the parts are relatively inexpensive, but what typically might be worn to where it should be replaced? Should I just fix the o-ring and gasket, and then save my money for the inevitable re-build?
Thanks, Rick

axl911

It's a major job to replace the head to chain housing gasket. You'll have to retime the engine. I would suggest doing pretty much evey seal there is there: valve cover, the cam to housing gasket, the chain housing to block gasket, cam to power steering gaskets, etc. It's probably doable withoug dropping the engine and going in from the rear. MikeJ retimed his engine like this. On the passenger side, not sure if you have space to take out the power steering assembly.

Oh...and you'll probably gain couple of horses afterward when you re-time the cams to correct any slip over the 159k miles.

PS. If your compression & leakdown are in good shape and burn no oil (valve guides are fine), why rebuild? Don't need it yet.

Mike J

I would not take off the cam carriers while the engine is in the car - it's so much easier (and cleaner) to work on the engine while its dropped.

However, its a shame to do this just for an oil leak - as said above, its quite a bit of work.

I would not use Porsche gaskets and O rings - use Wrightwood racing products. They materials are superior.

If you remove the cam carriers, you will need to do lots of cleaning, seal the cam carriers on the head with the correct adhesives, and do the torque sequence. For oil leaks, this the most important part by far, any screwups on the adhesive will show up as leaks. Then there is the retiming of the cams - certainly doable while in the engine (see pcarworkshop for pictures - engine rebuilding section), which will then allow for chain stretch,etc.

You will need enough room to pull the camshafts out, which means removing all the rockers, again a good arguement to drop the engine.

I found the chain ramps on my rebuild were in good shape, but I replaced them anyways. The chains themselves were good as well. Since you have a '95, you likely have the cams with the woodruff keyways so you can use indexed chain wheels, which is good for a manual timing. Use 1.0mm for the timing, that seems to work well.

I would only do this if the oil leak was so bad that it was causing major issues. A bit of seepage or drip, I would just keep on putting oil in the engine until I was ready to drop the engine and rebuild it.

Cheers,

Mike

element

Does Wrightwood make gaskets for the valve covers? I need to do my lowers (just bought the car) and from the service records they were done 2 years ago and leaking again.. so either a bad (over torqued) install or the gaskets werent good? Looking for advice on something that will either stop the leaks or i just need to install new ones with proper torque on the bolts.

phil.

Falcondrivr

Thanks Mike. It leaks about a quarter sized from the right and a dime sized puddle from the left each time it's parked. At the end of 3 30-40 minute DE sessions it looks like the rear of my car has been lightly sprayed with oil. Otherwise, the car is perfect...I didn't realize that it was such a major deal. Thought I might be able to just go in and replace the o-rings and gasket without completely removing the cams.
I did all the valve cover gaskets last year too, along with plugs, wires, all the stuff you do while the engine is out.
I guess I should try to keep living with it. Maybe I should buy some of that crap the guy makes a boat bottom out of a screen door with on TV and spray it up into the crack?

Falcondrivr

Oh yeah, I did call the local dealer's service manager. He's a fellow DE instructor, and actually is trying to court older car's business. They have a deal for older models where the labor rate is $89. I also just got a coupon for 20% off any maintenance or repair in their service department.
He said the book says 7.2 hours after the engine r&r. I guess if I really want it done I could pay them the $868...

Mike J

I guess I will ask a silly question : You sure the oil is leaking between the heads and the cam towers? That its not coming from above that, and seeping between the cylinders to look that way? I know its a dumb question, but I have to ask.

Do not be too afraid of doing this, its not that hard. Since you will not be touching the cylinders or heads themselves, the chances of screwing up go down quite a bit. You have to be careful on the placement of the cam carriers on the heads - the adhesive/sealer has to be spread evenly, and the torque even so the cam carrier does not twist. If it does, the cam will bind in its bearings.

Check these pictures from my web site - they might help you visualize it:

http://www.pcarworkshop.com/index.ph...cylinders_back

http://www.pcarworkshop.com/index.ph..._timing_Part_I

Cheers,

Mike

Mike J

I do not think they do, and I used Porsche gaskets on the valve covers.

There is a lot of technique involved here, mostly making sure all surfaces are CLEAN (I mean so clean that you would run your tongue on the surface), that you coat the rubber gaskets with lubricant, the grooves in the valve covers are really clean (easier said than done), and the torquing is done evenly and right. That is the part that most people screw up...

Cheers,

Mike

Ed Hughes

What Mike says. I've built 911 motors, and with the simpler engine, I can't imagine doing this with the engine in the car.

In 911 land, leaks between the cam towers and the head top surface are sometimes the cause of leaks. I'd assume the same could be true for 993 motors. That is NOT fun, stripping down to fix a leak there. I was forced to upgrade to Mahle high compression 3.4L pistons and cylinders to fix a leak I had there after I rebuilt the engine. That, and the twin plug setup were a $7000 penalty I paid to fix the leak there. I'd still be smelling a little oil upon startup if I wasn't motivated to tear her down to fix. Loctite 574 was the factory recommended sealant for this joint, it isn't as good as Threebond 1101.

I hope yours is indeed at the chain boxes or the cam o ring.

Falcondrivr

What's above that? Upper vc gaskets? They were last done in June 2005 at 104,500 miles. Someplace called "Mellow Mushroom" or something in Marin...

The source of the leak is one guy's opinion. He's a pretty good engine guy, who mostly does older 911 stuff. I did mention it to another mechanic who does more 993 stuff, and he looked puzzled and said that "That's not something we see much on 993 mtors." The problem is that these 2 guys know each other...

It sounds to me like I'd love it if the leak was from anywhere else. Ideas?

Mike J

too much trouble to get some pictures? Before, and then after a good cleaning with brake cleaner, might be able to see the leak trails.

Falcondrivr

I'm going to do some more deep investigation this week.
BTW, I'm up early for work. Go to bed!

ja78911sc

Is the oil leaking down the back side of the chain housing? Do you have any oil pooling on the top of the engine tin that is in front of the chain housing cover?

Just curious.....