Ade - C4 91

Hi All,

Has anyone else noticed corrosion around underside of the engine carrier. By carrier I mean the pressed metal item that the engine is mounted into which in turn mounts into the rear of the car.

Mine is quite rusty and although just surface rust, it's fairly widespread, esp. where the rear muffler and Converter sit.

Does anyone know how problematic this is?

Ade
91 C4

J richard

Yea, this appears to be a fairly common problem. Due to the heat buildup around the cat and the rear muffler it seems that the engine pan (not to be mistaken for the under tray) tends to rust on the 964. I never had this problem with other 911's even though the pan looks almost identical on earlier cars. Go figure. The pan basically keeps dirt and debris from getting into the engine compartment from below. This pan does not hold the engine up, Its held up by the crossmember that sits just inside of the engine compartment. If you take it off and clean it up and repaint it you should get some more life out of it, otherwise replacement is not all that expensive.

Hope this helps, happy holidays

phil@tech9

Ade,

It is very common on these cars to find corrosion on the tinwork.

I believe one of the biggest culprits, for a majority of cars that I see, is the washing of the vehicle then putting it in the garage without giving it a run down the road to dry it off. It is amazing how many 964's that I see, and when I quiz the owner about the 'washing practice' they say 'Oh Yes, that applies to me !'.
I think that a majority of the Rennlisters are aware of this, but maybe damage was done by a previous owner. The rear tinwork sections are exposed to debris and road grime from the rear wheels, and is common to see 'holes' in them. These must be replaced as soon as the problem is diagnosed, as poor cylinder cooling can result !

Ade - C4 91

Thanks Guys, I guessed as much. The Tin is not perforated at all but has a lot of surface rust. I treated it with rust kill and intend to seal it, I will eventually replace it, but it must be an engine out job.

Phil, I think I remember seeing holes in the small Angled tin sections that are covered in foil. These are towards the rear of the converter area but above, next to the heads. Do you know how easy they are to remove and replace?

Regards,

Ade
91 C4

phil@tech9

Ade,

The sections that are covered in foil are plastic, therefore do not worry.

You are right about engine out to replace the pieces, although the side pieces can be replaced in-situ.

964Cab

Hi,

I didn't have to take the engine out to remove that rear tin panel on my '90 C4. I took the primary muffler and heat exchanger cross-over pipe and those tin panels off (except for the gearbox side tin panels) so the mech could more easily approach the chain housings when he renewed my cam gear large "O" rings. The engine stayed in the whole time. I left off the two side tin panels that foul easy access to the plugs and valve lash adj processes. Also, if I can find 3 5/8" dia heater tubing to connect the blower motor to the heat exchanger cross-over pipe I'll leave that rear tin panel off as well as it fouls access to the lower twin dist's cap bolts.

I suspect that when rain drop through the tail that the water settles inside on those tin panels and rust.
Thanks,

patrick