james944

Hi Guys,
Thanks to Fred's engine mount thread, I'll be replacing my engine mounts in the next couple of weeks (have the RS mounts on order) and I was thinking while I'm in there I might check the engine tin / tinware / shroud (whatever the pieces are called) for any rust (unlikely, but you never know) and clean the pieces up.

Anyone know what's involved in removing them? From looking around here, it looks like for the sides it's just 3 bolts each to the head, and the bolts where the pieces join each other. Is the rear a pain? Does the primary muffler have to come off?

If this is a pretty easy job I'll do it, if big parts of the exhaust have to come off, I probably clean them up as best I can while in place, and leave it at that.

Also, I know I've seen the threads, but what's the latest thinking on the covers that hang down around the motor (the silver looking ones, that some people say are heat shields...) I've been thinking of getting rid of them.

Any advice would be appreciated.
Thanks,
James

jsacrey

Hey James, from my first round of adjusting the valves, I think you'd be hard-pressed to get the tins out without removing the catalytic converter and the secondary muffler. Those two things were the first things I removed to start on the valves.

Jim

elbeee964

Guess I'm a 'some people'.
Absent those silvery shields I'd worry mightily about radiative heat transfer slowly broiling everything line-of-sight & close to those exhaust lines.

james944

Jim, Thanks for the tip. The secondary is gone, but I'm hesitant to undue the cat since I don't have a lift or a proper place to work. Maybe I won't give my tins a thorough cleaning.

Lonnie, That's what I'm afraid of. Like I said, the secondary is gone and I know the cat has it's own heat shields, but part of me is sure those shields are there for a reason.

Another part of me says that the heat exchangers get hot too and they are inside the shields, so when you park they are radiating heat right back up into the cylinders and heads. That can't be good. Also, I know the 993 doesn't have these (different exhaust I know, but mufflers on each side...).

I don't mean to troll, really, I'd just like to hear peoples opinions and experiences.

Did earlier cars have shields like these? Has anyone removed them and found that it caused problems?

Duck

Mine have been off for a year. Do not know any long term issues though. I have the Heet Sheet protecting the plug wires and maybe a little protection for the valves.

The silver covers on my car were black with gunk and the insulation on the back was a mess.

elbeee964

The classic 'cooking' items to be learned from '75-'77 motor history was the 'soft' metal of the valve stem seal, and the elastomer bits (rubber).
[And those stem seals went bad within 50k miles -- The nadir of all that Porsches should stand for. Never, again, Porsche -- never, again. "Porsches don't break"-durability. Ooops -- then there's the 996/Boxster main seal... ]

Aluminums and steels seem up to exhaust pipe near-proximity duty.

jsacrey

If you do happen to take the plunge and pull it all apart, use some Simple Green to clean covers. Mine were totally black from road grunge and turned out that they were a bright silver underneath! I couldn't believe how much gunk was on them.

Gus

James - taking the CAT off is not an issue - just make sure that you break the O2 sensor loose before you undo the CAT - think all nuts bolts are 13mm - Just jack up left rear and remove wheel - install jack stand - Undo the O2 - then loosen the rear clamp first, then remove the front 4 nuts, washer and 4 bolts - slide rear clamp backwards - then CAT will pull free - install is reverse. This will give you a good look at the side tin - The secondary muffler is removed about the same way - jack up, remove right wheel - position jack stand, loosen clamp at primary muffler or by-pass pipe, remove two 13 mm bolts from front of secondary muffler, just behind lower shock mount - pull muffelr out - Now you can get at TIN - Note on both sides there are a couple of 10mm bolts that go into the rear tin plate that are hard to get to -
Hope this helps

ilko

If you have the cat, leave the shields alone. If you don't have it, feel free to take them off.

My car is cat-less, heat exchanger-less, muffler-less, and I tin-less. No issues.

Gus

Did you leave the tins all around the engine in place to reduce the flow of hot air up into the engine compartment - or have you removed the tin over the CAT that the O2 sensor wire runs through??
Run an intake air temp check - I ran without tins for a little while until I checked my air intake temp and found that it was unusually high because it was pulling in more lower hot air - especially at taffic lights. Replaced tin, re-routed intake and am now into cool air -

Tom W

FWIW, my car still has the tin in place to control heat flow and air flow. This is a car where I remove the fender fuel filling and hinges on the front hood because they weigh 3 lbs (each) and went through great expense to lose weight. If the shop thought the tin wasn't necessary, it would be long gone (but it's still there).

It's obviously easiest to remove it and have it cleaned and painted or powder coated when the engine is out (which is what happened to mine).

Gus

Tom - Understand - weight savings is a major effort - trying to figure out what is necessary and what isn't can make your mind work overtime - Did you replace the 4 corners, hood and rear deck with glass or fiber? What have you gotten your weight down to??

james944

Tom, you mean the engine tin that bolts to the heads and blocks hot air from getting into the engine bay right. I know those are important. I only want to clean that. Or do you mean you still have the silver fiber and foam shields that cover the lower valve covers? I'm pretty sure those were absent from most factory race cars, and it was those that I was considering removing, but after reading this thread I probably will not.

I might be wrong.

If you take the cat off you have to replace the gasket between it and the heat exchangers. Right? Can anyone confirm that is part number: 964 111 198 00.
Thanks,
James

Jonnygo1

FWIW, I've replaced the factory exhaust with the Fabspeed cat bypass and dual muffler. While doing this, I got rid of all that plastic/foam stuff on the lower part of the engine. The bypass runs alot cooler than the cat and I have had no problems.

dfinnegan

That's correct.